branches: avoid unnecessary changectx.branch() calls This requires reading from the changelog, which can be costly over NFS. Note that this does not totally remove reading from the changelog; we still do that when calling changectx.closesbranch(). That call will be removed in a later patch. Running hg branches on the PyPy repo (with 996) over a busy NFS server, before this change: $ time hg --profile branches > /dev/null CallCount Recursive Total(s) Inline(s) module:lineno(function) 2042 0 2.2827 2.2827 <open> 2036 0 0.9840 0.9840 <method 'close' of 'file' objects> 2036 0 0.0464 0.0464 <method 'read' of 'file' objects> 5233 0 0.1985 0.0453 mercurial.repoview:161(changelog) 10462 0 0.0791 0.0314 mercurial.changelog:133(tip) 5233 0 0.0388 0.0176 mercurial.localrepo:26(__get__) 10462 0 0.0250 0.0126 <len> 5233 0 0.0059 0.0039 mercurial.repoview:112(filterrevs) 10462 0 0.0029 0.0029 <hash> 2034 0 0.0444 0.0444 <method 'seek' of 'file' objects> 5340 0 0.0390 0.0390 mercurial.revlog:296(rev) 2582 0 0.0371 0.0371 <zlib.decompress> 3155 0 0.1963 0.0366 mercurial.context:202(__init__) 3155 0 0.1238 0.0306 mercurial.repoview:161(changelog) 3155 0 0.0261 0.0080 mercurial.changelog:183(rev) 9465 0 0.0061 0.0061 <isinstance> 1096 0 0.0023 0.0023 <binascii.unhexlify> 4251 0 0.0014 0.0014 <len> 2059 0 3.7341 0.0332 mercurial.changelog:270(read) 2059 0 3.6304 0.0307 mercurial.revlog:907(revision) 2057 0 0.0262 0.0137 mercurial.changelog:28(decodeextra) 4118 0 0.0094 0.0094 <method 'split' of 'str' objects> 4118 0 0.0270 0.0048 mercurial.encoding:61(tolocal) 2059 0 0.0040 0.0040 <method 'index' of 'str' objects> 10462 0 0.0791 0.0314 mercurial.changelog:133(tip) 10462 0 0.0289 0.0207 mercurial.changelog:190(node) 10462 0 0.0188 0.0091 <len> 52433 20932 0.0478 0.0310 <len> 20932 0 0.0221 0.0168 mercurial.revlog:262(__len__) 2059 0 3.6304 0.0307 mercurial.revlog:907(revision) real 0m4.361s user 0m0.986s sys 0m0.237s After this change: $ time hg --profile branches > /dev/null CallCount Recursive Total(s) Inline(s) module:lineno(function) 1069 0 1.1098 1.1098 <open> 1063 0 0.4865 0.4865 <method 'close' of 'file' objects> 4122 0 0.1811 0.0404 mercurial.repoview:161(changelog) 8240 0 0.0712 0.0272 mercurial.changelog:133(tip) 4122 0 0.0378 0.0177 mercurial.localrepo:26(__get__) 8240 0 0.0221 0.0115 <len> 4122 0 0.0057 0.0033 mercurial.repoview:112(filterrevs) 8240 0 0.0025 0.0025 <hash> 3029 0 0.1979 0.0371 mercurial.context:202(__init__) 3029 0 0.1278 0.0310 mercurial.repoview:161(changelog) 3029 0 0.0230 0.0081 mercurial.changelog:183(rev) 9087 0 0.0061 0.0061 <isinstance> 1096 0 0.0026 0.0026 <binascii.unhexlify> 4125 0 0.0014 0.0014 <len> 4229 0 0.0337 0.0337 mercurial.revlog:296(rev) 1061 0 0.0296 0.0296 <method 'seek' of 'file' objects> 1063 0 0.0292 0.0292 <method 'read' of 'file' objects> 8240 0 0.0712 0.0272 mercurial.changelog:133(tip) 8240 0 0.0271 0.0196 mercurial.changelog:190(node) 8240 0 0.0169 0.0083 <len> 40476 16488 0.0422 0.0271 <len> 16488 0 0.0193 0.0152 mercurial.revlog:262(__len__) 1342 0 0.0241 0.0241 <zlib.decompress> 9445 0 0.0336 0.0224 mercurial.changelog:190(node) 9445 0 0.0112 0.0112 mercurial.revlog:317(node) 1074 0 1.9102 0.0224 mercurial.changelog:270(read) 1074 0 1.8397 0.0202 mercurial.revlog:907(revision) 1073 0 0.0187 0.0099 mercurial.changelog:28(decodeextra) 2148 0 0.0061 0.0061 <method 'split' of 'str' objects> 2148 0 0.0184 0.0034 mercurial.encoding:61(tolocal) real 0m2.402s user 0m0.735s sys 0m0.177s

--- a/mercurial/commands.py	Fri Nov 15 23:18:08 2013 -0500
+++ b/mercurial/commands.py	Fri Nov 15 23:18:08 2013 -0500
@@ -1013,7 +1013,7 @@
 
     hexfunc = ui.debugflag and hex or short
 
-    activebranches = set([repo[n].branch() for n in repo.heads()])
+    allheads = set(repo.heads())
     branches = []
     for tag, heads in repo.branchmap().iteritems():
         for h in reversed(heads):
@@ -1024,12 +1024,12 @@
                 break
         else:
             tip = repo[heads[-1]]
-        isactive = tag in activebranches and isopen
-        branches.append((tip, isactive, isopen))
-    branches.sort(key=lambda i: (i[1], i[0].rev(), i[0].branch(), i[2]),
+        isactive = isopen and bool(set(heads) & allheads)
+        branches.append((tag, tip, isactive, isopen))
+    branches.sort(key=lambda i: (i[2], i[1].rev(), i[0], i[3]),
                   reverse=True)
 
-    for ctx, isactive, isopen in branches:
+    for tag, ctx, isactive, isopen in branches:
         if (not active) or isactive:
             if isactive:
                 label = 'branches.active'
@@ -1042,16 +1042,16 @@
             else:
                 label = 'branches.inactive'
                 notice = _(' (inactive)')
-            if ctx.branch() == repo.dirstate.branch():
+            if tag == repo.dirstate.branch():
                 label = 'branches.current'
-            rev = str(ctx.rev()).rjust(31 - encoding.colwidth(ctx.branch()))
+            rev = str(ctx.rev()).rjust(31 - encoding.colwidth(tag))
             rev = ui.label('%s:%s' % (rev, hexfunc(ctx.node())),
                            'log.changeset changeset.%s' % ctx.phasestr())
-            tag = ui.label(ctx.branch(), label)
+            labeledtag = ui.label(tag, label)
             if ui.quiet:
-                ui.write("%s\n" % tag)
+                ui.write("%s\n" % labeledtag)
             else:
-                ui.write("%s %s%s\n" % (tag, rev, notice))
+                ui.write("%s %s%s\n" % (labeledtag, rev, notice))
 
 @command('bundle',
     [('f', 'force', None, _('run even when the destination is unrelated')),