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Differential D7069

copies: simplify the handling of merges
ClosedPublic

Authored by marmoute on Oct 12 2019, 12:46 PM.

Details

Reviewers
martinvonz
Group Reviewers
hg-reviewers
Commits
rHG32187ae9eeb3: copies: simplify the handling of merges
rHG0aef9177a653: copies: simplify the handling of merges
Summary

Instead of stacking copies for both parent on the head, we move copies outside
of the heap into a dedicated dictionary. The two side of merge can we merged
sooner, making the algorithm simpler.

This simplicity reflect in the heap structure and speed up the execution for
copies involving a large amount of merges.

Here are timing for perfpathcopies of multiple revision pairs.

  • filelog: timing using filelog (with the introrev condition dropped)
  • base: this series base
  • before: the parent of this changeset
  • after: this changeset

revision: large amount; added files: large amount; rename small amount; c3b14617fbd7 9ba6ab77fd29
filelog: ! wall 3.679613 comb 3.680000 user 3.580000 sys 0.100000 (median of 3)
base: ! wall 8.884369 comb 8.880000 user 8.850000 sys 0.030000 (median of 3)
before: ! wall 8.443747 comb 8.420000 user 8.410000 sys 0.010000 (median of 3)
after: ! wall 4.697917 comb 4.690000 user 4.660000 sys 0.030000 (median of 3)
revision: large amount; added files: small amount; rename small amount; c3b14617fbd7 f650a9b140d2
filelog: ! wall 0.003357 comb 0.010000 user 0.010000 sys 0.000000 (median of 781)
base: ! wall 12.398524 comb 12.400000 user 12.330000 sys 0.070000 (median of 3)
before: ! wall 10.852593 comb 10.850000 user 10.800000 sys 0.050000 (median of 3)
after: ! wall 6.750832 comb 6.750000 user 6.640000 sys 0.110000 (median of 3)
revision: large amount; added files: large amount; rename large amount; 08ea3258278e d9fa043f30c0
filelog: ! wall 2.754687 comb 2.760000 user 2.650000 sys 0.110000 (median of 4)
base: ! wall 1.423166 comb 1.420000 user 1.400000 sys 0.020000 (median of 8)
before: ! wall 1.068041 comb 1.060000 user 1.050000 sys 0.010000 (median of 10)
after: ! wall 1.045916 comb 1.050000 user 1.040000 sys 0.010000 (median of 10)
revision: small amount; added files: large amount; rename large amount; df6f7a526b60 a83dc6a2d56f
filelog: ! wall 1.552293 comb 1.550000 user 1.510000 sys 0.040000 (median of 6
base: ! wall 0.022662 comb 0.020000 user 0.020000 sys 0.000000 (median of 128)
before: ! wall 0.021111 comb 0.020000 user 0.020000 sys 0.000000 (median of 139)
after: ! wall 0.021577 comb 0.020000 user 0.020000 sys 0.000000 (median of 138)
revision: small amount; added files: large amount; rename small amount; 4aa4e1f8e19a 169138063d63
filelog: ! wall 1.500983 comb 1.500000 user 1.420000 sys 0.080000 (median of 7)
base: ! wall 0.006956 comb 0.010000 user 0.010000 sys 0.000000 (median of 392)
before: ! wall 0.004356 comb 0.010000 user 0.010000 sys 0.000000 (median of 675)
after: ! wall 0.004329 comb 0.000000 user 0.000000 sys 0.000000 (median of 682)
revision: small amount; added files: small amount; rename small amount; 4bc173b045a6 964879152e2e
filelog: ! wall 0.011745 comb 0.020000 user 0.020000 sys 0.000000 (median of 250)
base: ! wall 0.000156 comb 0.000000 user 0.000000 sys 0.000000 (median of 17180)
before: ! wall 0.000100 comb 0.000000 user 0.000000 sys 0.000000 (median of 26912)
after: ! wall 0.000105 comb 0.000000 user 0.000000 sys 0.000000 (median of 25689)
revision: medium amount; added files: large amount; rename medium amount; c95f1ced15f2 2c68e87c3efe
filelog: ! wall 3.228230 comb 3.230000 user 3.110000 sys 0.120000 (median of 4)
base: ! wall 0.997640 comb 1.000000 user 0.980000 sys 0.020000 (median of 10)
before: ! wall 0.778291 comb 0.780000 user 0.780000 sys 0.000000 (median of 13)
after: ! wall 0.706594 comb 0.710000 user 0.710000 sys 0.000000 (median of 15)
revision: medium amount; added files: medium amount; rename small amount; d343da0c55a8 d7746d32bf9d
filelog: ! wall 1.052501 comb 1.060000 user 1.040000 sys 0.020000 (median of 10
base: ! wall 0.214519 comb 0.220000 user 0.220000 sys 0.000000 (median of 45)
before: ! wall 0.160804 comb 0.160000 user 0.160000 sys 0.000000 (median of 62)
after: ! wall 0.163736 comb 0.160000 user 0.160000 sys 0.000000 (median of 60)

