undo-files: factor the vfs map in a repository property

We define it in multiple locations and inconsistencies are appearing. So we now
have a single definition point.

mercurial/interfaces/repository.py

@@ -1,2058 +1,2062 b''
 # repository.py - Interfaces and base classes for repositories and peers.
 # coding: utf-8
 #
 # Copyright 2017 Gregory Szorc <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 
 from ..i18n import _
 from .. import error
 from . import util as interfaceutil
 
 # Local repository feature string.
 
 # Revlogs are being used for file storage.
 REPO_FEATURE_REVLOG_FILE_STORAGE = b'revlogfilestorage'
 # The storage part of the repository is shared from an external source.
 REPO_FEATURE_SHARED_STORAGE = b'sharedstore'
 # LFS supported for backing file storage.
 REPO_FEATURE_LFS = b'lfs'
 # Repository supports being stream cloned.
 REPO_FEATURE_STREAM_CLONE = b'streamclone'
 # Repository supports (at least) some sidedata to be stored
 REPO_FEATURE_SIDE_DATA = b'side-data'
 # Files storage may lack data for all ancestors.
 REPO_FEATURE_SHALLOW_FILE_STORAGE = b'shallowfilestorage'
 
 REVISION_FLAG_CENSORED = 1 << 15
 REVISION_FLAG_ELLIPSIS = 1 << 14
 REVISION_FLAG_EXTSTORED = 1 << 13
 REVISION_FLAG_HASCOPIESINFO = 1 << 12
 
 REVISION_FLAGS_KNOWN = (
     REVISION_FLAG_CENSORED
     | REVISION_FLAG_ELLIPSIS
     | REVISION_FLAG_EXTSTORED
     | REVISION_FLAG_HASCOPIESINFO
 )
 
 CG_DELTAMODE_STD = b'default'
 CG_DELTAMODE_PREV = b'previous'
 CG_DELTAMODE_FULL = b'fulltext'
 CG_DELTAMODE_P1 = b'p1'
 
 
 ## Cache related constants:
 #
 # Used to control which cache should be warmed in a repo.updatecaches(…) call.
 
 # Warm branchmaps of all known repoview's filter-level
 CACHE_BRANCHMAP_ALL = b"branchmap-all"
 # Warm branchmaps of repoview's filter-level used by server
 CACHE_BRANCHMAP_SERVED = b"branchmap-served"
 # Warm internal changelog cache (eg: persistent nodemap)
 CACHE_CHANGELOG_CACHE = b"changelog-cache"
 # Warm full manifest cache
 CACHE_FULL_MANIFEST = b"full-manifest"
 # Warm file-node-tags cache
 CACHE_FILE_NODE_TAGS = b"file-node-tags"
 # Warm internal manifestlog cache (eg: persistent nodemap)
 CACHE_MANIFESTLOG_CACHE = b"manifestlog-cache"
 # Warn rev branch cache
 CACHE_REV_BRANCH = b"rev-branch-cache"
 # Warm tags' cache for default repoview'
 CACHE_TAGS_DEFAULT = b"tags-default"
 # Warm tags' cache for  repoview's filter-level used by server
 CACHE_TAGS_SERVED = b"tags-served"
 
 # the cache to warm by default after a simple transaction
 # (this is a mutable set to let extension update it)
 CACHES_DEFAULT = {
     CACHE_BRANCHMAP_SERVED,
 }
 
 # the caches to warm when warming all of them
 # (this is a mutable set to let extension update it)
 CACHES_ALL = {
     CACHE_BRANCHMAP_SERVED,
     CACHE_BRANCHMAP_ALL,
     CACHE_CHANGELOG_CACHE,
     CACHE_FILE_NODE_TAGS,
     CACHE_FULL_MANIFEST,
     CACHE_MANIFESTLOG_CACHE,
     CACHE_TAGS_DEFAULT,
     CACHE_TAGS_SERVED,
 }
 
 # the cache to warm by default on simple call
 # (this is a mutable set to let extension update it)
 CACHES_POST_CLONE = CACHES_ALL.copy()
 CACHES_POST_CLONE.discard(CACHE_FILE_NODE_TAGS)
 
 
 class ipeerconnection(interfaceutil.Interface):
     """Represents a "connection" to a repository.
 
     This is the base interface for representing a connection to a repository.
     It holds basic properties and methods applicable to all peer types.
 
     This is not a complete interface definition and should not be used
     outside of this module.
     """
 
     ui = interfaceutil.Attribute("""ui.ui instance""")
     path = interfaceutil.Attribute("""a urlutil.path instance or None""")
 
     def url():
         """Returns a URL string representing this peer.
 
         Currently, implementations expose the raw URL used to construct the
         instance. It may contain credentials as part of the URL. The
         expectations of the value aren't well-defined and this could lead to
         data leakage.
 
         TODO audit/clean consumers and more clearly define the contents of this
         value.
         """
 
     def local():
         """Returns a local repository instance.
 
         If the peer represents a local repository, returns an object that
         can be used to interface with it. Otherwise returns ``None``.
         """
 
     def canpush():
         """Returns a boolean indicating if this peer can be pushed to."""
 
     def close():
         """Close the connection to this peer.
 
         This is called when the peer will no longer be used. Resources
         associated with the peer should be cleaned up.
         """
 
 
 class ipeercapabilities(interfaceutil.Interface):
     """Peer sub-interface related to capabilities."""
 
     def capable(name):
         """Determine support for a named capability.
 
         Returns ``False`` if capability not supported.
 
         Returns ``True`` if boolean capability is supported. Returns a string
         if capability support is non-boolean.
 
         Capability strings may or may not map to wire protocol capabilities.
         """
 
     def requirecap(name, purpose):
         """Require a capability to be present.
 
         Raises a ``CapabilityError`` if the capability isn't present.
         """
 
 
 class ipeercommands(interfaceutil.Interface):
     """Client-side interface for communicating over the wire protocol.
 
     This interface is used as a gateway to the Mercurial wire protocol.
     methods commonly call wire protocol commands of the same name.
     """
 
     def branchmap():
         """Obtain heads in named branches.
 
         Returns a dict mapping branch name to an iterable of nodes that are
         heads on that branch.
         """
 
     def capabilities():
         """Obtain capabilities of the peer.
 
         Returns a set of string capabilities.
         """
 
     def clonebundles():
         """Obtains the clone bundles manifest for the repo.
 
         Returns the manifest as unparsed bytes.
         """
 
     def debugwireargs(one, two, three=None, four=None, five=None):
         """Used to facilitate debugging of arguments passed over the wire."""
 
     def getbundle(source, **kwargs):
         """Obtain remote repository data as a bundle.
 
         This command is how the bulk of repository data is transferred from
         the peer to the local repository
 
         Returns a generator of bundle data.
         """
 
     def heads():
         """Determine all known head revisions in the peer.
 
         Returns an iterable of binary nodes.
         """
 
     def known(nodes):
         """Determine whether multiple nodes are known.
 
         Accepts an iterable of nodes whose presence to check for.
 
         Returns an iterable of booleans indicating of the corresponding node
         at that index is known to the peer.
         """
 
     def listkeys(namespace):
         """Obtain all keys in a pushkey namespace.
 
         Returns an iterable of key names.
         """
 
     def lookup(key):
         """Resolve a value to a known revision.
 
         Returns a binary node of the resolved revision on success.
         """
 
     def pushkey(namespace, key, old, new):
         """Set a value using the ``pushkey`` protocol.
 
         Arguments correspond to the pushkey namespace and key to operate on and
         the old and new values for that key.
 
         Returns a string with the peer result. The value inside varies by the
         namespace.
         """
 
     def stream_out():
         """Obtain streaming clone data.
 
         Successful result should be a generator of data chunks.
         """
 
     def unbundle(bundle, heads, url):
         """Transfer repository data to the peer.
 
         This is how the bulk of data during a push is transferred.
 
         Returns the integer number of heads added to the peer.
         """
 
 
 class ipeerlegacycommands(interfaceutil.Interface):
     """Interface for implementing support for legacy wire protocol commands.
 
     Wire protocol commands transition to legacy status when they are no longer
     used by modern clients. To facilitate identifying which commands are
     legacy, the interfaces are split.
     """
 
     def between(pairs):
         """Obtain nodes between pairs of nodes.
 
         ``pairs`` is an iterable of node pairs.
 
         Returns an iterable of iterables of nodes corresponding to each
         requested pair.
         """
 
     def branches(nodes):
         """Obtain ancestor changesets of specific nodes back to a branch point.
 
         For each requested node, the peer finds the first ancestor node that is
         a DAG root or is a merge.
 
         Returns an iterable of iterables with the resolved values for each node.
         """
 
     def changegroup(nodes, source):
         """Obtain a changegroup with data for descendants of specified nodes."""
 
     def changegroupsubset(bases, heads, source):
         pass
 
 
 class ipeercommandexecutor(interfaceutil.Interface):
     """Represents a mechanism to execute remote commands.
 
     This is the primary interface for requesting that wire protocol commands
     be executed. Instances of this interface are active in a context manager
     and have a well-defined lifetime. When the context manager exits, all
     outstanding requests are waited on.
     """
 
     def callcommand(name, args):
         """Request that a named command be executed.
 
         Receives the command name and a dictionary of command arguments.
 
         Returns a ``concurrent.futures.Future`` that will resolve to the
         result of that command request. That exact value is left up to
         the implementation and possibly varies by command.
 
         Not all commands can coexist with other commands in an executor
         instance: it depends on the underlying wire protocol transport being
         used and the command itself.
 
         Implementations MAY call ``sendcommands()`` automatically if the
         requested command can not coexist with other commands in this executor.
 
         Implementations MAY call ``sendcommands()`` automatically when the
         future's ``result()`` is called. So, consumers using multiple
         commands with an executor MUST ensure that ``result()`` is not called
         until all command requests have been issued.
         """
 
     def sendcommands():
         """Trigger submission of queued command requests.
 
         Not all transports submit commands as soon as they are requested to
         run. When called, this method forces queued command requests to be
         issued. It will no-op if all commands have already been sent.
 
         When called, no more new commands may be issued with this executor.
         """
 
     def close():
         """Signal that this command request is finished.
 
         When called, no more new commands may be issued. All outstanding
         commands that have previously been issued are waited on before
         returning. This not only includes waiting for the futures to resolve,
         but also waiting for all response data to arrive. In other words,
         calling this waits for all on-wire state for issued command requests
         to finish.
 
         When used as a context manager, this method is called when exiting the
         context manager.
 
         This method may call ``sendcommands()`` if there are buffered commands.
         """
 
 
 class ipeerrequests(interfaceutil.Interface):
     """Interface for executing commands on a peer."""
 
     limitedarguments = interfaceutil.Attribute(
         """True if the peer cannot receive large argument value for commands."""
     )
 
     def commandexecutor():
         """A context manager that resolves to an ipeercommandexecutor.
 
         The object this resolves to can be used to issue command requests
         to the peer.
 
         Callers should call its ``callcommand`` method to issue command
         requests.
 
         A new executor should be obtained for each distinct set of commands
         (possibly just a single command) that the consumer wants to execute
         as part of a single operation or round trip. This is because some
         peers are half-duplex and/or don't support persistent connections.
         e.g. in the case of HTTP peers, commands sent to an executor represent
         a single HTTP request. While some peers may support multiple command
         sends over the wire per executor, consumers need to code to the least
         capable peer. So it should be assumed that command executors buffer
         called commands until they are told to send them and that each
         command executor could result in a new connection or wire-level request
         being issued.
         """
 
 
 class ipeerbase(ipeerconnection, ipeercapabilities, ipeerrequests):
     """Unified interface for peer repositories.
 
     All peer instances must conform to this interface.
     """
 
 
 class ipeerv2(ipeerconnection, ipeercapabilities, ipeerrequests):
     """Unified peer interface for wire protocol version 2 peers."""
 
     apidescriptor = interfaceutil.Attribute(
         """Data structure holding description of server API."""
     )
 
 
 @interfaceutil.implementer(ipeerbase)
 class peer:
     """Base class for peer repositories."""
 
     limitedarguments = False
 
     def __init__(self, ui, path=None):
         self.ui = ui
         self.path = path
 
     def capable(self, name):
         caps = self.capabilities()
         if name in caps:
             return True
 
         name = b'%s=' % name
         for cap in caps:
             if cap.startswith(name):
                 return cap[len(name) :]
 
         return False
 
     def requirecap(self, name, purpose):
         if self.capable(name):
             return
 
         raise error.CapabilityError(
             _(
                 b'cannot %s; remote repository does not support the '
                 b'\'%s\' capability'
             )
             % (purpose, name)
         )
 
 
 class iverifyproblem(interfaceutil.Interface):
     """Represents a problem with the integrity of the repository.
 
     Instances of this interface are emitted to describe an integrity issue
     with a repository (e.g. corrupt storage, missing data, etc).
 
     Instances are essentially messages associated with severity.
     """
 
     warning = interfaceutil.Attribute(
         """Message indicating a non-fatal problem."""
     )
 
     error = interfaceutil.Attribute("""Message indicating a fatal problem.""")
 
     node = interfaceutil.Attribute(
         """Revision encountering the problem.
 
         ``None`` means the problem doesn't apply to a single revision.
         """
     )
 
 
 class irevisiondelta(interfaceutil.Interface):
     """Represents a delta between one revision and another.
 
     Instances convey enough information to allow a revision to be exchanged
     with another repository.
 
     Instances represent the fulltext revision data or a delta against
     another revision. Therefore the ``revision`` and ``delta`` attributes
     are mutually exclusive.
 
     Typically used for changegroup generation.
     """
 
     node = interfaceutil.Attribute("""20 byte node of this revision.""")
 
     p1node = interfaceutil.Attribute(
         """20 byte node of 1st parent of this revision."""
     )
 
     p2node = interfaceutil.Attribute(
         """20 byte node of 2nd parent of this revision."""
     )
 
     linknode = interfaceutil.Attribute(
         """20 byte node of the changelog revision this node is linked to."""
     )
 
     flags = interfaceutil.Attribute(
         """2 bytes of integer flags that apply to this revision.
 
         This is a bitwise composition of the ``REVISION_FLAG_*`` constants.
         """
     )
 
     basenode = interfaceutil.Attribute(
         """20 byte node of the revision this data is a delta against.
 
         ``nullid`` indicates that the revision is a full revision and not
         a delta.
         """
     )
 
     baserevisionsize = interfaceutil.Attribute(
         """Size of base revision this delta is against.
 
         May be ``None`` if ``basenode`` is ``nullid``.
         """
     )
 
     revision = interfaceutil.Attribute(
         """Raw fulltext of revision data for this node."""
     )
 
     delta = interfaceutil.Attribute(
         """Delta between ``basenode`` and ``node``.
 
         Stored in the bdiff delta format.
         """
     )
 
     sidedata = interfaceutil.Attribute(
         """Raw sidedata bytes for the given revision."""
     )
 
     protocol_flags = interfaceutil.Attribute(
         """Single byte of integer flags that can influence the protocol.
 
         This is a bitwise composition of the ``storageutil.CG_FLAG*`` constants.
         """
     )
 
 
 class ifilerevisionssequence(interfaceutil.Interface):
     """Contains index data for all revisions of a file.
 
     Types implementing this behave like lists of tuples. The index
     in the list corresponds to the revision number. The values contain
     index metadata.
 
     The *null* revision (revision number -1) is always the last item
     in the index.
     """
 
     def __len__():
         """The total number of revisions."""
 
     def __getitem__(rev):
         """Returns the object having a specific revision number.
 
         Returns an 8-tuple with the following fields:
 
         offset+flags
            Contains the offset and flags for the revision. 64-bit unsigned
            integer where first 6 bytes are the offset and the next 2 bytes
            are flags. The offset can be 0 if it is not used by the store.
         compressed size
             Size of the revision data in the store. It can be 0 if it isn't
             needed by the store.
         uncompressed size
             Fulltext size. It can be 0 if it isn't needed by the store.
         base revision
             Revision number of revision the delta for storage is encoded
             against. -1 indicates not encoded against a base revision.
         link revision
             Revision number of changelog revision this entry is related to.
         p1 revision
             Revision number of 1st parent. -1 if no 1st parent.
         p2 revision
             Revision number of 2nd parent. -1 if no 1st parent.
         node
             Binary node value for this revision number.
 
         Negative values should index off the end of the sequence. ``-1``
         should return the null revision. ``-2`` should return the most
         recent revision.
         """
 
     def __contains__(rev):
         """Whether a revision number exists."""
 
     def insert(self, i, entry):
         """Add an item to the index at specific revision."""
 
 
 class ifileindex(interfaceutil.Interface):
     """Storage interface for index data of a single file.
 
     File storage data is divided into index metadata and data storage.
     This interface defines the index portion of the interface.
 
     The index logically consists of:
 
     * A mapping between revision numbers and nodes.
     * DAG data (storing and querying the relationship between nodes).
     * Metadata to facilitate storage.
     """
 
     nullid = interfaceutil.Attribute(
         """node for the null revision for use as delta base."""
     )
 
     def __len__():
         """Obtain the number of revisions stored for this file."""
 
     def __iter__():
         """Iterate over revision numbers for this file."""
 
     def hasnode(node):
         """Returns a bool indicating if a node is known to this store.
 
         Implementations must only return True for full, binary node values:
         hex nodes, revision numbers, and partial node matches must be
         rejected.
 
         The null node is never present.
         """
 
     def revs(start=0, stop=None):
         """Iterate over revision numbers for this file, with control."""
 
     def parents(node):
         """Returns a 2-tuple of parent nodes for a revision.
 
         Values will be ``nullid`` if the parent is empty.
         """
 
     def parentrevs(rev):
         """Like parents() but operates on revision numbers."""
 
     def rev(node):
         """Obtain the revision number given a node.
 
         Raises ``error.LookupError`` if the node is not known.
         """
 
     def node(rev):
         """Obtain the node value given a revision number.
 
         Raises ``IndexError`` if the node is not known.
         """
 
     def lookup(node):
         """Attempt to resolve a value to a node.
 
         Value can be a binary node, hex node, revision number, or a string
         that can be converted to an integer.
 
         Raises ``error.LookupError`` if a node could not be resolved.
         """
 
     def linkrev(rev):
         """Obtain the changeset revision number a revision is linked to."""
 
     def iscensored(rev):
         """Return whether a revision's content has been censored."""
 
     def commonancestorsheads(node1, node2):
         """Obtain an iterable of nodes containing heads of common ancestors.
 
         See ``ancestor.commonancestorsheads()``.
         """
 
     def descendants(revs):
         """Obtain descendant revision numbers for a set of revision numbers.
 
         If ``nullrev`` is in the set, this is equivalent to ``revs()``.
         """
 
     def heads(start=None, stop=None):
         """Obtain a list of nodes that are DAG heads, with control.
 
         The set of revisions examined can be limited by specifying
         ``start`` and ``stop``. ``start`` is a node. ``stop`` is an
         iterable of nodes. DAG traversal starts at earlier revision
         ``start`` and iterates forward until any node in ``stop`` is
         encountered.
         """
 
     def children(node):
         """Obtain nodes that are children of a node.
 
         Returns a list of nodes.
         """
 
 
 class ifiledata(interfaceutil.Interface):
     """Storage interface for data storage of a specific file.
 
     This complements ``ifileindex`` and provides an interface for accessing
     data for a tracked file.
     """
 
     def size(rev):
         """Obtain the fulltext size of file data.
 
         Any metadata is excluded from size measurements.
         """
 
     def revision(node, raw=False):
         """Obtain fulltext data for a node.
 
         By default, any storage transformations are applied before the data
         is returned. If ``raw`` is True, non-raw storage transformations
         are not applied.
 
         The fulltext data may contain a header containing metadata. Most
         consumers should use ``read()`` to obtain the actual file data.
         """
 
     def rawdata(node):
         """Obtain raw data for a node."""
 
     def read(node):
         """Resolve file fulltext data.
 
         This is similar to ``revision()`` except any metadata in the data
         headers is stripped.
         """
 
     def renamed(node):
         """Obtain copy metadata for a node.
 
         Returns ``False`` if no copy metadata is stored or a 2-tuple of
         (path, node) from which this revision was copied.
         """
 
     def cmp(node, fulltext):
         """Compare fulltext to another revision.
 
         Returns True if the fulltext is different from what is stored.
 
         This takes copy metadata into account.
 
         TODO better document the copy metadata and censoring logic.
         """
 
     def emitrevisions(
         nodes,
         nodesorder=None,
         revisiondata=False,
         assumehaveparentrevisions=False,
         deltamode=CG_DELTAMODE_STD,
     ):
         """Produce ``irevisiondelta`` for revisions.
 
         Given an iterable of nodes, emits objects conforming to the
         ``irevisiondelta`` interface that describe revisions in storage.
 
         This method is a generator.
 
         The input nodes may be unordered. Implementations must ensure that a
         node's parents are emitted before the node itself. Transitively, this
         means that a node may only be emitted once all its ancestors in
         ``nodes`` have also been emitted.
 
         By default, emits "index" data (the ``node``, ``p1node``, and
         ``p2node`` attributes). If ``revisiondata`` is set, revision data
         will also be present on the emitted objects.
 
         With default argument values, implementations can choose to emit
         either fulltext revision data or a delta. When emitting deltas,
         implementations must consider whether the delta's base revision
         fulltext is available to the receiver.
 
         The base revision fulltext is guaranteed to be available if any of
         the following are met:
 
         * Its fulltext revision was emitted by this method call.
         * A delta for that revision was emitted by this method call.
         * ``assumehaveparentrevisions`` is True and the base revision is a
           parent of the node.
 
         ``nodesorder`` can be used to control the order that revisions are
         emitted. By default, revisions can be reordered as long as they are
         in DAG topological order (see above). If the value is ``nodes``,
         the iteration order from ``nodes`` should be used. If the value is
         ``storage``, then the native order from the backing storage layer
         is used. (Not all storage layers will have strong ordering and behavior
         of this mode is storage-dependent.) ``nodes`` ordering can force
         revisions to be emitted before their ancestors, so consumers should
         use it with care.
 
         The ``linknode`` attribute on the returned ``irevisiondelta`` may not
         be set and it is the caller's responsibility to resolve it, if needed.
 
         If ``deltamode`` is CG_DELTAMODE_PREV and revision data is requested,
         all revision data should be emitted as deltas against the revision
         emitted just prior. The initial revision should be a delta against its
         1st parent.
         """
 
 
 class ifilemutation(interfaceutil.Interface):
     """Storage interface for mutation events of a tracked file."""
 
     def add(filedata, meta, transaction, linkrev, p1, p2):
         """Add a new revision to the store.
 
         Takes file data, dictionary of metadata, a transaction, linkrev,
         and parent nodes.
 
         Returns the node that was added.
 
         May no-op if a revision matching the supplied data is already stored.
         """
 
     def addrevision(
         revisiondata,
         transaction,
         linkrev,
         p1,
         p2,
         node=None,
         flags=0,
         cachedelta=None,
     ):
         """Add a new revision to the store and return its number.
 
         This is similar to ``add()`` except it operates at a lower level.
 
         The data passed in already contains a metadata header, if any.
 
         ``node`` and ``flags`` can be used to define the expected node and
         the flags to use with storage. ``flags`` is a bitwise value composed
         of the various ``REVISION_FLAG_*`` constants.
 
