branchmap: avoid ancestor computations in absence of non-continous branches

The branchhead computation is one of the more heavy operations for
bigger repositories as it has to scan all changesets and potentially
involves the expensive computation of the ancestor sets. Redo the
computation to handle the common cases directly and use tighter
conditions for when the ancestor scan is necessary. Most importantly,
avoid it completely if the non-continous branches are processed in one
update as seen in the initial computation after a clone.

For the Mercurial repository, it gives a small 2-3% performance boost.
For the NetBSD test repository, it cuts the time in half.

Differential Revision: https://phab.mercurial-scm.org/D9631

mercurial/branchmap.py

@@ -1,765 +1,814 b''
 # branchmap.py - logic to computes, maintain and stores branchmap for local repo
 #
 # Copyright 2005-2007 Matt 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.
 
 from __future__ import absolute_import
 
 import struct
 
 from .node import (
     bin,
     hex,
     nullid,
     nullrev,
 )
 from . import (
     encoding,
     error,
     pycompat,
     scmutil,
     util,
 )
 from .utils import (
     repoviewutil,
     stringutil,
 )
 
 if pycompat.TYPE_CHECKING:
     from typing import (
         Any,
         Callable,
         Dict,
         Iterable,
         List,
         Optional,
         Set,
         Tuple,
         Union,
     )
 
     assert any(
         (
             Any,
             Callable,
             Dict,
             Iterable,
             List,
             Optional,
             Set,
             Tuple,
             Union,
         )
     )
 
 subsettable = repoviewutil.subsettable
 
 calcsize = struct.calcsize
 pack_into = struct.pack_into
 unpack_from = struct.unpack_from
 
 
 class BranchMapCache(object):
     """mapping of filtered views of repo with their branchcache"""
 
     def __init__(self):
         self._per_filter = {}
 
     def __getitem__(self, repo):
         self.updatecache(repo)
         return self._per_filter[repo.filtername]
 
     def updatecache(self, repo):
         """Update the cache for the given filtered view on a repository"""
         # This can trigger updates for the caches for subsets of the filtered
         # view, e.g. when there is no cache for this filtered view or the cache
         # is stale.
 
         cl = repo.changelog
         filtername = repo.filtername
         bcache = self._per_filter.get(filtername)
         if bcache is None or not bcache.validfor(repo):
             # cache object missing or cache object stale? Read from disk
             bcache = branchcache.fromfile(repo)
 
         revs = []
         if bcache is None:
             # no (fresh) cache available anymore, perhaps we can re-use
             # the cache for a subset, then extend that to add info on missing
             # revisions.
             subsetname = subsettable.get(filtername)
             if subsetname is not None:
                 subset = repo.filtered(subsetname)
                 bcache = self[subset].copy()
                 extrarevs = subset.changelog.filteredrevs - cl.filteredrevs
                 revs.extend(r for r in extrarevs if r <= bcache.tiprev)
             else:
                 # nothing to fall back on, start empty.
                 bcache = branchcache()
 
         revs.extend(cl.revs(start=bcache.tiprev + 1))
         if revs:
             bcache.update(repo, revs)
 
         assert bcache.validfor(repo), filtername
         self._per_filter[repo.filtername] = bcache
 
     def replace(self, repo, remotebranchmap):
         """Replace the branchmap cache for a repo with a branch mapping.
 
         This is likely only called during clone with a branch map from a
         remote.
 
         """
         cl = repo.changelog
         clrev = cl.rev
         clbranchinfo = cl.branchinfo
         rbheads = []
         closed = set()
         for bheads in pycompat.itervalues(remotebranchmap):
             rbheads += bheads
             for h in bheads:
                 r = clrev(h)
                 b, c = clbranchinfo(r)
                 if c:
                     closed.add(h)
 
         if rbheads:
             rtiprev = max((int(clrev(node)) for node in rbheads))
             cache = branchcache(
                 remotebranchmap,
                 repo[rtiprev].node(),
                 rtiprev,
                 closednodes=closed,
             )
 
             # Try to stick it as low as possible
             # filter above served are unlikely to be fetch from a clone
             for candidate in (b'base', b'immutable', b'served'):
                 rview = repo.filtered(candidate)
                 if cache.validfor(rview):
                     self._per_filter[candidate] = cache
                     cache.write(rview)
                     return
 
     def clear(self):
         self._per_filter.clear()
 
 
 def _unknownnode(node):
     """raises ValueError when branchcache found a node which does not exists"""
     raise ValueError('node %s does not exist' % pycompat.sysstr(hex(node)))
 
 
 def _branchcachedesc(repo):
     if repo.filtername is not None:
         return b'branch cache (%s)' % repo.filtername
     else:
         return b'branch cache'
 
 
 class branchcache(object):
     """A dict like object that hold branches heads cache.
 
     This cache is used to avoid costly computations to determine all the
     branch heads of a repo.
 
     The cache is serialized on disk in the following format:
 
     <tip hex node> <tip rev number> [optional filtered repo hex hash]
     <branch head hex node> <open/closed state> <branch name>
     <branch head hex node> <open/closed state> <branch name>
     ...
 
     The first line is used to check if the cache is still valid. If the
     branch cache is for a filtered repo view, an optional third hash is
     included that hashes the hashes of all filtered revisions.
 
     The open/closed state is represented by a single letter 'o' or 'c'.
     This field can be used to avoid changelog reads when determining if a
     branch head closes a branch or not.
     """
 
     def __init__(
         self,
         entries=(),
         tipnode=nullid,
         tiprev=nullrev,
         filteredhash=None,
         closednodes=None,
         hasnode=None,
     ):
         # type: (Union[Dict[bytes, List[bytes]], Iterable[Tuple[bytes, List[bytes]]]], bytes,  int, Optional[bytes], Optional[Set[bytes]], Optional[Callable[[bytes], bool]]) -> None
         """hasnode is a function which can be used to verify whether changelog
         has a given node or not. If it's not provided, we assume that every node
         we have exists in changelog"""
         self.tipnode = tipnode
         self.tiprev = tiprev
         self.filteredhash = filteredhash
         # closednodes is a set of nodes that close their branch. If the branch
         # cache has been updated, it may contain nodes that are no longer
         # heads.
         if closednodes is None:
             self._closednodes = set()
         else:
             self._closednodes = closednodes
         self._entries = dict(entries)
         # whether closed nodes are verified or not
         self._closedverified = False
         # branches for which nodes are verified
         self._verifiedbranches = set()
         self._hasnode = hasnode
         if self._hasnode is None:
             self._hasnode = lambda x: True
 
     def _verifyclosed(self):
         """ verify the closed nodes we have """
         if self._closedverified:
             return
         for node in self._closednodes:
             if not self._hasnode(node):
                 _unknownnode(node)
 
         self._closedverified = True
 
     def _verifybranch(self, branch):
         """ verify head nodes for the given branch. """
         if branch not in self._entries or branch in self._verifiedbranches:
             return
         for n in self._entries[branch]:
             if not self._hasnode(n):
                 _unknownnode(n)
 
         self._verifiedbranches.add(branch)
 
     def _verifyall(self):
         """ verifies nodes of all the branches """
         needverification = set(self._entries.keys()) - self._verifiedbranches
         for b in needverification:
             self._verifybranch(b)
 
     def __iter__(self):
         return iter(self._entries)
 
     def __setitem__(self, key, value):
         self._entries[key] = value
 
     def __getitem__(self, key):
         self._verifybranch(key)
         return self._entries[key]
 
     def __contains__(self, key):
         self._verifybranch(key)
         return key in self._entries
 
     def iteritems(self):
         for k, v in pycompat.iteritems(self._entries):
             self._verifybranch(k)
             yield k, v
 
     items = iteritems
 
     def hasbranch(self, label):
         """ checks whether a branch of this name exists or not """
         self._verifybranch(label)
         return label in self._entries
 
     @classmethod
     def fromfile(cls, repo):
         f = None
         try:
             f = repo.cachevfs(cls._filename(repo))
             lineiter = iter(f)
             cachekey = next(lineiter).rstrip(b'\n').split(b" ", 2)
             last, lrev = cachekey[:2]
             last, lrev = bin(last), int(lrev)
             filteredhash = None
             hasnode = repo.changelog.hasnode
             if len(cachekey) > 2:
                 filteredhash = bin(cachekey[2])
             bcache = cls(
                 tipnode=last,
                 tiprev=lrev,
                 filteredhash=filteredhash,
                 hasnode=hasnode,
             )
             if not bcache.validfor(repo):
                 # invalidate the cache
                 raise ValueError('tip differs')
             bcache.load(repo, lineiter)
         except (IOError, OSError):
             return None
 
         except Exception as inst:
             if repo.ui.debugflag:
                 msg = b'invalid %s: %s\n'
                 repo.ui.debug(
                     msg
                     % (
                         _branchcachedesc(repo),
                         pycompat.bytestr(
                             inst
                         ),  # pytype: disable=wrong-arg-types
                     )
                 )
             bcache = None
 
         finally:
             if f:
                 f.close()
 
         return bcache
 
     def load(self, repo, lineiter):
         """fully loads the branchcache by reading from the file using the line
         iterator passed"""
         for line in lineiter:
             line = line.rstrip(b'\n')
             if not line:
                 continue
             node, state, label = line.split(b" ", 2)
             if state not in b'oc':
                 raise ValueError('invalid branch state')
             label = encoding.tolocal(label.strip())
             node = bin(node)
             self._entries.setdefault(label, []).append(node)
             if state == b'c':
                 self._closednodes.add(node)
 
