changing-files: add clean computation of changed files for roots

The `files` field is not reliable, so we need to compute things from scratch. We
start with the simplest case root changesets. In the beginning they was nothing,
then user said "let there be files" and there were added files.

Differential Revision: https://phab.mercurial-scm.org/D9126

mercurial/metadata.py

@@ -1,650 +1,665 b''
 # metadata.py -- code related to various metadata computation and access.
 #
 # Copyright 2019 Google, Inc <[e-mail]>
 # Copyright 2020 Pierre-Yves David <[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, print_function
 
 import multiprocessing
 import struct
 
 from . import (
     error,
     node,
     pycompat,
     util,
 )
 
 from .revlogutils import (
     flagutil as sidedataflag,
     sidedata as sidedatamod,
 )
 
 
 class ChangingFiles(object):
     """A class recording the changes made to files by a changeset
 
     Actions performed on files are gathered into 3 sets:
 
     - added:   files actively added in the changeset.
     - merged:  files whose history got merged
     - removed: files removed in the revision
     - salvaged: files that might have been deleted by a merge but were not
     - touched: files affected by the merge
 
     and copies information is held by 2 mappings
 
     - copied_from_p1: {"<new-name>": "<source-name-in-p1>"} mapping for copies
     - copied_from_p2: {"<new-name>": "<source-name-in-p2>"} mapping for copies
 
     See their inline help for details.
     """
 
     def __init__(
         self,
         touched=None,
         added=None,
         removed=None,
         merged=None,
         salvaged=None,
         p1_copies=None,
         p2_copies=None,
     ):
         self._added = set(() if added is None else added)
         self._merged = set(() if merged is None else merged)
         self._removed = set(() if removed is None else removed)
         self._touched = set(() if touched is None else touched)
         self._salvaged = set(() if salvaged is None else salvaged)
         self._touched.update(self._added)
         self._touched.update(self._merged)
         self._touched.update(self._removed)
         self._p1_copies = dict(() if p1_copies is None else p1_copies)
         self._p2_copies = dict(() if p2_copies is None else p2_copies)
 
     def __eq__(self, other):
         return (
             self.added == other.added
             and self.merged == other.merged
             and self.removed == other.removed
             and self.salvaged == other.salvaged
             and self.touched == other.touched
             and self.copied_from_p1 == other.copied_from_p1
             and self.copied_from_p2 == other.copied_from_p2
         )
 
     @util.propertycache
     def added(self):
         """files actively added in the changeset
 
         Any file present in that revision that was absent in all the changeset's
         parents.
 
         In case of merge, this means a file absent in one of the parents but
         existing in the other will *not* be contained in this set. (They were
         added by an ancestor)
         """
         return frozenset(self._added)
 
     def mark_added(self, filename):
         if 'added' in vars(self):
             del self.added
         self._added.add(filename)
         self.mark_touched(filename)
 
     def update_added(self, filenames):
         for f in filenames:
             self.mark_added(f)
 
     @util.propertycache
     def merged(self):
         """files actively merged during a merge
 
         Any modified files which had modification on both size that needed merging.
 
         In this case a new filenode was created and it has two parents.
         """
         return frozenset(self._merged)
 
     def mark_merged(self, filename):
         if 'merged' in vars(self):
             del self.merged
         self._merged.add(filename)
         self.mark_touched(filename)
 
     def update_merged(self, filenames):
         for f in filenames:
             self.mark_merged(f)
 
     @util.propertycache
     def removed(self):
         """files actively removed by the changeset
 
         In case of merge this will only contain the set of files removing "new"
         content. For any file absent in the current changeset:
 
         a) If the file exists in both parents, it is clearly "actively" removed
         by this changeset.
 
         b) If a file exists in only one parent and in none of the common
         ancestors, then the file was newly added in one of the merged branches
         and then got "actively" removed.
 
         c) If a file exists in only one parent and at least one of the common
         ancestors using the same filenode, then the file was unchanged on one
         side and deleted on the other side. The merge "passively" propagated
         that deletion, but didn't "actively" remove the file. In this case the
         file is *not* included in the `removed` set.
 
         d) If a file exists in only one parent and at least one of the common
         ancestors using a different filenode, then the file was changed on one
         side and removed on the other side. The merge process "actively"
         decided to drop the new change and delete the file. Unlike in the
         previous case, (c), the file included in the `removed` set.
 
