changelog: optionally store added and removed files in changeset extras

As mentioned in an earlier patch, copies._chain() is used a lot in the
changeset-centric version of pathcopies(). It is expensive because it
needs to look at the manifest in order to filter out copies whose
target file has since been removed. I want to store the sets of added
and removed files in the changeset in order to speed that up. This
patch does the writing part of that. It could easily be a separate
config, but it's currently tied to experimental.copies.write-to since
that's the only real use case (it will also make the {file_*} template
keywords faster, but I doubt that anyone cares enough about those to
write extra metadata for them).

The new information is stored in the changeset extras. Since they're
always subsets of the changeset's "files" list, they're stored as
indexes into that list. I've stored the indexes as stringified ints
separated by NUL bytes. The size of 00changelog.d for the hg repo
increased in size by 0.28% percent (compared to the size with only
copy information in the changesets, which in turn is 0.17% larger than
without copy information). We could store only the delta between the
indexes and we could store them in binary, but the chosen format is
more readable.

We could also have implemented this as a cache outside the
changelog. One advantage of doing it that way is that we would get the
speedups from the {file_*} template keywords also on old
repos. Another advantage is that it we can rewrite the cache if we
find a bug in how we calculate the set of files. A disadvantage is
that it would be more complex. Another is that it would surely use
more space. We already write the copy information to the changeset
extras, so it seems like a small step to also write these file sets.

Differential Revision: https://phab.mercurial-scm.org/D6416

mercurial/changelog.py

@@ -99,6 +99,14 b' def decodecopies(data):'
         # 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('%d' % i)
+    return '\0'.join(indices)
+
 def stripdesc(desc):
     """strip trailing whitespace and leading and trailing empty lines"""
     return '\n'.join([l.rstrip() for l in desc.splitlines()]).strip('\n')
@@ -564,7 +572,8 b' class changelog(revlog.revlog):'
         return l[3:]
 
     def add(self, manifest, files, desc, transaction, p1, p2,
-                  user, date=None, extra=None, p1copies=None, p2copies=None):
+                  user, date=None, extra=None, p1copies=None, p2copies=None,
+                  filesadded=None, filesremoved=None):
         # Convert to UTF-8 encoded bytestrings as the very first
         # thing: calling any method on a localstr object will turn it
         # into a str object and the cached UTF-8 string is thus lost.
@@ -593,17 +602,23 b' class changelog(revlog.revlog):'
             elif branch in (".", "null", "tip"):
                 raise error.StorageError(_('the name \'%s\' is reserved')
                                          % branch)
-        if (p1copies is not None or p2copies is not None) and extra is None:
+        extrasentries = p1copies, p2copies, filesadded, filesremoved
+        if extra is None and any(x is not None for x in extrasentries):
             extra = {}
         if p1copies is not None:
             extra['p1copies'] = encodecopies(p1copies)
         if p2copies is not None:
             extra['p2copies'] = encodecopies(p2copies)
+        sortedfiles = sorted(files)
+        if filesadded is not None:
+            extra['filesadded'] = encodefileindices(sortedfiles, filesadded)
+        if filesremoved is not None:
+            extra['filesremoved'] = encodefileindices(sortedfiles, filesremoved)
 
         if extra:
             extra = encodeextra(extra)
             parseddate = "%s %s" % (parseddate, extra)
-        l = [hex(manifest), user, parseddate] + sorted(files) + ["", desc]
+        l = [hex(manifest), user, parseddate] + sortedfiles + ["", desc]
         text = "\n".join(l)
         return self.addrevision(text, transaction, len(self), p1, p2)
 

mercurial/localrepo.py

@@ -2589,10 +2589,13 b' class localrepository(object):'
 
         writecopiesto = self.ui.config('experimental', 'copies.write-to')
         writefilecopymeta = writecopiesto != 'changeset-only'
+        writechangesetcopy = (writecopiesto in
+                              ('changeset-only', 'compatibility'))
         p1copies, p2copies = None, None
-        if writecopiesto in ('changeset-only', 'compatibility'):
+        if writechangesetcopy:
             p1copies = ctx.p1copies()
             p2copies = ctx.p2copies()
+        filesadded, filesremoved = None, None
         with self.lock(), self.transaction("commit") as tr:
             trp = weakref.proxy(tr)
 
@@ -2601,6 +2604,9 b' class localrepository(object):'
                 self.ui.debug('reusing known manifest\n')
                 mn = ctx.manifestnode()
                 files = ctx.files()
+                if writechangesetcopy:
+                    filesadded = ctx.filesadded()
+                    filesremoved = ctx.filesremoved()
             elif ctx.files():
                 m1ctx = p1.manifestctx()
                 m2ctx = p2.manifestctx()
@@ -2667,6 +2673,11 b' class localrepository(object):'
                     mn = mctx.write(trp, linkrev,
                                     p1.manifestnode(), p2.manifestnode(),
                                     added, drop, match=self.narrowmatch())
+
+                    if writechangesetcopy:
+                        filesadded = [f for f in changed
+                                      if not (f in m1 or f in m2)]
+                        filesremoved = removed
                 else:
                     self.ui.debug('reusing manifest from p1 (listed files '
                                   'actually unchanged)\n')
@@ -2683,6 +2694,8 b' class localrepository(object):'
                 # filelogs.
                 p1copies = p1copies or None
                 p2copies = p2copies or None
+                filesadded = filesadded or None
+                filesremoved = filesremoved or None
 