         ``add()`` is usually called when adding files from e.g. the working
         directory. ``addrevision()`` is often called by ``add()`` and for
         scenarios where revision data has already been computed, such as when
         applying raw data from a peer repo.
         """
 
     def addgroup(
         deltas,
         linkmapper,
         transaction,
         addrevisioncb=None,
         duplicaterevisioncb=None,
         maybemissingparents=False,
     ):
         """Process a series of deltas for storage.
 
         ``deltas`` is an iterable of 7-tuples of
         (node, p1, p2, linknode, deltabase, delta, flags) defining revisions
         to add.
 
         The ``delta`` field contains ``mpatch`` data to apply to a base
         revision, identified by ``deltabase``. The base node can be
         ``nullid``, in which case the header from the delta can be ignored
         and the delta used as the fulltext.
 
         ``alwayscache`` instructs the lower layers to cache the content of the
         newly added revision, even if it needs to be explicitly computed.
         This used to be the default when ``addrevisioncb`` was provided up to
         Mercurial 5.8.
 
         ``addrevisioncb`` should be called for each new rev as it is committed.
         ``duplicaterevisioncb`` should be called for all revs with a
         pre-existing node.
 
         ``maybemissingparents`` is a bool indicating whether the incoming
         data may reference parents/ancestor revisions that aren't present.
         This flag is set when receiving data into a "shallow" store that
         doesn't hold all history.
 
         Returns a list of nodes that were processed. A node will be in the list
         even if it existed in the store previously.
         """
 
     def censorrevision(tr, node, tombstone=b''):
         """Remove the content of a single revision.
 
         The specified ``node`` will have its content purged from storage.
         Future attempts to access the revision data for this node will
         result in failure.
 
         A ``tombstone`` message can optionally be stored. This message may be
         displayed to users when they attempt to access the missing revision
         data.
 
         Storage backends may have stored deltas against the previous content
         in this revision. As part of censoring a revision, these storage
         backends are expected to rewrite any internally stored deltas such
         that they no longer reference the deleted content.
         """
 
     def getstrippoint(minlink):
         """Find the minimum revision that must be stripped to strip a linkrev.
 
         Returns a 2-tuple containing the minimum revision number and a set
         of all revisions numbers that would be broken by this strip.
 
         TODO this is highly revlog centric and should be abstracted into
         a higher-level deletion API. ``repair.strip()`` relies on this.
         """
 
     def strip(minlink, transaction):
         """Remove storage of items starting at a linkrev.
 
         This uses ``getstrippoint()`` to determine the first node to remove.
         Then it effectively truncates storage for all revisions after that.
 
         TODO this is highly revlog centric and should be abstracted into a
         higher-level deletion API.
         """
 
 
 class ifilestorage(ifileindex, ifiledata, ifilemutation):
     """Complete storage interface for a single tracked file."""
 
     def files():
         """Obtain paths that are backing storage for this file.
 
         TODO this is used heavily by verify code and there should probably
         be a better API for that.
         """
 
     def storageinfo(
         exclusivefiles=False,
         sharedfiles=False,
         revisionscount=False,
         trackedsize=False,
         storedsize=False,
     ):
         """Obtain information about storage for this file's data.
 
         Returns a dict describing storage for this tracked path. The keys
         in the dict map to arguments of the same. The arguments are bools
         indicating whether to calculate and obtain that data.
 
         exclusivefiles
            Iterable of (vfs, path) describing files that are exclusively
            used to back storage for this tracked path.
 
         sharedfiles
            Iterable of (vfs, path) describing files that are used to back
            storage for this tracked path. Those files may also provide storage
            for other stored entities.
 
         revisionscount
            Number of revisions available for retrieval.
 
         trackedsize
            Total size in bytes of all tracked revisions. This is a sum of the
            length of the fulltext of all revisions.
 
         storedsize
            Total size in bytes used to store data for all tracked revisions.
            This is commonly less than ``trackedsize`` due to internal usage
            of deltas rather than fulltext revisions.
 
         Not all storage backends may support all queries are have a reasonable
         value to use. In that case, the value should be set to ``None`` and
         callers are expected to handle this special value.
         """
 
     def verifyintegrity(state):
         """Verifies the integrity of file storage.
 
         ``state`` is a dict holding state of the verifier process. It can be
         used to communicate data between invocations of multiple storage
         primitives.
 
         If individual revisions cannot have their revision content resolved,
         the method is expected to set the ``skipread`` key to a set of nodes
         that encountered problems.  If set, the method can also add the node(s)
         to ``safe_renamed`` in order to indicate nodes that may perform the
         rename checks with currently accessible data.
 
         The method yields objects conforming to the ``iverifyproblem``
         interface.
         """
 
 
 class idirs(interfaceutil.Interface):
     """Interface representing a collection of directories from paths.
 
     This interface is essentially a derived data structure representing
     directories from a collection of paths.
     """
 
     def addpath(path):
         """Add a path to the collection.
 
         All directories in the path will be added to the collection.
         """
 
     def delpath(path):
         """Remove a path from the collection.
 
         If the removal was the last path in a particular directory, the
         directory is removed from the collection.
         """
 
     def __iter__():
         """Iterate over the directories in this collection of paths."""
 
     def __contains__(path):
         """Whether a specific directory is in this collection."""
 
 
 class imanifestdict(interfaceutil.Interface):
     """Interface representing a manifest data structure.
 
     A manifest is effectively a dict mapping paths to entries. Each entry
     consists of a binary node and extra flags affecting that entry.
     """
 
     def __getitem__(path):
         """Returns the binary node value for a path in the manifest.
 
         Raises ``KeyError`` if the path does not exist in the manifest.
 
         Equivalent to ``self.find(path)[0]``.
         """
 
     def find(path):
         """Returns the entry for a path in the manifest.
 
         Returns a 2-tuple of (node, flags).
 
         Raises ``KeyError`` if the path does not exist in the manifest.
         """
 
     def __len__():
         """Return the number of entries in the manifest."""
 
     def __nonzero__():
         """Returns True if the manifest has entries, False otherwise."""
 
     __bool__ = __nonzero__
 
     def __setitem__(path, node):
         """Define the node value for a path in the manifest.
 
         If the path is already in the manifest, its flags will be copied to
         the new entry.
         """
 
     def __contains__(path):
         """Whether a path exists in the manifest."""
 
     def __delitem__(path):
         """Remove a path from the manifest.
 
         Raises ``KeyError`` if the path is not in the manifest.
         """
 
     def __iter__():
         """Iterate over paths in the manifest."""
 
     def iterkeys():
         """Iterate over paths in the manifest."""
 
     def keys():
         """Obtain a list of paths in the manifest."""
 
     def filesnotin(other, match=None):
         """Obtain the set of paths in this manifest but not in another.
 
         ``match`` is an optional matcher function to be applied to both
         manifests.
 
         Returns a set of paths.
         """
 
     def dirs():
         """Returns an object implementing the ``idirs`` interface."""
 
     def hasdir(dir):
         """Returns a bool indicating if a directory is in this manifest."""
 
     def walk(match):
         """Generator of paths in manifest satisfying a matcher.
 
         If the matcher has explicit files listed and they don't exist in
         the manifest, ``match.bad()`` is called for each missing file.
         """
 
     def diff(other, match=None, clean=False):
         """Find differences between this manifest and another.
 
         This manifest is compared to ``other``.
 
         If ``match`` is provided, the two manifests are filtered against this
         matcher and only entries satisfying the matcher are compared.
 
         If ``clean`` is True, unchanged files are included in the returned
         object.
 
         Returns a dict with paths as keys and values of 2-tuples of 2-tuples of
         the form ``((node1, flag1), (node2, flag2))`` where ``(node1, flag1)``
         represents the node and flags for this manifest and ``(node2, flag2)``
         are the same for the other manifest.
         """
 
     def setflag(path, flag):
         """Set the flag value for a given path.
 
         Raises ``KeyError`` if the path is not already in the manifest.
         """
 
     def get(path, default=None):
         """Obtain the node value for a path or a default value if missing."""
 
     def flags(path):
         """Return the flags value for a path (default: empty bytestring)."""
 
     def copy():
         """Return a copy of this manifest."""
 
     def items():
         """Returns an iterable of (path, node) for items in this manifest."""
 
     def iteritems():
         """Identical to items()."""
 
     def iterentries():
         """Returns an iterable of (path, node, flags) for this manifest.
 
         Similar to ``iteritems()`` except items are a 3-tuple and include
         flags.
         """
 
     def text():
         """Obtain the raw data representation for this manifest.
 
         Result is used to create a manifest revision.
         """
 
     def fastdelta(base, changes):
         """Obtain a delta between this manifest and another given changes.
 
         ``base`` in the raw data representation for another manifest.
 
         ``changes`` is an iterable of ``(path, to_delete)``.
 
         Returns a 2-tuple containing ``bytearray(self.text())`` and the
         delta between ``base`` and this manifest.
 
         If this manifest implementation can't support ``fastdelta()``,
         raise ``mercurial.manifest.FastdeltaUnavailable``.
         """
 
 
 class imanifestrevisionbase(interfaceutil.Interface):
     """Base interface representing a single revision of a manifest.
 
     Should not be used as a primary interface: should always be inherited
     as part of a larger interface.
     """
 
     def copy():
         """Obtain a copy of this manifest instance.
 
         Returns an object conforming to the ``imanifestrevisionwritable``
         interface. The instance will be associated with the same
         ``imanifestlog`` collection as this instance.
         """
 
     def read():
         """Obtain the parsed manifest data structure.
 
         The returned object conforms to the ``imanifestdict`` interface.
         """
 
 
 class imanifestrevisionstored(imanifestrevisionbase):
     """Interface representing a manifest revision committed to storage."""
 
     def node():
         """The binary node for this manifest."""
 
     parents = interfaceutil.Attribute(
         """List of binary nodes that are parents for this manifest revision."""
     )
 
     def readdelta(shallow=False):
         """Obtain the manifest data structure representing changes from parent.
 
         This manifest is compared to its 1st parent. A new manifest representing
         those differences is constructed.
 
         The returned object conforms to the ``imanifestdict`` interface.
         """
 
     def readfast(shallow=False):
         """Calls either ``read()`` or ``readdelta()``.
 
         The faster of the two options is called.
         """
 
     def find(key):
         """Calls self.read().find(key)``.
 
         Returns a 2-tuple of ``(node, flags)`` or raises ``KeyError``.
         """
 
 
 class imanifestrevisionwritable(imanifestrevisionbase):
     """Interface representing a manifest revision that can be committed."""
 
     def write(transaction, linkrev, p1node, p2node, added, removed, match=None):
         """Add this revision to storage.
 
         Takes a transaction object, the changeset revision number it will
         be associated with, its parent nodes, and lists of added and
         removed paths.
 
         If match is provided, storage can choose not to inspect or write out
         items that do not match. Storage is still required to be able to provide
         the full manifest in the future for any directories written (these
         manifests should not be "narrowed on disk").
 
         Returns the binary node of the created revision.
         """
 
 
 class imanifeststorage(interfaceutil.Interface):
     """Storage interface for manifest data."""
 
     nodeconstants = interfaceutil.Attribute(
         """nodeconstants used by the current repository."""
     )
 
     tree = interfaceutil.Attribute(
         """The path to the directory this manifest tracks.
 
         The empty bytestring represents the root manifest.
         """
     )
 
     index = interfaceutil.Attribute(
         """An ``ifilerevisionssequence`` instance."""
     )
 
     opener = interfaceutil.Attribute(
         """VFS opener to use to access underlying files used for storage.
 
         TODO this is revlog specific and should not be exposed.
         """
     )
 
     _generaldelta = interfaceutil.Attribute(
         """Whether generaldelta storage is being used.
 
         TODO this is revlog specific and should not be exposed.
         """
     )
 
     fulltextcache = interfaceutil.Attribute(
         """Dict with cache of fulltexts.
 
         TODO this doesn't feel appropriate for the storage interface.
         """
     )
 
     def __len__():
         """Obtain the number of revisions stored for this manifest."""
 
     def __iter__():
         """Iterate over revision numbers for this manifest."""
 
     def rev(node):
         """Obtain the revision number given a binary node.
 
         Raises ``error.LookupError`` if the node is not known.
         """
 
     def node(rev):
         """Obtain the node value given a revision number.
 
         Raises ``error.LookupError`` if the revision is not known.
         """
 
     def lookup(value):
         """Attempt to resolve a value to a node.
 
         Value can be a binary node, hex node, revision number, or a bytes
         that can be converted to an integer.
 
         Raises ``error.LookupError`` if a ndoe could not be resolved.
         """
 
     def parents(node):
         """Returns a 2-tuple of parent nodes for a node.
 
         Values will be ``nullid`` if the parent is empty.
         """
 
     def parentrevs(rev):
         """Like parents() but operates on revision numbers."""
 
     def linkrev(rev):
         """Obtain the changeset revision number a revision is linked to."""
 
     def revision(node, _df=None):
         """Obtain fulltext data for a node."""
 
     def rawdata(node, _df=None):
         """Obtain raw data for a node."""
 
     def revdiff(rev1, rev2):
         """Obtain a delta between two revision numbers.
 
         The returned data is the result of ``bdiff.bdiff()`` on the raw
         revision data.
         """
 
     def cmp(node, fulltext):
         """Compare fulltext to another revision.
 
         Returns True if the fulltext is different from what is stored.
         """
 
     def emitrevisions(
         nodes,
         nodesorder=None,
         revisiondata=False,
         assumehaveparentrevisions=False,
     ):
         """Produce ``irevisiondelta`` describing revisions.
 
         See the documentation for ``ifiledata`` for more.
         """
 
     def addgroup(
         deltas,
         linkmapper,
         transaction,
         addrevisioncb=None,
         duplicaterevisioncb=None,
     ):
         """Process a series of deltas for storage.
 
         See the documentation in ``ifilemutation`` for more.
         """
 
     def rawsize(rev):
         """Obtain the size of tracked data.
 
         Is equivalent to ``len(m.rawdata(node))``.
 
         TODO this method is only used by upgrade code and may be removed.
         """
 
     def getstrippoint(minlink):
         """Find minimum revision that must be stripped to strip a linkrev.
 
         See the documentation in ``ifilemutation`` for more.
         """
 
     def strip(minlink, transaction):
         """Remove storage of items starting at a linkrev.
 
         See the documentation in ``ifilemutation`` for more.
         """
 
     def checksize():
         """Obtain the expected sizes of backing files.
 
         TODO this is used by verify and it should not be part of the interface.
         """
 
     def files():
         """Obtain paths that are backing storage for this manifest.
 
         TODO this is used by verify and there should probably be a better API
         for this functionality.
         """
 
     def deltaparent(rev):
         """Obtain the revision that a revision is delta'd against.
 
         TODO delta encoding is an implementation detail of storage and should
         not be exposed to the storage interface.
         """
 
     def clone(tr, dest, **kwargs):
         """Clone this instance to another."""
 
     def clearcaches(clear_persisted_data=False):
         """Clear any caches associated with this instance."""
 
     def dirlog(d):
         """Obtain a manifest storage instance for a tree."""
 
     def add(
         m, transaction, link, p1, p2, added, removed, readtree=None, match=None
     ):
         """Add a revision to storage.
 
         ``m`` is an object conforming to ``imanifestdict``.
 
         ``link`` is the linkrev revision number.
 
         ``p1`` and ``p2`` are the parent revision numbers.
 
         ``added`` and ``removed`` are iterables of added and removed paths,
         respectively.
 
         ``readtree`` is a function that can be used to read the child tree(s)
         when recursively writing the full tree structure when using
         treemanifets.
 
         ``match`` is a matcher that can be used to hint to storage that not all
         paths must be inspected; this is an optimization and can be safely
         ignored. Note that the storage must still be able to reproduce a full
         manifest including files that did not match.
         """
 
     def storageinfo(
         exclusivefiles=False,
         sharedfiles=False,
         revisionscount=False,
         trackedsize=False,
         storedsize=False,
     ):
         """Obtain information about storage for this manifest's data.
 
         See ``ifilestorage.storageinfo()`` for a description of this method.
         This one behaves the same way, except for manifest data.
         """
 
 
 class imanifestlog(interfaceutil.Interface):
     """Interface representing a collection of manifest snapshots.
 
     Represents the root manifest in a repository.
 
     Also serves as a means to access nested tree manifests and to cache
     tree manifests.
     """
 
     nodeconstants = interfaceutil.Attribute(
         """nodeconstants used by the current repository."""
     )
 
     def __getitem__(node):
         """Obtain a manifest instance for a given binary node.
 
         Equivalent to calling ``self.get('', node)``.
 
         The returned object conforms to the ``imanifestrevisionstored``
         interface.
         """
 
     def get(tree, node, verify=True):
         """Retrieve the manifest instance for a given directory and binary node.
 
         ``node`` always refers to the node of the root manifest (which will be
         the only manifest if flat manifests are being used).
 
         If ``tree`` is the empty string, the root manifest is returned.
         Otherwise the manifest for the specified directory will be returned
         (requires tree manifests).
 
         If ``verify`` is True, ``LookupError`` is raised if the node is not
         known.
 
         The returned object conforms to the ``imanifestrevisionstored``
         interface.
         """
 
     def getstorage(tree):
         """Retrieve an interface to storage for a particular tree.
 
         If ``tree`` is the empty bytestring, storage for the root manifest will
         be returned. Otherwise storage for a tree manifest is returned.
 
         TODO formalize interface for returned object.
         """
 
     def clearcaches():
         """Clear caches associated with this collection."""
 
     def rev(node):
         """Obtain the revision number for a binary node.
 
         Raises ``error.LookupError`` if the node is not known.
         """
 
     def update_caches(transaction):
         """update whatever cache are relevant for the used storage."""
 
 
 class ilocalrepositoryfilestorage(interfaceutil.Interface):
     """Local repository sub-interface providing access to tracked file storage.
 
     This interface defines how a repository accesses storage for a single
     tracked file path.
     """
 
     def file(f):
         """Obtain a filelog for a tracked path.
 
         The returned type conforms to the ``ifilestorage`` interface.
         """
 
 
 class ilocalrepositorymain(interfaceutil.Interface):
     """Main interface for local repositories.
 
     This currently captures the reality of things - not how things should be.
     """
 
     nodeconstants = interfaceutil.Attribute(
         """Constant nodes matching the hash function used by the repository."""
     )
     nullid = interfaceutil.Attribute(
         """null revision for the hash function used by the repository."""
     )
 
     supported = interfaceutil.Attribute(
         """Set of requirements that this repo is capable of opening."""
     )
 
     requirements = interfaceutil.Attribute(
         """Set of requirements this repo uses."""
     )
 
     features = interfaceutil.Attribute(
         """Set of "features" this repository supports.
 
         A "feature" is a loosely-defined term. It can refer to a feature
         in the classical sense or can describe an implementation detail
         of the repository. For example, a ``readonly`` feature may denote
         the repository as read-only. Or a ``revlogfilestore`` feature may
         denote that the repository is using revlogs for file storage.
 
         The intent of features is to provide a machine-queryable mechanism
         for repo consumers to test for various repository characteristics.
 
         Features are similar to ``requirements``. The main difference is that
         requirements are stored on-disk and represent requirements to open the
         repository. Features are more run-time capabilities of the repository
         and more granular capabilities (which may be derived from requirements).
         """
     )
 
     filtername = interfaceutil.Attribute(
         """Name of the repoview that is active on this repo."""
     )
 
+    vfs_map = interfaceutil.Attribute(
+        """a bytes-key → vfs mapping used by transaction and others"""
+    )
+
     wvfs = interfaceutil.Attribute(
         """VFS used to access the working directory."""
     )
 
     vfs = interfaceutil.Attribute(
         """VFS rooted at the .hg directory.
 
         Used to access repository data not in the store.
         """
     )
 
     svfs = interfaceutil.Attribute(
         """VFS rooted at the store.
 
         Used to access repository data in the store. Typically .hg/store.
         But can point elsewhere if the store is shared.
         """
     )
 
     root = interfaceutil.Attribute(
         """Path to the root of the working directory."""
     )
 
     path = interfaceutil.Attribute("""Path to the .hg directory.""")
 
     origroot = interfaceutil.Attribute(
         """The filesystem path that was used to construct the repo."""
     )
 
     auditor = interfaceutil.Attribute(
         """A pathauditor for the working directory.
 
         This checks if a path refers to a nested repository.
 
         Operates on the filesystem.
         """
     )
 
     nofsauditor = interfaceutil.Attribute(
         """A pathauditor for the working directory.
 
         This is like ``auditor`` except it doesn't do filesystem checks.
         """
     )
 
     baseui = interfaceutil.Attribute(
         """Original ui instance passed into constructor."""
     )
 
     ui = interfaceutil.Attribute("""Main ui instance for this instance.""")
 
     sharedpath = interfaceutil.Attribute(
         """Path to the .hg directory of the repo this repo was shared from."""
     )
 
     store = interfaceutil.Attribute("""A store instance.""")
 
     spath = interfaceutil.Attribute("""Path to the store.""")
 
     sjoin = interfaceutil.Attribute("""Alias to self.store.join.""")
 
     cachevfs = interfaceutil.Attribute(
         """A VFS used to access the cache directory.
 
         Typically .hg/cache.
         """
     )
 
     wcachevfs = interfaceutil.Attribute(
         """A VFS used to access the cache directory dedicated to working copy
 
         Typically .hg/wcache.
         """
     )
 
     filteredrevcache = interfaceutil.Attribute(
         """Holds sets of revisions to be filtered."""
     )
 
     names = interfaceutil.Attribute("""A ``namespaces`` instance.""")
 
     filecopiesmode = interfaceutil.Attribute(
         """The way files copies should be dealt with in this repo."""
     )
 
     def close():
         """Close the handle on this repository."""
 
     def peer(path=None):
         """Obtain an object conforming to the ``peer`` interface."""
 
     def unfiltered():
         """Obtain an unfiltered/raw view of this repo."""
 
     def filtered(name, visibilityexceptions=None):
         """Obtain a named view of this repository."""
 
     obsstore = interfaceutil.Attribute("""A store of obsolescence data.""")
 
     changelog = interfaceutil.Attribute("""A handle on the changelog revlog.""")
 
     manifestlog = interfaceutil.Attribute(
         """An instance conforming to the ``imanifestlog`` interface.
 
         Provides access to manifests for the repository.
         """
     )
 
     dirstate = interfaceutil.Attribute("""Working directory state.""")
 
     narrowpats = interfaceutil.Attribute(
         """Matcher patterns for this repository's narrowspec."""
     )
 
     def narrowmatch(match=None, includeexact=False):
         """Obtain a matcher for the narrowspec."""
 
     def setnarrowpats(newincludes, newexcludes):
         """Define the narrowspec for this repository."""
 
     def __getitem__(changeid):
         """Try to resolve a changectx."""
 
     def __contains__(changeid):
         """Whether a changeset exists."""
 
     def __nonzero__():
         """Always returns True."""
         return True
 
     __bool__ = __nonzero__
 
     def __len__():
         """Returns the number of changesets in the repo."""
 
     def __iter__():
         """Iterate over revisions in the changelog."""
 
     def revs(expr, *args):
         """Evaluate a revset.
 
         Emits revisions.
         """
 
     def set(expr, *args):
         """Evaluate a revset.
 
         Emits changectx instances.
         """
 
     def anyrevs(specs, user=False, localalias=None):
         """Find revisions matching one of the given revsets."""
 
     def url():
         """Returns a string representing the location of this repo."""
 
     def hook(name, throw=False, **args):
         """Call a hook."""
 
     def tags():
         """Return a mapping of tag to node."""
 
     def tagtype(tagname):
         """Return the type of a given tag."""
 
     def tagslist():
         """Return a list of tags ordered by revision."""
 
     def nodetags(node):
         """Return the tags associated with a node."""
 
     def nodebookmarks(node):
         """Return the list of bookmarks pointing to the specified node."""
 
     def branchmap():
         """Return a mapping of branch to heads in that branch."""
 
     def revbranchcache():
         pass
 
     def register_changeset(rev, changelogrevision):
         """Extension point for caches for new nodes.
 