         Summary table for merge:
 
         case | exists in parents | exists in gca || removed
          (a) |       both        |     *         ||   yes
          (b) |       one         |     none      ||   yes
          (c) |       one         | same filenode ||   no
          (d) |       one         |  new filenode ||   yes
         """
         return frozenset(self._removed)
 
     def mark_removed(self, filename):
         if 'removed' in vars(self):
             del self.removed
         self._removed.add(filename)
         self.mark_touched(filename)
 
     def update_removed(self, filenames):
         for f in filenames:
             self.mark_removed(f)
 
     @util.propertycache
     def salvaged(self):
         """files that might have been deleted by a merge, but still exists.
 
         During a merge, the manifest merging might select some files for
         removal, or for a removed/changed conflict. If at commit time the file
         still exists, its removal was "reverted" and the file is "salvaged"
         """
         return frozenset(self._salvaged)
 
     def mark_salvaged(self, filename):
         if "salvaged" in vars(self):
             del self.salvaged
         self._salvaged.add(filename)
         self.mark_touched(filename)
 
     def update_salvaged(self, filenames):
         for f in filenames:
             self.mark_salvaged(f)
 
     @util.propertycache
     def touched(self):
         """files either actively modified, added or removed"""
         return frozenset(self._touched)
 
     def mark_touched(self, filename):
         if 'touched' in vars(self):
             del self.touched
         self._touched.add(filename)
 
     def update_touched(self, filenames):
         for f in filenames:
             self.mark_touched(f)
 
     @util.propertycache
     def copied_from_p1(self):
         return self._p1_copies.copy()
 
     def mark_copied_from_p1(self, source, dest):
         if 'copied_from_p1' in vars(self):
             del self.copied_from_p1
         self._p1_copies[dest] = source
 
     def update_copies_from_p1(self, copies):
         for dest, source in copies.items():
             self.mark_copied_from_p1(source, dest)
 
     @util.propertycache
     def copied_from_p2(self):
         return self._p2_copies.copy()
 
     def mark_copied_from_p2(self, source, dest):
         if 'copied_from_p2' in vars(self):
             del self.copied_from_p2
         self._p2_copies[dest] = source
 
     def update_copies_from_p2(self, copies):
         for dest, source in copies.items():
             self.mark_copied_from_p2(source, dest)
 
 
 def compute_all_files_changes(ctx):
     """compute the files changed by a revision"""
+    p1 = ctx.p1()
+    p2 = ctx.p2()
+    if p1.rev() == node.nullrev and p2.rev() == node.nullrev:
+        return _process_root(ctx)
     filescopies = computechangesetcopies(ctx)
     filesadded = computechangesetfilesadded(ctx)
     filesremoved = computechangesetfilesremoved(ctx)
     filesmerged = computechangesetfilesmerged(ctx)
     files = ChangingFiles()
     files.update_touched(ctx.files())
     files.update_added(filesadded)
     files.update_removed(filesremoved)
     files.update_merged(filesmerged)
     files.update_copies_from_p1(filescopies[0])
     files.update_copies_from_p2(filescopies[1])
     return files
 
 
+def _process_root(ctx):
+    """compute the appropriate changed files for a changeset with no parents
+    """
+    # Simple, there was nothing before it, so everything is added.
+    md = ChangingFiles()
+    manifest = ctx.manifest()
+    for filename in manifest:
+        md.mark_added(filename)
+    return md
+
+
 def computechangesetfilesadded(ctx):
     """return the list of files added in a changeset
     """
     added = []
     for f in ctx.files():
         if not any(f in p for p in ctx.parents()):
             added.append(f)
     return added
 
 
 def get_removal_filter(ctx, x=None):
     """return a function to detect files "wrongly" detected as `removed`
 
