Mercurial > hgsubversion

diff hgsubversion/maps.py @ 889:7a98fbadcae9

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revsets: huge speedups for fromsvn and svnrev I have a hgsubversion repo that contains over 300,000 commits. In that repo, this patch improves performance as follows: hg --time log -r 'first(fromsvn())' Before: 40.3 sec After: 0.8 sec hg --time log -r 'svnrev(350000)' Before: 40.3 sec After: 0.1 sec Note: the performance of these revset implementations is very sensitive to doing as little work as possible per line of the rev_map file. I originally attempted to hide the file format details by hoisting the parsing of each line up into RevMap.readmapfile, but the current less abstract code is dramatically (10x or more) faster. If the revmap file is missing, we error out and print a message describing what to do.
author Bryan O'Sullivan <bryano@fb.com>
date Sat, 12 May 2012 05:38:34 -0700
parents 0de18c5c2e35
children 83cc6e9e8425
line wrap: on
line diff
--- a/hgsubversion/maps.py
+++ b/hgsubversion/maps.py
@@ -1,5 +1,6 @@
 ''' Module for self-contained maps. '''
 
+import errno
 import os
 from mercurial import util as hgutil
 from mercurial import node
@@ -182,7 +183,8 @@ class RevMap(dict):
 
     def __init__(self, repo):
         dict.__init__(self)
-        self.path = os.path.join(repo.path, 'svn', 'rev_map')
+        self.path = self.mappath(repo)
+        self.repo = repo
         self.ypath = os.path.join(repo.path, 'svn', 'lastpulled')
         # TODO(durin42): Consider moving management of the youngest
         # file to svnmeta itself rather than leaving it here.
@@ -212,13 +214,26 @@ class RevMap(dict):
         check = lambda x: x[0][1] == branch and x[0][0] < rev.revnum
         return sorted(filter(check, self.iteritems()), reverse=True)
 
-    def _load(self):
-        f = open(self.path)
+    @staticmethod
+    def mappath(repo):
+        return os.path.join(repo.path, 'svn', 'rev_map')
+
+    @classmethod
+    def readmapfile(cls, repo, missingok=True):
+        try:
+            f = open(cls.mappath(repo))
+        except IOError, err:
+            if not missingok or err.errno != errno.ENOENT:
+                raise
+            return iter([])
         ver = int(f.readline())
-        if ver != self.VERSION:
+        if ver != cls.VERSION:
             print 'revmap too new -- please upgrade'
             raise NotImplementedError
-        for l in f:
+        return f
+
+    def _load(self):
+        for l in self.readmapfile(self.repo):
             revnum, ha, branch = l.split(' ', 2)
             if branch == '\n':
                 branch = None
@@ -230,7 +245,6 @@ class RevMap(dict):
             if revnum < self.oldest or not self.oldest:
                 self.oldest = revnum
             dict.__setitem__(self, (revnum, branch), node.bin(ha))
-        f.close()
 
     def _write(self):
         f = open(self.path, 'w')