         Multiple consumers are expected to need parts of the changelogrevision,
         so it is provided as optimization to avoid duplicate lookups. A simple
         cache would be fragile when other revisions are accessed, too."""
         pass
 
     def branchtip(branchtip, ignoremissing=False):
         """Return the tip node for a given branch."""
 
     def lookup(key):
         """Resolve the node for a revision."""
 
     def lookupbranch(key):
         """Look up the branch name of the given revision or branch name."""
 
     def known(nodes):
         """Determine whether a series of nodes is known.
 
         Returns a list of bools.
         """
 
     def local():
         """Whether the repository is local."""
         return True
 
     def publishing():
         """Whether the repository is a publishing repository."""
 
     def cancopy():
         pass
 
     def shared():
         """The type of shared repository or None."""
 
     def wjoin(f, *insidef):
         """Calls self.vfs.reljoin(self.root, f, *insidef)"""
 
     def setparents(p1, p2):
         """Set the parent nodes of the working directory."""
 
     def filectx(path, changeid=None, fileid=None):
         """Obtain a filectx for the given file revision."""
 
     def getcwd():
         """Obtain the current working directory from the dirstate."""
 
     def pathto(f, cwd=None):
         """Obtain the relative path to a file."""
 
     def adddatafilter(name, fltr):
         pass
 
     def wread(filename):
         """Read a file from wvfs, using data filters."""
 
     def wwrite(filename, data, flags, backgroundclose=False, **kwargs):
         """Write data to a file in the wvfs, using data filters."""
 
     def wwritedata(filename, data):
         """Resolve data for writing to the wvfs, using data filters."""
 
     def currenttransaction():
         """Obtain the current transaction instance or None."""
 
     def transaction(desc, report=None):
         """Open a new transaction to write to the repository."""
 
     def undofiles():
         """Returns a list of (vfs, path) for files to undo transactions."""
 
     def recover():
         """Roll back an interrupted transaction."""
 
     def rollback(dryrun=False, force=False):
         """Undo the last transaction.
 
         DANGEROUS.
         """
 
     def updatecaches(tr=None, full=False, caches=None):
         """Warm repo caches."""
 
     def invalidatecaches():
         """Invalidate cached data due to the repository mutating."""
 
     def invalidatevolatilesets():
         pass
 
     def invalidatedirstate():
         """Invalidate the dirstate."""
 
     def invalidate(clearfilecache=False):
         pass
 
     def invalidateall():
         pass
 
     def lock(wait=True):
         """Lock the repository store and return a lock instance."""
 
     def wlock(wait=True):
         """Lock the non-store parts of the repository."""
 
     def currentwlock():
         """Return the wlock if it's held or None."""
 
     def checkcommitpatterns(wctx, match, status, fail):
         pass
 
     def commit(
         text=b'',
         user=None,
         date=None,
         match=None,
         force=False,
         editor=False,
         extra=None,
     ):
         """Add a new revision to the repository."""
 
     def commitctx(ctx, error=False, origctx=None):
         """Commit a commitctx instance to the repository."""
 
     def destroying():
         """Inform the repository that nodes are about to be destroyed."""
 
     def destroyed():
         """Inform the repository that nodes have been destroyed."""
 
     def status(
         node1=b'.',
         node2=None,
         match=None,
         ignored=False,
         clean=False,
         unknown=False,
         listsubrepos=False,
     ):
         """Convenience method to call repo[x].status()."""
 
     def addpostdsstatus(ps):
         pass
 
     def postdsstatus():
         pass
 
     def clearpostdsstatus():
         pass
 
     def heads(start=None):
         """Obtain list of nodes that are DAG heads."""
 
     def branchheads(branch=None, start=None, closed=False):
         pass
 
     def branches(nodes):
         pass
 
     def between(pairs):
         pass
 
     def checkpush(pushop):
         pass
 
     prepushoutgoinghooks = interfaceutil.Attribute("""util.hooks instance.""")
 
     def pushkey(namespace, key, old, new):
         pass
 
     def listkeys(namespace):
         pass
 
     def debugwireargs(one, two, three=None, four=None, five=None):
         pass
 
     def savecommitmessage(text):
         pass
 
     def register_sidedata_computer(
         kind, category, keys, computer, flags, replace=False
     ):
         pass
 
     def register_wanted_sidedata(category):
         pass
 
 
 class completelocalrepository(
     ilocalrepositorymain, ilocalrepositoryfilestorage
 ):
     """Complete interface for a local repository."""
 
 
 class iwireprotocolcommandcacher(interfaceutil.Interface):
     """Represents a caching backend for wire protocol commands.
 
     Wire protocol version 2 supports transparent caching of many commands.
     To leverage this caching, servers can activate objects that cache
     command responses. Objects handle both cache writing and reading.
     This interface defines how that response caching mechanism works.
 
     Wire protocol version 2 commands emit a series of objects that are
     serialized and sent to the client. The caching layer exists between
     the invocation of the command function and the sending of its output
     objects to an output layer.
 
     Instances of this interface represent a binding to a cache that
     can serve a response (in place of calling a command function) and/or
     write responses to a cache for subsequent use.
 
     When a command request arrives, the following happens with regards
     to this interface:
 
     1. The server determines whether the command request is cacheable.
     2. If it is, an instance of this interface is spawned.
     3. The cacher is activated in a context manager (``__enter__`` is called).
     4. A cache *key* for that request is derived. This will call the
        instance's ``adjustcachekeystate()`` method so the derivation
        can be influenced.
     5. The cacher is informed of the derived cache key via a call to
        ``setcachekey()``.
     6. The cacher's ``lookup()`` method is called to test for presence of
        the derived key in the cache.
     7. If ``lookup()`` returns a hit, that cached result is used in place
        of invoking the command function. ``__exit__`` is called and the instance
        is discarded.
     8. The command function is invoked.
     9. ``onobject()`` is called for each object emitted by the command
        function.
     10. After the final object is seen, ``onfinished()`` is called.
     11. ``__exit__`` is called to signal the end of use of the instance.
 
     Cache *key* derivation can be influenced by the instance.
 
     Cache keys are initially derived by a deterministic representation of
     the command request. This includes the command name, arguments, protocol
     version, etc. This initial key derivation is performed by CBOR-encoding a
     data structure and feeding that output into a hasher.
 
     Instances of this interface can influence this initial key derivation
     via ``adjustcachekeystate()``.
 
     The instance is informed of the derived cache key via a call to
     ``setcachekey()``. The instance must store the key locally so it can
     be consulted on subsequent operations that may require it.
 
     When constructed, the instance has access to a callable that can be used
     for encoding response objects. This callable receives as its single
     argument an object emitted by a command function. It returns an iterable
     of bytes chunks representing the encoded object. Unless the cacher is
     caching native Python objects in memory or has a way of reconstructing
     the original Python objects, implementations typically call this function
     to produce bytes from the output objects and then store those bytes in
     the cache. When it comes time to re-emit those bytes, they are wrapped
     in a ``wireprototypes.encodedresponse`` instance to tell the output
     layer that they are pre-encoded.
 
     When receiving the objects emitted by the command function, instances
     can choose what to do with those objects. The simplest thing to do is
     re-emit the original objects. They will be forwarded to the output
     layer and will be processed as if the cacher did not exist.
 
     Implementations could also choose to not emit objects - instead locally
     buffering objects or their encoded representation. They could then emit
     a single "coalesced" object when ``onfinished()`` is called. In
     this way, the implementation would function as a filtering layer of
     sorts.
 
     When caching objects, typically the encoded form of the object will
     be stored. Keep in mind that if the original object is forwarded to
     the output layer, it will need to be encoded there as well. For large
     output, this redundant encoding could add overhead. Implementations
     could wrap the encoded object data in ``wireprototypes.encodedresponse``
     instances to avoid this overhead.
     """
 
     def __enter__():
         """Marks the instance as active.
 
         Should return self.
         """
 
     def __exit__(exctype, excvalue, exctb):
         """Called when cacher is no longer used.
 
         This can be used by implementations to perform cleanup actions (e.g.
         disconnecting network sockets, aborting a partially cached response.
         """
 
     def adjustcachekeystate(state):
         """Influences cache key derivation by adjusting state to derive key.
 
         A dict defining the state used to derive the cache key is passed.
 
         Implementations can modify this dict to record additional state that
         is wanted to influence key derivation.
 
         Implementations are *highly* encouraged to not modify or delete
         existing keys.
         """
 
     def setcachekey(key):
         """Record the derived cache key for this request.
 
         Instances may mutate the key for internal usage, as desired. e.g.
         instances may wish to prepend the repo name, introduce path
         components for filesystem or URL addressing, etc. Behavior is up to
         the cache.
 
         Returns a bool indicating if the request is cacheable by this
         instance.
         """
 
     def lookup():
         """Attempt to resolve an entry in the cache.
 
         The instance is instructed to look for the cache key that it was
         informed about via the call to ``setcachekey()``.
 
         If there's no cache hit or the cacher doesn't wish to use the cached
         entry, ``None`` should be returned.
 
         Else, a dict defining the cached result should be returned. The
         dict may have the following keys:
 
         objs
            An iterable of objects that should be sent to the client. That
            iterable of objects is expected to be what the command function
            would return if invoked or an equivalent representation thereof.
         """
 
     def onobject(obj):
         """Called when a new object is emitted from the command function.
 
         Receives as its argument the object that was emitted from the
         command function.
 
         This method returns an iterator of objects to forward to the output
         layer. The easiest implementation is a generator that just
         ``yield obj``.
         """
 
     def onfinished():
         """Called after all objects have been emitted from the command function.
 
         Implementations should return an iterator of objects to forward to
         the output layer.
 
         This method can be a generator.
         """

mercurial/localrepo.py

@@ -1,3995 +1,4000 b''
 # localrepo.py - read/write repository class for mercurial
 # coding: utf-8
 #
 # Copyright 2005-2007 Olivia Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 
 import functools
 import os
 import random
 import re
 import sys
 import time
 import weakref
 
 from concurrent import futures
 from typing import (
     Optional,
 )
 
 from .i18n import _
 from .node import (
     bin,
     hex,
     nullrev,
     sha1nodeconstants,
     short,
 )
 from .pycompat import (
     delattr,
     getattr,
 )
 from . import (
     bookmarks,
     branchmap,
     bundle2,
     bundlecaches,
     changegroup,
     color,
     commit,
     context,
     dirstate,
     discovery,
     encoding,
     error,
     exchange,
     extensions,
     filelog,
     hook,
     lock as lockmod,
     match as matchmod,
     mergestate as mergestatemod,
     mergeutil,
     namespaces,
     narrowspec,
     obsolete,
     pathutil,
     phases,
     pushkey,
     pycompat,
     rcutil,
     repoview,
     requirements as requirementsmod,
     revlog,
     revset,
     revsetlang,
     scmutil,
     sparse,
     store as storemod,
     subrepoutil,
     tags as tagsmod,
     transaction,
     txnutil,
     util,
     vfs as vfsmod,
     wireprototypes,
 )
 
 from .interfaces import (
     repository,
     util as interfaceutil,
 )
 
 from .utils import (
     hashutil,
     procutil,
     stringutil,
     urlutil,
 )
 
 from .revlogutils import (
     concurrency_checker as revlogchecker,
     constants as revlogconst,
     sidedata as sidedatamod,
 )
 
 release = lockmod.release
 urlerr = util.urlerr
 urlreq = util.urlreq
 
 RE_SKIP_DIRSTATE_ROLLBACK = re.compile(
     b"^((dirstate|narrowspec.dirstate).*|branch$)"
 )
 
 # set of (path, vfs-location) tuples. vfs-location is:
 # - 'plain for vfs relative paths
 # - '' for svfs relative paths
 _cachedfiles = set()
 
 
 class _basefilecache(scmutil.filecache):
     """All filecache usage on repo are done for logic that should be unfiltered"""
 
     def __get__(self, repo, type=None):
         if repo is None:
             return self
         # proxy to unfiltered __dict__ since filtered repo has no entry
         unfi = repo.unfiltered()
         try:
             return unfi.__dict__[self.sname]
         except KeyError:
             pass
         return super(_basefilecache, self).__get__(unfi, type)
 
     def set(self, repo, value):
         return super(_basefilecache, self).set(repo.unfiltered(), value)
 
 
 class repofilecache(_basefilecache):
     """filecache for files in .hg but outside of .hg/store"""
 
     def __init__(self, *paths):
         super(repofilecache, self).__init__(*paths)
         for path in paths:
             _cachedfiles.add((path, b'plain'))
 
     def join(self, obj, fname):
         return obj.vfs.join(fname)
 
 
 class storecache(_basefilecache):
     """filecache for files in the store"""
 
     def __init__(self, *paths):
         super(storecache, self).__init__(*paths)
         for path in paths:
             _cachedfiles.add((path, b''))
 
     def join(self, obj, fname):
         return obj.sjoin(fname)
 
 
 class changelogcache(storecache):
     """filecache for the changelog"""
 
     def __init__(self):
         super(changelogcache, self).__init__()
         _cachedfiles.add((b'00changelog.i', b''))
         _cachedfiles.add((b'00changelog.n', b''))
 
     def tracked_paths(self, obj):
         paths = [self.join(obj, b'00changelog.i')]
         if obj.store.opener.options.get(b'persistent-nodemap', False):
             paths.append(self.join(obj, b'00changelog.n'))
         return paths
 
 
 class manifestlogcache(storecache):
     """filecache for the manifestlog"""
 
     def __init__(self):
         super(manifestlogcache, self).__init__()
         _cachedfiles.add((b'00manifest.i', b''))
         _cachedfiles.add((b'00manifest.n', b''))
 
     def tracked_paths(self, obj):
         paths = [self.join(obj, b'00manifest.i')]
         if obj.store.opener.options.get(b'persistent-nodemap', False):
             paths.append(self.join(obj, b'00manifest.n'))
         return paths
 
 
 class mixedrepostorecache(_basefilecache):
     """filecache for a mix files in .hg/store and outside"""
 
     def __init__(self, *pathsandlocations):
         # scmutil.filecache only uses the path for passing back into our
         # join(), so we can safely pass a list of paths and locations
         super(mixedrepostorecache, self).__init__(*pathsandlocations)
         _cachedfiles.update(pathsandlocations)
 
     def join(self, obj, fnameandlocation):
         fname, location = fnameandlocation
         if location == b'plain':
             return obj.vfs.join(fname)
         else:
             if location != b'':
                 raise error.ProgrammingError(
                     b'unexpected location: %s' % location
                 )
             return obj.sjoin(fname)
 
 
 def isfilecached(repo, name):
     """check if a repo has already cached "name" filecache-ed property
 
     This returns (cachedobj-or-None, iscached) tuple.
     """
     cacheentry = repo.unfiltered()._filecache.get(name, None)
     if not cacheentry:
         return None, False
     return cacheentry.obj, True
 
 
 class unfilteredpropertycache(util.propertycache):
     """propertycache that apply to unfiltered repo only"""
 
     def __get__(self, repo, type=None):
         unfi = repo.unfiltered()
         if unfi is repo:
             return super(unfilteredpropertycache, self).__get__(unfi)
         return getattr(unfi, self.name)
 
 
 class filteredpropertycache(util.propertycache):
     """propertycache that must take filtering in account"""
 
     def cachevalue(self, obj, value):
         object.__setattr__(obj, self.name, value)
 
 
 def hasunfilteredcache(repo, name):
     """check if a repo has an unfilteredpropertycache value for <name>"""
     return name in vars(repo.unfiltered())
 
 
 def unfilteredmethod(orig):
     """decorate method that always need to be run on unfiltered version"""
 
     @functools.wraps(orig)
     def wrapper(repo, *args, **kwargs):
         return orig(repo.unfiltered(), *args, **kwargs)
 
     return wrapper
 
 
 moderncaps = {
     b'lookup',
     b'branchmap',
     b'pushkey',
     b'known',
     b'getbundle',
     b'unbundle',
 }
 legacycaps = moderncaps.union({b'changegroupsubset'})
 
 
 @interfaceutil.implementer(repository.ipeercommandexecutor)
 class localcommandexecutor:
     def __init__(self, peer):
         self._peer = peer
         self._sent = False
         self._closed = False
 
     def __enter__(self):
         return self
 
     def __exit__(self, exctype, excvalue, exctb):
         self.close()
 
     def callcommand(self, command, args):
         if self._sent:
             raise error.ProgrammingError(
                 b'callcommand() cannot be used after sendcommands()'
             )
 
         if self._closed:
             raise error.ProgrammingError(
                 b'callcommand() cannot be used after close()'
             )
 
         # We don't need to support anything fancy. Just call the named
         # method on the peer and return a resolved future.
         fn = getattr(self._peer, pycompat.sysstr(command))
 
         f = futures.Future()
 
         try:
             result = fn(**pycompat.strkwargs(args))
         except Exception:
             pycompat.future_set_exception_info(f, sys.exc_info()[1:])
         else:
             f.set_result(result)
 
         return f
 
     def sendcommands(self):
         self._sent = True
 
     def close(self):
         self._closed = True
 
 
 @interfaceutil.implementer(repository.ipeercommands)
 class localpeer(repository.peer):
     '''peer for a local repo; reflects only the most recent API'''
 
     def __init__(self, repo, caps=None, path=None):
         super(localpeer, self).__init__(repo.ui, path=path)
 
         if caps is None:
             caps = moderncaps.copy()
         self._repo = repo.filtered(b'served')
 
         if repo._wanted_sidedata:
             formatted = bundle2.format_remote_wanted_sidedata(repo)
             caps.add(b'exp-wanted-sidedata=' + formatted)
 
         self._caps = repo._restrictcapabilities(caps)
 
     # Begin of _basepeer interface.
 
     def url(self):
         return self._repo.url()
 
     def local(self):
         return self._repo
 
     def canpush(self):
         return True
 
     def close(self):
         self._repo.close()
 
     # End of _basepeer interface.
 
     # Begin of _basewirecommands interface.
 
     def branchmap(self):
         return self._repo.branchmap()
 
     def capabilities(self):
         return self._caps
 
     def clonebundles(self):
         return self._repo.tryread(bundlecaches.CB_MANIFEST_FILE)
 
     def debugwireargs(self, one, two, three=None, four=None, five=None):
         """Used to test argument passing over the wire"""
         return b"%s %s %s %s %s" % (
             one,
             two,
             pycompat.bytestr(three),
             pycompat.bytestr(four),
             pycompat.bytestr(five),
         )
 
     def getbundle(
         self,
         source,
         heads=None,
         common=None,
         bundlecaps=None,
         remote_sidedata=None,
         **kwargs
     ):
         chunks = exchange.getbundlechunks(
             self._repo,
             source,
             heads=heads,
             common=common,
             bundlecaps=bundlecaps,
             remote_sidedata=remote_sidedata,
             **kwargs
         )[1]
         cb = util.chunkbuffer(chunks)
 
         if exchange.bundle2requested(bundlecaps):
             # When requesting a bundle2, getbundle returns a stream to make the
             # wire level function happier. We need to build a proper object
             # from it in local peer.
             return bundle2.getunbundler(self.ui, cb)
         else:
             return changegroup.getunbundler(b'01', cb, None)
 
     def heads(self):
         return self._repo.heads()
 
     def known(self, nodes):
         return self._repo.known(nodes)
 
     def listkeys(self, namespace):
         return self._repo.listkeys(namespace)
 
     def lookup(self, key):
         return self._repo.lookup(key)
 
     def pushkey(self, namespace, key, old, new):
         return self._repo.pushkey(namespace, key, old, new)
 
     def stream_out(self):
         raise error.Abort(_(b'cannot perform stream clone against local peer'))
 
     def unbundle(self, bundle, heads, url):
         """apply a bundle on a repo
 
         This function handles the repo locking itself."""
         try:
             try:
                 bundle = exchange.readbundle(self.ui, bundle, None)
                 ret = exchange.unbundle(self._repo, bundle, heads, b'push', url)
                 if util.safehasattr(ret, b'getchunks'):
                     # This is a bundle20 object, turn it into an unbundler.
                     # This little dance should be dropped eventually when the
                     # API is finally improved.
                     stream = util.chunkbuffer(ret.getchunks())
                     ret = bundle2.getunbundler(self.ui, stream)
                 return ret
             except Exception as exc:
                 # If the exception contains output salvaged from a bundle2
                 # reply, we need to make sure it is printed before continuing
                 # to fail. So we build a bundle2 with such output and consume
                 # it directly.
                 #
                 # This is not very elegant but allows a "simple" solution for
                 # issue4594
                 output = getattr(exc, '_bundle2salvagedoutput', ())
                 if output:
                     bundler = bundle2.bundle20(self._repo.ui)
                     for out in output:
                         bundler.addpart(out)
                     stream = util.chunkbuffer(bundler.getchunks())
                     b = bundle2.getunbundler(self.ui, stream)
                     bundle2.processbundle(self._repo, b)
                 raise
         except error.PushRaced as exc:
             raise error.ResponseError(
                 _(b'push failed:'), stringutil.forcebytestr(exc)
             )
 
     # End of _basewirecommands interface.
 
     # Begin of peer interface.
 
     def commandexecutor(self):
         return localcommandexecutor(self)
 
     # End of peer interface.
 
 
 @interfaceutil.implementer(repository.ipeerlegacycommands)
 class locallegacypeer(localpeer):
     """peer extension which implements legacy methods too; used for tests with
     restricted capabilities"""
 
     def __init__(self, repo, path=None):
         super(locallegacypeer, self).__init__(repo, caps=legacycaps, path=path)
 
     # Begin of baselegacywirecommands interface.
 
     def between(self, pairs):
         return self._repo.between(pairs)
 
     def branches(self, nodes):
         return self._repo.branches(nodes)
 
     def changegroup(self, nodes, source):
         outgoing = discovery.outgoing(
             self._repo, missingroots=nodes, ancestorsof=self._repo.heads()
         )
         return changegroup.makechangegroup(self._repo, outgoing, b'01', source)
 
     def changegroupsubset(self, bases, heads, source):
         outgoing = discovery.outgoing(
             self._repo, missingroots=bases, ancestorsof=heads
         )
         return changegroup.makechangegroup(self._repo, outgoing, b'01', source)
 
     # End of baselegacywirecommands interface.
 
 
 # Functions receiving (ui, features) that extensions can register to impact
 # the ability to load repositories with custom requirements. Only
 # functions defined in loaded extensions are called.
 #
 # The function receives a set of requirement strings that the repository
 # is capable of opening. Functions will typically add elements to the
 # set to reflect that the extension knows how to handle that requirements.
 featuresetupfuncs = set()
 
 
 def _getsharedvfs(hgvfs, requirements):
     """returns the vfs object pointing to root of shared source
     repo for a shared repository
 
     hgvfs is vfs pointing at .hg/ of current repo (shared one)
     requirements is a set of requirements of current repo (shared one)
     """
     # The ``shared`` or ``relshared`` requirements indicate the
     # store lives in the path contained in the ``.hg/sharedpath`` file.
     # This is an absolute path for ``shared`` and relative to
     # ``.hg/`` for ``relshared``.
     sharedpath = hgvfs.read(b'sharedpath').rstrip(b'\n')
     if requirementsmod.RELATIVE_SHARED_REQUIREMENT in requirements:
         sharedpath = util.normpath(hgvfs.join(sharedpath))
 
     sharedvfs = vfsmod.vfs(sharedpath, realpath=True)
 
     if not sharedvfs.exists():
         raise error.RepoError(
             _(b'.hg/sharedpath points to nonexistent directory %s')
             % sharedvfs.base
         )
     return sharedvfs
 
 
 def _readrequires(vfs, allowmissing):
     """reads the require file present at root of this vfs
     and return a set of requirements
 
     If allowmissing is True, we suppress FileNotFoundError if raised"""
     # requires file contains a newline-delimited list of
     # features/capabilities the opener (us) must have in order to use
     # the repository. This file was introduced in Mercurial 0.9.2,
     # which means very old repositories may not have one. We assume
     # a missing file translates to no requirements.
     read = vfs.tryread if allowmissing else vfs.read
     return set(read(b'requires').splitlines())
 
 
 def makelocalrepository(baseui, path: bytes, intents=None):
     """Create a local repository object.
 