     When a file is removed relative to p1 in a merge, this
     function determines whether the absence is due to a
     deletion from a parent, or whether the merge commit
     itself deletes the file. We decide this by doing a
     simplified three way merge of the manifest entry for
     the file. There are two ways we decide the merge
     itself didn't delete a file:
     - neither parent (nor the merge) contain the file
     - exactly one parent contains the file, and that
       parent has the same filelog entry as the merge
       ancestor (or all of them if there two). In other
       words, that parent left the file unchanged while the
       other one deleted it.
     One way to think about this is that deleting a file is
     similar to emptying it, so the list of changed files
     should be similar either way. The computation
     described above is not done directly in _filecommit
     when creating the list of changed files, however
     it does something very similar by comparing filelog
     nodes.
     """
 
     if x is not None:
         p1, p2, m1, m2 = x
     else:
         p1 = ctx.p1()
         p2 = ctx.p2()
         m1 = p1.manifest()
         m2 = p2.manifest()
 
     @util.cachefunc
     def mas():
         p1n = p1.node()
         p2n = p2.node()
         cahs = ctx.repo().changelog.commonancestorsheads(p1n, p2n)
         if not cahs:
             cahs = [node.nullrev]
         return [ctx.repo()[r].manifest() for r in cahs]
 
     def deletionfromparent(f):
         if f in m1:
             return f not in m2 and all(
                 f in ma and ma.find(f) == m1.find(f) for ma in mas()
             )
         elif f in m2:
             return all(f in ma and ma.find(f) == m2.find(f) for ma in mas())
         else:
             return True
 
     return deletionfromparent
 
 
 def computechangesetfilesremoved(ctx):
     """return the list of files removed in a changeset
     """
     removed = []
     for f in ctx.files():
         if f not in ctx:
             removed.append(f)
     if removed:
         rf = get_removal_filter(ctx)
         removed = [r for r in removed if not rf(r)]
     return removed
 
 
 def computechangesetfilesmerged(ctx):
     """return the list of files merged in a changeset
     """
     merged = []
     if len(ctx.parents()) < 2:
         return merged
     for f in ctx.files():
         if f in ctx:
             fctx = ctx[f]
             parents = fctx._filelog.parents(fctx._filenode)
             if parents[1] != node.nullid:
                 merged.append(f)
     return merged
 
 
 def computechangesetcopies(ctx):
     """return the copies data for a changeset
 
     The copies data are returned as a pair of dictionnary (p1copies, p2copies).
 
     Each dictionnary are in the form: `{newname: oldname}`
     """
     p1copies = {}
     p2copies = {}
     p1 = ctx.p1()
     p2 = ctx.p2()
     narrowmatch = ctx._repo.narrowmatch()
     for dst in ctx.files():
         if not narrowmatch(dst) or dst not in ctx:
             continue
         copied = ctx[dst].renamed()
         if not copied:
             continue
         src, srcnode = copied
         if src in p1 and p1[src].filenode() == srcnode:
             p1copies[dst] = src
         elif src in p2 and p2[src].filenode() == srcnode:
             p2copies[dst] = src
     return p1copies, p2copies
 
 
 def encodecopies(files, copies):
     items = []
     for i, dst in enumerate(files):
         if dst in copies:
             items.append(b'%d\0%s' % (i, copies[dst]))
     if len(items) != len(copies):
         raise error.ProgrammingError(
             b'some copy targets missing from file list'
         )
     return b"\n".join(items)
 
 
 def decodecopies(files, data):
     try:
         copies = {}
         if not data:
             return copies
         for l in data.split(b'\n'):
             strindex, src = l.split(b'\0')
             i = int(strindex)
             dst = files[i]
             copies[dst] = src
         return copies
     except (ValueError, IndexError):
         # Perhaps someone had chosen the same key name (e.g. "p1copies") and
         # used different syntax for the value.
         return None
 
 
 def encodefileindices(files, subset):
     subset = set(subset)
     indices = []
     for i, f in enumerate(files):
         if f in subset:
             indices.append(b'%d' % i)
     return b'\n'.join(indices)
 
 
 def decodefileindices(files, data):
     try:
         subset = []
         if not data:
             return subset
         for strindex in data.split(b'\n'):
             i = int(strindex)
             if i < 0 or i >= len(files):
                 return None
             subset.append(files[i])
         return subset
     except (ValueError, IndexError):
         # Perhaps someone had chosen the same key name (e.g. "added") and
         # used different syntax for the value.
         return None
 
