D6277: copies: filter out copies from non-existent source later in _chain()
martinvonz (Martin von Zweigbergk)
phabricator at mercurial-scm.org
Thu Apr 18 13:58:44 EDT 2019
martinvonz created this revision.
Herald added a subscriber: mercurial-devel.
Herald added a reviewer: hg-reviewers.
_changesetforwardcopies() repeatedly calls _chain(). That is very
expensive because _chain() does lookups in the manifest. I hope to
split up the function in two parts: 1) simple chaining, not
considering end points, and 2) filter out files that don't exist in
the end points (and ping-pong copies/renames).
This patches gets us closer to that by moving the check for
non-existent source later in the function. Now there are no more
checks for "src" and "dst" in the first loop; all the filtering of
invalid copies is done in the second loop. The code also looks much
more consistent now.
No measureable impact on `hg debugpathcopies 4.0 4.8`. That shouldn't
be surprising since the only case we're doing more checks now is in
case of chained copies/renames, which are quire rare in practice.
diff --git a/mercurial/copies.py b/mercurial/copies.py
@@ -134,13 +134,16 @@
if t[v] != k:
# file wasn't renamed back to itself (i.e. case 4, not 3)
t[k] = t[v]
- elif v in src:
- # file is a copy of an existing file, i.e. case 6.
+ # Renamed only in 'b', i.e. cases 5 & 6. We'll remove case 5 later.
t[k] = v
for k, v in list(t.items()):
+ # remove copies from files that didn't exist, i.e. case 5
+ if v not in src:
+ del t[k]
# remove criss-crossed copies, i.e. case 3
- if k in src and v in dst:
+ elif k in src and v in dst:
# remove copies to files that were then removed, i.e. case 1
# and file 'y' in cases 3 & 4 (in case of rename)
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