     @staticmethod
     def _filename(repo):
         """name of a branchcache file for a given repo or repoview"""
         filename = b"branch2"
         if repo.filtername:
             filename = b'%s-%s' % (filename, repo.filtername)
         return filename
 
     def validfor(self, repo):
         """Is the cache content valid regarding a repo
 
         - False when cached tipnode is unknown or if we detect a strip.
         - True when cache is up to date or a subset of current repo."""
         try:
             return (self.tipnode == repo.changelog.node(self.tiprev)) and (
                 self.filteredhash == scmutil.filteredhash(repo, self.tiprev)
             )
         except IndexError:
             return False
 
     def _branchtip(self, heads):
         """Return tuple with last open head in heads and false,
         otherwise return last closed head and true."""
         tip = heads[-1]
         closed = True
         for h in reversed(heads):
             if h not in self._closednodes:
                 tip = h
                 closed = False
                 break
         return tip, closed
 
     def branchtip(self, branch):
         """Return the tipmost open head on branch head, otherwise return the
         tipmost closed head on branch.
         Raise KeyError for unknown branch."""
         return self._branchtip(self[branch])[0]
 
     def iteropen(self, nodes):
         return (n for n in nodes if n not in self._closednodes)
 
     def branchheads(self, branch, closed=False):
         self._verifybranch(branch)
         heads = self._entries[branch]
         if not closed:
             heads = list(self.iteropen(heads))
         return heads
 
     def iterbranches(self):
         for bn, heads in pycompat.iteritems(self):
             yield (bn, heads) + self._branchtip(heads)
 
     def iterheads(self):
         """ returns all the heads """
         self._verifyall()
         return pycompat.itervalues(self._entries)
 
     def copy(self):
         """return an deep copy of the branchcache object"""
         return type(self)(
             self._entries,
             self.tipnode,
             self.tiprev,
             self.filteredhash,
             self._closednodes,
         )
 
     def write(self, repo):
         try:
             f = repo.cachevfs(self._filename(repo), b"w", atomictemp=True)
             cachekey = [hex(self.tipnode), b'%d' % self.tiprev]
             if self.filteredhash is not None:
                 cachekey.append(hex(self.filteredhash))
             f.write(b" ".join(cachekey) + b'\n')
             nodecount = 0
             for label, nodes in sorted(pycompat.iteritems(self._entries)):
                 label = encoding.fromlocal(label)
                 for node in nodes:
                     nodecount += 1
                     if node in self._closednodes:
                         state = b'c'
                     else:
                         state = b'o'
                     f.write(b"%s %s %s\n" % (hex(node), state, label))
             f.close()
             repo.ui.log(
                 b'branchcache',
                 b'wrote %s with %d labels and %d nodes\n',
                 _branchcachedesc(repo),
                 len(self._entries),
                 nodecount,
             )
         except (IOError, OSError, error.Abort) as inst:
             # Abort may be raised by read only opener, so log and continue
             repo.ui.debug(
                 b"couldn't write branch cache: %s\n"
                 % stringutil.forcebytestr(inst)
             )
 
     def update(self, repo, revgen):
         """Given a branchhead cache, self, that may have extra nodes or be
         missing heads, and a generator of nodes that are strictly a superset of
         heads missing, this function updates self to be correct.
         """
         starttime = util.timer()
         cl = repo.changelog
         # collect new branch entries
         newbranches = {}
         getbranchinfo = repo.revbranchcache().branchinfo
         for r in revgen:
             branch, closesbranch = getbranchinfo(r)
             newbranches.setdefault(branch, []).append(r)
             if closesbranch:
                 self._closednodes.add(cl.node(r))
 
-        # fetch current topological heads to speed up filtering
-        topoheads = set(cl.headrevs())
-
         # new tip revision which we found after iterating items from new
         # branches
         ntiprev = self.tiprev
 
-        # if older branchheads are reachable from new ones, they aren't
-        # really branchheads. Note checking parents is insufficient:
-        # 1 (branch a) -> 2 (branch b) -> 3 (branch a)
+        # Delay fetching the topological heads until they are needed.
+        # A repository without non-continous branches can skip this part.
+        topoheads = None
+
+        # If a changeset is visible, its parents must be visible too, so
+        # use the faster unfiltered parent accessor.
+        parentrevs = repo.unfiltered().changelog.parentrevs
+
         for branch, newheadrevs in pycompat.iteritems(newbranches):
+            # For every branch, compute the new branchheads.
+            # A branchhead is a revision such that no descendant is on
+            # the same branch.
+            #
+            # The branchheads are computed iteratively in revision order.
+            # This ensures topological order, i.e. parents are processed
+            # before their children. Ancestors are inclusive here, i.e.
+            # any revision is an ancestor of itself.
+            #
+            # Core observations:
+            # - The current revision is always a branchhead for the
+            #   repository up to that point.
+            # - It is the first revision of the branch if and only if
+            #   there was no branchhead before. In that case, it is the
+            #   only branchhead as there are no possible ancestors on
+            #   the same branch.
+            # - If a parent is on the same branch, a branchhead can
+            #   only be an ancestor of that parent, if it is parent
+            #   itself. Otherwise it would have been removed as ancestor
+            #   of that parent before.
+            # - Therefore, if all parents are on the same branch, they
+            #   can just be removed from the branchhead set.
+            # - If one parent is on the same branch and the other is not
+            #   and there was exactly one branchhead known, the existing
+            #   branchhead can only be an ancestor if it is the parent.
+            #   Otherwise it would have been removed as ancestor of
+            #   the parent before. The other parent therefore can't have
+            #   a branchhead as ancestor.
+            # - In all other cases, the parents on different branches
+            #   could have a branchhead as ancestor. Those parents are
+            #   kept in the "uncertain" set. If all branchheads are also
+            #   topological heads, they can't have descendants and further
+            #   checks can be skipped. Otherwise, the ancestors of the
+            #   "uncertain" set are removed from branchheads.
+            #   This computation is heavy and avoided if at all possible.
             bheads = self._entries.setdefault(branch, [])
             bheadset = {cl.rev(node) for node in bheads}
-
-            # This have been tested True on all internal usage of this function.
-            # run it again in case of doubt
-            # assert not (set(bheadrevs) & set(newheadrevs))
-            bheadset.update(newheadrevs)
+            uncertain = set()
+            for newrev in sorted(newheadrevs):
+                if not bheadset:
+                    bheadset.add(newrev)
+                    continue
 
-            # This prunes out two kinds of heads - heads that are superseded by
-            # a head in newheadrevs, and newheadrevs that are not heads because
-            # an existing head is their descendant.
-            uncertain = bheadset - topoheads
+                parents = [p for p in parentrevs(newrev) if p != nullrev]
+                samebranch = set()
+                otherbranch = set()
+                for p in parents:
+                    if p in bheadset or getbranchinfo(p)[0] == branch:
+                        samebranch.add(p)
+                    else:
+                        otherbranch.add(p)
+                if otherbranch and not (len(bheadset) == len(samebranch) == 1):
+                    uncertain.update(otherbranch)
+                bheadset.difference_update(samebranch)
+                bheadset.add(newrev)
+
             if uncertain:
-                floorrev = min(uncertain)
+                if topoheads is None:
+                    topoheads = set(cl.headrevs())
+                if bheadset - topoheads:
+                    floorrev = min(bheadset)
                 ancestors = set(cl.ancestors(newheadrevs, floorrev))
                 bheadset -= ancestors
             bheadrevs = sorted(bheadset)
             self[branch] = [cl.node(rev) for rev in bheadrevs]
             tiprev = bheadrevs[-1]
             if tiprev > ntiprev:
                 ntiprev = tiprev
 
         if ntiprev > self.tiprev:
             self.tiprev = ntiprev
             self.tipnode = cl.node(ntiprev)
 
         if not self.validfor(repo):
             # cache key are not valid anymore
             self.tipnode = nullid
             self.tiprev = nullrev
             for heads in self.iterheads():
                 tiprev = max(cl.rev(node) for node in heads)
                 if tiprev > self.tiprev:
                     self.tipnode = cl.node(tiprev)
                     self.tiprev = tiprev
         self.filteredhash = scmutil.filteredhash(repo, self.tiprev)
 
         duration = util.timer() - starttime
         repo.ui.log(
             b'branchcache',
             b'updated %s in %.4f seconds\n',
             _branchcachedesc(repo),
             duration,
         )
 
         self.write(repo)
 
 
 class remotebranchcache(branchcache):
     """Branchmap info for a remote connection, should not write locally"""
 
     def write(self, repo):
         pass
 
 
 # Revision branch info cache
 
 _rbcversion = b'-v1'
 _rbcnames = b'rbc-names' + _rbcversion
 _rbcrevs = b'rbc-revs' + _rbcversion
 # [4 byte hash prefix][4 byte branch name number with sign bit indicating open]
 _rbcrecfmt = b'>4sI'
 _rbcrecsize = calcsize(_rbcrecfmt)
 _rbcnodelen = 4
 _rbcbranchidxmask = 0x7FFFFFFF
 _rbccloseflag = 0x80000000
 
 
 class revbranchcache(object):
     """Persistent cache, mapping from revision number to branch name and close.
     This is a low level cache, independent of filtering.
 
