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.
Test uncommit - set up the config
$ cat >> $HGRCPATH <<EOF
> [experimental]
> evolution.createmarkers=True
> evolution.allowunstable=True
> [extensions]
> uncommit =
> drawdag=$TESTDIR/drawdag.py
> EOF
Build up a repo
$ hg init repo
$ cd repo
$ hg bookmark foo
Help for uncommit
$ hg help uncommit
hg uncommit [OPTION]... [FILE]...
uncommit part or all of a local changeset
This command undoes the effect of a local commit, returning the affected
files to their uncommitted state. This means that files modified or
deleted in the changeset will be left unchanged, and so will remain
modified in the working directory.
If no files are specified, the commit will be pruned, unless --keep is
given.
(use 'hg help -e uncommit' to show help for the uncommit extension)
options ([+] can be repeated):
--keep allow an empty commit after uncommiting
-I --include PATTERN [+] include names matching the given patterns
-X --exclude PATTERN [+] exclude names matching the given patterns
(some details hidden, use --verbose to show complete help)
Uncommit with no commits should fail
$ hg uncommit
abort: cannot uncommit null changeset
(no changeset checked out)
[255]
Create some commits
$ touch files
$ hg add files
$ for i in a ab abc abcd abcde; do echo $i > files; echo $i > file-$i; hg add file-$i; hg commit -m "added file-$i"; done
$ ls
file-a
file-ab
file-abc
file-abcd
file-abcde
files
$ hg log -G -T '{rev}:{node} {desc}' --hidden
@ 4:6c4fd43ed714e7fcd8adbaa7b16c953c2e985b60 added file-abcde
|
o 3:6db330d65db434145c0b59d291853e9a84719b24 added file-abcd
|
o 2:abf2df566fc193b3ac34d946e63c1583e4d4732b added file-abc
|
o 1:69a232e754b08d568c4899475faf2eb44b857802 added file-ab
|
o 0:3004d2d9b50883c1538fc754a3aeb55f1b4084f6 added file-a
Simple uncommit off the top, also moves bookmark
$ hg bookmark
* foo 4:6c4fd43ed714
$ hg uncommit
$ hg status
M files
A file-abcde
$ hg bookmark
* foo 3:6db330d65db4
$ hg log -G -T '{rev}:{node} {desc}' --hidden
x 4:6c4fd43ed714e7fcd8adbaa7b16c953c2e985b60 added file-abcde
|
@ 3:6db330d65db434145c0b59d291853e9a84719b24 added file-abcd
|
o 2:abf2df566fc193b3ac34d946e63c1583e4d4732b added file-abc
|
o 1:69a232e754b08d568c4899475faf2eb44b857802 added file-ab
|
o 0:3004d2d9b50883c1538fc754a3aeb55f1b4084f6 added file-a
Recommit
$ hg commit -m 'new change abcde'
$ hg status
$ hg heads -T '{rev}:{node} {desc}'
5:0c07a3ccda771b25f1cb1edbd02e683723344ef1 new change abcde (no-eol)
Uncommit of non-existent and unchanged files has no effect
$ hg uncommit nothinghere
nothing to uncommit
[1]
$ hg status
$ hg uncommit file-abc
nothing to uncommit
[1]
$ hg status
Try partial uncommit, also moves bookmark
$ hg bookmark
* foo 5:0c07a3ccda77
$ hg uncommit files
$ hg status
M files
$ hg bookmark
* foo 6:3727deee06f7
$ hg heads -T '{rev}:{node} {desc}'
6:3727deee06f72f5ffa8db792ee299cf39e3e190b new change abcde (no-eol)
$ hg log -r . -p -T '{rev}:{node} {desc}'
6:3727deee06f72f5ffa8db792ee299cf39e3e190b new change abcdediff -r 6db330d65db4 -r 3727deee06f7 file-abcde
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/file-abcde Thu Jan 01 00:00:00 1970 +0000
@@ -0,0 +1,1 @@
+abcde
$ hg log -G -T '{rev}:{node} {desc}' --hidden
@ 6:3727deee06f72f5ffa8db792ee299cf39e3e190b new change abcde
|
| x 5:0c07a3ccda771b25f1cb1edbd02e683723344ef1 new change abcde
|/
| x 4:6c4fd43ed714e7fcd8adbaa7b16c953c2e985b60 added file-abcde
|/
o 3:6db330d65db434145c0b59d291853e9a84719b24 added file-abcd
|
o 2:abf2df566fc193b3ac34d946e63c1583e4d4732b added file-abc
|
o 1:69a232e754b08d568c4899475faf2eb44b857802 added file-ab
|
