Mercurial > public > mercurial-scm > hg-stable

diff mercurial/revlog.py @ 26118:049005de325e

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revlog: add an aggressivemergedelta option This adds an option for delta'ing against both p1 and p2 when applying merge revisions and picking whichever is smallest. Some before and after stats on manifest.d size: internal large repo: before: 1.2 GB after: 930 MB mozilla-central: before: 261 MB after: 92 MB
author Durham Goode <durham@fb.com>
date Sun, 30 Aug 2015 14:03:32 -0700
parents 4dc5b51f38fe
children eb97d49768cc
line wrap: on
line diff
--- a/mercurial/revlog.py	Sun Aug 30 13:58:11 2015 -0700
+++ b/mercurial/revlog.py	Sun Aug 30 14:03:32 2015 -0700
@@ -210,6 +210,7 @@
         self._chunkcache = (0, '')
         self._chunkcachesize = 65536
         self._maxchainlen = None
+        self._aggressivemergedeltas = False
         self.index = []
         self._pcache = {}
         self._nodecache = {nullid: nullrev}
@@ -227,6 +228,8 @@
                 self._chunkcachesize = opts['chunkcachesize']
             if 'maxchainlen' in opts:
                 self._maxchainlen = opts['maxchainlen']
+            if 'aggressivemergedeltas' in opts:
+                self._aggressivemergedeltas = opts['aggressivemergedeltas']
 
         if self._chunkcachesize <= 0:
             raise RevlogError(_('revlog chunk cache size %r is not greater '
@@ -1343,15 +1346,34 @@
         # should we try to build a delta?
         if prev != nullrev:
             if self._generaldelta:
-                # Pick whichever parent is closer to us (to minimize the
-                # chance of having to build a fulltext). Since
-                # nullrev == -1, any non-merge commit will always pick p1r.
-                drev = p2r if p2r > p1r else p1r
-                d = builddelta(drev)
-                # If the chosen delta will result in us making a full text,
-                # give it one last try against prev.
-                if drev != prev and not self._isgooddelta(d, textlen):
-                    d = builddelta(prev)
+                if p2r != nullrev and self._aggressivemergedeltas:
+                    d = builddelta(p1r)
+                    d2 = builddelta(p2r)
+                    p1good = self._isgooddelta(d, textlen)
+                    p2good = self._isgooddelta(d2, textlen)
+                    if p1good and p2good:
+                        # If both are good deltas, choose the smallest
+                        if d2[1] < d[1]:
+                            d = d2
+                    elif p2good:
+                        # If only p2 is good, use it
+                        d = d2
+                    elif p1good:
+                        pass
+                    else:
+                        # Neither is good, try against prev to hopefully save us
+                        # a fulltext.
+                        d = builddelta(prev)
+                else:
+                    # Pick whichever parent is closer to us (to minimize the
+                    # chance of having to build a fulltext). Since
+                    # nullrev == -1, any non-merge commit will always pick p1r.
+                    drev = p2r if p2r > p1r else p1r
+                    d = builddelta(drev)
+                    # If the chosen delta will result in us making a full text,
+                    # give it one last try against prev.
+                    if drev != prev and not self._isgooddelta(d, textlen):
+                        d = builddelta(prev)
             else:
                 d = builddelta(prev)
             dist, l, data, base, chainbase, chainlen, compresseddeltalen = d