changeset 20207:cd62532c62a1

obsolete: order of magnitude speedup in _computebumpedset Reminder: a changeset is said "bumped" if it tries to obsolete a immutable changeset. The previous algorithm for computing bumped changeset was: 1) Get all public changesets 2) Find all they successors 3) Search for stuff that are eligible for being "bumped" (mutable and non obsolete) The entry size of this algorithm is `O(len(public))` which is mostly the same as `O(len(repo))`. Even this this approach mean fewer obsolescence marker are traveled, this is not very scalable. The new algorithm is: 1) For each potential bumped changesets (non obsolete mutable) 2) iterate over precursors 3) if a precursors is public. changeset is bumped We travel more obsolescence marker, but the entry size is much smaller since the amount of potential bumped should remains mostly stable with time `O(1)`. On some confidential gigantic repo this move bumped computation from 15.19s to 0.46s (×33 speedup…). On "smaller" repo (mercurial, cubicweb's review) no significant gain were seen. The additional traversal of obsolescence marker is probably probably counter balance the advantage of it. Other optimisation could be done in the future (eg: sharing precursors cache for divergence detection)
author Pierre-Yves David <pierre-yves.david@ens-lyon.org>
date Mon, 23 Dec 2013 15:29:51 -0800
parents cdcbe103b69a
children 174d9b8baf5d
files mercurial/obsolete.py
diffstat 1 files changed, 21 insertions(+), 8 deletions(-) [+]
line wrap: on
line diff
--- a/mercurial/obsolete.py	Mon Dec 23 13:36:13 2013 -0800
+++ b/mercurial/obsolete.py	Mon Dec 23 15:29:51 2013 -0800
@@ -84,6 +84,7 @@
 """
 import struct
 import util, base85, node
+import phases
 from i18n import _
 
 _pack = struct.pack
@@ -786,14 +787,26 @@
 @cachefor('bumped')
 def _computebumpedset(repo):
     """the set of revs trying to obsolete public revisions"""
-    # get all possible bumped changesets
-    tonode = repo.changelog.node
-    publicnodes = (tonode(r) for r in repo.revs('public()'))
-    successors = allsuccessors(repo.obsstore, publicnodes,
-                               ignoreflags=bumpedfix)
-    # revision public or already obsolete don't count as bumped
-    query = '%ld - obsolete() - public()'
-    return set(repo.revs(query, _knownrevs(repo, successors)))
+    bumped = set()
+    # utils function (avoid attribut lookup in the loop)
+    phase = repo._phasecache.phase # would be faster to grab the full list
+    public = phases.public
+    cl = repo.changelog
+    torev = cl.nodemap.get
+    obs = getrevs(repo, 'obsolete')
+    for rev in repo:
+        # We only evaluate mutable, non-obsolete revision
+        if (public < phase(repo, rev)) and (rev not in obs):
+            node = cl.node(rev)
+            # (future) A cache of precursors may worth if split is very common
+            for pnode in allprecursors(repo.obsstore, [node],
+                                       ignoreflags=bumpedfix):
+                prev = torev(pnode) # unfiltered! but so is phasecache
+                if (prev is not None) and (phase(repo, prev) <= public):
+                    # we have a public precursors
+                    bumped.add(rev)
+                    break # Next draft!
+    return bumped
 
 @cachefor('divergent')
 def _computedivergentset(repo):