     Given arguments needed to construct a local repository, this function
     performs various early repository loading functionality (such as
     reading the ``.hg/requires`` and ``.hg/hgrc`` files), validates that
     the repository can be opened, derives a type suitable for representing
     that repository, and returns an instance of it.
 
     The returned object conforms to the ``repository.completelocalrepository``
     interface.
 
     The repository type is derived by calling a series of factory functions
     for each aspect/interface of the final repository. These are defined by
     ``REPO_INTERFACES``.
 
     Each factory function is called to produce a type implementing a specific
     interface. The cumulative list of returned types will be combined into a
     new type and that type will be instantiated to represent the local
     repository.
 
     The factory functions each receive various state that may be consulted
     as part of deriving a type.
 
     Extensions should wrap these factory functions to customize repository type
     creation. Note that an extension's wrapped function may be called even if
     that extension is not loaded for the repo being constructed. Extensions
     should check if their ``__name__`` appears in the
     ``extensionmodulenames`` set passed to the factory function and no-op if
     not.
     """
     ui = baseui.copy()
     # Prevent copying repo configuration.
     ui.copy = baseui.copy
 
     # Working directory VFS rooted at repository root.
     wdirvfs = vfsmod.vfs(path, expandpath=True, realpath=True)
 
     # Main VFS for .hg/ directory.
     hgpath = wdirvfs.join(b'.hg')
     hgvfs = vfsmod.vfs(hgpath, cacheaudited=True)
     # Whether this repository is shared one or not
     shared = False
     # If this repository is shared, vfs pointing to shared repo
     sharedvfs = None
 
     # The .hg/ path should exist and should be a directory. All other
     # cases are errors.
     if not hgvfs.isdir():
         try:
             hgvfs.stat()
         except FileNotFoundError:
             pass
         except ValueError as e:
             # Can be raised on Python 3.8 when path is invalid.
             raise error.Abort(
                 _(b'invalid path %s: %s') % (path, stringutil.forcebytestr(e))
             )
 
         raise error.RepoError(_(b'repository %s not found') % path)
 
     requirements = _readrequires(hgvfs, True)
     shared = (
         requirementsmod.SHARED_REQUIREMENT in requirements
         or requirementsmod.RELATIVE_SHARED_REQUIREMENT in requirements
     )
     storevfs = None
     if shared:
         # This is a shared repo
         sharedvfs = _getsharedvfs(hgvfs, requirements)
         storevfs = vfsmod.vfs(sharedvfs.join(b'store'))
     else:
         storevfs = vfsmod.vfs(hgvfs.join(b'store'))
 
     # if .hg/requires contains the sharesafe requirement, it means
     # there exists a `.hg/store/requires` too and we should read it
     # NOTE: presence of SHARESAFE_REQUIREMENT imply that store requirement
     # is present. We never write SHARESAFE_REQUIREMENT for a repo if store
     # is not present, refer checkrequirementscompat() for that
     #
     # However, if SHARESAFE_REQUIREMENT is not present, it means that the
     # repository was shared the old way. We check the share source .hg/requires
     # for SHARESAFE_REQUIREMENT to detect whether the current repository needs
     # to be reshared
     hint = _(b"see `hg help config.format.use-share-safe` for more information")
     if requirementsmod.SHARESAFE_REQUIREMENT in requirements:
         if (
             shared
             and requirementsmod.SHARESAFE_REQUIREMENT
             not in _readrequires(sharedvfs, True)
         ):
             mismatch_warn = ui.configbool(
                 b'share', b'safe-mismatch.source-not-safe.warn'
             )
             mismatch_config = ui.config(
                 b'share', b'safe-mismatch.source-not-safe'
             )
             mismatch_verbose_upgrade = ui.configbool(
                 b'share', b'safe-mismatch.source-not-safe:verbose-upgrade'
             )
             if mismatch_config in (
                 b'downgrade-allow',
                 b'allow',
                 b'downgrade-abort',
             ):
                 # prevent cyclic import localrepo -> upgrade -> localrepo
                 from . import upgrade
 
                 upgrade.downgrade_share_to_non_safe(
                     ui,
                     hgvfs,
                     sharedvfs,
                     requirements,
                     mismatch_config,
                     mismatch_warn,
                     mismatch_verbose_upgrade,
                 )
             elif mismatch_config == b'abort':
                 raise error.Abort(
                     _(b"share source does not support share-safe requirement"),
                     hint=hint,
                 )
             else:
                 raise error.Abort(
                     _(
                         b"share-safe mismatch with source.\nUnrecognized"
                         b" value '%s' of `share.safe-mismatch.source-not-safe`"
                         b" set."
                     )
                     % mismatch_config,
                     hint=hint,
                 )
         else:
             requirements |= _readrequires(storevfs, False)
     elif shared:
         sourcerequires = _readrequires(sharedvfs, False)
         if requirementsmod.SHARESAFE_REQUIREMENT in sourcerequires:
             mismatch_config = ui.config(b'share', b'safe-mismatch.source-safe')
             mismatch_warn = ui.configbool(
                 b'share', b'safe-mismatch.source-safe.warn'
             )
             mismatch_verbose_upgrade = ui.configbool(
                 b'share', b'safe-mismatch.source-safe:verbose-upgrade'
             )
             if mismatch_config in (
                 b'upgrade-allow',
                 b'allow',
                 b'upgrade-abort',
             ):
                 # prevent cyclic import localrepo -> upgrade -> localrepo
                 from . import upgrade
 
                 upgrade.upgrade_share_to_safe(
                     ui,
                     hgvfs,
                     storevfs,
                     requirements,
                     mismatch_config,
                     mismatch_warn,
                     mismatch_verbose_upgrade,
                 )
             elif mismatch_config == b'abort':
                 raise error.Abort(
                     _(
                         b'version mismatch: source uses share-safe'
                         b' functionality while the current share does not'
                     ),
                     hint=hint,
                 )
             else:
                 raise error.Abort(
                     _(
                         b"share-safe mismatch with source.\nUnrecognized"
                         b" value '%s' of `share.safe-mismatch.source-safe` set."
                     )
                     % mismatch_config,
                     hint=hint,
                 )
 
     # The .hg/hgrc file may load extensions or contain config options
     # that influence repository construction. Attempt to load it and
     # process any new extensions that it may have pulled in.
     if loadhgrc(ui, wdirvfs, hgvfs, requirements, sharedvfs):
         afterhgrcload(ui, wdirvfs, hgvfs, requirements)
         extensions.loadall(ui)
         extensions.populateui(ui)
 
     # Set of module names of extensions loaded for this repository.
     extensionmodulenames = {m.__name__ for n, m in extensions.extensions(ui)}
 
     supportedrequirements = gathersupportedrequirements(ui)
 
     # We first validate the requirements are known.
     ensurerequirementsrecognized(requirements, supportedrequirements)
 
     # Then we validate that the known set is reasonable to use together.
     ensurerequirementscompatible(ui, requirements)
 
     # TODO there are unhandled edge cases related to opening repositories with
     # shared storage. If storage is shared, we should also test for requirements
     # compatibility in the pointed-to repo. This entails loading the .hg/hgrc in
     # that repo, as that repo may load extensions needed to open it. This is a
     # bit complicated because we don't want the other hgrc to overwrite settings
     # in this hgrc.
     #
     # This bug is somewhat mitigated by the fact that we copy the .hg/requires
     # file when sharing repos. But if a requirement is added after the share is
     # performed, thereby introducing a new requirement for the opener, we may
     # will not see that and could encounter a run-time error interacting with
     # that shared store since it has an unknown-to-us requirement.
 
     # At this point, we know we should be capable of opening the repository.
     # Now get on with doing that.
 
     features = set()
 
     # The "store" part of the repository holds versioned data. How it is
     # accessed is determined by various requirements. If `shared` or
     # `relshared` requirements are present, this indicates current repository
     # is a share and store exists in path mentioned in `.hg/sharedpath`
     if shared:
         storebasepath = sharedvfs.base
         cachepath = sharedvfs.join(b'cache')
         features.add(repository.REPO_FEATURE_SHARED_STORAGE)
     else:
         storebasepath = hgvfs.base
         cachepath = hgvfs.join(b'cache')
     wcachepath = hgvfs.join(b'wcache')
 
     # The store has changed over time and the exact layout is dictated by
     # requirements. The store interface abstracts differences across all
     # of them.
     store = makestore(
         requirements,
         storebasepath,
         lambda base: vfsmod.vfs(base, cacheaudited=True),
     )
     hgvfs.createmode = store.createmode
 
     storevfs = store.vfs
     storevfs.options = resolvestorevfsoptions(ui, requirements, features)
 
     if (
         requirementsmod.REVLOGV2_REQUIREMENT in requirements
         or requirementsmod.CHANGELOGV2_REQUIREMENT in requirements
     ):
         features.add(repository.REPO_FEATURE_SIDE_DATA)
         # the revlogv2 docket introduced race condition that we need to fix
         features.discard(repository.REPO_FEATURE_STREAM_CLONE)
 
     # The cache vfs is used to manage cache files.
     cachevfs = vfsmod.vfs(cachepath, cacheaudited=True)
     cachevfs.createmode = store.createmode
     # The cache vfs is used to manage cache files related to the working copy
     wcachevfs = vfsmod.vfs(wcachepath, cacheaudited=True)
     wcachevfs.createmode = store.createmode
 
     # Now resolve the type for the repository object. We do this by repeatedly
     # calling a factory function to produces types for specific aspects of the
     # repo's operation. The aggregate returned types are used as base classes
     # for a dynamically-derived type, which will represent our new repository.
 
     bases = []
     extrastate = {}
 
     for iface, fn in REPO_INTERFACES:
         # We pass all potentially useful state to give extensions tons of
         # flexibility.
         typ = fn()(
             ui=ui,
             intents=intents,
             requirements=requirements,
             features=features,
             wdirvfs=wdirvfs,
             hgvfs=hgvfs,
             store=store,
             storevfs=storevfs,
             storeoptions=storevfs.options,
             cachevfs=cachevfs,
             wcachevfs=wcachevfs,
             extensionmodulenames=extensionmodulenames,
             extrastate=extrastate,
             baseclasses=bases,
         )
 
         if not isinstance(typ, type):
             raise error.ProgrammingError(
                 b'unable to construct type for %s' % iface
             )
 
         bases.append(typ)
 
     # type() allows you to use characters in type names that wouldn't be
     # recognized as Python symbols in source code. We abuse that to add
     # rich information about our constructed repo.
     name = pycompat.sysstr(
         b'derivedrepo:%s<%s>' % (wdirvfs.base, b','.join(sorted(requirements)))
     )
 
     cls = type(name, tuple(bases), {})
 
     return cls(
         baseui=baseui,
         ui=ui,
         origroot=path,
         wdirvfs=wdirvfs,
         hgvfs=hgvfs,
         requirements=requirements,
         supportedrequirements=supportedrequirements,
         sharedpath=storebasepath,
         store=store,
         cachevfs=cachevfs,
         wcachevfs=wcachevfs,
         features=features,
         intents=intents,
     )
 
 
 def loadhgrc(
     ui,
     wdirvfs: vfsmod.vfs,
     hgvfs: vfsmod.vfs,
     requirements,
     sharedvfs: Optional[vfsmod.vfs] = None,
 ):
     """Load hgrc files/content into a ui instance.
 
     This is called during repository opening to load any additional
     config files or settings relevant to the current repository.
 
     Returns a bool indicating whether any additional configs were loaded.
 
     Extensions should monkeypatch this function to modify how per-repo
     configs are loaded. For example, an extension may wish to pull in
     configs from alternate files or sources.
 
     sharedvfs is vfs object pointing to source repo if the current one is a
     shared one
     """
     if not rcutil.use_repo_hgrc():
         return False
 
     ret = False
     # first load config from shared source if we has to
     if requirementsmod.SHARESAFE_REQUIREMENT in requirements and sharedvfs:
         try:
             ui.readconfig(sharedvfs.join(b'hgrc'), root=sharedvfs.base)
             ret = True
         except IOError:
             pass
 
     try:
         ui.readconfig(hgvfs.join(b'hgrc'), root=wdirvfs.base)
         ret = True
     except IOError:
         pass
 
     try:
         ui.readconfig(hgvfs.join(b'hgrc-not-shared'), root=wdirvfs.base)
         ret = True
     except IOError:
         pass
 
     return ret
 
 
 def afterhgrcload(ui, wdirvfs, hgvfs, requirements):
     """Perform additional actions after .hg/hgrc is loaded.
 
     This function is called during repository loading immediately after
     the .hg/hgrc file is loaded and before per-repo extensions are loaded.
 
     The function can be used to validate configs, automatically add
     options (including extensions) based on requirements, etc.
     """
 
     # Map of requirements to list of extensions to load automatically when
     # requirement is present.
     autoextensions = {
         b'git': [b'git'],
         b'largefiles': [b'largefiles'],
         b'lfs': [b'lfs'],
     }
 
     for requirement, names in sorted(autoextensions.items()):
         if requirement not in requirements:
             continue
 
         for name in names:
             if not ui.hasconfig(b'extensions', name):
                 ui.setconfig(b'extensions', name, b'', source=b'autoload')
 
 
 def gathersupportedrequirements(ui):
     """Determine the complete set of recognized requirements."""
     # Start with all requirements supported by this file.
     supported = set(localrepository._basesupported)
 
     # Execute ``featuresetupfuncs`` entries if they belong to an extension
     # relevant to this ui instance.
     modules = {m.__name__ for n, m in extensions.extensions(ui)}
 
     for fn in featuresetupfuncs:
         if fn.__module__ in modules:
             fn(ui, supported)
 
     # Add derived requirements from registered compression engines.
     for name in util.compengines:
         engine = util.compengines[name]
         if engine.available() and engine.revlogheader():
             supported.add(b'exp-compression-%s' % name)
             if engine.name() == b'zstd':
                 supported.add(requirementsmod.REVLOG_COMPRESSION_ZSTD)
 
     return supported
 
 
 def ensurerequirementsrecognized(requirements, supported):
     """Validate that a set of local requirements is recognized.
 
     Receives a set of requirements. Raises an ``error.RepoError`` if there
     exists any requirement in that set that currently loaded code doesn't
     recognize.
 
     Returns a set of supported requirements.
     """
     missing = set()
 
     for requirement in requirements:
         if requirement in supported:
             continue
 
         if not requirement or not requirement[0:1].isalnum():
             raise error.RequirementError(_(b'.hg/requires file is corrupt'))
 
         missing.add(requirement)
 
     if missing:
         raise error.RequirementError(
             _(b'repository requires features unknown to this Mercurial: %s')
             % b' '.join(sorted(missing)),
             hint=_(
                 b'see https://mercurial-scm.org/wiki/MissingRequirement '
                 b'for more information'
             ),
         )
 
 
 def ensurerequirementscompatible(ui, requirements):
     """Validates that a set of recognized requirements is mutually compatible.
 
     Some requirements may not be compatible with others or require
     config options that aren't enabled. This function is called during
     repository opening to ensure that the set of requirements needed
     to open a repository is sane and compatible with config options.
 
     Extensions can monkeypatch this function to perform additional
     checking.
 
     ``error.RepoError`` should be raised on failure.
     """
     if (
         requirementsmod.SPARSE_REQUIREMENT in requirements
         and not sparse.enabled
     ):
         raise error.RepoError(
             _(
                 b'repository is using sparse feature but '
                 b'sparse is not enabled; enable the '
                 b'"sparse" extensions to access'
             )
         )
 
 
 def makestore(requirements, path, vfstype):
     """Construct a storage object for a repository."""
     if requirementsmod.STORE_REQUIREMENT in requirements:
         if requirementsmod.FNCACHE_REQUIREMENT in requirements:
             dotencode = requirementsmod.DOTENCODE_REQUIREMENT in requirements
             return storemod.fncachestore(path, vfstype, dotencode)
 
         return storemod.encodedstore(path, vfstype)
 
     return storemod.basicstore(path, vfstype)
 
 
 def resolvestorevfsoptions(ui, requirements, features):
     """Resolve the options to pass to the store vfs opener.
 
     The returned dict is used to influence behavior of the storage layer.
     """
     options = {}
 
     if requirementsmod.TREEMANIFEST_REQUIREMENT in requirements:
         options[b'treemanifest'] = True
 
     # experimental config: format.manifestcachesize
     manifestcachesize = ui.configint(b'format', b'manifestcachesize')
     if manifestcachesize is not None:
         options[b'manifestcachesize'] = manifestcachesize
 
     # In the absence of another requirement superseding a revlog-related
     # requirement, we have to assume the repo is using revlog version 0.
     # This revlog format is super old and we don't bother trying to parse
     # opener options for it because those options wouldn't do anything
     # meaningful on such old repos.
     if (
         requirementsmod.REVLOGV1_REQUIREMENT in requirements
         or requirementsmod.REVLOGV2_REQUIREMENT in requirements
     ):
         options.update(resolverevlogstorevfsoptions(ui, requirements, features))
     else:  # explicitly mark repo as using revlogv0
         options[b'revlogv0'] = True
 
     if requirementsmod.COPIESSDC_REQUIREMENT in requirements:
         options[b'copies-storage'] = b'changeset-sidedata'
     else:
         writecopiesto = ui.config(b'experimental', b'copies.write-to')
         copiesextramode = (b'changeset-only', b'compatibility')
         if writecopiesto in copiesextramode:
             options[b'copies-storage'] = b'extra'
 
     return options
 
 
 def resolverevlogstorevfsoptions(ui, requirements, features):
     """Resolve opener options specific to revlogs."""
 
     options = {}
     options[b'flagprocessors'] = {}
 
     if requirementsmod.REVLOGV1_REQUIREMENT in requirements:
         options[b'revlogv1'] = True
     if requirementsmod.REVLOGV2_REQUIREMENT in requirements:
         options[b'revlogv2'] = True
     if requirementsmod.CHANGELOGV2_REQUIREMENT in requirements:
         options[b'changelogv2'] = True
         cmp_rank = ui.configbool(b'experimental', b'changelog-v2.compute-rank')
         options[b'changelogv2.compute-rank'] = cmp_rank
 
     if requirementsmod.GENERALDELTA_REQUIREMENT in requirements:
         options[b'generaldelta'] = True
 
     # experimental config: format.chunkcachesize
     chunkcachesize = ui.configint(b'format', b'chunkcachesize')
     if chunkcachesize is not None:
         options[b'chunkcachesize'] = chunkcachesize
 
     deltabothparents = ui.configbool(
         b'storage', b'revlog.optimize-delta-parent-choice'
     )
     options[b'deltabothparents'] = deltabothparents
     dps_cgds = ui.configint(
         b'storage',
         b'revlog.delta-parent-search.candidate-group-chunk-size',
     )
     options[b'delta-parent-search.candidate-group-chunk-size'] = dps_cgds
     options[b'debug-delta'] = ui.configbool(b'debug', b'revlog.debug-delta')
 
     issue6528 = ui.configbool(b'storage', b'revlog.issue6528.fix-incoming')
     options[b'issue6528.fix-incoming'] = issue6528
 
     lazydelta = ui.configbool(b'storage', b'revlog.reuse-external-delta')
     lazydeltabase = False
     if lazydelta:
         lazydeltabase = ui.configbool(
             b'storage', b'revlog.reuse-external-delta-parent'
         )
     if lazydeltabase is None:
         lazydeltabase = not scmutil.gddeltaconfig(ui)
     options[b'lazydelta'] = lazydelta
     options[b'lazydeltabase'] = lazydeltabase
 
     chainspan = ui.configbytes(b'experimental', b'maxdeltachainspan')
     if 0 <= chainspan:
         options[b'maxdeltachainspan'] = chainspan
 
     mmapindexthreshold = ui.configbytes(b'experimental', b'mmapindexthreshold')
     if mmapindexthreshold is not None:
         options[b'mmapindexthreshold'] = mmapindexthreshold
 
     withsparseread = ui.configbool(b'experimental', b'sparse-read')
     srdensitythres = float(
         ui.config(b'experimental', b'sparse-read.density-threshold')
     )
     srmingapsize = ui.configbytes(b'experimental', b'sparse-read.min-gap-size')
     options[b'with-sparse-read'] = withsparseread
     options[b'sparse-read-density-threshold'] = srdensitythres
     options[b'sparse-read-min-gap-size'] = srmingapsize
 
     sparserevlog = requirementsmod.SPARSEREVLOG_REQUIREMENT in requirements
     options[b'sparse-revlog'] = sparserevlog
     if sparserevlog:
         options[b'generaldelta'] = True
 
     maxchainlen = None
     if sparserevlog:
         maxchainlen = revlogconst.SPARSE_REVLOG_MAX_CHAIN_LENGTH
     # experimental config: format.maxchainlen
     maxchainlen = ui.configint(b'format', b'maxchainlen', maxchainlen)
     if maxchainlen is not None:
         options[b'maxchainlen'] = maxchainlen
 
     for r in requirements:
         # we allow multiple compression engine requirement to co-exist because
         # strickly speaking, revlog seems to support mixed compression style.
         #
         # The compression used for new entries will be "the last one"
         prefix = r.startswith
         if prefix(b'revlog-compression-') or prefix(b'exp-compression-'):
             options[b'compengine'] = r.split(b'-', 2)[2]
 
     options[b'zlib.level'] = ui.configint(b'storage', b'revlog.zlib.level')
     if options[b'zlib.level'] is not None:
         if not (0 <= options[b'zlib.level'] <= 9):
             msg = _(b'invalid value for `storage.revlog.zlib.level` config: %d')
             raise error.Abort(msg % options[b'zlib.level'])
     options[b'zstd.level'] = ui.configint(b'storage', b'revlog.zstd.level')
     if options[b'zstd.level'] is not None:
         if not (0 <= options[b'zstd.level'] <= 22):
             msg = _(b'invalid value for `storage.revlog.zstd.level` config: %d')
             raise error.Abort(msg % options[b'zstd.level'])
 
     if requirementsmod.NARROW_REQUIREMENT in requirements:
         options[b'enableellipsis'] = True
 
     if ui.configbool(b'experimental', b'rust.index'):
         options[b'rust.index'] = True
     if requirementsmod.NODEMAP_REQUIREMENT in requirements:
         slow_path = ui.config(
             b'storage', b'revlog.persistent-nodemap.slow-path'
         )
         if slow_path not in (b'allow', b'warn', b'abort'):
             default = ui.config_default(
                 b'storage', b'revlog.persistent-nodemap.slow-path'
             )
             msg = _(
                 b'unknown value for config '
                 b'"storage.revlog.persistent-nodemap.slow-path": "%s"\n'
             )
             ui.warn(msg % slow_path)
             if not ui.quiet:
                 ui.warn(_(b'falling back to default value: %s\n') % default)
             slow_path = default
 
         msg = _(
             b"accessing `persistent-nodemap` repository without associated "
             b"fast implementation."
         )
         hint = _(
             b"check `hg help config.format.use-persistent-nodemap` "
             b"for details"
         )
         if not revlog.HAS_FAST_PERSISTENT_NODEMAP:
             if slow_path == b'warn':
                 msg = b"warning: " + msg + b'\n'
                 ui.warn(msg)
                 if not ui.quiet:
                     hint = b'(' + hint + b')\n'
                     ui.warn(hint)
             if slow_path == b'abort':
                 raise error.Abort(msg, hint=hint)
         options[b'persistent-nodemap'] = True
     if requirementsmod.DIRSTATE_V2_REQUIREMENT in requirements:
         slow_path = ui.config(b'storage', b'dirstate-v2.slow-path')
         if slow_path not in (b'allow', b'warn', b'abort'):
             default = ui.config_default(b'storage', b'dirstate-v2.slow-path')
             msg = _(b'unknown value for config "dirstate-v2.slow-path": "%s"\n')
             ui.warn(msg % slow_path)
             if not ui.quiet:
                 ui.warn(_(b'falling back to default value: %s\n') % default)
             slow_path = default
 
         msg = _(
             b"accessing `dirstate-v2` repository without associated "
             b"fast implementation."
         )
         hint = _(
             b"check `hg help config.format.use-dirstate-v2` " b"for details"
         )
         if not dirstate.HAS_FAST_DIRSTATE_V2:
             if slow_path == b'warn':
                 msg = b"warning: " + msg + b'\n'
                 ui.warn(msg)
                 if not ui.quiet:
                     hint = b'(' + hint + b')\n'
                     ui.warn(hint)
             if slow_path == b'abort':
                 raise error.Abort(msg, hint=hint)
     if ui.configbool(b'storage', b'revlog.persistent-nodemap.mmap'):
         options[b'persistent-nodemap.mmap'] = True
     if ui.configbool(b'devel', b'persistent-nodemap'):
         options[b'devel-force-nodemap'] = True
 
     return options
 
 
 def makemain(**kwargs):
     """Produce a type conforming to ``ilocalrepositorymain``."""
     return localrepository
 
