[PATCH 2 of 2 v2] revset: use localrepo persistent branch name caching

[Mads Kiilerich]

# HG changeset patch
# User Mads Kiilerich <madski at unity3d.com>
# Date 1413396807 -7200
#      Wed Oct 15 20:13:27 2014 +0200
# Node ID 4cb47516ed19199839174415927e2c53c66cd765
# Parent  bf7a0169677c0545a63e64690b0e49e50b376703
revset: use localrepo persistent branch name caching

Branch name filtering in revsets was expensive. For every rev it created a
changectx and called .branch(). (Using changelog.branchinfo() would be up to
25% faster.)

Instead, use the new localrepo caching branch lookup method and improve
performance up to 4-6 times.

To prove it, the following revset was run on the relatively small hg repo:

  branch(stable)&branch(default)

Before, it took like 1.2 s every time.

With this change, it is a little bit faster first time (primarily because the
new code path uses changelog.branchinfo instead changectx.branch). When the
cache is fully updated it takes 0.3 s, making it 4 times as fast.

Similar tests on Unity's repo show 6 x improvements.

diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -489,16 +489,16 @@ def branch(repo, subset, x):
             # note: falls through to the revspec case if no branch with
             # this name exists
             if pattern in repo.branchmap():
-                return subset.filter(lambda r: matcher(repo[r].branch()))
+                return subset.filter(lambda r: matcher(repo.branch(r)))
         else:
-            return subset.filter(lambda r: matcher(repo[r].branch()))
+            return subset.filter(lambda r: matcher(repo.branch(r)))
 
     s = getset(repo, spanset(repo), x)
     b = set()
     for r in s:
-        b.add(repo[r].branch())
+        b.add(repo.branch(r))
     c = s.__contains__
-    return subset.filter(lambda r: c(r) or repo[r].branch() in b)
+    return subset.filter(lambda r: c(r) or repo.branch(r) in b)
 
 def bumped(repo, subset, x):
     """``bumped()``
@@ -1431,7 +1431,7 @@ def matching(repo, subset, x):
     getfieldfuncs = []
     _funcs = {
         'user': lambda r: repo[r].user(),
-        'branch': lambda r: repo[r].branch(),
+        'branch': repo.branch,
         'date': lambda r: repo[r].date(),
         'description': lambda r: repo[r].description(),
         'files': lambda r: repo[r].files(),
@@ -1532,9 +1532,9 @@ def sort(repo, subset, x):
             elif k == '-rev':
                 e.append(-r)
             elif k == 'branch':
-                e.append(c.branch())
+                e.append(repo.branch(r))
             elif k == '-branch':
-                e.append(invert(c.branch()))
+                e.append(invert(repo.branch(r)))
             elif k == 'desc':
                 e.append(c.description())
             elif k == '-desc':
diff --git a/tests/test-revset.t b/tests/test-revset.t
--- a/tests/test-revset.t
+++ b/tests/test-revset.t
@@ -744,6 +744,64 @@ issue2437
   $ log 'ancestors(8) and (heads(branch("-a-b-c-")) or heads(branch(é)))'
   4
 
+branchname caching
+
+ cache creation
+  $ rm .hg/cache/branchnames
+  $ log 'branch("-a-b-c-")'
+  4
+  $ "$TESTDIR/md5sum.py" .hg/cache/branchnames
+  c31b7e7bdc4e1f69133685cf82550eac  .hg/cache/branchnames
+ handling of invalid cache file
+  $ echo > .hg/cache/branchnames
+  $ log 'branch("-a-b-c-")'
+  4
+  $ "$TESTDIR/md5sum.py" .hg/cache/branchnames
+  c31b7e7bdc4e1f69133685cf82550eac  .hg/cache/branchnames
+ handling of extra trailing data
+  $ echo >> .hg/cache/branchnames
+  $ log 'branch("-a-b-c-")'
+  4
+  $ "$TESTDIR/md5sum.py" .hg/cache/branchnames
+  c31b7e7bdc4e1f69133685cf82550eac  .hg/cache/branchnames
+ update after commit
+  $ hg tag tag
+  $ "$TESTDIR/md5sum.py" .hg/cache/branchnames
+  c31b7e7bdc4e1f69133685cf82550eac  .hg/cache/branchnames
+  $ log 'branch("-a-b-c-")'
+  4
+  $ "$TESTDIR/md5sum.py" .hg/cache/branchnames
+  77d75afbf592f045b609c3a68986a908  .hg/cache/branchnames
+ $ update after rollback
+  $ hg up -qr '.^'
+  $ hg rollback -qf
+  $ "$TESTDIR/md5sum.py" .hg/cache/branchnames
+  77d75afbf592f045b609c3a68986a908  .hg/cache/branchnames
+  $ log 'branch("-a-b-c-")'
+  4
+  $ "$TESTDIR/md5sum.py" .hg/cache/branchnames
+  c31b7e7bdc4e1f69133685cf82550eac  .hg/cache/branchnames
+ handle non-tip node change (could be a problem with some cache invalidation schemes)
+  $ hg bundle -q --all bu.hg
+  $ hg --config extensions.strip= strip --no-b -qr 8
+  $ hg up -q 7
+  $ hg branch -q hacked
+  $ hg ci --amend -qm 'hacked'
+  $ hg pull -q bu.hg -r 24286f4ae135
+  $ log 'branch("hacked")'
+  7
+  $ "$TESTDIR/md5sum.py" .hg/cache/branchnames
+  7e7547be03cd3badb5053899aea5c532  .hg/cache/branchnames
+  $ hg --config extensions.strip= strip --no-b -qr 7:
+  $ hg pull -q bu.hg
+  $ rm bu.hg
+  $ hg up -qr tip
+  $ log 'branch("-a-b-c-")'
+  4
+  $ "$TESTDIR/md5sum.py" .hg/cache/branchnames
+  753e486275e544c562da095fd116a441  .hg/cache/branchnames
+(the cache file still contains the now unused 'hacked' branch name)
+
 issue2654: report a parse error if the revset was not completely parsed
 
   $ log '1 OR 2'