o 0:3004d2d9b50883c1538fc754a3aeb55f1b4084f6 added file-a
$ hg commit -m 'update files for abcde'
Uncommit with dirty state
$ echo "foo" >> files
$ cat files
abcde
foo
$ hg status
M files
$ hg uncommit
abort: uncommitted changes
[255]
$ hg uncommit files
$ cat files
abcde
foo
$ hg commit --amend -m "files abcde + foo"
Testing the 'experimental.uncommitondirtywdir' config
$ echo "bar" >> files
$ hg uncommit
abort: uncommitted changes
[255]
$ hg uncommit --config experimental.uncommitondirtywdir=True
$ hg commit -m "files abcde + foo"
Uncommit in the middle of a stack, does not move bookmark
$ hg checkout '.^^^'
1 files updated, 0 files merged, 2 files removed, 0 files unresolved
(leaving bookmark foo)
$ hg log -r . -p -T '{rev}:{node} {desc}'
2:abf2df566fc193b3ac34d946e63c1583e4d4732b added file-abcdiff -r 69a232e754b0 -r abf2df566fc1 file-abc
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/file-abc Thu Jan 01 00:00:00 1970 +0000
@@ -0,0 +1,1 @@
+abc
diff -r 69a232e754b0 -r abf2df566fc1 files
--- a/files Thu Jan 01 00:00:00 1970 +0000
+++ b/files Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +1,1 @@
-ab
+abc
$ hg bookmark
foo 10:48e5bd7cd583
$ hg uncommit
3 new orphan changesets
$ hg status
M files
A file-abc
$ hg heads -T '{rev}:{node} {desc}'
10:48e5bd7cd583eb24164ef8b89185819c84c96ed7 files abcde + foo (no-eol)
$ hg bookmark
foo 10:48e5bd7cd583
$ hg commit -m 'new abc'
created new head
Partial uncommit in the middle, does not move bookmark
$ hg checkout '.^'
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg log -r . -p -T '{rev}:{node} {desc}'
1:69a232e754b08d568c4899475faf2eb44b857802 added file-abdiff -r 3004d2d9b508 -r 69a232e754b0 file-ab
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/file-ab Thu Jan 01 00:00:00 1970 +0000
@@ -0,0 +1,1 @@
+ab
diff -r 3004d2d9b508 -r 69a232e754b0 files
--- a/files Thu Jan 01 00:00:00 1970 +0000
+++ b/files Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +1,1 @@
-a
+ab
$ hg bookmark
foo 10:48e5bd7cd583
$ hg uncommit file-ab
1 new orphan changesets
$ hg status
A file-ab
$ hg heads -T '{rev}:{node} {desc}\n'
12:8eb87968f2edb7f27f27fe676316e179de65fff6 added file-ab
11:5dc89ca4486f8a88716c5797fa9f498d13d7c2e1 new abc
10:48e5bd7cd583eb24164ef8b89185819c84c96ed7 files abcde + foo
$ hg bookmark
foo 10:48e5bd7cd583
$ hg commit -m 'update ab'
$ hg status
$ hg heads -T '{rev}:{node} {desc}\n'
13:f21039c59242b085491bb58f591afc4ed1c04c09 update ab
11:5dc89ca4486f8a88716c5797fa9f498d13d7c2e1 new abc
10:48e5bd7cd583eb24164ef8b89185819c84c96ed7 files abcde + foo
$ hg log -G -T '{rev}:{node} {desc}' --hidden
@ 13:f21039c59242b085491bb58f591afc4ed1c04c09 update ab
|
o 12:8eb87968f2edb7f27f27fe676316e179de65fff6 added file-ab
|
| * 11:5dc89ca4486f8a88716c5797fa9f498d13d7c2e1 new abc
| |
| | * 10:48e5bd7cd583eb24164ef8b89185819c84c96ed7 files abcde + foo
| | |
| | | x 9:8a6b58c173ca6a2e3745d8bd86698718d664bc6c files abcde + foo
| | |/
| | | x 8:39ad452c7f684a55d161c574340c5766c4569278 update files for abcde
| | |/
| | | x 7:0977fa602c2fd7d8427ed4e7ee15ea13b84c9173 update files for abcde
| | |/
| | * 6:3727deee06f72f5ffa8db792ee299cf39e3e190b new change abcde
| | |
| | | x 5:0c07a3ccda771b25f1cb1edbd02e683723344ef1 new change abcde
| | |/
| | | x 4:6c4fd43ed714e7fcd8adbaa7b16c953c2e985b60 added file-abcde
| | |/
| | * 3:6db330d65db434145c0b59d291853e9a84719b24 added file-abcd
| | |
| | x 2:abf2df566fc193b3ac34d946e63c1583e4d4732b added file-abc
| |/
| x 1:69a232e754b08d568c4899475faf2eb44b857802 added file-ab
|/
o 0:3004d2d9b50883c1538fc754a3aeb55f1b4084f6 added file-a
Uncommit with draft parent
$ hg uncommit
$ hg phase -r .