 
 @interfaceutil.implementer(repository.ilocalrepositoryfilestorage)
 class revlogfilestorage:
     """File storage when using revlogs."""
 
     def file(self, path):
         if path.startswith(b'/'):
             path = path[1:]
 
         return filelog.filelog(self.svfs, path)
 
 
 @interfaceutil.implementer(repository.ilocalrepositoryfilestorage)
 class revlognarrowfilestorage:
     """File storage when using revlogs and narrow files."""
 
     def file(self, path):
         if path.startswith(b'/'):
             path = path[1:]
 
         return filelog.narrowfilelog(self.svfs, path, self._storenarrowmatch)
 
 
 def makefilestorage(requirements, features, **kwargs):
     """Produce a type conforming to ``ilocalrepositoryfilestorage``."""
     features.add(repository.REPO_FEATURE_REVLOG_FILE_STORAGE)
     features.add(repository.REPO_FEATURE_STREAM_CLONE)
 
     if requirementsmod.NARROW_REQUIREMENT in requirements:
         return revlognarrowfilestorage
     else:
         return revlogfilestorage
 
 
 # List of repository interfaces and factory functions for them. Each
 # will be called in order during ``makelocalrepository()`` to iteratively
 # derive the final type for a local repository instance. We capture the
 # function as a lambda so we don't hold a reference and the module-level
 # functions can be wrapped.
 REPO_INTERFACES = [
     (repository.ilocalrepositorymain, lambda: makemain),
     (repository.ilocalrepositoryfilestorage, lambda: makefilestorage),
 ]
 
 
 @interfaceutil.implementer(repository.ilocalrepositorymain)
 class localrepository:
     """Main class for representing local repositories.
 
     All local repositories are instances of this class.
 
     Constructed on its own, instances of this class are not usable as
     repository objects. To obtain a usable repository object, call
     ``hg.repository()``, ``localrepo.instance()``, or
     ``localrepo.makelocalrepository()``. The latter is the lowest-level.
     ``instance()`` adds support for creating new repositories.
     ``hg.repository()`` adds more extension integration, including calling
     ``reposetup()``. Generally speaking, ``hg.repository()`` should be
     used.
     """
 
     _basesupported = {
         requirementsmod.ARCHIVED_PHASE_REQUIREMENT,
         requirementsmod.BOOKMARKS_IN_STORE_REQUIREMENT,
         requirementsmod.CHANGELOGV2_REQUIREMENT,
         requirementsmod.COPIESSDC_REQUIREMENT,
         requirementsmod.DIRSTATE_TRACKED_HINT_V1,
         requirementsmod.DIRSTATE_V2_REQUIREMENT,
         requirementsmod.DOTENCODE_REQUIREMENT,
         requirementsmod.FNCACHE_REQUIREMENT,
         requirementsmod.GENERALDELTA_REQUIREMENT,
         requirementsmod.INTERNAL_PHASE_REQUIREMENT,
         requirementsmod.NODEMAP_REQUIREMENT,
         requirementsmod.RELATIVE_SHARED_REQUIREMENT,
         requirementsmod.REVLOGV1_REQUIREMENT,
         requirementsmod.REVLOGV2_REQUIREMENT,
         requirementsmod.SHARED_REQUIREMENT,
         requirementsmod.SHARESAFE_REQUIREMENT,
         requirementsmod.SPARSE_REQUIREMENT,
         requirementsmod.SPARSEREVLOG_REQUIREMENT,
         requirementsmod.STORE_REQUIREMENT,
         requirementsmod.TREEMANIFEST_REQUIREMENT,
     }
 
     # list of prefix for file which can be written without 'wlock'
     # Extensions should extend this list when needed
     _wlockfreeprefix = {
         # We migh consider requiring 'wlock' for the next
         # two, but pretty much all the existing code assume
         # wlock is not needed so we keep them excluded for
         # now.
         b'hgrc',
         b'requires',
         # XXX cache is a complicatged business someone
         # should investigate this in depth at some point
         b'cache/',
         # XXX bisect was still a bit too messy at the time
         # this changeset was introduced. Someone should fix
         # the remainig bit and drop this line
         b'bisect.state',
     }
 
     def __init__(
         self,
         baseui,
         ui,
         origroot: bytes,
         wdirvfs: vfsmod.vfs,
         hgvfs: vfsmod.vfs,
         requirements,
         supportedrequirements,
         sharedpath: bytes,
         store,
         cachevfs: vfsmod.vfs,
         wcachevfs: vfsmod.vfs,
         features,
         intents=None,
     ):
         """Create a new local repository instance.
 
         Most callers should use ``hg.repository()``, ``localrepo.instance()``,
         or ``localrepo.makelocalrepository()`` for obtaining a new repository
         object.
 
         Arguments:
 
         baseui
            ``ui.ui`` instance that ``ui`` argument was based off of.
 
         ui
            ``ui.ui`` instance for use by the repository.
 
         origroot
            ``bytes`` path to working directory root of this repository.
 
         wdirvfs
            ``vfs.vfs`` rooted at the working directory.
 
         hgvfs
            ``vfs.vfs`` rooted at .hg/
 
         requirements
            ``set`` of bytestrings representing repository opening requirements.
 
         supportedrequirements
            ``set`` of bytestrings representing repository requirements that we
            know how to open. May be a supetset of ``requirements``.
 
         sharedpath
            ``bytes`` Defining path to storage base directory. Points to a
            ``.hg/`` directory somewhere.
 
         store
            ``store.basicstore`` (or derived) instance providing access to
            versioned storage.
 
         cachevfs
            ``vfs.vfs`` used for cache files.
 
         wcachevfs
            ``vfs.vfs`` used for cache files related to the working copy.
 
         features
            ``set`` of bytestrings defining features/capabilities of this
            instance.
 
         intents
            ``set`` of system strings indicating what this repo will be used
            for.
         """
         self.baseui = baseui
         self.ui = ui
         self.origroot = origroot
         # vfs rooted at working directory.
         self.wvfs = wdirvfs
         self.root = wdirvfs.base
         # vfs rooted at .hg/. Used to access most non-store paths.
         self.vfs = hgvfs
         self.path = hgvfs.base
         self.requirements = requirements
         self.nodeconstants = sha1nodeconstants
         self.nullid = self.nodeconstants.nullid
         self.supported = supportedrequirements
         self.sharedpath = sharedpath
         self.store = store
         self.cachevfs = cachevfs
         self.wcachevfs = wcachevfs
         self.features = features
 
         self.filtername = None
 
         if self.ui.configbool(b'devel', b'all-warnings') or self.ui.configbool(
             b'devel', b'check-locks'
         ):
             self.vfs.audit = self._getvfsward(self.vfs.audit)
         # A list of callback to shape the phase if no data were found.
         # Callback are in the form: func(repo, roots) --> processed root.
         # This list it to be filled by extension during repo setup
         self._phasedefaults = []
 
         color.setup(self.ui)
 
         self.spath = self.store.path
         self.svfs = self.store.vfs
         self.sjoin = self.store.join
         if self.ui.configbool(b'devel', b'all-warnings') or self.ui.configbool(
             b'devel', b'check-locks'
         ):
             if util.safehasattr(self.svfs, b'vfs'):  # this is filtervfs
                 self.svfs.vfs.audit = self._getsvfsward(self.svfs.vfs.audit)
             else:  # standard vfs
                 self.svfs.audit = self._getsvfsward(self.svfs.audit)
 
         self._dirstatevalidatewarned = False
 
         self._branchcaches = branchmap.BranchMapCache()
         self._revbranchcache = None
         self._filterpats = {}
         self._datafilters = {}
         self._transref = self._lockref = self._wlockref = None
 
         # A cache for various files under .hg/ that tracks file changes,
         # (used by the filecache decorator)
         #
         # Maps a property name to its util.filecacheentry
         self._filecache = {}
 
         # hold sets of revision to be filtered
         # should be cleared when something might have changed the filter value:
         # - new changesets,
         # - phase change,
         # - new obsolescence marker,
         # - working directory parent change,
         # - bookmark changes
         self.filteredrevcache = {}
 
         self._dirstate = None
         # post-dirstate-status hooks
         self._postdsstatus = []
 
         self._pending_narrow_pats = None
         self._pending_narrow_pats_dirstate = None
 
         # generic mapping between names and nodes
         self.names = namespaces.namespaces()
 
         # Key to signature value.
         self._sparsesignaturecache = {}
         # Signature to cached matcher instance.
         self._sparsematchercache = {}
 
         self._extrafilterid = repoview.extrafilter(ui)
 
         self.filecopiesmode = None
         if requirementsmod.COPIESSDC_REQUIREMENT in self.requirements:
             self.filecopiesmode = b'changeset-sidedata'
 
         self._wanted_sidedata = set()
         self._sidedata_computers = {}
         sidedatamod.set_sidedata_spec_for_repo(self)
 
     def _getvfsward(self, origfunc):
         """build a ward for self.vfs"""
         rref = weakref.ref(self)
 
         def checkvfs(path, mode=None):
             ret = origfunc(path, mode=mode)
             repo = rref()
             if (
                 repo is None
                 or not util.safehasattr(repo, b'_wlockref')
                 or not util.safehasattr(repo, b'_lockref')
             ):
                 return
             if mode in (None, b'r', b'rb'):
                 return
             if path.startswith(repo.path):
                 # truncate name relative to the repository (.hg)
                 path = path[len(repo.path) + 1 :]
             if path.startswith(b'cache/'):
                 msg = b'accessing cache with vfs instead of cachevfs: "%s"'
                 repo.ui.develwarn(msg % path, stacklevel=3, config=b"cache-vfs")
             # path prefixes covered by 'lock'
             vfs_path_prefixes = (
                 b'journal.',
                 b'undo.',
                 b'strip-backup/',
                 b'cache/',
             )
             if any(path.startswith(prefix) for prefix in vfs_path_prefixes):
                 if repo._currentlock(repo._lockref) is None:
                     repo.ui.develwarn(
                         b'write with no lock: "%s"' % path,
                         stacklevel=3,
                         config=b'check-locks',
                     )
             elif repo._currentlock(repo._wlockref) is None:
                 # rest of vfs files are covered by 'wlock'
                 #
                 # exclude special files
                 for prefix in self._wlockfreeprefix:
                     if path.startswith(prefix):
                         return
                 repo.ui.develwarn(
                     b'write with no wlock: "%s"' % path,
                     stacklevel=3,
                     config=b'check-locks',
                 )
             return ret
 
         return checkvfs
 
     def _getsvfsward(self, origfunc):
         """build a ward for self.svfs"""
         rref = weakref.ref(self)
 
         def checksvfs(path, mode=None):
             ret = origfunc(path, mode=mode)
             repo = rref()
             if repo is None or not util.safehasattr(repo, b'_lockref'):
                 return
             if mode in (None, b'r', b'rb'):
                 return
             if path.startswith(repo.sharedpath):
                 # truncate name relative to the repository (.hg)
                 path = path[len(repo.sharedpath) + 1 :]
             if repo._currentlock(repo._lockref) is None:
                 repo.ui.develwarn(
                     b'write with no lock: "%s"' % path, stacklevel=4
                 )
             return ret
 
         return checksvfs
 
+    @property
+    def vfs_map(self):
+        return {
+            b'': self.svfs,
+            b'plain': self.vfs,
+            b'store': self.svfs,
+        }
+
     def close(self):
         self._writecaches()
 
     def _writecaches(self):
         if self._revbranchcache:
             self._revbranchcache.write()
 
     def _restrictcapabilities(self, caps):
         if self.ui.configbool(b'experimental', b'bundle2-advertise'):
             caps = set(caps)
             capsblob = bundle2.encodecaps(
                 bundle2.getrepocaps(self, role=b'client')
             )
             caps.add(b'bundle2=' + urlreq.quote(capsblob))
         if self.ui.configbool(b'experimental', b'narrow'):
             caps.add(wireprototypes.NARROWCAP)
         return caps
 
     # Don't cache auditor/nofsauditor, or you'll end up with reference cycle:
     # self -> auditor -> self._checknested -> self
 
     @property
     def auditor(self):
         # This is only used by context.workingctx.match in order to
         # detect files in subrepos.
         return pathutil.pathauditor(self.root, callback=self._checknested)
 
     @property
     def nofsauditor(self):
         # This is only used by context.basectx.match in order to detect
         # files in subrepos.
         return pathutil.pathauditor(
             self.root, callback=self._checknested, realfs=False, cached=True
         )
 
     def _checknested(self, path):
         """Determine if path is a legal nested repository."""
         if not path.startswith(self.root):
             return False
         subpath = path[len(self.root) + 1 :]
         normsubpath = util.pconvert(subpath)
 
         # XXX: Checking against the current working copy is wrong in
         # the sense that it can reject things like
         #
         #   $ hg cat -r 10 sub/x.txt
         #
         # if sub/ is no longer a subrepository in the working copy
         # parent revision.
         #
         # However, it can of course also allow things that would have
         # been rejected before, such as the above cat command if sub/
         # is a subrepository now, but was a normal directory before.
         # The old path auditor would have rejected by mistake since it
         # panics when it sees sub/.hg/.
         #
         # All in all, checking against the working copy seems sensible
         # since we want to prevent access to nested repositories on
         # the filesystem *now*.
         ctx = self[None]
         parts = util.splitpath(subpath)
         while parts:
             prefix = b'/'.join(parts)
             if prefix in ctx.substate:
                 if prefix == normsubpath:
                     return True
                 else:
                     sub = ctx.sub(prefix)
                     return sub.checknested(subpath[len(prefix) + 1 :])
             else:
                 parts.pop()
         return False
 
     def peer(self, path=None):
         return localpeer(self, path=path)  # not cached to avoid reference cycle
 
     def unfiltered(self):
         """Return unfiltered version of the repository
 
         Intended to be overwritten by filtered repo."""
         return self
 
     def filtered(self, name, visibilityexceptions=None):
         """Return a filtered version of a repository
 
         The `name` parameter is the identifier of the requested view. This
         will return a repoview object set "exactly" to the specified view.
 
         This function does not apply recursive filtering to a repository. For
         example calling `repo.filtered("served")` will return a repoview using
         the "served" view, regardless of the initial view used by `repo`.
 
         In other word, there is always only one level of `repoview` "filtering".
         """
         if self._extrafilterid is not None and b'%' not in name:
             name = name + b'%' + self._extrafilterid
 
         cls = repoview.newtype(self.unfiltered().__class__)
         return cls(self, name, visibilityexceptions)
 
     @mixedrepostorecache(
         (b'bookmarks', b'plain'),
         (b'bookmarks.current', b'plain'),
         (b'bookmarks', b''),
         (b'00changelog.i', b''),
     )
     def _bookmarks(self):
         # Since the multiple files involved in the transaction cannot be
         # written atomically (with current repository format), there is a race
         # condition here.
         #
         # 1) changelog content A is read
         # 2) outside transaction update changelog to content B
         # 3) outside transaction update bookmark file referring to content B
         # 4) bookmarks file content is read and filtered against changelog-A
         #
         # When this happens, bookmarks against nodes missing from A are dropped.
         #
         # Having this happening during read is not great, but it become worse
         # when this happen during write because the bookmarks to the "unknown"
         # nodes will be dropped for good. However, writes happen within locks.
         # This locking makes it possible to have a race free consistent read.
         # For this purpose data read from disc before locking  are
         # "invalidated" right after the locks are taken. This invalidations are
         # "light", the `filecache` mechanism keep the data in memory and will
         # reuse them if the underlying files did not changed. Not parsing the
         # same data multiple times helps performances.
         #
         # Unfortunately in the case describe above, the files tracked by the
         # bookmarks file cache might not have changed, but the in-memory
         # content is still "wrong" because we used an older changelog content
         # to process the on-disk data. So after locking, the changelog would be
         # refreshed but `_bookmarks` would be preserved.
         # Adding `00changelog.i` to the list of tracked file is not
         # enough, because at the time we build the content for `_bookmarks` in
         # (4), the changelog file has already diverged from the content used
         # for loading `changelog` in (1)
         #
         # To prevent the issue, we force the changelog to be explicitly
         # reloaded while computing `_bookmarks`. The data race can still happen
         # without the lock (with a narrower window), but it would no longer go
         # undetected during the lock time refresh.
         #
         # The new schedule is as follow
         #
         # 1) filecache logic detect that `_bookmarks` needs to be computed
         # 2) cachestat for `bookmarks` and `changelog` are captured (for book)
         # 3) We force `changelog` filecache to be tested
         # 4) cachestat for `changelog` are captured (for changelog)
         # 5) `_bookmarks` is computed and cached
         #
         # The step in (3) ensure we have a changelog at least as recent as the
         # cache stat computed in (1). As a result at locking time:
         #  * if the changelog did not changed since (1) -> we can reuse the data
         #  * otherwise -> the bookmarks get refreshed.
         self._refreshchangelog()
         return bookmarks.bmstore(self)
 
     def _refreshchangelog(self):
         """make sure the in memory changelog match the on-disk one"""
         if 'changelog' in vars(self) and self.currenttransaction() is None:
             del self.changelog
 
     @property
     def _activebookmark(self):
         return self._bookmarks.active
 
     # _phasesets depend on changelog. what we need is to call
     # _phasecache.invalidate() if '00changelog.i' was changed, but it
     # can't be easily expressed in filecache mechanism.
     @storecache(b'phaseroots', b'00changelog.i')
     def _phasecache(self):
         return phases.phasecache(self, self._phasedefaults)
 
     @storecache(b'obsstore')
     def obsstore(self):
         return obsolete.makestore(self.ui, self)
 
     @changelogcache()
     def changelog(repo):
         # load dirstate before changelog to avoid race see issue6303
         repo.dirstate.prefetch_parents()
         return repo.store.changelog(
             txnutil.mayhavepending(repo.root),
             concurrencychecker=revlogchecker.get_checker(repo.ui, b'changelog'),
         )
 
     @manifestlogcache()
     def manifestlog(self):
         return self.store.manifestlog(self, self._storenarrowmatch)
 
     @unfilteredpropertycache
     def dirstate(self):
         if self._dirstate is None:
             self._dirstate = self._makedirstate()
         else:
             self._dirstate.refresh()
         return self._dirstate
 
     def _makedirstate(self):
         """Extension point for wrapping the dirstate per-repo."""
         sparsematchfn = None
         if sparse.use_sparse(self):
             sparsematchfn = lambda: sparse.matcher(self)
         v2_req = requirementsmod.DIRSTATE_V2_REQUIREMENT
         th = requirementsmod.DIRSTATE_TRACKED_HINT_V1
         use_dirstate_v2 = v2_req in self.requirements
         use_tracked_hint = th in self.requirements
 
         return dirstate.dirstate(
             self.vfs,
             self.ui,
             self.root,
             self._dirstatevalidate,
             sparsematchfn,
             self.nodeconstants,
             use_dirstate_v2,
             use_tracked_hint=use_tracked_hint,
         )
 
     def _dirstatevalidate(self, node):
         try:
             self.changelog.rev(node)
             return node
         except error.LookupError:
             if not self._dirstatevalidatewarned:
                 self._dirstatevalidatewarned = True
                 self.ui.warn(
                     _(b"warning: ignoring unknown working parent %s!\n")
                     % short(node)
                 )
             return self.nullid
 
     @storecache(narrowspec.FILENAME)
     def narrowpats(self):
         """matcher patterns for this repository's narrowspec
 
         A tuple of (includes, excludes).
         """
         # the narrow management should probably move into its own object
         val = self._pending_narrow_pats
         if val is None:
             val = narrowspec.load(self)
         return val
 
     @storecache(narrowspec.FILENAME)
     def _storenarrowmatch(self):
         if requirementsmod.NARROW_REQUIREMENT not in self.requirements:
             return matchmod.always()
         include, exclude = self.narrowpats
         return narrowspec.match(self.root, include=include, exclude=exclude)
 
     @storecache(narrowspec.FILENAME)
     def _narrowmatch(self):
         if requirementsmod.NARROW_REQUIREMENT not in self.requirements:
             return matchmod.always()
         narrowspec.checkworkingcopynarrowspec(self)
         include, exclude = self.narrowpats
         return narrowspec.match(self.root, include=include, exclude=exclude)
 
     def narrowmatch(self, match=None, includeexact=False):
         """matcher corresponding the the repo's narrowspec
 
         If `match` is given, then that will be intersected with the narrow
         matcher.
 