     Branch names are stored in rbc-names in internal encoding separated by 0.
     rbc-names is append-only, and each branch name is only stored once and will
     thus have a unique index.
 
     The branch info for each revision is stored in rbc-revs as constant size
     records. The whole file is read into memory, but it is only 'parsed' on
     demand. The file is usually append-only but will be truncated if repo
     modification is detected.
     The record for each revision contains the first 4 bytes of the
     corresponding node hash, and the record is only used if it still matches.
     Even a completely trashed rbc-revs fill thus still give the right result
     while converging towards full recovery ... assuming no incorrectly matching
     node hashes.
     The record also contains 4 bytes where 31 bits contains the index of the
     branch and the last bit indicate that it is a branch close commit.
     The usage pattern for rbc-revs is thus somewhat similar to 00changelog.i
     and will grow with it but be 1/8th of its size.
     """
 
     def __init__(self, repo, readonly=True):
         assert repo.filtername is None
         self._repo = repo
         self._names = []  # branch names in local encoding with static index
         self._rbcrevs = bytearray()
         self._rbcsnameslen = 0  # length of names read at _rbcsnameslen
         try:
             bndata = repo.cachevfs.read(_rbcnames)
             self._rbcsnameslen = len(bndata)  # for verification before writing
             if bndata:
                 self._names = [
                     encoding.tolocal(bn) for bn in bndata.split(b'\0')
                 ]
         except (IOError, OSError):
             if readonly:
                 # don't try to use cache - fall back to the slow path
                 self.branchinfo = self._branchinfo
 
         if self._names:
             try:
                 data = repo.cachevfs.read(_rbcrevs)
                 self._rbcrevs[:] = data
             except (IOError, OSError) as inst:
                 repo.ui.debug(
                     b"couldn't read revision branch cache: %s\n"
                     % stringutil.forcebytestr(inst)
                 )
         # remember number of good records on disk
         self._rbcrevslen = min(
             len(self._rbcrevs) // _rbcrecsize, len(repo.changelog)
         )
         if self._rbcrevslen == 0:
             self._names = []
         self._rbcnamescount = len(self._names)  # number of names read at
         # _rbcsnameslen
 
     def _clear(self):
         self._rbcsnameslen = 0
         del self._names[:]
         self._rbcnamescount = 0
         self._rbcrevslen = len(self._repo.changelog)
         self._rbcrevs = bytearray(self._rbcrevslen * _rbcrecsize)
         util.clearcachedproperty(self, b'_namesreverse')
 
     @util.propertycache
     def _namesreverse(self):
         return {b: r for r, b in enumerate(self._names)}
 
     def branchinfo(self, rev):
         """Return branch name and close flag for rev, using and updating
         persistent cache."""
         changelog = self._repo.changelog
         rbcrevidx = rev * _rbcrecsize
 
         # avoid negative index, changelog.read(nullrev) is fast without cache
         if rev == nullrev:
             return changelog.branchinfo(rev)
 
         # if requested rev isn't allocated, grow and cache the rev info
         if len(self._rbcrevs) < rbcrevidx + _rbcrecsize:
             return self._branchinfo(rev)
 
         # fast path: extract data from cache, use it if node is matching
         reponode = changelog.node(rev)[:_rbcnodelen]
         cachenode, branchidx = unpack_from(
             _rbcrecfmt, util.buffer(self._rbcrevs), rbcrevidx
         )
         close = bool(branchidx & _rbccloseflag)
         if close:
             branchidx &= _rbcbranchidxmask
         if cachenode == b'\0\0\0\0':
             pass
         elif cachenode == reponode:
             try:
                 return self._names[branchidx], close
             except IndexError:
                 # recover from invalid reference to unknown branch
                 self._repo.ui.debug(
                     b"referenced branch names not found"
                     b" - rebuilding revision branch cache from scratch\n"
                 )
                 self._clear()
         else:
             # rev/node map has changed, invalidate the cache from here up
             self._repo.ui.debug(
                 b"history modification detected - truncating "
                 b"revision branch cache to revision %d\n" % rev
             )
             truncate = rbcrevidx + _rbcrecsize
             del self._rbcrevs[truncate:]
             self._rbcrevslen = min(self._rbcrevslen, truncate)
 
         # fall back to slow path and make sure it will be written to disk
         return self._branchinfo(rev)
 
     def _branchinfo(self, rev):
         """Retrieve branch info from changelog and update _rbcrevs"""
         changelog = self._repo.changelog
         b, close = changelog.branchinfo(rev)
         if b in self._namesreverse:
             branchidx = self._namesreverse[b]
         else:
             branchidx = len(self._names)
             self._names.append(b)
             self._namesreverse[b] = branchidx
         reponode = changelog.node(rev)
         if close:
             branchidx |= _rbccloseflag
         self._setcachedata(rev, reponode, branchidx)
         return b, close
 
     def setdata(self, branch, rev, node, close):
         """add new data information to the cache"""
         if branch in self._namesreverse:
             branchidx = self._namesreverse[branch]
         else:
             branchidx = len(self._names)
             self._names.append(branch)
             self._namesreverse[branch] = branchidx
         if close:
             branchidx |= _rbccloseflag
         self._setcachedata(rev, node, branchidx)
         # If no cache data were readable (non exists, bad permission, etc)
         # the cache was bypassing itself by setting:
         #
         #   self.branchinfo = self._branchinfo
         #
         # Since we now have data in the cache, we need to drop this bypassing.
         if 'branchinfo' in vars(self):
             del self.branchinfo
 
     def _setcachedata(self, rev, node, branchidx):
         """Writes the node's branch data to the in-memory cache data."""
         if rev == nullrev:
             return
         rbcrevidx = rev * _rbcrecsize
         if len(self._rbcrevs) < rbcrevidx + _rbcrecsize:
             self._rbcrevs.extend(
                 b'\0'
                 * (len(self._repo.changelog) * _rbcrecsize - len(self._rbcrevs))
             )
         pack_into(_rbcrecfmt, self._rbcrevs, rbcrevidx, node, branchidx)
         self._rbcrevslen = min(self._rbcrevslen, rev)
 
         tr = self._repo.currenttransaction()
         if tr:
             tr.addfinalize(b'write-revbranchcache', self.write)
 
     def write(self, tr=None):
         """Save branch cache if it is dirty."""
         repo = self._repo
         wlock = None
         step = b''
         try:
             # write the new names
             if self._rbcnamescount < len(self._names):
                 wlock = repo.wlock(wait=False)
                 step = b' names'
                 self._writenames(repo)
 
             # write the new revs
             start = self._rbcrevslen * _rbcrecsize
             if start != len(self._rbcrevs):
                 step = b''
                 if wlock is None:
                     wlock = repo.wlock(wait=False)
                 self._writerevs(repo, start)
 
         except (IOError, OSError, error.Abort, error.LockError) as inst:
             repo.ui.debug(
                 b"couldn't write revision branch cache%s: %s\n"
                 % (step, stringutil.forcebytestr(inst))
             )
         finally:
             if wlock is not None:
                 wlock.release()
 
     def _writenames(self, repo):
         """ write the new branch names to revbranchcache """
         if self._rbcnamescount != 0:
             f = repo.cachevfs.open(_rbcnames, b'ab')
             if f.tell() == self._rbcsnameslen:
                 f.write(b'\0')
             else:
                 f.close()
                 repo.ui.debug(b"%s changed - rewriting it\n" % _rbcnames)
                 self._rbcnamescount = 0
                 self._rbcrevslen = 0
         if self._rbcnamescount == 0:
             # before rewriting names, make sure references are removed
             repo.cachevfs.unlinkpath(_rbcrevs, ignoremissing=True)
             f = repo.cachevfs.open(_rbcnames, b'wb')
         f.write(
             b'\0'.join(
                 encoding.fromlocal(b)
                 for b in self._names[self._rbcnamescount :]
             )
         )
         self._rbcsnameslen = f.tell()
         f.close()
         self._rbcnamescount = len(self._names)
 
     def _writerevs(self, repo, start):
         """ write the new revs to revbranchcache """
         revs = min(len(repo.changelog), len(self._rbcrevs) // _rbcrecsize)
         with repo.cachevfs.open(_rbcrevs, b'ab') as f:
             if f.tell() != start:
                 repo.ui.debug(
                     b"truncating cache/%s to %d\n" % (_rbcrevs, start)
                 )
                 f.seek(start)
                 if f.tell() != start:
                     start = 0
                     f.seek(start)
                 f.truncate()
             end = revs * _rbcrecsize
             f.write(self._rbcrevs[start:end])
         self._rbcrevslen = revs

relnotes/next

@@ -1,62 +1,66 b''
 == New Features ==
 
  * There is a new config section for templates used by hg commands. It
    is called `[command-templates]`. Some existing config options have
    been deprecated in favor of config options in the new
    section. These are: `ui.logtemplate` to `command-templates.log`,
    `ui.graphnodetemplate` to `command-templates.graphnode`,
    `ui.mergemarkertemplate` to `command-templates.mergemarker`,
    `ui.pre-merge-tool-output-template` to
    `command-templates.pre-merge-tool-output`.
 