Diff Detail

Repository
rHG Mercurial
Lint
Lint Skipped
Unit
Unit Tests Skipped

Event Timeline

marmoute created this revision.Oct 12 2019, 12:46 PM
martinvonz accepted this revision.Oct 14 2019, 12:54 PM
martinvonz added a subscriber: martinvonz.
martinvonz added inline comments.
mercurial/copies.py
199–200

list(roots) is simpler and clearer to me

200

and here {r: {} for r in roots} is simpler and clearer to me

This revision is now accepted and ready to land.Oct 14 2019, 12:54 PM
marmoute updated this revision to Diff 17195.Oct 16 2019, 3:44 AM
marmoute added a commit: rHG0aef9177a653: copies: simplify the handling of merges.Oct 16 2019, 12:20 PM
Closed by commit rHG0aef9177a653: copies: simplify the handling of merges (authored by marmoute). · Explain Why
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mmercurial/copies.py (48 lines)

Diff 17195

mercurial/copies.py

if p == node.nullrev: if p == node.nullrev:
continue continue
if p not in children: if p not in children:
children[p] = [r] children[p] = [r]
else: else:
children[p].append(r) children[p].append(r)
roots = set(children) - set(missingrevs) roots = set(children) - set(missingrevs)
# 'work' contains 3-tuples of a (revision number, parent number, copies). work = list(roots)
# The parent number is only used for knowing which parent the copies dict all_copies = {r: {} for r in roots}
martinvonzUnsubmitted
Not Done

list(roots) is simpler and clearer to me

martinvonz: `list(roots)` is simpler and clearer to me
martinvonzUnsubmitted
Not Done

and here {r: {} for r in roots} is simpler and clearer to me

martinvonz: and here `{r: {} for r in roots}` is simpler and clearer to me
# came from.
# NOTE: To reduce costly copying the 'copies' dicts, we reuse the same
# instance for *one* of the child nodes (the last one). Once an instance
# has been put on the queue, it is thus no longer safe to modify it.
# Conversely, it *is* safe to modify an instance popped off the queue.
work = [(r, 1, {}) for r in roots]
heapq.heapify(work) heapq.heapify(work)
alwaysmatch = match.always() alwaysmatch = match.always()
while work: while work:
r, i1, copies = heapq.heappop(work) r = heapq.heappop(work)
if work and work[0][0] == r: copies = all_copies.pop(r)
# We are tracing copies from both parents
r, i2, copies2 = heapq.heappop(work)
for dst, src in copies2.items():
# Unlike when copies are stored in the filelog, we consider
# it a copy even if the destination already existed on the
# other branch. It's simply too expensive to check if the
# file existed in the manifest.
if dst not in copies:
# If it was copied on the p1 side, leave it as copied from
# that side, even if it was also copied on the p2 side.
copies[dst] = copies2[dst]
if r == b.rev(): if r == b.rev():
return copies return copies
for i, c in enumerate(children[r]): for i, c in enumerate(children[r]):
childctx = repo[c] childctx = repo[c]
if r == childctx.p1().rev(): if r == childctx.p1().rev():
parent = 1 parent = 1
childcopies = childctx.p1copies() childcopies = childctx.p1copies()
else: else:
newcopies = copies.copy() newcopies = copies.copy()
else: else:
newcopies = copies newcopies = copies
if childcopies: if childcopies:
newcopies = _chain(newcopies, childcopies) newcopies = _chain(newcopies, childcopies)
for f in childctx.filesremoved(): for f in childctx.filesremoved():
if f in newcopies: if f in newcopies:
del newcopies[f] del newcopies[f]
heapq.heappush(work, (c, parent, newcopies)) othercopies = all_copies.get(c)
if othercopies is None:
heapq.heappush(work, c)
all_copies[c] = newcopies
else:
# we are the second parent to work on c, we need to merge our
# work with the other.
#
# Unlike when copies are stored in the filelog, we consider
# it a copy even if the destination already existed on the
# other branch. It's simply too expensive to check if the
# file existed in the manifest.
#
# In case of conflict, parent 1 take precedence over parent 2.
# This is an arbitrary choice made anew when implementing
# changeset based copies. It was made without regards with
# potential filelog related behavior.
if parent == 1:
othercopies.update(newcopies)
else:
newcopies.update(othercopies)
all_copies[c] = newcopies
assert False assert False
def _forwardcopies(a, b, base=None, match=None): def _forwardcopies(a, b, base=None, match=None):
"""find {dst@b: src@a} copy mapping where a is an ancestor of b""" """find {dst@b: src@a} copy mapping where a is an ancestor of b"""
if base is None: if base is None:
base = a base = a