 
 # see mercurial/helptext/internals/revlogs.txt for details about the format
 
 ACTION_MASK = int("111" "00", 2)
 # note: untouched file used as copy source will as `000` for this mask.
 ADDED_FLAG = int("001" "00", 2)
 MERGED_FLAG = int("010" "00", 2)
 REMOVED_FLAG = int("011" "00", 2)
 # `100` is reserved for future use
 TOUCHED_FLAG = int("101" "00", 2)
 
 COPIED_MASK = int("11", 2)
 COPIED_FROM_P1_FLAG = int("10", 2)
 COPIED_FROM_P2_FLAG = int("11", 2)
 
 # structure is <flag><filename-end><copy-source>
 INDEX_HEADER = struct.Struct(">L")
 INDEX_ENTRY = struct.Struct(">bLL")
 
 
 def encode_files_sidedata(files):
     all_files = set(files.touched - files.salvaged)
     all_files.update(files.copied_from_p1.values())
     all_files.update(files.copied_from_p2.values())
     all_files = sorted(all_files)
     file_idx = {f: i for (i, f) in enumerate(all_files)}
     file_idx[None] = 0
 
     chunks = [INDEX_HEADER.pack(len(all_files))]
 
     filename_length = 0
     for f in all_files:
         filename_size = len(f)
         filename_length += filename_size
         flag = 0
         if f in files.added:
             flag |= ADDED_FLAG
         elif f in files.merged:
             flag |= MERGED_FLAG
         elif f in files.removed:
             flag |= REMOVED_FLAG
         elif f in files.touched:
             flag |= TOUCHED_FLAG
 
         copy = None
         if f in files.copied_from_p1:
             flag |= COPIED_FROM_P1_FLAG
             copy = files.copied_from_p1.get(f)
         elif f in files.copied_from_p2:
             copy = files.copied_from_p2.get(f)
             flag |= COPIED_FROM_P2_FLAG
         copy_idx = file_idx[copy]
         chunks.append(INDEX_ENTRY.pack(flag, filename_length, copy_idx))
     chunks.extend(all_files)
     return {sidedatamod.SD_FILES: b''.join(chunks)}
 
 
 def decode_files_sidedata(sidedata):
     md = ChangingFiles()
     raw = sidedata.get(sidedatamod.SD_FILES)
 
     if raw is None:
         return md
 
     copies = []
     all_files = []
 
     assert len(raw) >= INDEX_HEADER.size
     total_files = INDEX_HEADER.unpack_from(raw, 0)[0]
 
     offset = INDEX_HEADER.size
     file_offset_base = offset + (INDEX_ENTRY.size * total_files)
     file_offset_last = file_offset_base
 
     assert len(raw) >= file_offset_base
 
     for idx in range(total_files):
         flag, file_end, copy_idx = INDEX_ENTRY.unpack_from(raw, offset)
         file_end += file_offset_base
         filename = raw[file_offset_last:file_end]
         filesize = file_end - file_offset_last
         assert len(filename) == filesize
         offset += INDEX_ENTRY.size
         file_offset_last = file_end
         all_files.append(filename)
         if flag & ACTION_MASK == ADDED_FLAG:
             md.mark_added(filename)
         elif flag & ACTION_MASK == MERGED_FLAG:
             md.mark_merged(filename)
         elif flag & ACTION_MASK == REMOVED_FLAG:
             md.mark_removed(filename)
         elif flag & ACTION_MASK == TOUCHED_FLAG:
             md.mark_touched(filename)
 
         copied = None
         if flag & COPIED_MASK == COPIED_FROM_P1_FLAG:
             copied = md.mark_copied_from_p1
         elif flag & COPIED_MASK == COPIED_FROM_P2_FLAG:
             copied = md.mark_copied_from_p2
 
         if copied is not None:
             copies.append((copied, filename, copy_idx))
 
     for copied, filename, copy_idx in copies:
         copied(all_files[copy_idx], filename)
 
     return md
 
 
 def _getsidedata(srcrepo, rev):
     ctx = srcrepo[rev]
     files = compute_all_files_changes(ctx)
     return encode_files_sidedata(files)
 
 
 def getsidedataadder(srcrepo, destrepo):
     use_w = srcrepo.ui.configbool(b'experimental', b'worker.repository-upgrade')
     if pycompat.iswindows or not use_w:
         return _get_simple_sidedata_adder(srcrepo, destrepo)
     else:
         return _get_worker_sidedata_adder(srcrepo, destrepo)
 
 
 def _sidedata_worker(srcrepo, revs_queue, sidedata_queue, tokens):
     """The function used by worker precomputing sidedata
 
     It read an input queue containing revision numbers
     It write in an output queue containing (rev, <sidedata-map>)
 
     The `None` input value is used as a stop signal.
 