  * There is a new set of config options for the template used for the
    one-line commit summary displayed by various commands, such as `hg
    rebase`. The main one is `command-templates.oneline-summary`. That
    can be overridden per command with
    `command-templates.oneline-summary.<command>`, where `<command>`
    can be e.g. `rebase`. As part of this effort, the default format
    from `hg rebase` was reorganized a bit.
 
  * `hg strip`, from the strip extension, is now a core command, `hg
    debugstrip`. The extension remains for compatibility.
 
  * `hg diff` and `hg extdiff` now support `--from <rev>` and `--to <rev>`
    arguments as clearer alternatives to `-r <revs>`. `-r <revs>` has been
    deprecated.
 
  * The memory footprint per changeset during pull/unbundle
    operations has been further reduced.
 
  * There is a new internal merge tool called `internal:mergediff` (can
    be set as the value for the `merge` config in the `[ui]`
    section). It resolves merges the same was as `internal:merge` and
    `internal:merge3`, but it shows conflicts differently. Instead of
    showing 2 or 3 snapshots of the conflicting pieces of code, it
    shows one snapshot and a diff. This may be useful when at least one
    side of the conflict is similar to the base. The new marker style
    is also supported by "premerge" as
    `merge-tools.<tool>.premerge=keep-mergediff`.
 
  * External hooks are now called with `HGPLAIN=1` preset.
 
+ * The `branchmap` cache is updated more intelligently and can be
+   significantly faster for repositories with many branches and changesets.
+
+
 == New Experimental Features ==
 
 * `experimental.single-head-per-branch:public-changes-only` can be used
   restrict the single head check to public revision. This is useful for
   overlay repository that have both a publishing and non-publishing view
   of the same storage.
 
 
 == Bug Fixes ==
 
 
 
 == Backwards Compatibility Changes ==
 
  * `--force-lock` and `--force-wlock` options on `hg debuglock` command are
    renamed to `--force-free-lock` and `--force-free-wlock` respectively.
 
 
 == Internal API Changes ==
 
 

tests/test-branches.t

@@ -1,990 +1,1244 b''
   $ hg init a
   $ cd a
 
 Verify checking branch of nullrev before the cache is created doesnt crash
   $ hg log -r 'branch(.)' -T '{branch}\n'
 
 Basic test
   $ echo 'root' >root
   $ hg add root
   $ hg commit -d '0 0' -m "Adding root node"
 
   $ echo 'a' >a
   $ hg add a
   $ hg branch a
   marked working directory as branch a
   (branches are permanent and global, did you want a bookmark?)
   $ hg commit -d '1 0' -m "Adding a branch"
 
   $ hg branch q
   marked working directory as branch q
   $ echo 'aa' >a
   $ hg branch -C
   reset working directory to branch a
   $ hg commit -d '2 0' -m "Adding to a branch"
 
   $ hg update -C 0
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ echo 'b' >b
   $ hg add b
   $ hg branch b
   marked working directory as branch b
   $ hg commit -d '2 0' -m "Adding b branch"
 
   $ echo 'bh1' >bh1
   $ hg add bh1
   $ hg commit -d '3 0' -m "Adding b branch head 1"
 
   $ hg update -C 2
   1 files updated, 0 files merged, 2 files removed, 0 files unresolved
   $ echo 'bh2' >bh2
   $ hg add bh2
   $ hg commit -d '4 0' -m "Adding b branch head 2"
 
   $ echo 'c' >c
   $ hg add c
   $ hg branch c
   marked working directory as branch c
   $ hg commit -d '5 0' -m "Adding c branch"
 
 reserved names
 
   $ hg branch tip
   abort: the name 'tip' is reserved
   [10]
   $ hg branch null
   abort: the name 'null' is reserved
   [10]
   $ hg branch .
   abort: the name '.' is reserved
   [10]
 
 invalid characters
 
   $ hg branch 'foo:bar'
   abort: ':' cannot be used in a name
   [10]
 
   $ hg branch 'foo
   > bar'
   abort: '\n' cannot be used in a name
   [10]
 
 trailing or leading spaces should be stripped before testing duplicates
 
   $ hg branch 'b '
   abort: a branch of the same name already exists
   (use 'hg update' to switch to it)
   [10]
 
   $ hg branch ' b'
   abort: a branch of the same name already exists
   (use 'hg update' to switch to it)
   [10]
 
 verify update will accept invalid legacy branch names
 
   $ hg init test-invalid-branch-name
   $ cd test-invalid-branch-name
   $ hg unbundle -u "$TESTDIR"/bundles/test-invalid-branch-name.hg
   adding changesets
   adding manifests
   adding file changes
   added 3 changesets with 3 changes to 2 files
   new changesets f0e4c7f04036:33c2ceb9310b (3 drafts)
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
   $ hg update '"colon:test"'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ cd ..
 
   $ echo 'd' >d
   $ hg add d
   $ hg branch 'a branch name much longer than the default justification used by branches'
   marked working directory as branch a branch name much longer than the default justification used by branches
   $ hg commit -d '6 0' -m "Adding d branch"
 
   $ hg branches
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   b                              4:aee39cd168d0
   c                              6:589736a22561 (inactive)
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
 
 -------
 
   $ hg branches -a
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   b                              4:aee39cd168d0
 
 --- Branch a
 
   $ hg log -b a
   changeset:   5:d8cbc61dbaa6
   branch:      a
   parent:      2:881fe2b92ad0
   user:        test
   date:        Thu Jan 01 00:00:04 1970 +0000
   summary:     Adding b branch head 2
   
   changeset:   2:881fe2b92ad0
   branch:      a
   user:        test
   date:        Thu Jan 01 00:00:02 1970 +0000
   summary:     Adding to a branch
   
   changeset:   1:dd6b440dd85a
   branch:      a
   user:        test
   date:        Thu Jan 01 00:00:01 1970 +0000
   summary:     Adding a branch
   
 
 ---- Branch b
 
   $ hg log -b b
   changeset:   4:aee39cd168d0
   branch:      b
   user:        test
   date:        Thu Jan 01 00:00:03 1970 +0000
   summary:     Adding b branch head 1
   
   changeset:   3:ac22033332d1
   branch:      b
   parent:      0:19709c5a4e75
   user:        test
   date:        Thu Jan 01 00:00:02 1970 +0000
   summary:     Adding b branch
   
 
 ---- going to test branch listing by rev
   $ hg branches -r0
   default                        0:19709c5a4e75 (inactive)
   $ hg branches -qr0
   default
 --- now more than one rev
   $ hg branches -r2:5
   b                              4:aee39cd168d0
   a                              5:d8cbc61dbaa6 (inactive)
   $ hg branches -qr2:5
   b
   a
 ---- going to test branch closing
 
   $ hg branches
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   b                              4:aee39cd168d0
   c                              6:589736a22561 (inactive)
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
   $ hg up -C b
   2 files updated, 0 files merged, 4 files removed, 0 files unresolved
   $ echo 'xxx1' >> b
   $ hg commit -d '7 0' -m 'adding cset to branch b'
   $ hg up -C aee39cd168d0
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ echo 'xxx2' >> b
   $ hg commit -d '8 0' -m 'adding head to branch b'
   created new head
   $ echo 'xxx3' >> b
   $ hg commit -d '9 0' -m 'adding another cset to branch b'
   $ hg branches
   b                             10:bfbe841b666e
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   c                              6:589736a22561 (inactive)
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
   $ hg heads --closed
   changeset:   10:bfbe841b666e
   branch:      b
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:09 1970 +0000
   summary:     adding another cset to branch b
   
   changeset:   8:eebb944467c9
   branch:      b
   parent:      4:aee39cd168d0
   user:        test
   date:        Thu Jan 01 00:00:07 1970 +0000
   summary:     adding cset to branch b
   
   changeset:   7:10ff5895aa57
   branch:      a branch name much longer than the default justification used by branches
   user:        test
   date:        Thu Jan 01 00:00:06 1970 +0000
   summary:     Adding d branch
   
   changeset:   6:589736a22561
   branch:      c
   user:        test
   date:        Thu Jan 01 00:00:05 1970 +0000
   summary:     Adding c branch
   
   changeset:   5:d8cbc61dbaa6
   branch:      a
   parent:      2:881fe2b92ad0
   user:        test
   date:        Thu Jan 01 00:00:04 1970 +0000
   summary:     Adding b branch head 2
   
   changeset:   0:19709c5a4e75
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     Adding root node
   
   $ hg heads
   changeset:   10:bfbe841b666e
   branch:      b
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:09 1970 +0000
   summary:     adding another cset to branch b
   
   changeset:   8:eebb944467c9
   branch:      b
   parent:      4:aee39cd168d0
   user:        test
   date:        Thu Jan 01 00:00:07 1970 +0000
   summary:     adding cset to branch b
   
   changeset:   7:10ff5895aa57
   branch:      a branch name much longer than the default justification used by branches
   user:        test
   date:        Thu Jan 01 00:00:06 1970 +0000
   summary:     Adding d branch
   
   changeset:   6:589736a22561
   branch:      c
   user:        test
   date:        Thu Jan 01 00:00:05 1970 +0000
   summary:     Adding c branch
   
   changeset:   5:d8cbc61dbaa6
   branch:      a
   parent:      2:881fe2b92ad0
   user:        test
   date:        Thu Jan 01 00:00:04 1970 +0000
   summary:     Adding b branch head 2
   
   changeset:   0:19709c5a4e75
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     Adding root node
   
