changegroup: compute seen files as changesets are added (
issue4750)
Before this patch, addchangegroup() would walk the changelog and compute
the set of seen files between applying changesets and applying
manifests. When cloning large repositories such as mozilla-central,
this consumed a non-trivial amount of time. On my MBP, this walk takes
~10s. On a dainty EC2 instance, this was measured to take ~125s! On the
latter machine, this delay was enough for the Mercurial server to
disconnect the client, thinking it had timed out, thus causing a clone
to abort.
This patch enables the changelog to compute the set of changed files as
new revisions are added. By doing so, we:
* avoid a potentially heavy computation between changelog and manifest
processing by spreading the computation across all changelog additions
* avoid extra reads from the changelog by operating on the data as it is
added
The downside of this is that the add revision callback does result in
extra I/O. Before, we would perform a flush (and subsequent read to
construct the full revision) when new delta chains were created. For
changelogs, this is typically every 2-4 revisions. Using the callback
guarantees there will be a flush after every added revision *and* an
open + read of the changelog to obtain the full revision in order to
read the added files. So, this increases the frequency of these
operations by the average chain length. In the future, the revlog
should be smart enough to know how to read revisions that haven't been
flushed yet, thus eliminating this extra I/O.
On my MBP, the total CPU times for an `hg unbundle` with a local
mozilla-central gzip bundle containing 251,934 changesets and 211,065
files did not have a statistically significant change with this patch,
holding steady around 360s. So, the increased revlog flushing did not
have an effect.
With this patch, there is no longer a visible pause between applying
changeset and manifest data. Before, it sure felt like Mercurial was
lethargic making this transition. Now, the transition is nearly
instantaneous, giving the impression that Mercurial is faster. Of course,
eliminating this pause means that the potential for network disconnect due
to channel inactivity during the changelog walk is eliminated as well.
And that is the impetus behind this change.
#require svn13
$ svnupanddisplay()
> {
> (
> cd $1;
> svn up -q;
> svn st -v | sed 's/ */ /g' | sort
> limit=''
> if [ $2 -gt 0 ]; then
> limit="--limit=$2"
> fi
> svn log --xml -v $limit | python "$TESTDIR/svnxml.py"
> )
> }
$ cat >> $HGRCPATH <<EOF
> [extensions]
> convert =
> EOF
$ hg init a
Add
$ echo a > a/a
$ mkdir -p a/d1/d2
$ echo b > a/d1/d2/b
$ hg --cwd a ci -d '0 0' -A -m 'add a file'
adding a
adding d1/d2/b
Modify
$ svn-safe-append.py a a/a
$ hg --cwd a ci -d '1 0' -m 'modify a file'
$ hg --cwd a tip -q
1:e0e2b8a9156b
$ hg convert -d svn a
assuming destination a-hg
initializing svn repository 'a-hg'
initializing svn working copy 'a-hg-wc'
scanning source...
sorting...
converting...
1 add a file
0 modify a file
$ svnupanddisplay a-hg-wc 2
2 1 test d1
2 1 test d1/d2 (glob)
2 1 test d1/d2/b (glob)
2 2 test .
2 2 test a
revision: 2
author: test
msg: modify a file
M /a
revision: 1
author: test
msg: add a file
A /a
A /d1
A /d1/d2
A /d1/d2/b
$ ls a a-hg-wc
a:
a
d1
a-hg-wc:
a
d1
$ cmp a/a a-hg-wc/a
Rename
$ hg --cwd a mv a b
$ hg --cwd a ci -d '2 0' -m 'rename a file'
$ hg --cwd a tip -q
2:eb5169441d43
$ hg convert -d svn a
assuming destination a-hg
initializing svn working copy 'a-hg-wc'
scanning source...
sorting...
converting...
0 rename a file
$ svnupanddisplay a-hg-wc 1
3 1 test d1
3 1 test d1/d2 (glob)
3 1 test d1/d2/b (glob)
3 3 test .
3 3 test b
revision: 3
author: test
msg: rename a file
D /a
A /b (from /a@2)
$ ls a a-hg-wc
a:
b
d1
a-hg-wc:
b
d1
Copy
$ hg --cwd a cp b c
$ hg --cwd a ci -d '3 0' -m 'copy a file'
$ hg --cwd a tip -q
3:60effef6ab48
$ hg convert -d svn a
assuming destination a-hg
initializing svn working copy 'a-hg-wc'
scanning source...
sorting...
converting...
0 copy a file
$ svnupanddisplay a-hg-wc 1
4 1 test d1
4 1 test d1/d2 (glob)
4 1 test d1/d2/b (glob)
4 3 test b
4 4 test .
4 4 test c
revision: 4
author: test
msg: copy a file
A /c (from /b@3)
$ ls a a-hg-wc
a:
b
c
d1
a-hg-wc:
b
c
d1
$ hg --cwd a rm b
Remove
$ hg --cwd a ci -d '4 0' -m 'remove a file'
$ hg --cwd a tip -q
4:87bbe3013fb6
$ hg convert -d svn a
assuming destination a-hg
initializing svn working copy 'a-hg-wc'
scanning source...
sorting...
converting...
