[PATCH 3 of 3] locate: use ctx.matches instead of ctx.walk

[Siddharth Agarwal]

# HG changeset patch
# User Siddharth Agarwal <sid0 at fb.com>
# Date 1406956614 25200
#      Fri Aug 01 22:16:54 2014 -0700
# Node ID bc2877c860bb8bbb689d488869fdab1ee5232f97
# Parent  5e4d9c7cfc107374e85f8ca69746801257e322fa
locate: use ctx.matches instead of ctx.walk

On mozilla-central, which is around 100,000 files, best of 5:

$ hg --time locate > /dev/null
before: real 1.460 secs (user 1.140+0.000 sys 0.320+0.000)
after:  real 0.620 secs (user 0.610+0.000 sys 0.020+0.000)

$ hg --time locate README > /dev/null
before: real 0.630 secs (user 0.330+0.000 sys 0.290+0.000)
after:  real 0.120 secs (user 0.110+0.000 sys 0.020+0.000)

Larger repositories see correspondingly larger performance gains.

diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -4040,11 +4040,11 @@
     rev = scmutil.revsingle(repo, opts.get('rev'), None).node()
 
     ret = 1
-    m = scmutil.match(repo[rev], pats, opts, default='relglob')
+    ctx = repo[rev]
+    m = scmutil.match(ctx, pats, opts, default='relglob')
     m.bad = lambda x, y: False
-    for abs in repo[rev].walk(m):
-        if not rev and abs not in repo.dirstate:
-            continue
+
+    for abs in ctx.matches(m):
         if opts.get('fullpath'):
             ui.write(repo.wjoin(abs), end)
         else: