# HG changeset patch
# User Bryan O'Sullivan <bryano@fb.com>
# Date 1336826314 25200
# Node ID 7a98fbadcae985374d481c4beb2ecc3eb6d42d2a
# Parent  c6388ed0ec0a59e70189f95869c8f2087fcbb8a6
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.

diff --git a/hgsubversion/maps.py b/hgsubversion/maps.py
--- 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')
diff --git a/hgsubversion/util.py b/hgsubversion/util.py
--- a/hgsubversion/util.py
+++ b/hgsubversion/util.py
@@ -1,3 +1,4 @@
+import errno
 import re
 import os
 import urllib
@@ -13,6 +14,8 @@ try:
 except ImportError:
     pass
 
+import maps
+
 ignoredfiles = set(['.hgtags', '.hgsvnexternals', '.hgsub', '.hgsubstate'])
 
 b_re = re.compile(r'^\+\+\+ b\/([^\n]*)', re.MULTILINE)
@@ -279,11 +282,17 @@ def revset_fromsvn(repo, subset, x):
     '''
     args = revset.getargs(x, 0, 0, "fromsvn takes no arguments")
 
-    def matches(r):
-        convertinfo = repo[r].extra().get('convert_revision', '')
-        return convertinfo[:4] == 'svn:'
-
-    return [r for r in subset if matches(r)]
+    rev = repo.changelog.rev
+    bin = node.bin
+    try:
+        svnrevs = set(rev(bin(l.split(' ', 2)[1]))
+                      for l in maps.RevMap.readmapfile(repo, missingok=False))
+        return filter(svnrevs.__contains__, subset)
+    except IOError, err:
+        if err.errno != errno.ENOENT:
+            raise
+        raise hgutil.Abort("svn metadata is missing - "
+                           "run 'hg svn rebuildmeta' to reconstruct it")
 
 def revset_svnrev(repo, subset, x):
     '''``svnrev(number)``
@@ -294,17 +303,25 @@ def revset_svnrev(repo, subset, x):
     rev = revset.getstring(args[0],
                            "the argument to svnrev() must be a number")
     try:
-        rev = int(rev)
+        revnum = int(rev)
     except ValueError:
         raise error.ParseError("the argument to svnrev() must be a number")
 
-    def matches(r):
-        convertinfo = repo[r].extra().get('convert_revision', '')
-        if convertinfo[:4] != 'svn:':
-            return False
-        return int(convertinfo[40:].rsplit('@', 1)[-1]) == rev
-
-    return [r for r in subset if matches(r)]
+    rev = rev + ' '
+    revs = []
+    try:
+        for l in maps.RevMap.readmapfile(repo, missingok=False):
+            if l.startswith(rev):
+                n = l.split(' ', 2)[1]
+                r = repo[node.bin(n)].rev()
+                if r in subset:
+                    revs.append(r)
+        return revs
+    except IOError, err:
+        if err.errno != errno.ENOENT:
+            raise
+        raise hgutil.Abort("svn metadata is missing - "
+                           "run 'hg svn rebuildmeta' to reconstruct it")
 
 revsets = {
     'fromsvn': revset_fromsvn,