     The `tokens` semaphore is user to avoid having too many unprocessed
     entries. The workers needs to acquire one token before fetching a task.
     They will be released by the consumer of the produced data.
     """
     tokens.acquire()
     rev = revs_queue.get()
     while rev is not None:
         data = _getsidedata(srcrepo, rev)
         sidedata_queue.put((rev, data))
         tokens.acquire()
         rev = revs_queue.get()
     # processing of `None` is completed, release the token.
     tokens.release()
 
 
 BUFF_PER_WORKER = 50
 
 
 def _get_worker_sidedata_adder(srcrepo, destrepo):
     """The parallel version of the sidedata computation
 
     This code spawn a pool of worker that precompute a buffer of sidedata
     before we actually need them"""
     # avoid circular import copies -> scmutil -> worker -> copies
     from . import worker
 
     nbworkers = worker._numworkers(srcrepo.ui)
 
     tokens = multiprocessing.BoundedSemaphore(nbworkers * BUFF_PER_WORKER)
     revsq = multiprocessing.Queue()
     sidedataq = multiprocessing.Queue()
 
     assert srcrepo.filtername is None
     # queue all tasks beforehand, revision numbers are small and it make
     # synchronisation simpler
     #
     # Since the computation for each node can be quite expensive, the overhead
     # of using a single queue is not revelant. In practice, most computation
     # are fast but some are very expensive and dominate all the other smaller
     # cost.
     for r in srcrepo.changelog.revs():
         revsq.put(r)
     # queue the "no more tasks" markers
     for i in range(nbworkers):
         revsq.put(None)
 
     allworkers = []
     for i in range(nbworkers):
         args = (srcrepo, revsq, sidedataq, tokens)
         w = multiprocessing.Process(target=_sidedata_worker, args=args)
         allworkers.append(w)
         w.start()
 
     # dictionnary to store results for revision higher than we one we are
     # looking for. For example, if we need the sidedatamap for 42, and 43 is
     # received, when shelve 43 for later use.
     staging = {}
 
     def sidedata_companion(revlog, rev):
         sidedata = {}
         if util.safehasattr(revlog, b'filteredrevs'):  # this is a changelog
             # Is the data previously shelved ?
             sidedata = staging.pop(rev, None)
             if sidedata is None:
                 # look at the queued result until we find the one we are lookig
                 # for (shelve the other ones)
                 r, sidedata = sidedataq.get()
                 while r != rev:
                     staging[r] = sidedata
                     r, sidedata = sidedataq.get()
             tokens.release()
         return False, (), sidedata
 
     return sidedata_companion
 
 
 def _get_simple_sidedata_adder(srcrepo, destrepo):
     """The simple version of the sidedata computation
 
     It just compute it in the same thread on request"""
 
     def sidedatacompanion(revlog, rev):
         sidedata = {}
         if util.safehasattr(revlog, 'filteredrevs'):  # this is a changelog
             sidedata = _getsidedata(srcrepo, rev)
         return False, (), sidedata
 
     return sidedatacompanion
 
 
 def getsidedataremover(srcrepo, destrepo):
     def sidedatacompanion(revlog, rev):
         f = ()
         if util.safehasattr(revlog, 'filteredrevs'):  # this is a changelog
             if revlog.flags(rev) & sidedataflag.REVIDX_SIDEDATA:
                 f = (
                     sidedatamod.SD_P1COPIES,
                     sidedatamod.SD_P2COPIES,
                     sidedatamod.SD_FILESADDED,
                     sidedatamod.SD_FILESREMOVED,
                 )
         return False, f, {}
 
     return sidedatacompanion