             # update changelog
             self.ui.note(_("committing changelog\n"))
@@ -2690,7 +2703,7 b' class localrepository(object):'
             n = self.changelog.add(mn, files, ctx.description(),
                                    trp, p1.node(), p2.node(),
                                    user, ctx.date(), ctx.extra().copy(),
-                                   p1copies, p2copies)
+                                   p1copies, p2copies, filesadded, filesremoved)
             xp1, xp2 = p1.hex(), p2 and p2.hex() or ''
             self.hook('pretxncommit', throw=True, node=hex(n), parent1=xp1,
                       parent2=xp2)

tests/test-copies-in-changeset.t

@@ -5,6 +5,7 b''
   > copies.read-from=changeset-only
   > [alias]
   > changesetcopies = log -r . -T 'files: {files}
+  >   {extras % "{ifcontains("files", key, "{key}: {value}\n")}"}
   >   {extras % "{ifcontains("copies", key, "{key}: {value}\n")}"}'
   > showcopies = log -r . -T '{file_copies % "{source} -> {name}\n"}'
   > [extensions]
@@ -24,6 +25,8 b' Check that copies are recorded correctly'
   $ hg ci -m 'copy a to b, c, and d'
   $ hg changesetcopies
   files: b c d
+  filesadded: 0\x001\x002 (esc)
+  
   p1copies: b\x00a (esc)
   c\x00a (esc)
   d\x00a (esc)
@@ -43,6 +46,9 b' Check that renames are recorded correctl'
   $ hg ci -m 'rename b to b2'
   $ hg changesetcopies
   files: b b2
+  filesadded: 1
+  filesremoved: 0
+  
   p1copies: b2\x00b (esc)
   $ hg showcopies
   b -> b2
@@ -60,6 +66,7 b' even though there is no filelog entry.'
   $ hg ci -m 'move b onto d'
   $ hg changesetcopies
   files: c
+  
   p1copies: c\x00b2 (esc)
   $ hg showcopies
   b2 -> c
@@ -88,6 +95,8 b" File 'f' exists only in p1, so 'i' shoul"
   $ hg ci -m 'merge'
   $ hg changesetcopies
   files: g h i
+  filesadded: 0\x001\x002 (esc)
+  
   p1copies: g\x00a (esc)
   i\x00f (esc)
   p2copies: h\x00d (esc)
@@ -102,6 +111,9 b' Test writing to both changeset and filel'
   $ hg ci -m 'copy a to j' --config experimental.copies.write-to=compatibility
   $ hg changesetcopies
   files: j
+  filesadded: 0
+  filesremoved: 
+  
   p1copies: j\x00a (esc)
   p2copies: 
   $ hg debugdata j 0
@@ -122,6 +134,9 b" won't have to fall back to reading from "
   $ hg ci -m 'modify j' --config experimental.copies.write-to=compatibility
   $ hg changesetcopies
   files: j
+  filesadded: 
+  filesremoved: 
+  
   p1copies: 
   p2copies: 
 
@@ -131,6 +146,7 b' Test writing only to filelog'
   $ hg ci -m 'copy a to k' --config experimental.copies.write-to=filelog-only
   $ hg changesetcopies
   files: k
+  
   $ hg debugdata k 0
   \x01 (esc)
   copy: a
@@ -157,9 +173,9 b' Test rebasing a commit with copy informa'
   $ hg mv a b
   $ hg ci -qm 'rename a to b'
   $ hg rebase -d 1 --config rebase.experimental.inmemory=yes
-  rebasing 2:55d0b405c1b2 "rename a to b" (tip)
+  rebasing 2:acfc33f3aa6d "rename a to b" (tip)
   merging a and b to b
-  saved backup bundle to $TESTTMP/rebase-rename/.hg/strip-backup/55d0b405c1b2-78df867e-rebase.hg
+  saved backup bundle to $TESTTMP/rebase-rename/.hg/strip-backup/acfc33f3aa6d-81d0180d-rebase.hg
   $ hg st --change . --copies
   A b
     a

tests/test-copies.t

@@ -551,14 +551,15 b' Grafting revision 4 on top of revision 2'
 
   $ hg up 2 -q
   $ hg graft -r 4 --base 3 --hidden
-  grafting 4:af28412ec03c "added d, modified b" (tip)
+  grafting 4:af28412ec03c "added d, modified b" (tip) (no-changeset !)
+  grafting 4:6325ca0b7a1c "added d, modified b" (tip) (changeset !)
   merging b1 and b to b1
 
   $ hg l -l1 -p
   @  5 added d, modified b
   |  b1
   ~  diff -r 5a4825cc2926 -r 94a2f1a0e8e2 b1 (no-changeset !)
-  ~  diff -r f5474f5023a8 -r ef7c02d69f3d b1 (changeset !)
+  ~  diff -r df722b7fe2d5 -r ba3ddbbdfd96 b1 (changeset !)
      --- a/b1	Thu Jan 01 00:00:00 1970 +0000
      +++ b/b1	Thu Jan 01 00:00:00 1970 +0000
      @@ -1,1 +1,2 @@
@@ -618,7 +619,8 b' merging csets is a descendant of the bas'
      a
 
   $ hg rebase -r . -d 2 -t :other
-  rebasing 5:5018b1509e94 "added willconflict and d" (tip)
+  rebasing 5:5018b1509e94 "added willconflict and d" (tip) (no-changeset !)
+  rebasing 5:619047c26bf8 "added willconflict and d" (tip) (changeset !)
 
   $ hg up 3 -q
   $ hg l --hidden
@@ -641,4 +643,5 b' Now if we trigger a merge between revisi'
 neither of the merging csets will be a descendant of the base revision:
 
   $ hg graft -r 6 --base 4 --hidden -t :other
-  grafting 6:99802e4f1e46 "added willconflict and d" (tip)
+  grafting 6:99802e4f1e46 "added willconflict and d" (tip) (no-changeset !)
+  grafting 6:9ddc6fb3b691 "added willconflict and d" (tip) (changeset !)