   $ hg commit -d '9 0' --close-branch -m 'prune bad branch'
   $ hg branches -a
   b                              8:eebb944467c9
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   $ hg up -C b
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg commit -d '9 0' --close-branch -m 'close this part branch too'
   $ hg commit -d '9 0' --close-branch -m 're-closing this branch'
   abort: current revision is already a branch closing head
   [10]
 
   $ hg log -r tip --debug
   changeset:   12:e3d49c0575d8fc2cb1cd6859c747c14f5f6d499f
   branch:      b
   tag:         tip
   phase:       draft
   parent:      8:eebb944467c9fb9651ed232aeaf31b3c0a7fc6c1
   parent:      -1:0000000000000000000000000000000000000000
   manifest:    8:6f9ed32d2b310e391a4f107d5f0f071df785bfee
   user:        test
   date:        Thu Jan 01 00:00:09 1970 +0000
   extra:       branch=b
   extra:       close=1
   description:
   close this part branch too
   
   
 --- b branch should be inactive
 
   $ hg branches
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   c                              6:589736a22561 (inactive)
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
   $ hg branches -c
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   b                             12:e3d49c0575d8 (closed)
   c                              6:589736a22561 (inactive)
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
   $ hg branches -a
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   $ hg branches -q
   a branch name much longer than the default justification used by branches
   c
   a
   default
   $ hg heads b
   no open branch heads found on branches b
   [1]
   $ hg heads --closed b
   changeset:   12:e3d49c0575d8
   branch:      b
   tag:         tip
   parent:      8:eebb944467c9
   user:        test
   date:        Thu Jan 01 00:00:09 1970 +0000
   summary:     close this part branch too
   
   changeset:   11:d3f163457ebf
   branch:      b
   user:        test
   date:        Thu Jan 01 00:00:09 1970 +0000
   summary:     prune bad branch
   
   $ echo 'xxx4' >> b
   $ hg commit -d '9 0' -m 'reopen branch with a change'
   reopening closed branch head 12
 
 --- branch b is back in action
 
   $ hg branches -a
   b                             13:e23b5505d1ad
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
 
 ---- test heads listings
 
   $ hg heads
   changeset:   13:e23b5505d1ad
   branch:      b
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:09 1970 +0000
   summary:     reopen branch with a change
   
   changeset:   7:10ff5895aa57
   branch:      a branch name much longer than the default justification used by branches
   user:        test
   date:        Thu Jan 01 00:00:06 1970 +0000
   summary:     Adding d branch
   
   changeset:   6:589736a22561
   branch:      c
   user:        test
   date:        Thu Jan 01 00:00:05 1970 +0000
   summary:     Adding c branch
   
   changeset:   5:d8cbc61dbaa6
   branch:      a
   parent:      2:881fe2b92ad0
   user:        test
   date:        Thu Jan 01 00:00:04 1970 +0000
   summary:     Adding b branch head 2
   
   changeset:   0:19709c5a4e75
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     Adding root node
   
 
 branch default
 
   $ hg heads default
   changeset:   0:19709c5a4e75
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     Adding root node
   
 
 branch a
 
   $ hg heads a
   changeset:   5:d8cbc61dbaa6
   branch:      a
   parent:      2:881fe2b92ad0
   user:        test
   date:        Thu Jan 01 00:00:04 1970 +0000
   summary:     Adding b branch head 2
   
   $ hg heads --active a
   no open branch heads found on branches a
   [1]
 
 branch b
 
   $ hg heads b
   changeset:   13:e23b5505d1ad
   branch:      b
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:09 1970 +0000
   summary:     reopen branch with a change
   
   $ hg heads --closed b
   changeset:   13:e23b5505d1ad
   branch:      b
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:09 1970 +0000
   summary:     reopen branch with a change
   
   changeset:   11:d3f163457ebf
   branch:      b
   user:        test
   date:        Thu Jan 01 00:00:09 1970 +0000
   summary:     prune bad branch
   
 
 reclose branch
 
   $ hg up -C c
   3 files updated, 0 files merged, 2 files removed, 0 files unresolved
   $ hg commit -d '9 0' --close-branch -m 'reclosing this branch'
   $ hg branches
   b                             13:e23b5505d1ad
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
   $ hg branches --closed
   b                             13:e23b5505d1ad
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   c                             14:f894c25619d3 (closed)
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
 
 multihead branch
 
   $ hg up -C default
   0 files updated, 0 files merged, 3 files removed, 0 files unresolved
   $ hg branch m
   marked working directory as branch m
   $ touch m
   $ hg add m
   $ hg commit -d '10 0' -m 'multihead base'
   $ echo "m1" >m
   $ hg commit -d '10 0' -m 'head 1'
   $ hg up -C '.^'
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ echo "m2" >m
   $ hg commit -d '10 0' -m 'head 2'
   created new head
   $ hg log -b m
   changeset:   17:df343b0df04f
   branch:      m
   tag:         tip
   parent:      15:f3447637f53e
   user:        test
   date:        Thu Jan 01 00:00:10 1970 +0000
   summary:     head 2
   
   changeset:   16:a58ca5d3bdf3
   branch:      m
   user:        test
   date:        Thu Jan 01 00:00:10 1970 +0000
   summary:     head 1
   
   changeset:   15:f3447637f53e
   branch:      m
   parent:      0:19709c5a4e75
   user:        test
   date:        Thu Jan 01 00:00:10 1970 +0000
   summary:     multihead base
   
   $ hg heads --topo m
   changeset:   17:df343b0df04f
   branch:      m
   tag:         tip
   parent:      15:f3447637f53e
   user:        test
   date:        Thu Jan 01 00:00:10 1970 +0000
   summary:     head 2
   
   changeset:   16:a58ca5d3bdf3
   branch:      m
   user:        test
   date:        Thu Jan 01 00:00:10 1970 +0000
   summary:     head 1
   
   $ hg branches
   m                             17:df343b0df04f
   b                             13:e23b5505d1ad
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
 
 partially merge multihead branch
 
   $ hg up -C default
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg branch md
   marked working directory as branch md
   $ hg merge m
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)
   $ hg commit -d '11 0' -m 'merge head 2'
   $ hg heads --topo m
   changeset:   16:a58ca5d3bdf3
   branch:      m
   user:        test
   date:        Thu Jan 01 00:00:10 1970 +0000
   summary:     head 1
   
   $ hg branches
   md                            18:c914c99f1fbb
   m                             17:df343b0df04f
   b                             13:e23b5505d1ad
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
 
 partially close multihead branch
 
   $ hg up -C a58ca5d3bdf3
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
   $ hg commit -d '12 0' -m 'close head 1' --close-branch
   $ hg heads --topo m
   changeset:   19:cd21a80baa3d
   branch:      m
   tag:         tip
   parent:      16:a58ca5d3bdf3
   user:        test
   date:        Thu Jan 01 00:00:12 1970 +0000
   summary:     close head 1
   
   $ hg branches
   md                            18:c914c99f1fbb
   b                             13:e23b5505d1ad
   a branch name much longer than the default justification used by branches 7:10ff5895aa57
   m                             17:df343b0df04f (inactive)
   a                              5:d8cbc61dbaa6 (inactive)
   default                        0:19709c5a4e75 (inactive)
 
 default branch colors:
 
   $ cat <<EOF >> $HGRCPATH
   > [extensions]
   > color =
   > [color]
   > mode = ansi
   > EOF
 
   $ hg up -C b
   2 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg branches --color=always
   \x1b[0;0mmd\x1b[0m\x1b[0;33m                            18:c914c99f1fbb\x1b[0m (esc)
   \x1b[0;32mb\x1b[0m\x1b[0;33m                             13:e23b5505d1ad\x1b[0m (esc)
   \x1b[0;0ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;33m 7:10ff5895aa57\x1b[0m (esc)
   \x1b[0;0mm\x1b[0m\x1b[0;33m                             17:df343b0df04f\x1b[0m (inactive) (esc)
   \x1b[0;0ma\x1b[0m\x1b[0;33m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
   \x1b[0;0mdefault\x1b[0m\x1b[0;33m                        0:19709c5a4e75\x1b[0m (inactive) (esc)
 
 default closed branch color:
 
   $ hg branches --color=always --closed
   \x1b[0;0mmd\x1b[0m\x1b[0;33m                            18:c914c99f1fbb\x1b[0m (esc)
   \x1b[0;32mb\x1b[0m\x1b[0;33m                             13:e23b5505d1ad\x1b[0m (esc)
   \x1b[0;0ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;33m 7:10ff5895aa57\x1b[0m (esc)
   \x1b[0;0mm\x1b[0m\x1b[0;33m                             17:df343b0df04f\x1b[0m (inactive) (esc)
   \x1b[0;30;1mc\x1b[0m\x1b[0;33m                             14:f894c25619d3\x1b[0m (closed) (esc)
   \x1b[0;0ma\x1b[0m\x1b[0;33m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
   \x1b[0;0mdefault\x1b[0m\x1b[0;33m                        0:19709c5a4e75\x1b[0m (inactive) (esc)
 
