sparse-revlog: implement algorithm to write sparse delta chains (
issue5480)
The classic behavior of revlog._isgooddeltainfo is to consider the span size
of the whole delta chain, and limit it to 4 * textlen.
Once sparse-revlog writing is allowed (and enforced with a requirement),
revlog._isgooddeltainfo considers the span of the largest chunk as the
distance used in the verification, instead of using the span of the whole
delta chain.
In order to compute the span of the largest chunk, we need to slice into
chunks a chain with the new revision at the top of the revlog, and take the
maximal span of these chunks. The sparse read density is a parameter to the
slicing, as it will stop when the global read density reaches this threshold.
For instance, a density of 50% means that 2 of 4 read bytes are actually used
for the reconstruction of the revision (the others are part of other chains).
This allows a new revision to be potentially stored with a diff against
another revision anywhere in the history, instead of forcing it in the last 4
* textlen. The result is a much better compression on repositories that have
many concurrent branches. Here are a comparison between using deltas from
current upstream (aggressive-merge-deltas on by default) and deltas from a
sparse-revlog
Comparison of `.hg/store/` size:
mercurial (6.74% merges):
before: 46,831,873 bytes
after: 46,795,992 bytes (no relevant change)
pypy (8.30% merges):
before: 333,524,651 bytes
after: 308,417,511 bytes -8%
netbeans (34.21% merges):
before: 1,141,847,554 bytes
after: 1,131,093,161 bytes -1%
mozilla-central (4.84% merges):
before: 2,344,248,850 bytes
after: 2,328,459,258 bytes -1%
large-private-repo-A (merge 19.73%)
before: 41,510,550,163 bytes
after: 8,121,763,428 bytes -80%
large-private-repo-B (23.77%)
before: 58,702,221,709 bytes
after: 8,351,588,828 bytes -76%
Comparison of `00manifest.d` size:
mercurial (6.74% merges):
before: 6,143,044 bytes
after: 6,107,163 bytes
pypy (8.30% merges):
before: 52,941,780 bytes
after: 27,834,082 bytes -48%
netbeans (34.21% merges):
before: 130,088,982 bytes
after: 119,337,636 bytes -10%
mozilla-central (4.84% merges):
before: 215,096,339 bytes
after: 199,496,863 bytes -8%
large-private-repo-A (merge 19.73%)
before: 33,725,285,081 bytes
after: 390,302,545 bytes -99%
large-private-repo-B (23.77%)
before: 49,457,701,645 bytes
after: 1,366,752,187 bytes -97%
The better delta chains provide a performance boost in relevant repositories:
pypy, bundling 1000 revisions:
before: 1.670s
after: 1.149s -31%
Unbundling got a bit slower. probably because the sparse algorithm is still
pure
python.
pypy, unbundling 1000 revisions:
before: 4.062s
after: 4.507s +10%
Performance of bundle/unbundle in repository with few concurrent branches (eg:
mercurial) are unaffected.
No significant differences have been noticed then timing `hg push` and `hg
pull` locally. More state timings are being gathered.
Same as for aggressive-merge-delta, better delta comes with longer delta
chains. Longer chains have a performance impact. For example. The length of
the chain needed to get the manifest of pypy's tip moves from 82 item to 1929
items. This moves the restore time from 3.88ms to 11.3ms.
Delta chain length is an independent issue that affects repository without
this changes. It will be dealt with independently.
No significant differences have been observed on repositories where
`sparse-revlog` have not much effect (mercurial, unity, netbeans). On pypy,
small differences have been observed on some operation affected by delta chain
building and retrieval.
pypy, perfmanifest
before: 0.006162s
after: 0.017899s +190%
pypy, commit:
before: 0.382
after: 0.376 -1%
pypy, status:
before: 0.157
after: 0.168 +7%
More comprehensive and stable timing comparisons are in progress.
#require serve
$ hg init test
$ cd test
$ for i in 0 1 2 3 4 5 6 7 8; do
> echo $i >> foo
> hg commit -A -m $i
> done
adding foo
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 9 changesets, 9 total revisions
$ hg serve -p $HGPORT -d --pid-file=hg.pid
$ cat hg.pid >> $DAEMON_PIDS
$ cd ..
