( )⚙ D6277 copies: filter out copies from non-existent source later in _chain()

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Differential D6277

copies: filter out copies from non-existent source later in _chain()
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Authored by martinvonz on Apr 18 2019, 1:58 PM.

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rHGfdbeacb9d456: copies: filter out copies from non-existent source later in _chain()
Summary

_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 Detail

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rHG Mercurial
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Event Timeline

martinvonz created this revision.Apr 18 2019, 1:58 PM
martinvonz updated this revision to Diff 14951.Apr 28 2019, 3:00 AM
martinvonz updated this revision to Diff 14972.Apr 29 2019, 6:52 PM
Closed by commit rHGfdbeacb9d456: copies: filter out copies from non-existent source later in _chain() (authored by martinvonz). · Explain WhyMay 1 2019, 10:14 PM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mmercurial/copies.py (9 lines)

Diff 14951

mercurial/copies.py

# overwritten later, and case 3 will be removed later. # overwritten later, and case 3 will be removed later.
t = a.copy() t = a.copy()
for k, v in b.iteritems(): for k, v in b.iteritems():
if v in t: if v in t:
# found a chain, i.e. cases 3 & 4. # found a chain, i.e. cases 3 & 4.
if t[v] != k: if t[v] != k:
# file wasn't renamed back to itself (i.e. case 4, not 3) # file wasn't renamed back to itself (i.e. case 4, not 3)
t[k] = t[v] t[k] = t[v]
elif v in src: else:
# 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 t[k] = v
for k, v in list(t.items()): 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 # remove criss-crossed copies, i.e. case 3
if k in src and v in dst: elif k in src and v in dst:
del t[k] del t[k]
# remove copies to files that were then removed, i.e. case 1 # remove copies to files that were then removed, i.e. case 1
# and file 'y' in cases 3 & 4 (in case of rename) # and file 'y' in cases 3 & 4 (in case of rename)
elif k not in dst: elif k not in dst:
del t[k] del t[k]
return t return t