12: draft
$ hg commit -m 'update ab again'
Phase is preserved
$ hg uncommit --keep --config phases.new-commit=secret
$ hg phase -r .
15: draft
$ hg commit --amend -m 'update ab again'
Uncommit with public parent
$ hg phase -p "::.^"
$ hg uncommit
$ hg phase -r .
12: public
Partial uncommit with public parent
$ echo xyz > xyz
$ hg add xyz
$ hg commit -m "update ab and add xyz"
$ hg uncommit xyz
$ hg status
A xyz
$ hg phase -r .
18: draft
$ hg phase -r ".^"
12: public
Uncommit leaving an empty changeset
$ cd $TESTTMP
$ hg init repo1
$ cd repo1
$ hg debugdrawdag <<'EOS'
> Q
> |
> P
> EOS
$ hg up Q -q
$ hg uncommit --keep
$ hg log -G -T '{desc} FILES: {files}'
@ Q FILES:
|
| x Q FILES: Q
|/
o P FILES: P
$ hg status
A Q
$ cd ..
$ rm -rf repo1
Testing uncommit while merge
$ hg init repo2
$ cd repo2
Create some history
$ touch a
$ hg add a
$ for i in 1 2 3; do echo $i > a; hg commit -m "a $i"; done
$ hg checkout 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ touch b
$ hg add b
$ for i in 1 2 3; do echo $i > b; hg commit -m "b $i"; done
created new head
$ hg log -G -T '{rev}:{node} {desc}' --hidden
@ 5:2cd56cdde163ded2fbb16ba2f918c96046ab0bf2 b 3
|
o 4:c3a0d5bb3b15834ffd2ef9ef603e93ec65cf2037 b 2
|
o 3:49bb009ca26078726b8870f1edb29fae8f7618f5 b 1
|
| o 2:990982b7384266e691f1bc08ca36177adcd1c8a9 a 3
| |
| o 1:24d38e3cf160c7b6f5ffe82179332229886a6d34 a 2
|/
o 0:ea4e33293d4d274a2ba73150733c2612231f398c a 1
Add and expect uncommit to fail on both merge working dir and merge changeset
$ hg merge 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg uncommit
abort: outstanding uncommitted merge
[255]
$ hg uncommit --config experimental.uncommitondirtywdir=True
abort: cannot uncommit while merging
[255]
$ hg status
M a
$ hg commit -m 'merge a and b'
$ hg uncommit
abort: cannot uncommit merge changeset
[255]
$ hg status
$ hg log -G -T '{rev}:{node} {desc}' --hidden
@ 6:c03b9c37bc67bf504d4912061cfb527b47a63c6e merge a and b
|\
| o 5:2cd56cdde163ded2fbb16ba2f918c96046ab0bf2 b 3
| |
| o 4:c3a0d5bb3b15834ffd2ef9ef603e93ec65cf2037 b 2
| |
| o 3:49bb009ca26078726b8870f1edb29fae8f7618f5 b 1
| |
o | 2:990982b7384266e691f1bc08ca36177adcd1c8a9 a 3
| |
o | 1:24d38e3cf160c7b6f5ffe82179332229886a6d34 a 2
|/
o 0:ea4e33293d4d274a2ba73150733c2612231f398c a 1