   $ cat <<EOF >> $HGRCPATH
   > [extensions]
   > color =
   > [color]
   > branches.active = green
   > branches.closed = blue
   > branches.current = red
   > branches.inactive = magenta
   > log.changeset = cyan
   > EOF
 
 custom branch colors:
 
   $ hg branches --color=always
   \x1b[0;32mmd\x1b[0m\x1b[0;36m                            18:c914c99f1fbb\x1b[0m (esc)
   \x1b[0;31mb\x1b[0m\x1b[0;36m                             13:e23b5505d1ad\x1b[0m (esc)
   \x1b[0;32ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;36m 7:10ff5895aa57\x1b[0m (esc)
   \x1b[0;35mm\x1b[0m\x1b[0;36m                             17:df343b0df04f\x1b[0m (inactive) (esc)
   \x1b[0;35ma\x1b[0m\x1b[0;36m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
   \x1b[0;35mdefault\x1b[0m\x1b[0;36m                        0:19709c5a4e75\x1b[0m (inactive) (esc)
 
 custom closed branch color:
 
   $ hg branches --color=always --closed
   \x1b[0;32mmd\x1b[0m\x1b[0;36m                            18:c914c99f1fbb\x1b[0m (esc)
   \x1b[0;31mb\x1b[0m\x1b[0;36m                             13:e23b5505d1ad\x1b[0m (esc)
   \x1b[0;32ma branch name much longer than the default justification used by branches\x1b[0m\x1b[0;36m 7:10ff5895aa57\x1b[0m (esc)
   \x1b[0;35mm\x1b[0m\x1b[0;36m                             17:df343b0df04f\x1b[0m (inactive) (esc)
   \x1b[0;34mc\x1b[0m\x1b[0;36m                             14:f894c25619d3\x1b[0m (closed) (esc)
   \x1b[0;35ma\x1b[0m\x1b[0;36m                              5:d8cbc61dbaa6\x1b[0m (inactive) (esc)
   \x1b[0;35mdefault\x1b[0m\x1b[0;36m                        0:19709c5a4e75\x1b[0m (inactive) (esc)
 
 template output:
 
   $ hg branches -Tjson --closed
   [
    {
     "active": true,
     "branch": "md",
     "closed": false,
     "current": false,
     "node": "c914c99f1fbb2b1d785a0a939ed3f67275df18e9",
     "rev": 18
    },
    {
     "active": true,
     "branch": "b",
     "closed": false,
     "current": true,
     "node": "e23b5505d1ad24aab6f84fd8c7cb8cd8e5e93be0",
     "rev": 13
    },
    {
     "active": true,
     "branch": "a branch name much longer than the default justification used by branches",
     "closed": false,
     "current": false,
     "node": "10ff5895aa5793bd378da574af8cec8ea408d831",
     "rev": 7
    },
    {
     "active": false,
     "branch": "m",
     "closed": false,
     "current": false,
     "node": "df343b0df04feb2a946cd4b6e9520e552fef14ee",
     "rev": 17
    },
    {
     "active": false,
     "branch": "c",
     "closed": true,
     "current": false,
     "node": "f894c25619d3f1484639d81be950e0a07bc6f1f6",
     "rev": 14
    },
    {
     "active": false,
     "branch": "a",
     "closed": false,
     "current": false,
     "node": "d8cbc61dbaa6dc817175d1e301eecb863f280832",
     "rev": 5
    },
    {
     "active": false,
     "branch": "default",
     "closed": false,
     "current": false,
     "node": "19709c5a4e75bf938f8e349aff97438539bb729e",
     "rev": 0
    }
   ]
 
   $ hg branches --closed -T '{if(closed, "{branch}\n")}'
   c
 
   $ hg branches -T '{word(0, branch)}: {desc|firstline}\n'
   md: merge head 2
   b: reopen branch with a change
   a: Adding d branch
   m: head 2
   a: Adding b branch head 2
   default: Adding root node
 
   $ cat <<'EOF' > "$TESTTMP/map-myjson"
   > docheader = '\{\n'
   > docfooter = '\n}\n'
   > separator = ',\n'
   > branches = ' {dict(branch, node|short)|json}'
   > EOF
   $ hg branches -T "$TESTTMP/map-myjson"
   {
    {"branch": "md", "node": "c914c99f1fbb"},
    {"branch": "b", "node": "e23b5505d1ad"},
    {"branch": "a branch *", "node": "10ff5895aa57"}, (glob)
    {"branch": "m", "node": "df343b0df04f"},
    {"branch": "a", "node": "d8cbc61dbaa6"},
    {"branch": "default", "node": "19709c5a4e75"}
   }
 
   $ cat <<'EOF' >> .hg/hgrc
   > [templates]
   > myjson = ' {dict(branch, node|short)|json}'
   > myjson:docheader = '\{\n'
   > myjson:docfooter = '\n}\n'
   > myjson:separator = ',\n'
   > EOF
   $ hg branches -T myjson
   {
    {"branch": "md", "node": "c914c99f1fbb"},
    {"branch": "b", "node": "e23b5505d1ad"},
    {"branch": "a branch *", "node": "10ff5895aa57"}, (glob)
    {"branch": "m", "node": "df343b0df04f"},
    {"branch": "a", "node": "d8cbc61dbaa6"},
    {"branch": "default", "node": "19709c5a4e75"}
   }
 
   $ cat <<'EOF' >> .hg/hgrc
   > [templates]
   > :docheader = 'should not be selected as a docheader for literal templates\n'
   > EOF
   $ hg branches -T '{branch}\n'
   md
   b
   a branch name much longer than the default justification used by branches
   m
   a
   default
 
 Tests of revision branch name caching
 
 We rev branch cache is updated automatically. In these tests we use a trick to
 trigger rebuilds. We remove the branch head cache and run 'hg head' to cause a
 rebuild that also will populate the rev branch cache.
 
 revision branch cache is created when building the branch head cache
   $ rm -rf .hg/cache; hg head a -T '{rev}\n'
   5
   $ f --hexdump --size .hg/cache/rbc-*
   .hg/cache/rbc-names-v1: size=92
   0000: 64 65 66 61 75 6c 74 00 61 00 62 00 63 00 61 20 |default.a.b.c.a |
   0010: 62 72 61 6e 63 68 20 6e 61 6d 65 20 6d 75 63 68 |branch name much|
   0020: 20 6c 6f 6e 67 65 72 20 74 68 61 6e 20 74 68 65 | longer than the|
   0030: 20 64 65 66 61 75 6c 74 20 6a 75 73 74 69 66 69 | default justifi|
   0040: 63 61 74 69 6f 6e 20 75 73 65 64 20 62 79 20 62 |cation used by b|
   0050: 72 61 6e 63 68 65 73 00 6d 00 6d 64             |ranches.m.md|
   .hg/cache/rbc-revs-v1: size=160
   0000: 19 70 9c 5a 00 00 00 00 dd 6b 44 0d 00 00 00 01 |.p.Z.....kD.....|
   0010: 88 1f e2 b9 00 00 00 01 ac 22 03 33 00 00 00 02 |.........".3....|
   0020: ae e3 9c d1 00 00 00 02 d8 cb c6 1d 00 00 00 01 |................|
   0030: 58 97 36 a2 00 00 00 03 10 ff 58 95 00 00 00 04 |X.6.......X.....|
   0040: ee bb 94 44 00 00 00 02 5f 40 61 bb 00 00 00 02 |...D...._@a.....|
   0050: bf be 84 1b 00 00 00 02 d3 f1 63 45 80 00 00 02 |..........cE....|
   0060: e3 d4 9c 05 80 00 00 02 e2 3b 55 05 00 00 00 02 |.........;U.....|
   0070: f8 94 c2 56 80 00 00 03 f3 44 76 37 00 00 00 05 |...V.....Dv7....|
   0080: a5 8c a5 d3 00 00 00 05 df 34 3b 0d 00 00 00 05 |.........4;.....|
   0090: c9 14 c9 9f 00 00 00 06 cd 21 a8 0b 80 00 00 05 |.........!......|
 
 no errors when revbranchcache is not writable
 
   $ echo >> .hg/cache/rbc-revs-v1
   $ mv .hg/cache/rbc-revs-v1 .hg/cache/rbc-revs-v1_
   $ mkdir .hg/cache/rbc-revs-v1
   $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n'
   5
   $ rmdir .hg/cache/rbc-revs-v1
   $ mv .hg/cache/rbc-revs-v1_ .hg/cache/rbc-revs-v1
 
 no errors when wlock cannot be acquired
 
 #if unix-permissions
   $ mv .hg/cache/rbc-revs-v1 .hg/cache/rbc-revs-v1_
   $ rm -f .hg/cache/branch*
   $ chmod 555 .hg
   $ hg head a -T '{rev}\n'
   5
   $ chmod 755 .hg
   $ mv .hg/cache/rbc-revs-v1_ .hg/cache/rbc-revs-v1
 #endif
 