         If `includeexact` is True, then any exact matches from `match` will
         be included even if they're outside the narrowspec.
         """
         if match:
             if includeexact and not self._narrowmatch.always():
                 # do not exclude explicitly-specified paths so that they can
                 # be warned later on
                 em = matchmod.exact(match.files())
                 nm = matchmod.unionmatcher([self._narrowmatch, em])
                 return matchmod.intersectmatchers(match, nm)
             return matchmod.intersectmatchers(match, self._narrowmatch)
         return self._narrowmatch
 
     def setnarrowpats(self, newincludes, newexcludes):
         narrowspec.save(self, newincludes, newexcludes)
         self.invalidate(clearfilecache=True)
 
     @unfilteredpropertycache
     def _quick_access_changeid_null(self):
         return {
             b'null': (nullrev, self.nodeconstants.nullid),
             nullrev: (nullrev, self.nodeconstants.nullid),
             self.nullid: (nullrev, self.nullid),
         }
 
     @unfilteredpropertycache
     def _quick_access_changeid_wc(self):
         # also fast path access to the working copy parents
         # however, only do it for filter that ensure wc is visible.
         quick = self._quick_access_changeid_null.copy()
         cl = self.unfiltered().changelog
         for node in self.dirstate.parents():
             if node == self.nullid:
                 continue
             rev = cl.index.get_rev(node)
             if rev is None:
                 # unknown working copy parent case:
                 #
                 #   skip the fast path and let higher code deal with it
                 continue
             pair = (rev, node)
             quick[rev] = pair
             quick[node] = pair
             # also add the parents of the parents
             for r in cl.parentrevs(rev):
                 if r == nullrev:
                     continue
                 n = cl.node(r)
                 pair = (r, n)
                 quick[r] = pair
                 quick[n] = pair
         p1node = self.dirstate.p1()
         if p1node != self.nullid:
             quick[b'.'] = quick[p1node]
         return quick
 
     @unfilteredmethod
     def _quick_access_changeid_invalidate(self):
         if '_quick_access_changeid_wc' in vars(self):
             del self.__dict__['_quick_access_changeid_wc']
 
     @property
     def _quick_access_changeid(self):
         """an helper dictionnary for __getitem__ calls
 
         This contains a list of symbol we can recognise right away without
         further processing.
         """
         if self.filtername in repoview.filter_has_wc:
             return self._quick_access_changeid_wc
         return self._quick_access_changeid_null
 
     def __getitem__(self, changeid):
         # dealing with special cases
         if changeid is None:
             return context.workingctx(self)
         if isinstance(changeid, context.basectx):
             return changeid
 
         # dealing with multiple revisions
         if isinstance(changeid, slice):
             # wdirrev isn't contiguous so the slice shouldn't include it
             return [
                 self[i]
                 for i in range(*changeid.indices(len(self)))
                 if i not in self.changelog.filteredrevs
             ]
 
         # dealing with some special values
         quick_access = self._quick_access_changeid.get(changeid)
         if quick_access is not None:
             rev, node = quick_access
             return context.changectx(self, rev, node, maybe_filtered=False)
         if changeid == b'tip':
             node = self.changelog.tip()
             rev = self.changelog.rev(node)
             return context.changectx(self, rev, node)
 
         # dealing with arbitrary values
         try:
             if isinstance(changeid, int):
                 node = self.changelog.node(changeid)
                 rev = changeid
             elif changeid == b'.':
                 # this is a hack to delay/avoid loading obsmarkers
                 # when we know that '.' won't be hidden
                 node = self.dirstate.p1()
                 rev = self.unfiltered().changelog.rev(node)
             elif len(changeid) == self.nodeconstants.nodelen:
                 try:
                     node = changeid
                     rev = self.changelog.rev(changeid)
                 except error.FilteredLookupError:
                     changeid = hex(changeid)  # for the error message
                     raise
                 except LookupError:
                     # check if it might have come from damaged dirstate
                     #
                     # XXX we could avoid the unfiltered if we had a recognizable
                     # exception for filtered changeset access
                     if (
                         self.local()
                         and changeid in self.unfiltered().dirstate.parents()
                     ):
                         msg = _(b"working directory has unknown parent '%s'!")
                         raise error.Abort(msg % short(changeid))
                     changeid = hex(changeid)  # for the error message
                     raise
 
             elif len(changeid) == 2 * self.nodeconstants.nodelen:
                 node = bin(changeid)
                 rev = self.changelog.rev(node)
             else:
                 raise error.ProgrammingError(
                     b"unsupported changeid '%s' of type %s"
                     % (changeid, pycompat.bytestr(type(changeid)))
                 )
 
             return context.changectx(self, rev, node)
 
         except (error.FilteredIndexError, error.FilteredLookupError):
             raise error.FilteredRepoLookupError(
                 _(b"filtered revision '%s'") % pycompat.bytestr(changeid)
             )
         except (IndexError, LookupError):
             raise error.RepoLookupError(
                 _(b"unknown revision '%s'") % pycompat.bytestr(changeid)
             )
         except error.WdirUnsupported:
             return context.workingctx(self)
 
     def __contains__(self, changeid):
         """True if the given changeid exists"""
         try:
             self[changeid]
             return True
         except error.RepoLookupError:
             return False
 
     def __nonzero__(self):
         return True
 
     __bool__ = __nonzero__
 
     def __len__(self):
         # no need to pay the cost of repoview.changelog
         unfi = self.unfiltered()
         return len(unfi.changelog)
 
     def __iter__(self):
         return iter(self.changelog)
 
     def revs(self, expr: bytes, *args):
         """Find revisions matching a revset.
 
         The revset is specified as a string ``expr`` that may contain
         %-formatting to escape certain types. See ``revsetlang.formatspec``.
 
         Revset aliases from the configuration are not expanded. To expand
         user aliases, consider calling ``scmutil.revrange()`` or
         ``repo.anyrevs([expr], user=True)``.
 
         Returns a smartset.abstractsmartset, which is a list-like interface
         that contains integer revisions.
         """
         tree = revsetlang.spectree(expr, *args)
         return revset.makematcher(tree)(self)
 
     def set(self, expr: bytes, *args):
         """Find revisions matching a revset and emit changectx instances.
 
         This is a convenience wrapper around ``revs()`` that iterates the
         result and is a generator of changectx instances.
 
         Revset aliases from the configuration are not expanded. To expand
         user aliases, consider calling ``scmutil.revrange()``.
         """
         for r in self.revs(expr, *args):
             yield self[r]
 
     def anyrevs(self, specs: bytes, user=False, localalias=None):
         """Find revisions matching one of the given revsets.
 
         Revset aliases from the configuration are not expanded by default. To
         expand user aliases, specify ``user=True``. To provide some local
         definitions overriding user aliases, set ``localalias`` to
         ``{name: definitionstring}``.
         """
         if specs == [b'null']:
             return revset.baseset([nullrev])
         if specs == [b'.']:
             quick_data = self._quick_access_changeid.get(b'.')
             if quick_data is not None:
                 return revset.baseset([quick_data[0]])
         if user:
             m = revset.matchany(
                 self.ui,
                 specs,
                 lookup=revset.lookupfn(self),
                 localalias=localalias,
             )
         else:
             m = revset.matchany(None, specs, localalias=localalias)
         return m(self)
 
     def url(self) -> bytes:
         return b'file:' + self.root
 
     def hook(self, name, throw=False, **args):
         """Call a hook, passing this repo instance.
 
         This a convenience method to aid invoking hooks. Extensions likely
         won't call this unless they have registered a custom hook or are
         replacing code that is expected to call a hook.
         """
         return hook.hook(self.ui, self, name, throw, **args)
 
     @filteredpropertycache
     def _tagscache(self):
         """Returns a tagscache object that contains various tags related
         caches."""
 
         # This simplifies its cache management by having one decorated
         # function (this one) and the rest simply fetch things from it.
         class tagscache:
             def __init__(self):
                 # These two define the set of tags for this repository. tags
                 # maps tag name to node; tagtypes maps tag name to 'global' or
                 # 'local'. (Global tags are defined by .hgtags across all
                 # heads, and local tags are defined in .hg/localtags.)
                 # They constitute the in-memory cache of tags.
                 self.tags = self.tagtypes = None
 
                 self.nodetagscache = self.tagslist = None
 
         cache = tagscache()
         cache.tags, cache.tagtypes = self._findtags()
 
         return cache
 
     def tags(self):
         '''return a mapping of tag to node'''
         t = {}
         if self.changelog.filteredrevs:
             tags, tt = self._findtags()
         else:
             tags = self._tagscache.tags
         rev = self.changelog.rev
         for k, v in tags.items():
             try:
                 # ignore tags to unknown nodes
                 rev(v)
                 t[k] = v
             except (error.LookupError, ValueError):
                 pass
         return t
 
     def _findtags(self):
         """Do the hard work of finding tags.  Return a pair of dicts
         (tags, tagtypes) where tags maps tag name to node, and tagtypes
         maps tag name to a string like \'global\' or \'local\'.
         Subclasses or extensions are free to add their own tags, but
         should be aware that the returned dicts will be retained for the
         duration of the localrepo object."""
 
         # XXX what tagtype should subclasses/extensions use?  Currently
         # mq and bookmarks add tags, but do not set the tagtype at all.
         # Should each extension invent its own tag type?  Should there
         # be one tagtype for all such "virtual" tags?  Or is the status
         # quo fine?
 
         # map tag name to (node, hist)
         alltags = tagsmod.findglobaltags(self.ui, self)
         # map tag name to tag type
         tagtypes = {tag: b'global' for tag in alltags}
 
         tagsmod.readlocaltags(self.ui, self, alltags, tagtypes)
 
         # Build the return dicts.  Have to re-encode tag names because
         # the tags module always uses UTF-8 (in order not to lose info
         # writing to the cache), but the rest of Mercurial wants them in
         # local encoding.
         tags = {}
         for name, (node, hist) in alltags.items():
             if node != self.nullid:
                 tags[encoding.tolocal(name)] = node
         tags[b'tip'] = self.changelog.tip()
         tagtypes = {
             encoding.tolocal(name): value for (name, value) in tagtypes.items()
         }
         return (tags, tagtypes)
 
     def tagtype(self, tagname):
         """
         return the type of the given tag. result can be:
 
         'local'  : a local tag
         'global' : a global tag
         None     : tag does not exist
         """
 
         return self._tagscache.tagtypes.get(tagname)
 
     def tagslist(self):
         '''return a list of tags ordered by revision'''
         if not self._tagscache.tagslist:
             l = []
             for t, n in self.tags().items():
                 l.append((self.changelog.rev(n), t, n))
             self._tagscache.tagslist = [(t, n) for r, t, n in sorted(l)]
 
         return self._tagscache.tagslist
 
     def nodetags(self, node):
         '''return the tags associated with a node'''
         if not self._tagscache.nodetagscache:
             nodetagscache = {}
             for t, n in self._tagscache.tags.items():
                 nodetagscache.setdefault(n, []).append(t)
             for tags in nodetagscache.values():
                 tags.sort()
             self._tagscache.nodetagscache = nodetagscache
         return self._tagscache.nodetagscache.get(node, [])
 
     def nodebookmarks(self, node):
         """return the list of bookmarks pointing to the specified node"""
         return self._bookmarks.names(node)
 
     def branchmap(self):
         """returns a dictionary {branch: [branchheads]} with branchheads
         ordered by increasing revision number"""
         return self._branchcaches[self]
 
     @unfilteredmethod
     def revbranchcache(self):
         if not self._revbranchcache:
             self._revbranchcache = branchmap.revbranchcache(self.unfiltered())
         return self._revbranchcache
 
     def register_changeset(self, rev, changelogrevision):
         self.revbranchcache().setdata(rev, changelogrevision)
 
     def branchtip(self, branch, ignoremissing=False):
         """return the tip node for a given branch
 
         If ignoremissing is True, then this method will not raise an error.
         This is helpful for callers that only expect None for a missing branch
         (e.g. namespace).
 
         """
         try:
             return self.branchmap().branchtip(branch)
         except KeyError:
             if not ignoremissing:
                 raise error.RepoLookupError(_(b"unknown branch '%s'") % branch)
             else:
                 pass
 
     def lookup(self, key):
         node = scmutil.revsymbol(self, key).node()
         if node is None:
             raise error.RepoLookupError(_(b"unknown revision '%s'") % key)
         return node
 
     def lookupbranch(self, key):
         if self.branchmap().hasbranch(key):
             return key
 
         return scmutil.revsymbol(self, key).branch()
 
     def known(self, nodes):
         cl = self.changelog
         get_rev = cl.index.get_rev
         filtered = cl.filteredrevs
         result = []
         for n in nodes:
             r = get_rev(n)
             resp = not (r is None or r in filtered)
             result.append(resp)
         return result
 
     def local(self):
         return self
 
     def publishing(self):
         # it's safe (and desirable) to trust the publish flag unconditionally
         # so that we don't finalize changes shared between users via ssh or nfs
         return self.ui.configbool(b'phases', b'publish', untrusted=True)
 
     def cancopy(self):
         # so statichttprepo's override of local() works
         if not self.local():
             return False
         if not self.publishing():
             return True
         # if publishing we can't copy if there is filtered content
         return not self.filtered(b'visible').changelog.filteredrevs
 
     def shared(self):
         '''the type of shared repository (None if not shared)'''
         if self.sharedpath != self.path:
             return b'store'
         return None
 
     def wjoin(self, f: bytes, *insidef: bytes) -> bytes:
         return self.vfs.reljoin(self.root, f, *insidef)
 
     def setparents(self, p1, p2=None):
         if p2 is None:
             p2 = self.nullid
         self[None].setparents(p1, p2)
         self._quick_access_changeid_invalidate()
 
     def filectx(self, path: bytes, changeid=None, fileid=None, changectx=None):
         """changeid must be a changeset revision, if specified.
         fileid can be a file revision or node."""
         return context.filectx(
             self, path, changeid, fileid, changectx=changectx
         )
 
     def getcwd(self) -> bytes:
         return self.dirstate.getcwd()
 
     def pathto(self, f: bytes, cwd: Optional[bytes] = None) -> bytes:
         return self.dirstate.pathto(f, cwd)
 
     def _loadfilter(self, filter):
         if filter not in self._filterpats:
             l = []
             for pat, cmd in self.ui.configitems(filter):
                 if cmd == b'!':
                     continue
                 mf = matchmod.match(self.root, b'', [pat])
                 fn = None
                 params = cmd
                 for name, filterfn in self._datafilters.items():
                     if cmd.startswith(name):
                         fn = filterfn
                         params = cmd[len(name) :].lstrip()
                         break
                 if not fn:
                     fn = lambda s, c, **kwargs: procutil.filter(s, c)
                     fn.__name__ = 'commandfilter'
                 # Wrap old filters not supporting keyword arguments
                 if not pycompat.getargspec(fn)[2]:
                     oldfn = fn
                     fn = lambda s, c, oldfn=oldfn, **kwargs: oldfn(s, c)
                     fn.__name__ = 'compat-' + oldfn.__name__
                 l.append((mf, fn, params))
             self._filterpats[filter] = l
         return self._filterpats[filter]
 
     def _filter(self, filterpats, filename, data):
         for mf, fn, cmd in filterpats:
             if mf(filename):
                 self.ui.debug(
                     b"filtering %s through %s\n"
                     % (filename, cmd or pycompat.sysbytes(fn.__name__))
                 )
                 data = fn(data, cmd, ui=self.ui, repo=self, filename=filename)
                 break
 
         return data
 
     @unfilteredpropertycache
     def _encodefilterpats(self):
         return self._loadfilter(b'encode')
 
     @unfilteredpropertycache
     def _decodefilterpats(self):
         return self._loadfilter(b'decode')
 
     def adddatafilter(self, name, filter):
         self._datafilters[name] = filter
 
     def wread(self, filename: bytes) -> bytes:
         if self.wvfs.islink(filename):
             data = self.wvfs.readlink(filename)
         else:
             data = self.wvfs.read(filename)
         return self._filter(self._encodefilterpats, filename, data)
 
     def wwrite(
         self,
         filename: bytes,
         data: bytes,
         flags: bytes,
         backgroundclose=False,
         **kwargs
     ) -> int:
         """write ``data`` into ``filename`` in the working directory
 
         This returns length of written (maybe decoded) data.
         """
         data = self._filter(self._decodefilterpats, filename, data)
         if b'l' in flags:
             self.wvfs.symlink(data, filename)
         else:
             self.wvfs.write(
                 filename, data, backgroundclose=backgroundclose, **kwargs
             )
             if b'x' in flags:
                 self.wvfs.setflags(filename, False, True)
             else:
                 self.wvfs.setflags(filename, False, False)
         return len(data)
 
     def wwritedata(self, filename: bytes, data: bytes) -> bytes:
         return self._filter(self._decodefilterpats, filename, data)
 
     def currenttransaction(self):
         """return the current transaction or None if non exists"""
         if self._transref:
             tr = self._transref()
         else:
             tr = None
 
         if tr and tr.running():
             return tr
         return None
 
     def transaction(self, desc, report=None):
         if self.ui.configbool(b'devel', b'all-warnings') or self.ui.configbool(
             b'devel', b'check-locks'
         ):
             if self._currentlock(self._lockref) is None:
                 raise error.ProgrammingError(b'transaction requires locking')
         tr = self.currenttransaction()
         if tr is not None:
             return tr.nest(name=desc)
 
         # abort here if the journal already exists
         if self.svfs.exists(b"journal"):
             raise error.RepoError(
                 _(b"abandoned transaction found"),
                 hint=_(b"run 'hg recover' to clean up transaction"),
             )
 
         # At that point your dirstate should be clean:
         #
         # - If you don't have the wlock, why would you still have a dirty
         #   dirstate ?
         #
         # - If you hold the wlock, you should not be opening a transaction in
         #   the middle of a `distate.changing_*` block. The transaction needs to
         #   be open before that and wrap the change-context.
         #
         # - If you are not within a `dirstate.changing_*` context, why is our
         #   dirstate dirty?
         if self.dirstate._dirty:
             m = "cannot open a transaction with a dirty dirstate"
             raise error.ProgrammingError(m)
 
         idbase = b"%.40f#%f" % (random.random(), time.time())
         ha = hex(hashutil.sha1(idbase).digest())
         txnid = b'TXN:' + ha
         self.hook(b'pretxnopen', throw=True, txnname=desc, txnid=txnid)
 
         self._writejournal(desc)
         renames = [(vfs, x, undoname(x)) for vfs, x in self._journalfiles()]
         if report:
             rp = report
         else:
             rp = self.ui.warn
-        vfsmap = {b'plain': self.vfs, b'store': self.svfs}  # root of .hg/
+        vfsmap = self.vfs_map
         # we must avoid cyclic reference between repo and transaction.
         reporef = weakref.ref(self)
         # Code to track tag movement
         #
         # Since tags are all handled as file content, it is actually quite hard
         # to track these movement from a code perspective. So we fallback to a
         # tracking at the repository level. One could envision to track changes
         # to the '.hgtags' file through changegroup apply but that fails to
         # cope with case where transaction expose new heads without changegroup
         # being involved (eg: phase movement).
         #
         # For now, We gate the feature behind a flag since this likely comes
         # with performance impacts. The current code run more often than needed
         # and do not use caches as much as it could.  The current focus is on
         # the behavior of the feature so we disable it by default. The flag
         # will be removed when we are happy with the performance impact.
         #
         # Once this feature is no longer experimental move the following
         # documentation to the appropriate help section:
         #
         # The ``HG_TAG_MOVED`` variable will be set if the transaction touched
         # tags (new or changed or deleted tags). In addition the details of
         # these changes are made available in a file at:
         #     ``REPOROOT/.hg/changes/tags.changes``.
         # Make sure you check for HG_TAG_MOVED before reading that file as it
         # might exist from a previous transaction even if no tag were touched
         # in this one. Changes are recorded in a line base format::
         #
         #     <action> <hex-node> <tag-name>\n
         #
         # Actions are defined as follow:
         #   "-R": tag is removed,
         #   "+A": tag is added,
         #   "-M": tag is moved (old value),
         #   "+M": tag is moved (new value),
         tracktags = lambda x: None
         # experimental config: experimental.hook-track-tags
         shouldtracktags = self.ui.configbool(
             b'experimental', b'hook-track-tags'
         )
         if desc != b'strip' and shouldtracktags:
             oldheads = self.changelog.headrevs()
 
             def tracktags(tr2):
                 repo = reporef()
                 assert repo is not None  # help pytype
                 oldfnodes = tagsmod.fnoderevs(repo.ui, repo, oldheads)
                 newheads = repo.changelog.headrevs()
                 newfnodes = tagsmod.fnoderevs(repo.ui, repo, newheads)
                 # notes: we compare lists here.
                 # As we do it only once buiding set would not be cheaper
                 changes = tagsmod.difftags(repo.ui, repo, oldfnodes, newfnodes)
                 if changes:
                     tr2.hookargs[b'tag_moved'] = b'1'
                     with repo.vfs(
                         b'changes/tags.changes', b'w', atomictemp=True
                     ) as changesfile:
                         # note: we do not register the file to the transaction
                         # because we needs it to still exist on the transaction
                         # is close (for txnclose hooks)
                         tagsmod.writediff(changesfile, changes)
 
         def validate(tr2):
             """will run pre-closing hooks"""
             # XXX the transaction API is a bit lacking here so we take a hacky
             # path for now
             #
             # We cannot add this as a "pending" hooks since the 'tr.hookargs'
             # dict is copied before these run. In addition we needs the data
             # available to in memory hooks too.
             #
             # Moreover, we also need to make sure this runs before txnclose
             # hooks and there is no "pending" mechanism that would execute
             # logic only if hooks are about to run.
             #
             # Fixing this limitation of the transaction is also needed to track
             # other families of changes (bookmarks, phases, obsolescence).
             #
             # This will have to be fixed before we remove the experimental
             # gating.
             tracktags(tr2)
             repo = reporef()
             assert repo is not None  # help pytype
 
             singleheadopt = (b'experimental', b'single-head-per-branch')
             singlehead = repo.ui.configbool(*singleheadopt)
             if singlehead:
                 singleheadsub = repo.ui.configsuboptions(*singleheadopt)[1]
                 accountclosed = singleheadsub.get(
                     b"account-closed-heads", False
                 )
                 if singleheadsub.get(b"public-changes-only", False):
                     filtername = b"immutable"
                 else:
                     filtername = b"visible"
                 scmutil.enforcesinglehead(
                     repo, tr2, desc, accountclosed, filtername
                 )
             if hook.hashook(repo.ui, b'pretxnclose-bookmark'):
                 for name, (old, new) in sorted(
                     tr.changes[b'bookmarks'].items()
                 ):
                     args = tr.hookargs.copy()
                     args.update(bookmarks.preparehookargs(name, old, new))
                     repo.hook(
                         b'pretxnclose-bookmark',
                         throw=True,
                         **pycompat.strkwargs(args)
                     )
             if hook.hashook(repo.ui, b'pretxnclose-phase'):
                 cl = repo.unfiltered().changelog
                 for revs, (old, new) in tr.changes[b'phases']:
                     for rev in revs:
                         args = tr.hookargs.copy()
                         node = hex(cl.node(rev))
                         args.update(phases.preparehookargs(node, old, new))
                         repo.hook(
                             b'pretxnclose-phase',
                             throw=True,
                             **pycompat.strkwargs(args)
                         )
 
             repo.hook(
                 b'pretxnclose', throw=True, **pycompat.strkwargs(tr.hookargs)
             )
 
         def releasefn(tr, success):
             repo = reporef()
             if repo is None:
                 # If the repo has been GC'd (and this release function is being
                 # called from transaction.__del__), there's not much we can do,
                 # so just leave the unfinished transaction there and let the
                 # user run `hg recover`.
                 return
             if success:
                 # this should be explicitly invoked here, because
                 # in-memory changes aren't written out at closing
                 # transaction, if tr.addfilegenerator (via
                 # dirstate.write or so) isn't invoked while
                 # transaction running
                 repo.dirstate.write(None)
             else:
                 # discard all changes (including ones already written
                 # out) in this transaction
                 repo.invalidate(clearfilecache=True)
 
