[PATCH V2] copy: add flag for disabling copy tracing

Durham Goode durham at fb.com
Wed Feb 4 03:13:05 UTC 2015


# HG changeset patch
# User Durham Goode <durham at fb.com>
# Date 1422386787 28800
#      Tue Jan 27 11:26:27 2015 -0800
# Node ID 94d5d878251d92e97b47339110848205e54eb960
# Parent  e1dbe0b215ae137eec53ceb12440536d570a83d2
copy: add flag for disabling copy tracing

Copy tracing can be up to 50% of rebase time when rebasing medium sized stacks
of commits (~12 commits) in large repos (hundreds of thousands of files).
This provides the option of turning off the majority of copy tracing. It
does not turn off _forwardcopies() since that is used to carry copy
information inside a commit across a rebase.

This will affect the situation where a user edits a file, then rebases on top of
commits that have moved that file. The move will not be detected and the user
will have to manually resolve the issue.

Once the lazymanifest work goes in, we can make this smarter by only disabling
copy detection when we know all the target files exist in the destination (since
we will be able to cheaply detect this with lazymanifest.diff).

This takes a 12 commit rebase from 70s to 45s. Future patches will bring this
down further to 27s.

diff --git a/mercurial/copies.py b/mercurial/copies.py
--- a/mercurial/copies.py
+++ b/mercurial/copies.py
@@ -192,6 +192,9 @@ def _forwardcopies(a, b):
     return cm
 
 def _backwardrenames(a, b):
+    if a._repo.ui.config('experimental', 'copytracemode') == 'disabled':
+        return {}
+
     # Even though we're not taking copies into account, 1:n rename situations
     # can still exist (e.g. hg cp a b; hg mv a c). In those cases we
     # arbitrarily pick one of the renames.
@@ -261,6 +264,13 @@ def mergecopies(repo, c1, c2, ca):
     if c2.node() is None and c1.node() == repo.dirstate.p1():
         return repo.dirstate.copies(), {}, {}, {}
 
+    if repo.ui.config('experimental', 'copytracemode') == 'disabled':
+        # If we're just tracking against the parent, do a simple check.
+        # This is necessary to ensure copies survive rebasing.
+        if ca in c2.parents():
+            return pathcopies(ca, c2), {}, {}, {}
+        return {}, {}, {}, {}
+
     limit = _findlimit(repo, c1.rev(), c2.rev())
     if limit is None:
         # no common ancestor, no copies
diff --git a/tests/test-copy-move-merge.t b/tests/test-copy-move-merge.t
--- a/tests/test-copy-move-merge.t
+++ b/tests/test-copy-move-merge.t
@@ -61,4 +61,45 @@ file c
   1
   2
 
+Verify disabling copy tracing loses copy info
+
+  $ hg up -qC 2
+  $ hg rebase --keep -d 1 -b 2 --config extensions.rebase=
+  rebasing 2:add3f11052fa "other" (tip)
+  merging b and a to b
+  merging c and a to c
+
+  $ test -f a
+  [1]
+
+  $ cat b
+  0
+  1
+  2
+
+  $ cat c
+  0
+  1
+  2
+
+  $ hg strip -r . --config extensions.strip=
+  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  saved backup bundle to $TESTTMP/t/.hg/strip-backup/550bd84c0cd3-fc575957-backup.hg (glob)
+  $ hg up -qC 2
+  $ hg rebase --keep -d 1 -b 2 --config extensions.rebase= --config experimental.copytracemode=disabled
+  rebasing 2:add3f11052fa "other" (tip)
+  remote changed a which local deleted
+  use (c)hanged version or leave (d)eleted? c
+  $ cat a
+  0
+  1
+
+  $ cat b
+  1
+  2
+
+  $ cat c
+  1
+  2
+
   $ cd ..


More information about the Mercurial-devel mailing list