 recovery from invalid cache revs file with trailing data
   $ echo >> .hg/cache/rbc-revs-v1
   $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
   5
   truncating cache/rbc-revs-v1 to 160
   $ f --size .hg/cache/rbc-revs*
   .hg/cache/rbc-revs-v1: size=160
 recovery from invalid cache file with partial last record
   $ mv .hg/cache/rbc-revs-v1 .
   $ f -qDB 119 rbc-revs-v1 > .hg/cache/rbc-revs-v1
   $ f --size .hg/cache/rbc-revs*
   .hg/cache/rbc-revs-v1: size=119
   $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
   5
   truncating cache/rbc-revs-v1 to 112
   $ f --size .hg/cache/rbc-revs*
   .hg/cache/rbc-revs-v1: size=160
 recovery from invalid cache file with missing record - no truncation
   $ mv .hg/cache/rbc-revs-v1 .
   $ f -qDB 112 rbc-revs-v1 > .hg/cache/rbc-revs-v1
   $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
   5
   $ f --size .hg/cache/rbc-revs*
   .hg/cache/rbc-revs-v1: size=160
 recovery from invalid cache file with some bad records
   $ mv .hg/cache/rbc-revs-v1 .
   $ f -qDB 8 rbc-revs-v1 > .hg/cache/rbc-revs-v1
   $ f --size .hg/cache/rbc-revs*
   .hg/cache/rbc-revs-v1: size=8
   $ f -qDB 112 rbc-revs-v1 >> .hg/cache/rbc-revs-v1
   $ f --size .hg/cache/rbc-revs*
   .hg/cache/rbc-revs-v1: size=120
   $ hg log -r 'branch(.)' -T '{rev} ' --debug
   history modification detected - truncating revision branch cache to revision 13
   history modification detected - truncating revision branch cache to revision 1
   3 4 8 9 10 11 12 13 truncating cache/rbc-revs-v1 to 8
   $ rm -f .hg/cache/branch* && hg head a -T '{rev}\n' --debug
   5
   truncating cache/rbc-revs-v1 to 104
   $ f --size --hexdump --bytes=16 .hg/cache/rbc-revs*
   .hg/cache/rbc-revs-v1: size=160
   0000: 19 70 9c 5a 00 00 00 00 dd 6b 44 0d 00 00 00 01 |.p.Z.....kD.....|
 cache is updated when committing
   $ hg branch i-will-regret-this
   marked working directory as branch i-will-regret-this
   $ hg ci -m regrets
   $ f --size .hg/cache/rbc-*
   .hg/cache/rbc-names-v1: size=111
   .hg/cache/rbc-revs-v1: size=168
 update after rollback - the cache will be correct but rbc-names will will still
 contain the branch name even though it no longer is used
   $ hg up -qr '.^'
   $ hg rollback -qf
   $ f --size --hexdump .hg/cache/rbc-*
   .hg/cache/rbc-names-v1: size=111
   0000: 64 65 66 61 75 6c 74 00 61 00 62 00 63 00 61 20 |default.a.b.c.a |
   0010: 62 72 61 6e 63 68 20 6e 61 6d 65 20 6d 75 63 68 |branch name much|
   0020: 20 6c 6f 6e 67 65 72 20 74 68 61 6e 20 74 68 65 | longer than the|
   0030: 20 64 65 66 61 75 6c 74 20 6a 75 73 74 69 66 69 | default justifi|
   0040: 63 61 74 69 6f 6e 20 75 73 65 64 20 62 79 20 62 |cation used by b|
   0050: 72 61 6e 63 68 65 73 00 6d 00 6d 64 00 69 2d 77 |ranches.m.md.i-w|
   0060: 69 6c 6c 2d 72 65 67 72 65 74 2d 74 68 69 73    |ill-regret-this|
   .hg/cache/rbc-revs-v1: size=160
   0000: 19 70 9c 5a 00 00 00 00 dd 6b 44 0d 00 00 00 01 |.p.Z.....kD.....|
   0010: 88 1f e2 b9 00 00 00 01 ac 22 03 33 00 00 00 02 |.........".3....|
   0020: ae e3 9c d1 00 00 00 02 d8 cb c6 1d 00 00 00 01 |................|
   0030: 58 97 36 a2 00 00 00 03 10 ff 58 95 00 00 00 04 |X.6.......X.....|
   0040: ee bb 94 44 00 00 00 02 5f 40 61 bb 00 00 00 02 |...D...._@a.....|
   0050: bf be 84 1b 00 00 00 02 d3 f1 63 45 80 00 00 02 |..........cE....|
   0060: e3 d4 9c 05 80 00 00 02 e2 3b 55 05 00 00 00 02 |.........;U.....|
   0070: f8 94 c2 56 80 00 00 03 f3 44 76 37 00 00 00 05 |...V.....Dv7....|
   0080: a5 8c a5 d3 00 00 00 05 df 34 3b 0d 00 00 00 05 |.........4;.....|
   0090: c9 14 c9 9f 00 00 00 06 cd 21 a8 0b 80 00 00 05 |.........!......|
 cache is updated/truncated when stripping - it is thus very hard to get in a
 situation where the cache is out of sync and the hash check detects it
   $ hg --config extensions.strip= strip -r tip --nob
   $ f --size .hg/cache/rbc-revs*
   .hg/cache/rbc-revs-v1: size=152
 
 cache is rebuilt when corruption is detected
   $ echo > .hg/cache/rbc-names-v1
   $ hg log -r '5:&branch(.)' -T '{rev} ' --debug
   referenced branch names not found - rebuilding revision branch cache from scratch
   8 9 10 11 12 13 truncating cache/rbc-revs-v1 to 40
   $ f --size --hexdump .hg/cache/rbc-*
   .hg/cache/rbc-names-v1: size=84
   0000: 62 00 61 00 63 00 61 20 62 72 61 6e 63 68 20 6e |b.a.c.a branch n|
   0010: 61 6d 65 20 6d 75 63 68 20 6c 6f 6e 67 65 72 20 |ame much longer |
   0020: 74 68 61 6e 20 74 68 65 20 64 65 66 61 75 6c 74 |than the default|
   0030: 20 6a 75 73 74 69 66 69 63 61 74 69 6f 6e 20 75 | justification u|
   0040: 73 65 64 20 62 79 20 62 72 61 6e 63 68 65 73 00 |sed by branches.|
   0050: 6d 00 6d 64                                     |m.md|
   .hg/cache/rbc-revs-v1: size=152
   0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0020: 00 00 00 00 00 00 00 00 d8 cb c6 1d 00 00 00 01 |................|
   0030: 58 97 36 a2 00 00 00 02 10 ff 58 95 00 00 00 03 |X.6.......X.....|
   0040: ee bb 94 44 00 00 00 00 5f 40 61 bb 00 00 00 00 |...D...._@a.....|
   0050: bf be 84 1b 00 00 00 00 d3 f1 63 45 80 00 00 00 |..........cE....|
   0060: e3 d4 9c 05 80 00 00 00 e2 3b 55 05 00 00 00 00 |.........;U.....|
   0070: f8 94 c2 56 80 00 00 02 f3 44 76 37 00 00 00 04 |...V.....Dv7....|
   0080: a5 8c a5 d3 00 00 00 04 df 34 3b 0d 00 00 00 04 |.........4;.....|
   0090: c9 14 c9 9f 00 00 00 05                         |........|
 
 Test that cache files are created and grows correctly:
 
   $ rm .hg/cache/rbc*
   $ hg log -r "5 & branch(5)" -T "{rev}\n"
   5
   $ f --size --hexdump .hg/cache/rbc-*
   .hg/cache/rbc-names-v1: size=1
   0000: 61                                              |a|
   .hg/cache/rbc-revs-v1: size=152
   0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0020: 00 00 00 00 00 00 00 00 d8 cb c6 1d 00 00 00 00 |................|
   0030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
   0090: 00 00 00 00 00 00 00 00                         |........|
 
   $ cd ..
 
 Test for multiple incorrect branch cache entries:
 
   $ hg init b
   $ cd b
   $ touch f
   $ hg ci -Aqmf
   $ echo >> f
   $ hg ci -Amf
   $ hg branch -q branch
   $ hg ci -Amf
 
   $ f --size --hexdump .hg/cache/rbc-*
   .hg/cache/rbc-names-v1: size=14
   0000: 64 65 66 61 75 6c 74 00 62 72 61 6e 63 68       |default.branch|
   .hg/cache/rbc-revs-v1: size=24
   0000: 66 e5 f5 aa 00 00 00 00 fa 4c 04 e5 00 00 00 00 |f........L......|
   0010: 56 46 78 69 00 00 00 01                         |VFxi....|
   $ : > .hg/cache/rbc-revs-v1
 
 No superfluous rebuilding of cache:
   $ hg log -r "branch(null)&branch(branch)" --debug
   $ f --size --hexdump .hg/cache/rbc-*
   .hg/cache/rbc-names-v1: size=14
   0000: 64 65 66 61 75 6c 74 00 62 72 61 6e 63 68       |default.branch|
   .hg/cache/rbc-revs-v1: size=24
   0000: 66 e5 f5 aa 00 00 00 00 fa 4c 04 e5 00 00 00 00 |f........L......|
   0010: 56 46 78 69 00 00 00 01                         |VFxi....|
 
   $ cd ..
 