         tr = transaction.transaction(
             rp,
             self.svfs,
             vfsmap,
             b"journal",
             b"undo",
             aftertrans(renames),
             self.store.createmode,
             validator=validate,
             releasefn=releasefn,
             checkambigfiles=_cachedfiles,
             name=desc,
         )
         tr.changes[b'origrepolen'] = len(self)
         tr.changes[b'obsmarkers'] = set()
         tr.changes[b'phases'] = []
         tr.changes[b'bookmarks'] = {}
 
         tr.hookargs[b'txnid'] = txnid
         tr.hookargs[b'txnname'] = desc
         tr.hookargs[b'changes'] = tr.changes
         # note: writing the fncache only during finalize mean that the file is
         # outdated when running hooks. As fncache is used for streaming clone,
         # this is not expected to break anything that happen during the hooks.
         tr.addfinalize(b'flush-fncache', self.store.write)
 
         def txnclosehook(tr2):
             """To be run if transaction is successful, will schedule a hook run"""
             # Don't reference tr2 in hook() so we don't hold a reference.
             # This reduces memory consumption when there are multiple
             # transactions per lock. This can likely go away if issue5045
             # fixes the function accumulation.
             hookargs = tr2.hookargs
 
             def hookfunc(unused_success):
                 repo = reporef()
                 assert repo is not None  # help pytype
 
                 if hook.hashook(repo.ui, b'txnclose-bookmark'):
                     bmchanges = sorted(tr.changes[b'bookmarks'].items())
                     for name, (old, new) in bmchanges:
                         args = tr.hookargs.copy()
                         args.update(bookmarks.preparehookargs(name, old, new))
                         repo.hook(
                             b'txnclose-bookmark',
                             throw=False,
                             **pycompat.strkwargs(args)
                         )
 
                 if hook.hashook(repo.ui, b'txnclose-phase'):
                     cl = repo.unfiltered().changelog
                     phasemv = sorted(
                         tr.changes[b'phases'], key=lambda r: r[0][0]
                     )
                     for revs, (old, new) in phasemv:
                         for rev in revs:
                             args = tr.hookargs.copy()
                             node = hex(cl.node(rev))
                             args.update(phases.preparehookargs(node, old, new))
                             repo.hook(
                                 b'txnclose-phase',
                                 throw=False,
                                 **pycompat.strkwargs(args)
                             )
 
                 repo.hook(
                     b'txnclose', throw=False, **pycompat.strkwargs(hookargs)
                 )
 
             repo = reporef()
             assert repo is not None  # help pytype
             repo._afterlock(hookfunc)
 
         tr.addfinalize(b'txnclose-hook', txnclosehook)
         # Include a leading "-" to make it happen before the transaction summary
         # reports registered via scmutil.registersummarycallback() whose names
         # are 00-txnreport etc. That way, the caches will be warm when the
         # callbacks run.
         tr.addpostclose(b'-warm-cache', self._buildcacheupdater(tr))
 
         def txnaborthook(tr2):
             """To be run if transaction is aborted"""
             repo = reporef()
             assert repo is not None  # help pytype
             repo.hook(
                 b'txnabort', throw=False, **pycompat.strkwargs(tr2.hookargs)
             )
 
         tr.addabort(b'txnabort-hook', txnaborthook)
         # avoid eager cache invalidation. in-memory data should be identical
         # to stored data if transaction has no error.
         tr.addpostclose(b'refresh-filecachestats', self._refreshfilecachestats)
         self._transref = weakref.ref(tr)
         scmutil.registersummarycallback(self, tr, desc)
         # This only exist to deal with the need of rollback to have viable
         # parents at the end of the operation. So backup viable parents at the
         # time of this operation.
         #
         # We only do it when the `wlock` is taken, otherwise other might be
         # altering the dirstate under us.
         #
         # This is really not a great way to do this (first, because we cannot
         # always do it). There are more viable alternative that exists
         #
         # - backing only the working copy parent in a dedicated files and doing
         #   a clean "keep-update" to them on `hg rollback`.
         #
         # - slightly changing the behavior an applying a logic similar to "hg
         # strip" to pick a working copy destination on `hg rollback`
         if self.currentwlock() is not None:
             ds = self.dirstate
             if not self.vfs.exists(b'branch'):
                 # force a file to be written if None exist
                 ds.setbranch(b'default', None)
 
             def backup_dirstate(tr):
                 for f in ds.all_file_names():
                     # hardlink backup is okay because `dirstate` is always
                     # atomically written and possible data file are append only
                     # and resistant to trailing data.
                     tr.addbackup(f, hardlink=True, location=b'plain')
 
             tr.addvalidator(b'dirstate-backup', backup_dirstate)
         return tr
 
     def _journalfiles(self):
         return (
             (self.svfs, b'journal'),
             (self.vfs, b'journal.desc'),
         )
 
     def undofiles(self):
         return [(vfs, undoname(x)) for vfs, x in self._journalfiles()]
 
     @unfilteredmethod
     def _writejournal(self, desc):
         self.vfs.write(b"journal.desc", b"%d\n%s\n" % (len(self), desc))
 
     def recover(self):
         with self.lock():
             if self.svfs.exists(b"journal"):
                 self.ui.status(_(b"rolling back interrupted transaction\n"))
-                vfsmap = {
-                    b'': self.svfs,
-                    b'plain': self.vfs,
-                }
+                vfsmap = self.vfs_map
                 transaction.rollback(
                     self.svfs,
                     vfsmap,
                     b"journal",
                     self.ui.warn,
                     checkambigfiles=_cachedfiles,
                 )
                 self.invalidate()
                 return True
             else:
                 self.ui.warn(_(b"no interrupted transaction available\n"))
                 return False
 
     def rollback(self, dryrun=False, force=False):
         wlock = lock = None
         try:
             wlock = self.wlock()
             lock = self.lock()
             if self.svfs.exists(b"undo"):
                 return self._rollback(dryrun, force)
             else:
                 self.ui.warn(_(b"no rollback information available\n"))
                 return 1
         finally:
             release(lock, wlock)
 
     @unfilteredmethod  # Until we get smarter cache management
     def _rollback(self, dryrun, force):
         ui = self.ui
 
         parents = self.dirstate.parents()
         try:
             args = self.vfs.read(b'undo.desc').splitlines()
             (oldlen, desc, detail) = (int(args[0]), args[1], None)
             if len(args) >= 3:
                 detail = args[2]
             oldtip = oldlen - 1
 
             if detail and ui.verbose:
                 msg = _(
                     b'repository tip rolled back to revision %d'
                     b' (undo %s: %s)\n'
                 ) % (oldtip, desc, detail)
             else:
                 msg = _(
                     b'repository tip rolled back to revision %d (undo %s)\n'
                 ) % (oldtip, desc)
             parentgone = any(self[p].rev() > oldtip for p in parents)
         except IOError:
             msg = _(b'rolling back unknown transaction\n')
             desc = None
             parentgone = True
 
         if not force and self[b'.'] != self[b'tip'] and desc == b'commit':
             raise error.Abort(
                 _(
                     b'rollback of last commit while not checked out '
                     b'may lose data'
                 ),
                 hint=_(b'use -f to force'),
             )
 
         ui.status(msg)
         if dryrun:
             return 0
 
         self.destroying()
-        vfsmap = {b'plain': self.vfs, b'': self.svfs}
+        vfsmap = self.vfs_map
         skip_journal_pattern = None
         if not parentgone:
             skip_journal_pattern = RE_SKIP_DIRSTATE_ROLLBACK
         transaction.rollback(
             self.svfs,
             vfsmap,
             b'undo',
             ui.warn,
             checkambigfiles=_cachedfiles,
             skip_journal_pattern=skip_journal_pattern,
         )
         self.invalidate()
         self.dirstate.invalidate()
 
         if parentgone:
             # replace this with some explicit parent update in the future.
             has_node = self.changelog.index.has_node
             if not all(has_node(p) for p in self.dirstate._pl):
                 # There was no dirstate to backup initially, we need to drop
                 # the existing one.
                 with self.dirstate.changing_parents(self):
                     self.dirstate.setparents(self.nullid)
                     self.dirstate.clear()
 
             parents = tuple([p.rev() for p in self[None].parents()])
             if len(parents) > 1:
                 ui.status(
                     _(
                         b'working directory now based on '
                         b'revisions %d and %d\n'
                     )
                     % parents
                 )
             else:
                 ui.status(
                     _(b'working directory now based on revision %d\n') % parents
                 )
             mergestatemod.mergestate.clean(self)
 
         # TODO: if we know which new heads may result from this rollback, pass
         # them to destroy(), which will prevent the branchhead cache from being
         # invalidated.
         self.destroyed()
         return 0
 
     def _buildcacheupdater(self, newtransaction):
         """called during transaction to build the callback updating cache
 
         Lives on the repository to help extension who might want to augment
         this logic. For this purpose, the created transaction is passed to the
         method.
         """
         # we must avoid cyclic reference between repo and transaction.
         reporef = weakref.ref(self)
 
         def updater(tr):
             repo = reporef()
             assert repo is not None  # help pytype
             repo.updatecaches(tr)
 
         return updater
 
     @unfilteredmethod
     def updatecaches(self, tr=None, full=False, caches=None):
         """warm appropriate caches
 
         If this function is called after a transaction closed. The transaction
         will be available in the 'tr' argument. This can be used to selectively
         update caches relevant to the changes in that transaction.
 
         If 'full' is set, make sure all caches the function knows about have
         up-to-date data. Even the ones usually loaded more lazily.
 
         The `full` argument can take a special "post-clone" value. In this case
         the cache warming is made after a clone and of the slower cache might
         be skipped, namely the `.fnodetags` one. This argument is 5.8 specific
         as we plan for a cleaner way to deal with this for 5.9.
         """
         if tr is not None and tr.hookargs.get(b'source') == b'strip':
             # During strip, many caches are invalid but
             # later call to `destroyed` will refresh them.
             return
 
         unfi = self.unfiltered()
 
         if full:
             msg = (
                 "`full` argument for `repo.updatecaches` is deprecated\n"
                 "(use `caches=repository.CACHE_ALL` instead)"
             )
             self.ui.deprecwarn(msg, b"5.9")
             caches = repository.CACHES_ALL
             if full == b"post-clone":
                 caches = repository.CACHES_POST_CLONE
             caches = repository.CACHES_ALL
         elif caches is None:
             caches = repository.CACHES_DEFAULT
 
         if repository.CACHE_BRANCHMAP_SERVED in caches:
             if tr is None or tr.changes[b'origrepolen'] < len(self):
                 # accessing the 'served' branchmap should refresh all the others,
                 self.ui.debug(b'updating the branch cache\n')
                 self.filtered(b'served').branchmap()
                 self.filtered(b'served.hidden').branchmap()
                 # flush all possibly delayed write.
                 self._branchcaches.write_delayed(self)
 
         if repository.CACHE_CHANGELOG_CACHE in caches:
             self.changelog.update_caches(transaction=tr)
 
         if repository.CACHE_MANIFESTLOG_CACHE in caches:
             self.manifestlog.update_caches(transaction=tr)
 
         if repository.CACHE_REV_BRANCH in caches:
             rbc = unfi.revbranchcache()
             for r in unfi.changelog:
                 rbc.branchinfo(r)
             rbc.write()
 
         if repository.CACHE_FULL_MANIFEST in caches:
             # ensure the working copy parents are in the manifestfulltextcache
             for ctx in self[b'.'].parents():
                 ctx.manifest()  # accessing the manifest is enough
 
         if repository.CACHE_FILE_NODE_TAGS in caches:
             # accessing fnode cache warms the cache
             tagsmod.fnoderevs(self.ui, unfi, unfi.changelog.revs())
 
         if repository.CACHE_TAGS_DEFAULT in caches:
             # accessing tags warm the cache
             self.tags()
         if repository.CACHE_TAGS_SERVED in caches:
             self.filtered(b'served').tags()
 
         if repository.CACHE_BRANCHMAP_ALL in caches:
             # The CACHE_BRANCHMAP_ALL updates lazily-loaded caches immediately,
             # so we're forcing a write to cause these caches to be warmed up
             # even if they haven't explicitly been requested yet (if they've
             # never been used by hg, they won't ever have been written, even if
             # they're a subset of another kind of cache that *has* been used).
             for filt in repoview.filtertable.keys():
                 filtered = self.filtered(filt)
                 filtered.branchmap().write(filtered)
 
     def invalidatecaches(self):
         if '_tagscache' in vars(self):
             # can't use delattr on proxy
             del self.__dict__['_tagscache']
 
         self._branchcaches.clear()
         self.invalidatevolatilesets()
         self._sparsesignaturecache.clear()
 
     def invalidatevolatilesets(self):
         self.filteredrevcache.clear()
         obsolete.clearobscaches(self)
         self._quick_access_changeid_invalidate()
 
     def invalidatedirstate(self):
         """Invalidates the dirstate, causing the next call to dirstate
         to check if it was modified since the last time it was read,
         rereading it if it has.
 
         This is different to dirstate.invalidate() that it doesn't always
         rereads the dirstate. Use dirstate.invalidate() if you want to
         explicitly read the dirstate again (i.e. restoring it to a previous
         known good state)."""
         unfi = self.unfiltered()
         if 'dirstate' in unfi.__dict__:
             del unfi.__dict__['dirstate']
 
     def invalidate(self, clearfilecache=False):
         """Invalidates both store and non-store parts other than dirstate
 
         If a transaction is running, invalidation of store is omitted,
         because discarding in-memory changes might cause inconsistency
         (e.g. incomplete fncache causes unintentional failure, but
         redundant one doesn't).
         """
         unfiltered = self.unfiltered()  # all file caches are stored unfiltered
         for k in list(self._filecache.keys()):
             if (
                 k == b'changelog'
                 and self.currenttransaction()
                 and self.changelog._delayed
             ):
                 # The changelog object may store unwritten revisions. We don't
                 # want to lose them.
                 # TODO: Solve the problem instead of working around it.
                 continue
 
             if clearfilecache:
                 del self._filecache[k]
             try:
                 delattr(unfiltered, k)
             except AttributeError:
                 pass
         self.invalidatecaches()
         if not self.currenttransaction():
             # TODO: Changing contents of store outside transaction
             # causes inconsistency. We should make in-memory store
             # changes detectable, and abort if changed.
             self.store.invalidatecaches()
 
     def invalidateall(self):
         """Fully invalidates both store and non-store parts, causing the
         subsequent operation to reread any outside changes."""
         # extension should hook this to invalidate its caches
         self.invalidate()
         self.invalidatedirstate()
 
     @unfilteredmethod
     def _refreshfilecachestats(self, tr):
         """Reload stats of cached files so that they are flagged as valid"""
         for k, ce in self._filecache.items():
             k = pycompat.sysstr(k)
             if k == 'dirstate' or k not in self.__dict__:
                 continue
             ce.refresh()
 
     def _lock(
         self,
         vfs,
         lockname,
         wait,
         releasefn,
         acquirefn,
         desc,
     ):
         timeout = 0
         warntimeout = 0
         if wait:
             timeout = self.ui.configint(b"ui", b"timeout")
             warntimeout = self.ui.configint(b"ui", b"timeout.warn")
         # internal config: ui.signal-safe-lock
         signalsafe = self.ui.configbool(b'ui', b'signal-safe-lock')
 
         l = lockmod.trylock(
             self.ui,
             vfs,
             lockname,
             timeout,
             warntimeout,
             releasefn=releasefn,
             acquirefn=acquirefn,
             desc=desc,
             signalsafe=signalsafe,
         )
         return l
 
     def _afterlock(self, callback):
         """add a callback to be run when the repository is fully unlocked
 
         The callback will be executed when the outermost lock is released
         (with wlock being higher level than 'lock')."""
         for ref in (self._wlockref, self._lockref):
             l = ref and ref()
             if l and l.held:
                 l.postrelease.append(callback)
                 break
         else:  # no lock have been found.
             callback(True)
 
     def lock(self, wait=True):
         """Lock the repository store (.hg/store) and return a weak reference
         to the lock. Use this before modifying the store (e.g. committing or
         stripping). If you are opening a transaction, get a lock as well.)
 
         If both 'lock' and 'wlock' must be acquired, ensure you always acquires
         'wlock' first to avoid a dead-lock hazard."""
         l = self._currentlock(self._lockref)
         if l is not None:
             l.lock()
             return l
 
         l = self._lock(
             vfs=self.svfs,
             lockname=b"lock",
             wait=wait,
             releasefn=None,
             acquirefn=self.invalidate,
             desc=_(b'repository %s') % self.origroot,
         )
         self._lockref = weakref.ref(l)
         return l
 
     def wlock(self, wait=True):
         """Lock the non-store parts of the repository (everything under
         .hg except .hg/store) and return a weak reference to the lock.
 
         Use this before modifying files in .hg.
 
         If both 'lock' and 'wlock' must be acquired, ensure you always acquires
         'wlock' first to avoid a dead-lock hazard."""
         l = self._wlockref() if self._wlockref else None
         if l is not None and l.held:
             l.lock()
             return l
 
         # We do not need to check for non-waiting lock acquisition.  Such
         # acquisition would not cause dead-lock as they would just fail.
         if wait and (
             self.ui.configbool(b'devel', b'all-warnings')
             or self.ui.configbool(b'devel', b'check-locks')
         ):
             if self._currentlock(self._lockref) is not None:
                 self.ui.develwarn(b'"wlock" acquired after "lock"')
 
         def unlock():
             if self.dirstate.is_changing_any:
                 msg = b"wlock release in the middle of a changing parents"
                 self.ui.develwarn(msg)
                 self.dirstate.invalidate()
             else:
                 if self.dirstate._dirty:
                     msg = b"dirty dirstate on wlock release"
                     self.ui.develwarn(msg)
                 self.dirstate.write(None)
 
             unfi = self.unfiltered()
             if 'dirstate' in unfi.__dict__:
                 del unfi.__dict__['dirstate']
 
         l = self._lock(
             self.vfs,
             b"wlock",
             wait,
             unlock,
             self.invalidatedirstate,
             _(b'working directory of %s') % self.origroot,
         )
         self._wlockref = weakref.ref(l)
         return l
 
     def _currentlock(self, lockref):
         """Returns the lock if it's held, or None if it's not."""
         if lockref is None:
             return None
         l = lockref()
         if l is None or not l.held:
             return None
         return l
 
     def currentwlock(self):
         """Returns the wlock if it's held, or None if it's not."""
         return self._currentlock(self._wlockref)
 
     def checkcommitpatterns(self, wctx, match, status, fail):
         """check for commit arguments that aren't committable"""
         if match.isexact() or match.prefix():
             matched = set(status.modified + status.added + status.removed)
 
             for f in match.files():
                 f = self.dirstate.normalize(f)
                 if f == b'.' or f in matched or f in wctx.substate:
                     continue
                 if f in status.deleted:
                     fail(f, _(b'file not found!'))
                 # Is it a directory that exists or used to exist?
                 if self.wvfs.isdir(f) or wctx.p1().hasdir(f):
                     d = f + b'/'
                     for mf in matched:
                         if mf.startswith(d):
                             break
                     else:
                         fail(f, _(b"no match under directory!"))
                 elif f not in self.dirstate:
                     fail(f, _(b"file not tracked!"))
 
     @unfilteredmethod
     def commit(
         self,
         text=b"",
         user=None,
         date=None,
         match=None,
         force=False,
         editor=None,
         extra=None,
     ):
         """Add a new revision to current repository.
 
         Revision information is gathered from the working directory,
         match can be used to filter the committed files. If editor is
         supplied, it is called to get a commit message.
         """
         if extra is None:
             extra = {}
 
         def fail(f, msg):
             raise error.InputError(b'%s: %s' % (f, msg))
 
         if not match:
             match = matchmod.always()
 
         if not force:
             match.bad = fail
 
         # lock() for recent changelog (see issue4368)
         with self.wlock(), self.lock():
             wctx = self[None]
             merge = len(wctx.parents()) > 1
 
             if not force and merge and not match.always():
                 raise error.Abort(
                     _(
                         b'cannot partially commit a merge '
                         b'(do not specify files or patterns)'
                     )
                 )
 
             status = self.status(match=match, clean=force)
             if force:
                 status.modified.extend(
                     status.clean
                 )  # mq may commit clean files
 
             # check subrepos
             subs, commitsubs, newstate = subrepoutil.precommit(
                 self.ui, wctx, status, match, force=force
             )
 
             # make sure all explicit patterns are matched
             if not force:
                 self.checkcommitpatterns(wctx, match, status, fail)
 
             cctx = context.workingcommitctx(
                 self, status, text, user, date, extra
             )
 
             ms = mergestatemod.mergestate.read(self)
             mergeutil.checkunresolved(ms)
 
             # internal config: ui.allowemptycommit
             if cctx.isempty() and not self.ui.configbool(
                 b'ui', b'allowemptycommit'
             ):
                 self.ui.debug(b'nothing to commit, clearing merge state\n')
                 ms.reset()
                 return None
 
             if merge and cctx.deleted():
                 raise error.Abort(_(b"cannot commit merge with missing files"))
 
             if editor:
                 cctx._text = editor(self, cctx, subs)
             edited = text != cctx._text
 
             # Save commit message in case this transaction gets rolled back
             # (e.g. by a pretxncommit hook).  Leave the content alone on
             # the assumption that the user will use the same editor again.
             msg_path = self.savecommitmessage(cctx._text)
 
             # commit subs and write new state
             if subs:
                 uipathfn = scmutil.getuipathfn(self)
                 for s in sorted(commitsubs):
                     sub = wctx.sub(s)
                     self.ui.status(
                         _(b'committing subrepository %s\n')
                         % uipathfn(subrepoutil.subrelpath(sub))
                     )
                     sr = sub.commit(cctx._text, user, date)
                     newstate[s] = (newstate[s][0], sr)
                 subrepoutil.writestate(self, newstate)
 
             p1, p2 = self.dirstate.parents()
             hookp1, hookp2 = hex(p1), (p2 != self.nullid and hex(p2) or b'')
             try:
                 self.hook(
                     b"precommit", throw=True, parent1=hookp1, parent2=hookp2
                 )
                 with self.transaction(b'commit'):
                     ret = self.commitctx(cctx, True)
                     # update bookmarks, dirstate and mergestate
                     bookmarks.update(self, [p1, p2], ret)
                     cctx.markcommitted(ret)
                     ms.reset()
             except:  # re-raises
                 if edited:
                     self.ui.write(
                         _(b'note: commit message saved in %s\n') % msg_path
                     )
                     self.ui.write(
                         _(
                             b"note: use 'hg commit --logfile "
                             b"%s --edit' to reuse it\n"
                         )
                         % msg_path
                     )
                 raise
 
         def commithook(unused_success):
             # hack for command that use a temporary commit (eg: histedit)
             # temporary commit got stripped before hook release
             if self.changelog.hasnode(ret):
                 self.hook(
                     b"commit", node=hex(ret), parent1=hookp1, parent2=hookp2
                 )
 
         self._afterlock(commithook)
         return ret
 
     @unfilteredmethod
     def commitctx(self, ctx, error=False, origctx=None):
         return commit.commitctx(self, ctx, error=error, origctx=origctx)
 
     @unfilteredmethod
     def destroying(self):
         """Inform the repository that nodes are about to be destroyed.
         Intended for use by strip and rollback, so there's a common
         place for anything that has to be done before destroying history.
 