$ hg init new
http incoming
$ hg -R new incoming http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
changeset: 5:ad284ee3b5ee
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 5
changeset: 6:e9229f2de384
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 6
changeset: 7:d152815bb8db
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 7
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ hg -R new incoming -r 4 http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
local incoming
$ hg -R new incoming test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
changeset: 5:ad284ee3b5ee
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 5
changeset: 6:e9229f2de384
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 6
changeset: 7:d152815bb8db
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 7
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ hg -R new incoming -r 4 test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
limit to 2 changesets
$ hg -R new incoming -l 2 test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
limit to 2 changesets, test with -p --git
$ hg -R new incoming -l 2 -p --git test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
diff --git a/foo b/foo
new file mode 100644
--- /dev/null
+++ b/foo
@@ -0,0 +1,1 @@
+0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
diff --git a/foo b/foo
--- a/foo
+++ b/foo
@@ -1,1 +1,2 @@
0
+1
test with --bundle
$ hg -R new incoming --bundle test.hg http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
changeset: 5:ad284ee3b5ee
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 5
changeset: 6:e9229f2de384
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 6
changeset: 7:d152815bb8db
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 7
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ hg -R new incoming --bundle test2.hg test
comparing with test
changeset: 0:00a43fa82f62
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0
changeset: 1:5460a410df01
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 1
changeset: 2:d9f42cd1a1ec
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 2
changeset: 3:376476025137
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 3
changeset: 4:70d7eb252d49
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 4
changeset: 5:ad284ee3b5ee
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 5
changeset: 6:e9229f2de384
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 6
changeset: 7:d152815bb8db
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 7
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
test the resulting bundles
$ hg init temp
$ hg init temp2
$ hg -R temp unbundle test.hg
adding changesets
adding manifests
adding file changes
added 9 changesets with 9 changes to 1 files
new changesets 00a43fa82f62:e4feb4ac9035
(run 'hg update' to get a working copy)
$ hg -R temp2 unbundle test2.hg
adding changesets
adding manifests
adding file changes
added 9 changesets with 9 changes to 1 files
new changesets 00a43fa82f62:e4feb4ac9035
(run 'hg update' to get a working copy)
$ hg -R temp tip
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ hg -R temp2 tip
changeset: 8:e4feb4ac9035
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 8
$ rm -r temp temp2 new
test outgoing
$ hg clone test test-dev
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd test-dev
$ for i in 9 10 11 12 13; do
> echo $i >> foo
> hg commit -A -m $i
> done
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 14 changesets, 14 total revisions
$ cd ..
$ hg -R test-dev outgoing test
comparing with test
searching for changes
changeset: 9:d89d4abea5bc
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 9
changeset: 10:820095aa7158
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 10
changeset: 11:09ede2f3a638
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 11
changeset: 12:e576b1bed305
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 12
changeset: 13:96bbff09a7cc
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 13
test outgoing with secret changesets
$ hg -R test-dev phase --force --secret 9
$ hg -R test-dev outgoing test
comparing with test
searching for changes
no changes found (ignored 5 secret changesets)
[1]
$ hg -R test-dev phase --draft -r 'head()'
limit to 3 changesets
$ hg -R test-dev outgoing -l 3 test
comparing with test
searching for changes
changeset: 9:d89d4abea5bc
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 9
changeset: 10:820095aa7158
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 10
changeset: 11:09ede2f3a638
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 11
$ hg -R test-dev outgoing http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
searching for changes
changeset: 9:d89d4abea5bc
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 9
changeset: 10:820095aa7158
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 10
changeset: 11:09ede2f3a638
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 11
changeset: 12:e576b1bed305
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 12
changeset: 13:96bbff09a7cc
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 13
$ hg -R test-dev outgoing -r 11 http://localhost:$HGPORT/
comparing with http://localhost:$HGPORT/
searching for changes
changeset: 9:d89d4abea5bc
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 9
changeset: 10:820095aa7158
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 10
changeset: 11:09ede2f3a638
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 11
incoming from empty remote repository
$ hg init r1
$ hg init r2
$ echo a > r1/foo
$ hg -R r1 ci -Ama
adding foo
$ hg -R r1 incoming r2 --bundle x.hg
comparing with r2
searching for changes
no changes found
[1]
Create a "split" repo that pulls from r1 and pushes to r2, using default-push
$ hg clone r1 split
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cat > split/.hg/hgrc << EOF
> [paths]
> default = $TESTTMP/r3
> default-push = $TESTTMP/r2
> EOF
$ hg -R split outgoing
comparing with $TESTTMP/r2
searching for changes
changeset: 0:3e92d79f743a
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
Use default:pushurl instead of default-push
Windows needs a leading slash to make a URL that passes all of the checks
$ WD=`pwd`
#if windows
$ WD="/$WD"
#endif
$ cat > split/.hg/hgrc << EOF
> [paths]
> default = $WD/r3
> default:pushurl = file://$WD/r2
> EOF
$ hg -R split outgoing
comparing with file:/*/$TESTTMP/r2 (glob)
searching for changes
changeset: 0:3e92d79f743a
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
Push and then double-check outgoing
$ echo a >> split/foo
$ hg -R split commit -Ama
$ hg -R split push
pushing to file:/*/$TESTTMP/r2 (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
$ hg -R split outgoing
comparing with file:/*/$TESTTMP/r2 (glob)
searching for changes
no changes found
[1]