 Test to make sure that `--close-branch` only works on a branch head:
 --------------------------------------------------------------------
   $ hg init closebranch
   $ cd closebranch
   $ for ch in a b c; do
   > echo $ch > $ch
   > hg add $ch
   > hg ci -m "added "$ch
   > done;
 
   $ hg up -r "desc('added b')"
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
 
 trying to close branch from a cset which is not a branch head
 it should abort:
   $ hg ci -m "closing branch" --close-branch
   abort: can only close branch heads
   (use --force-close-branch to close branch from a non-head changeset)
   [10]
 
   $ hg up 0
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ hg log -GT "{rev}: {node|short} {desc|firstline}\n\t{branch}\n\n"
   o  2: 155349b645be added c
   |  	default
   |
   o  1: 5f6d8a4bf34a added b
   |  	default
   |
   @  0: 9092f1db7931 added a
      	default
   
 Test --force-close-branch to close a branch from a non-head changeset:
 ---------------------------------------------------------------------
 
   $ hg show stack --config extensions.show=
     o  1553 added c
     o  5f6d added b
     @  9092 added a
 
   $ hg ci -m "branch closed" --close-branch
   abort: can only close branch heads
   (use --force-close-branch to close branch from a non-head changeset)
   [10]
 
   $ hg ci -m "branch closed" --force-close-branch
   created new head
+  $ cd ..
+
+Test various special cases for the branchmap
+--------------------------------------------
+
+Basic fork of the same branch
+
+  $ hg init branchmap-testing1
+  $ cd branchmap-testing1
+  $ hg debugbuild '@A . :base . :p1 *base /p1'
+  $ hg log -G
+  o    changeset:   3:71ca9a6d524e
+  |\   branch:      A
+  | |  tag:         tip
+  | |  parent:      2:a3b807b3ff0b
+  | |  parent:      1:99ba08759bc7
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:03 1970 +0000
+  | |  summary:     r3
+  | |
+  | o  changeset:   2:a3b807b3ff0b
+  | |  branch:      A
+  | |  parent:      0:2ab8003a1750
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:02 1970 +0000
+  | |  summary:     r2
+  | |
+  o |  changeset:   1:99ba08759bc7
+  |/   branch:      A
+  |    tag:         p1
+  |    user:        debugbuilddag
+  |    date:        Thu Jan 01 00:00:01 1970 +0000
+  |    summary:     r1
+  |
+  o  changeset:   0:2ab8003a1750
+     branch:      A
+     tag:         base
+     user:        debugbuilddag
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     r0
+  
+  $ hg branches
+  A                              3:71ca9a6d524e
+  $ hg clone -r 1 -r 2 . ../branchmap-testing1-clone
+  adding changesets
+  adding manifests
+  adding file changes
+  added 3 changesets with 0 changes to 0 files (+1 heads)
+  new changesets 2ab8003a1750:a3b807b3ff0b
+  updating to branch A
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ cd ../branchmap-testing1-clone
+  $ hg pull ../branchmap-testing1
+  pulling from ../branchmap-testing1
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 0 changes to 0 files (-1 heads)
+  new changesets 71ca9a6d524e
+  (run 'hg update' to get a working copy)
+  $ hg branches
+  A                              3:71ca9a6d524e
+  $ cd ..
+
+Switching to a different branch and back
+
+  $ hg init branchmap-testing2
+  $ cd branchmap-testing2
+  $ hg debugbuild '@A . @B . @A .'
+  $ hg log -G
+  o  changeset:   2:9699e9f260b5
+  |  branch:      A
+  |  tag:         tip
+  |  user:        debugbuilddag
+  |  date:        Thu Jan 01 00:00:02 1970 +0000
+  |  summary:     r2
+  |
+  o  changeset:   1:0bc7d348d965
+  |  branch:      B
+  |  user:        debugbuilddag
+  |  date:        Thu Jan 01 00:00:01 1970 +0000
+  |  summary:     r1
+  |
+  o  changeset:   0:2ab8003a1750
+     branch:      A
+     user:        debugbuilddag
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     r0
+  
+  $ hg branches
+  A                              2:9699e9f260b5
+  B                              1:0bc7d348d965 (inactive)
+  $ hg clone -r 1 . ../branchmap-testing2-clone
+  adding changesets
+  adding manifests
+  adding file changes
+  added 2 changesets with 0 changes to 0 files
+  new changesets 2ab8003a1750:0bc7d348d965
+  updating to branch B
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ cd ../branchmap-testing2-clone
+  $ hg pull ../branchmap-testing2
+  pulling from ../branchmap-testing2
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 0 changes to 0 files
+  new changesets 9699e9f260b5
+  (run 'hg update' to get a working copy)
+  $ hg branches
+  A                              2:9699e9f260b5
+  B                              1:0bc7d348d965 (inactive)
+  $ cd ..
+
+A fork on a branch switching to a different branch and back
+is still collecting the fork.
+
+  $ hg init branchmap-testing3
+  $ cd branchmap-testing3
+  $ hg debugbuild '@A . :base . :p1 *base @B . @A /p1'
+  $ hg log -G
+  o    changeset:   4:3614a1711d23
+  |\   branch:      A
+  | |  tag:         tip
+  | |  parent:      3:e9c8abcf65aa
+  | |  parent:      1:99ba08759bc7
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:04 1970 +0000
+  | |  summary:     r4
+  | |
+  | o  changeset:   3:e9c8abcf65aa
+  | |  branch:      B
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:03 1970 +0000
+  | |  summary:     r3
+  | |
+  | o  changeset:   2:a3b807b3ff0b
+  | |  branch:      A
+  | |  parent:      0:2ab8003a1750
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:02 1970 +0000
+  | |  summary:     r2
+  | |
+  o |  changeset:   1:99ba08759bc7
+  |/   branch:      A
+  |    tag:         p1
+  |    user:        debugbuilddag
+  |    date:        Thu Jan 01 00:00:01 1970 +0000
+  |    summary:     r1
+  |
+  o  changeset:   0:2ab8003a1750
+     branch:      A
+     tag:         base
+     user:        debugbuilddag
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     r0
+  
+  $ hg branches
+  A                              4:3614a1711d23
+  B                              3:e9c8abcf65aa (inactive)
+  $ hg clone -r 1 -r 3 . ../branchmap-testing3-clone
+  adding changesets
+  adding manifests
+  adding file changes
+  added 4 changesets with 0 changes to 0 files (+1 heads)
+  new changesets 2ab8003a1750:e9c8abcf65aa
+  updating to branch A
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ cd ../branchmap-testing3-clone
+  $ hg pull ../branchmap-testing3
+  pulling from ../branchmap-testing3
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 0 changes to 0 files (-1 heads)
+  new changesets 3614a1711d23
+  (run 'hg update' to get a working copy)
+  $ hg branches
+  A                              4:3614a1711d23
+  B                              3:e9c8abcf65aa (inactive)
+  $ cd ..
+
+Intermediary parents are on different branches.
+
+  $ hg init branchmap-testing4
+  $ cd branchmap-testing4
+  $ hg debugbuild '@A . @B :base . @A :p1 *base @C . @A /p1'
+  $ hg log -G
+  o    changeset:   4:4bf67499b70a
+  |\   branch:      A
+  | |  tag:         tip
+  | |  parent:      3:4a546028fa8f
+  | |  parent:      1:0bc7d348d965
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:04 1970 +0000
+  | |  summary:     r4
+  | |
+  | o  changeset:   3:4a546028fa8f
+  | |  branch:      C
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:03 1970 +0000
+  | |  summary:     r3
+  | |
+  | o  changeset:   2:a3b807b3ff0b
+  | |  branch:      A
+  | |  parent:      0:2ab8003a1750
+  | |  user:        debugbuilddag
+  | |  date:        Thu Jan 01 00:00:02 1970 +0000
+  | |  summary:     r2
+  | |
+  o |  changeset:   1:0bc7d348d965
+  |/   branch:      B
+  |    tag:         p1
+  |    user:        debugbuilddag
+  |    date:        Thu Jan 01 00:00:01 1970 +0000
+  |    summary:     r1
+  |
+  o  changeset:   0:2ab8003a1750
+     branch:      A
+     tag:         base
+     user:        debugbuilddag
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     r0
+  
+  $ hg branches
+  A                              4:4bf67499b70a
+  C                              3:4a546028fa8f (inactive)
+  B                              1:0bc7d348d965 (inactive)
+  $ hg clone -r 1 -r 3 . ../branchmap-testing4-clone
+  adding changesets
+  adding manifests
+  adding file changes
+  added 4 changesets with 0 changes to 0 files (+1 heads)
+  new changesets 2ab8003a1750:4a546028fa8f
+  updating to branch B
+  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ cd ../branchmap-testing4-clone
+  $ hg pull ../branchmap-testing4
+  pulling from ../branchmap-testing4
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 0 changes to 0 files (-1 heads)
+  new changesets 4bf67499b70a
+  (run 'hg update' to get a working copy)
+  $ hg branches
+  A                              4:4bf67499b70a
+  C                              3:4a546028fa8f (inactive)
+  B                              1:0bc7d348d965 (inactive)
+  $ cd ..