         This is mostly useful for saving state that is in memory and waiting
         to be flushed when the current lock is released. Because a call to
         destroyed is imminent, the repo will be invalidated causing those
         changes to stay in memory (waiting for the next unlock), or vanish
         completely.
         """
         # When using the same lock to commit and strip, the phasecache is left
         # dirty after committing. Then when we strip, the repo is invalidated,
         # causing those changes to disappear.
         if '_phasecache' in vars(self):
             self._phasecache.write()
 
     @unfilteredmethod
     def destroyed(self):
         """Inform the repository that nodes have been destroyed.
         Intended for use by strip and rollback, so there's a common
         place for anything that has to be done after destroying history.
         """
         # When one tries to:
         # 1) destroy nodes thus calling this method (e.g. strip)
         # 2) use phasecache somewhere (e.g. commit)
         #
         # then 2) will fail because the phasecache contains nodes that were
         # removed. We can either remove phasecache from the filecache,
         # causing it to reload next time it is accessed, or simply filter
         # the removed nodes now and write the updated cache.
         self._phasecache.filterunknown(self)
         self._phasecache.write()
 
         # refresh all repository caches
         self.updatecaches()
 
         # Ensure the persistent tag cache is updated.  Doing it now
         # means that the tag cache only has to worry about destroyed
         # heads immediately after a strip/rollback.  That in turn
         # guarantees that "cachetip == currenttip" (comparing both rev
         # and node) always means no nodes have been added or destroyed.
 
         # XXX this is suboptimal when qrefresh'ing: we strip the current
         # head, refresh the tag cache, then immediately add a new head.
         # But I think doing it this way is necessary for the "instant
         # tag cache retrieval" case to work.
         self.invalidate()
 
     def status(
         self,
         node1=b'.',
         node2=None,
         match=None,
         ignored=False,
         clean=False,
         unknown=False,
         listsubrepos=False,
     ):
         '''a convenience method that calls node1.status(node2)'''
         return self[node1].status(
             node2, match, ignored, clean, unknown, listsubrepos
         )
 
     def addpostdsstatus(self, ps):
         """Add a callback to run within the wlock, at the point at which status
         fixups happen.
 
         On status completion, callback(wctx, status) will be called with the
         wlock held, unless the dirstate has changed from underneath or the wlock
         couldn't be grabbed.
 
         Callbacks should not capture and use a cached copy of the dirstate --
         it might change in the meanwhile. Instead, they should access the
         dirstate via wctx.repo().dirstate.
 
         This list is emptied out after each status run -- extensions should
         make sure it adds to this list each time dirstate.status is called.
         Extensions should also make sure they don't call this for statuses
         that don't involve the dirstate.
         """
 
         # The list is located here for uniqueness reasons -- it is actually
         # managed by the workingctx, but that isn't unique per-repo.
         self._postdsstatus.append(ps)
 
     def postdsstatus(self):
         """Used by workingctx to get the list of post-dirstate-status hooks."""
         return self._postdsstatus
 
     def clearpostdsstatus(self):
         """Used by workingctx to clear post-dirstate-status hooks."""
         del self._postdsstatus[:]
 
     def heads(self, start=None):
         if start is None:
             cl = self.changelog
             headrevs = reversed(cl.headrevs())
             return [cl.node(rev) for rev in headrevs]
 
         heads = self.changelog.heads(start)
         # sort the output in rev descending order
         return sorted(heads, key=self.changelog.rev, reverse=True)
 
     def branchheads(self, branch=None, start=None, closed=False):
         """return a (possibly filtered) list of heads for the given branch
 
         Heads are returned in topological order, from newest to oldest.
         If branch is None, use the dirstate branch.
         If start is not None, return only heads reachable from start.
         If closed is True, return heads that are marked as closed as well.
         """
         if branch is None:
             branch = self[None].branch()
         branches = self.branchmap()
         if not branches.hasbranch(branch):
             return []
         # the cache returns heads ordered lowest to highest
         bheads = list(reversed(branches.branchheads(branch, closed=closed)))
         if start is not None:
             # filter out the heads that cannot be reached from startrev
             fbheads = set(self.changelog.nodesbetween([start], bheads)[2])
             bheads = [h for h in bheads if h in fbheads]
         return bheads
 
     def branches(self, nodes):
         if not nodes:
             nodes = [self.changelog.tip()]
         b = []
         for n in nodes:
             t = n
             while True:
                 p = self.changelog.parents(n)
                 if p[1] != self.nullid or p[0] == self.nullid:
                     b.append((t, n, p[0], p[1]))
                     break
                 n = p[0]
         return b
 
     def between(self, pairs):
         r = []
 
         for top, bottom in pairs:
             n, l, i = top, [], 0
             f = 1
 
             while n != bottom and n != self.nullid:
                 p = self.changelog.parents(n)[0]
                 if i == f:
                     l.append(n)
                     f = f * 2
                 n = p
                 i += 1
 
             r.append(l)
 
         return r
 
     def checkpush(self, pushop):
         """Extensions can override this function if additional checks have
         to be performed before pushing, or call it if they override push
         command.
         """
 
     @unfilteredpropertycache
     def prepushoutgoinghooks(self):
         """Return util.hooks consists of a pushop with repo, remote, outgoing
         methods, which are called before pushing changesets.
         """
         return util.hooks()
 
     def pushkey(self, namespace, key, old, new):
         try:
             tr = self.currenttransaction()
             hookargs = {}
             if tr is not None:
                 hookargs.update(tr.hookargs)
             hookargs = pycompat.strkwargs(hookargs)
             hookargs['namespace'] = namespace
             hookargs['key'] = key
             hookargs['old'] = old
             hookargs['new'] = new
             self.hook(b'prepushkey', throw=True, **hookargs)
         except error.HookAbort as exc:
             self.ui.write_err(_(b"pushkey-abort: %s\n") % exc)
             if exc.hint:
                 self.ui.write_err(_(b"(%s)\n") % exc.hint)
             return False
         self.ui.debug(b'pushing key for "%s:%s"\n' % (namespace, key))
         ret = pushkey.push(self, namespace, key, old, new)
 
         def runhook(unused_success):
             self.hook(
                 b'pushkey',
                 namespace=namespace,
                 key=key,
                 old=old,
                 new=new,
                 ret=ret,
             )
 
         self._afterlock(runhook)
         return ret
 
     def listkeys(self, namespace):
         self.hook(b'prelistkeys', throw=True, namespace=namespace)
         self.ui.debug(b'listing keys for "%s"\n' % namespace)
         values = pushkey.list(self, namespace)
         self.hook(b'listkeys', namespace=namespace, values=values)
         return values
 
     def debugwireargs(self, one, two, three=None, four=None, five=None):
         '''used to test argument passing over the wire'''
         return b"%s %s %s %s %s" % (
             one,
             two,
             pycompat.bytestr(three),
             pycompat.bytestr(four),
             pycompat.bytestr(five),
         )
 
     def savecommitmessage(self, text):
         fp = self.vfs(b'last-message.txt', b'wb')
         try:
             fp.write(text)
         finally:
             fp.close()
         return self.pathto(fp.name[len(self.root) + 1 :])
 
     def register_wanted_sidedata(self, category):
         if repository.REPO_FEATURE_SIDE_DATA not in self.features:
             # Only revlogv2 repos can want sidedata.
             return
         self._wanted_sidedata.add(pycompat.bytestr(category))
 
     def register_sidedata_computer(
         self, kind, category, keys, computer, flags, replace=False
     ):
         if kind not in revlogconst.ALL_KINDS:
             msg = _(b"unexpected revlog kind '%s'.")
             raise error.ProgrammingError(msg % kind)
         category = pycompat.bytestr(category)
         already_registered = category in self._sidedata_computers.get(kind, [])
         if already_registered and not replace:
             msg = _(
                 b"cannot register a sidedata computer twice for category '%s'."
             )
             raise error.ProgrammingError(msg % category)
         if replace and not already_registered:
             msg = _(
                 b"cannot replace a sidedata computer that isn't registered "
                 b"for category '%s'."
             )
             raise error.ProgrammingError(msg % category)
         self._sidedata_computers.setdefault(kind, {})
         self._sidedata_computers[kind][category] = (keys, computer, flags)
 
 
 # used to avoid circular references so destructors work
 def aftertrans(files):
     renamefiles = [tuple(t) for t in files]
 
     def a():
         for vfs, src, dest in renamefiles:
             # if src and dest refer to a same file, vfs.rename is a no-op,
             # leaving both src and dest on disk. delete dest to make sure
             # the rename couldn't be such a no-op.
             vfs.tryunlink(dest)
             try:
                 vfs.rename(src, dest)
             except FileNotFoundError:  # journal file does not yet exist
                 pass
 
     return a
 
 
 def undoname(fn: bytes) -> bytes:
     base, name = os.path.split(fn)
     assert name.startswith(b'journal')
     return os.path.join(base, name.replace(b'journal', b'undo', 1))
 
 
 def instance(ui, path: bytes, create, intents=None, createopts=None):
     # prevent cyclic import localrepo -> upgrade -> localrepo
     from . import upgrade
 
     localpath = urlutil.urllocalpath(path)
     if create:
         createrepository(ui, localpath, createopts=createopts)
 
     def repo_maker():
         return makelocalrepository(ui, localpath, intents=intents)
 
     repo = repo_maker()
     repo = upgrade.may_auto_upgrade(repo, repo_maker)
     return repo
 
 
 def islocal(path: bytes) -> bool:
     return True
 
 
 def defaultcreateopts(ui, createopts=None):
     """Populate the default creation options for a repository.
 
     A dictionary of explicitly requested creation options can be passed
     in. Missing keys will be populated.
     """
     createopts = dict(createopts or {})
 
     if b'backend' not in createopts:
         # experimental config: storage.new-repo-backend
         createopts[b'backend'] = ui.config(b'storage', b'new-repo-backend')
 
     return createopts
 
 
 def clone_requirements(ui, createopts, srcrepo):
     """clone the requirements of a local repo for a local clone
 
     The store requirements are unchanged while the working copy requirements
     depends on the configuration
     """
     target_requirements = set()
     if not srcrepo.requirements:
         # this is a legacy revlog "v0" repository, we cannot do anything fancy
         # with it.
         return target_requirements
     createopts = defaultcreateopts(ui, createopts=createopts)
     for r in newreporequirements(ui, createopts):
         if r in requirementsmod.WORKING_DIR_REQUIREMENTS:
             target_requirements.add(r)
 
     for r in srcrepo.requirements:
         if r not in requirementsmod.WORKING_DIR_REQUIREMENTS:
             target_requirements.add(r)
     return target_requirements
 
 
 def newreporequirements(ui, createopts):
     """Determine the set of requirements for a new local repository.
 
     Extensions can wrap this function to specify custom requirements for
     new repositories.
     """
 
     if b'backend' not in createopts:
         raise error.ProgrammingError(
             b'backend key not present in createopts; '
             b'was defaultcreateopts() called?'
         )
 
     if createopts[b'backend'] != b'revlogv1':
         raise error.Abort(
             _(
                 b'unable to determine repository requirements for '
                 b'storage backend: %s'
             )
             % createopts[b'backend']
         )
 
     requirements = {requirementsmod.REVLOGV1_REQUIREMENT}
     if ui.configbool(b'format', b'usestore'):
         requirements.add(requirementsmod.STORE_REQUIREMENT)
         if ui.configbool(b'format', b'usefncache'):
             requirements.add(requirementsmod.FNCACHE_REQUIREMENT)
             if ui.configbool(b'format', b'dotencode'):
                 requirements.add(requirementsmod.DOTENCODE_REQUIREMENT)
 
     compengines = ui.configlist(b'format', b'revlog-compression')
     for compengine in compengines:
         if compengine in util.compengines:
             engine = util.compengines[compengine]
             if engine.available() and engine.revlogheader():
                 break
     else:
         raise error.Abort(
             _(
                 b'compression engines %s defined by '
                 b'format.revlog-compression not available'
             )
             % b', '.join(b'"%s"' % e for e in compengines),
             hint=_(
                 b'run "hg debuginstall" to list available '
                 b'compression engines'
             ),
         )
 
     # zlib is the historical default and doesn't need an explicit requirement.
     if compengine == b'zstd':
         requirements.add(b'revlog-compression-zstd')
     elif compengine != b'zlib':
         requirements.add(b'exp-compression-%s' % compengine)
 
     if scmutil.gdinitconfig(ui):
         requirements.add(requirementsmod.GENERALDELTA_REQUIREMENT)
         if ui.configbool(b'format', b'sparse-revlog'):
             requirements.add(requirementsmod.SPARSEREVLOG_REQUIREMENT)
 
     # experimental config: format.use-dirstate-v2
     # Keep this logic in sync with `has_dirstate_v2()` in `tests/hghave.py`
     if ui.configbool(b'format', b'use-dirstate-v2'):
         requirements.add(requirementsmod.DIRSTATE_V2_REQUIREMENT)
 
     # experimental config: format.exp-use-copies-side-data-changeset
     if ui.configbool(b'format', b'exp-use-copies-side-data-changeset'):
         requirements.add(requirementsmod.CHANGELOGV2_REQUIREMENT)
         requirements.add(requirementsmod.COPIESSDC_REQUIREMENT)
     if ui.configbool(b'experimental', b'treemanifest'):
         requirements.add(requirementsmod.TREEMANIFEST_REQUIREMENT)
 
     changelogv2 = ui.config(b'format', b'exp-use-changelog-v2')
     if changelogv2 == b'enable-unstable-format-and-corrupt-my-data':
         requirements.add(requirementsmod.CHANGELOGV2_REQUIREMENT)
 
     revlogv2 = ui.config(b'experimental', b'revlogv2')
     if revlogv2 == b'enable-unstable-format-and-corrupt-my-data':
         requirements.discard(requirementsmod.REVLOGV1_REQUIREMENT)
         requirements.add(requirementsmod.REVLOGV2_REQUIREMENT)
     # experimental config: format.internal-phase
     if ui.configbool(b'format', b'use-internal-phase'):
         requirements.add(requirementsmod.INTERNAL_PHASE_REQUIREMENT)
 
     # experimental config: format.exp-archived-phase
     if ui.configbool(b'format', b'exp-archived-phase'):
         requirements.add(requirementsmod.ARCHIVED_PHASE_REQUIREMENT)
 
     if createopts.get(b'narrowfiles'):
         requirements.add(requirementsmod.NARROW_REQUIREMENT)
 
     if createopts.get(b'lfs'):
         requirements.add(b'lfs')
 
     if ui.configbool(b'format', b'bookmarks-in-store'):
         requirements.add(requirementsmod.BOOKMARKS_IN_STORE_REQUIREMENT)
 
     if ui.configbool(b'format', b'use-persistent-nodemap'):
         requirements.add(requirementsmod.NODEMAP_REQUIREMENT)
 
     # if share-safe is enabled, let's create the new repository with the new
     # requirement
     if ui.configbool(b'format', b'use-share-safe'):
         requirements.add(requirementsmod.SHARESAFE_REQUIREMENT)
 
     # if we are creating a share-repo¹  we have to handle requirement
     # differently.
     #
     # [1] (i.e. reusing the store from another repository, just having a
     # working copy)
     if b'sharedrepo' in createopts:
         source_requirements = set(createopts[b'sharedrepo'].requirements)
 
         if requirementsmod.SHARESAFE_REQUIREMENT not in source_requirements:
             # share to an old school repository, we have to copy the
             # requirements and hope for the best.
             requirements = source_requirements
         else:
             # We have control on the working copy only, so "copy" the non
             # working copy part over, ignoring previous logic.
             to_drop = set()
             for req in requirements:
                 if req in requirementsmod.WORKING_DIR_REQUIREMENTS:
                     continue
                 if req in source_requirements:
                     continue
                 to_drop.add(req)
             requirements -= to_drop
             requirements |= source_requirements
 
         if createopts.get(b'sharedrelative'):
             requirements.add(requirementsmod.RELATIVE_SHARED_REQUIREMENT)
         else:
             requirements.add(requirementsmod.SHARED_REQUIREMENT)
 
     if ui.configbool(b'format', b'use-dirstate-tracked-hint'):
         version = ui.configint(b'format', b'use-dirstate-tracked-hint.version')
         msg = _(b"ignoring unknown tracked key version: %d\n")
         hint = _(
             b"see `hg help config.format.use-dirstate-tracked-hint-version"
         )
         if version != 1:
             ui.warn(msg % version, hint=hint)
         else:
             requirements.add(requirementsmod.DIRSTATE_TRACKED_HINT_V1)
 
     return requirements
 
 
 def checkrequirementscompat(ui, requirements):
     """Checks compatibility of repository requirements enabled and disabled.
 
     Returns a set of requirements which needs to be dropped because dependend
     requirements are not enabled. Also warns users about it"""
 
     dropped = set()
 
     if requirementsmod.STORE_REQUIREMENT not in requirements:
         if requirementsmod.BOOKMARKS_IN_STORE_REQUIREMENT in requirements:
             ui.warn(
                 _(
                     b'ignoring enabled \'format.bookmarks-in-store\' config '
                     b'beacuse it is incompatible with disabled '
                     b'\'format.usestore\' config\n'
                 )
             )
             dropped.add(requirementsmod.BOOKMARKS_IN_STORE_REQUIREMENT)
 
         if (
             requirementsmod.SHARED_REQUIREMENT in requirements
             or requirementsmod.RELATIVE_SHARED_REQUIREMENT in requirements
         ):
             raise error.Abort(
                 _(
                     b"cannot create shared repository as source was created"
                     b" with 'format.usestore' config disabled"
                 )
             )
 
         if requirementsmod.SHARESAFE_REQUIREMENT in requirements:
             if ui.hasconfig(b'format', b'use-share-safe'):
                 msg = _(
                     b"ignoring enabled 'format.use-share-safe' config because "
                     b"it is incompatible with disabled 'format.usestore'"
                     b" config\n"
                 )
                 ui.warn(msg)
             dropped.add(requirementsmod.SHARESAFE_REQUIREMENT)
 
     return dropped
 
 
 def filterknowncreateopts(ui, createopts):
     """Filters a dict of repo creation options against options that are known.
 
     Receives a dict of repo creation options and returns a dict of those
     options that we don't know how to handle.
 
     This function is called as part of repository creation. If the
     returned dict contains any items, repository creation will not
     be allowed, as it means there was a request to create a repository
     with options not recognized by loaded code.
 
     Extensions can wrap this function to filter out creation options
     they know how to handle.
     """
     known = {
         b'backend',
         b'lfs',
         b'narrowfiles',
         b'sharedrepo',
         b'sharedrelative',
         b'shareditems',
         b'shallowfilestore',
     }
 
     return {k: v for k, v in createopts.items() if k not in known}
 
 
 def createrepository(ui, path: bytes, createopts=None, requirements=None):
     """Create a new repository in a vfs.
 
     ``path`` path to the new repo's working directory.
     ``createopts`` options for the new repository.
     ``requirement`` predefined set of requirements.
                     (incompatible with ``createopts``)
 
     The following keys for ``createopts`` are recognized:
 
     backend
        The storage backend to use.
     lfs
        Repository will be created with ``lfs`` requirement. The lfs extension
        will automatically be loaded when the repository is accessed.
     narrowfiles
        Set up repository to support narrow file storage.
     sharedrepo
        Repository object from which storage should be shared.
     sharedrelative
        Boolean indicating if the path to the shared repo should be
        stored as relative. By default, the pointer to the "parent" repo
        is stored as an absolute path.
     shareditems
        Set of items to share to the new repository (in addition to storage).
     shallowfilestore
        Indicates that storage for files should be shallow (not all ancestor
        revisions are known).
     """
 
     if requirements is not None:
         if createopts is not None:
             msg = b'cannot specify both createopts and requirements'
             raise error.ProgrammingError(msg)
         createopts = {}
     else:
         createopts = defaultcreateopts(ui, createopts=createopts)
 
         unknownopts = filterknowncreateopts(ui, createopts)
 
         if not isinstance(unknownopts, dict):
             raise error.ProgrammingError(
                 b'filterknowncreateopts() did not return a dict'
             )
 
         if unknownopts:
             raise error.Abort(
                 _(
                     b'unable to create repository because of unknown '
                     b'creation option: %s'
                 )
                 % b', '.join(sorted(unknownopts)),
                 hint=_(b'is a required extension not loaded?'),
             )
 
         requirements = newreporequirements(ui, createopts=createopts)
         requirements -= checkrequirementscompat(ui, requirements)
 
     wdirvfs = vfsmod.vfs(path, expandpath=True, realpath=True)
 
     hgvfs = vfsmod.vfs(wdirvfs.join(b'.hg'))
     if hgvfs.exists():
         raise error.RepoError(_(b'repository %s already exists') % path)
 
     if b'sharedrepo' in createopts:
         sharedpath = createopts[b'sharedrepo'].sharedpath
 
         if createopts.get(b'sharedrelative'):
             try:
                 sharedpath = os.path.relpath(sharedpath, hgvfs.base)
                 sharedpath = util.pconvert(sharedpath)
             except (IOError, ValueError) as e:
                 # ValueError is raised on Windows if the drive letters differ
                 # on each path.
                 raise error.Abort(
                     _(b'cannot calculate relative path'),
                     hint=stringutil.forcebytestr(e),
                 )
 
     if not wdirvfs.exists():
         wdirvfs.makedirs()
 
     hgvfs.makedir(notindexed=True)
     if b'sharedrepo' not in createopts:
         hgvfs.mkdir(b'cache')
     hgvfs.mkdir(b'wcache')
 
     has_store = requirementsmod.STORE_REQUIREMENT in requirements
     if has_store and b'sharedrepo' not in createopts:
         hgvfs.mkdir(b'store')
 
         # We create an invalid changelog outside the store so very old
         # Mercurial versions (which didn't know about the requirements
         # file) encounter an error on reading the changelog. This
         # effectively locks out old clients and prevents them from
         # mucking with a repo in an unknown format.
         #
         # The revlog header has version 65535, which won't be recognized by
         # such old clients.
         hgvfs.append(
             b'00changelog.i',
             b'\0\0\xFF\xFF dummy changelog to prevent using the old repo '
             b'layout',
         )
 
     # Filter the requirements into working copy and store ones
     wcreq, storereq = scmutil.filterrequirements(requirements)
     # write working copy ones
     scmutil.writerequires(hgvfs, wcreq)
     # If there are store requirements and the current repository
     # is not a shared one, write stored requirements
     # For new shared repository, we don't need to write the store
     # requirements as they are already present in store requires
     if storereq and b'sharedrepo' not in createopts:
         storevfs = vfsmod.vfs(hgvfs.join(b'store'), cacheaudited=True)
         scmutil.writerequires(storevfs, storereq)
 
     # Write out file telling readers where to find the shared store.
     if b'sharedrepo' in createopts:
         hgvfs.write(b'sharedpath', sharedpath)
 
     if createopts.get(b'shareditems'):
         shared = b'\n'.join(sorted(createopts[b'shareditems'])) + b'\n'
         hgvfs.write(b'shared', shared)
 
 
 def poisonrepository(repo):
     """Poison a repository instance so it can no longer be used."""
     # Perform any cleanup on the instance.
     repo.close()
 
     # Our strategy is to replace the type of the object with one that
     # has all attribute lookups result in error.
     #
     # But we have to allow the close() method because some constructors
     # of repos call close() on repo references.
     class poisonedrepository:
         def __getattribute__(self, item):
             if item == 'close':
                 return object.__getattribute__(self, item)
 
             raise error.ProgrammingError(
                 b'repo instances should not be used after unshare'
             )
 
         def close(self):
             pass
 
     # We may have a repoview, which intercepts __setattr__. So be sure
     # we operate at the lowest level possible.
     object.__setattr__(repo, '__class__', poisonedrepository)