0 remove a file
$ svnupanddisplay a-hg-wc 1
5 1 test d1
5 1 test d1/d2 (glob)
5 1 test d1/d2/b (glob)
5 4 test c
5 5 test .
revision: 5
author: test
msg: remove a file
D /b
$ ls a a-hg-wc
a:
c
d1
a-hg-wc:
c
d1
Executable
#if execbit
$ chmod +x a/c
#else
$ echo fake >> a/c
#endif
$ hg --cwd a ci -d '5 0' -m 'make a file executable'
#if execbit
$ hg --cwd a tip -q
5:ff42e473c340
#else
$ hg --cwd a tip -q
5:817a700c8cf1
#endif
$ hg convert -d svn a
assuming destination a-hg
initializing svn working copy 'a-hg-wc'
scanning source...
sorting...
converting...
0 make a file executable
$ svnupanddisplay a-hg-wc 1
6 1 test d1
6 1 test d1/d2 (glob)
6 1 test d1/d2/b (glob)
6 6 test .
6 6 test c
revision: 6
author: test
msg: make a file executable
M /c
#if execbit
$ test -x a-hg-wc/c
#endif
#if symlink
Symlinks
$ ln -s a/missing a/link
$ hg --cwd a commit -Am 'add symlink'
adding link
$ hg --cwd a mv link newlink
$ hg --cwd a commit -m 'move symlink'
$ hg convert -d svn a a-svnlink
initializing svn repository 'a-svnlink'
initializing svn working copy 'a-svnlink-wc'
scanning source...
sorting...
converting...
7 add a file
6 modify a file
5 rename a file
4 copy a file
3 remove a file
2 make a file executable
1 add symlink
0 move symlink
$ svnupanddisplay a-svnlink-wc 1
8 1 test d1
8 1 test d1/d2
8 1 test d1/d2/b
8 6 test c
8 8 test .
8 8 test newlink
revision: 8
author: test
msg: move symlink
D /link
A /newlink (from /link@7)
Make sure our changes don't affect the rest of the test cases
$ hg --cwd a up 5
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg --cwd a --config extensions.strip= strip -r 6
saved backup bundle to $TESTTMP/a/.hg/strip-backup/bd4f7b7a7067-ed505e42-backup.hg (glob)
#endif
Convert with --full adds and removes files that didn't change
$ touch a/f
$ hg -R a ci -Aqmf
$ echo "rename c d" > filemap
$ hg convert -d svn a --filemap filemap --full
assuming destination a-hg
initializing svn working copy 'a-hg-wc'
scanning source...
sorting...
converting...
0 f
$ svnupanddisplay a-hg-wc 1
7 7 test .
7 7 test d
7 7 test f
revision: 7
author: test
msg: f
D /c
A /d
D /d1
A /f
$ rm -rf a a-hg a-hg-wc
Executable in new directory
$ hg init a
$ mkdir a/d1
$ echo a > a/d1/a
#if execbit
$ chmod +x a/d1/a
#else
$ echo fake >> a/d1/a
#endif
$ hg --cwd a ci -d '0 0' -A -m 'add executable file in new directory'
adding d1/a
$ hg convert -d svn a
assuming destination a-hg
initializing svn repository 'a-hg'
initializing svn working copy 'a-hg-wc'
scanning source...
sorting...
converting...
0 add executable file in new directory
$ svnupanddisplay a-hg-wc 1
1 1 test .
1 1 test d1
1 1 test d1/a (glob)
revision: 1
author: test
msg: add executable file in new directory
A /d1
A /d1/a
#if execbit
$ test -x a-hg-wc/d1/a
#endif
Copy to new directory
$ mkdir a/d2
$ hg --cwd a cp d1/a d2/a
$ hg --cwd a ci -d '1 0' -A -m 'copy file to new directory'
$ hg convert -d svn a
assuming destination a-hg
initializing svn working copy 'a-hg-wc'
scanning source...
sorting...
converting...
0 copy file to new directory
$ svnupanddisplay a-hg-wc 1
2 1 test d1
2 1 test d1/a (glob)
2 2 test .
2 2 test d2
2 2 test d2/a (glob)
revision: 2
author: test
msg: copy file to new directory
A /d2
A /d2/a (from /d1/a@1)
Branchy history
$ hg init b
$ echo base > b/b
$ hg --cwd b ci -d '0 0' -Ambase
adding b
$ svn-safe-append.py left-1 b/b
$ echo left-1 > b/left-1
$ hg --cwd b ci -d '1 0' -Amleft-1
adding left-1
$ svn-safe-append.py left-2 b/b
$ echo left-2 > b/left-2
$ hg --cwd b ci -d '2 0' -Amleft-2
adding left-2
$ hg --cwd b up 0
1 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ svn-safe-append.py right-1 b/b
$ echo right-1 > b/right-1
$ hg --cwd b ci -d '3 0' -Amright-1
adding right-1
created new head
$ svn-safe-append.py right-2 b/b
$ echo right-2 > b/right-2
$ hg --cwd b ci -d '4 0' -Amright-2
adding right-2
$ hg --cwd b up -C 2
3 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ hg --cwd b merge
merging b
warning: conflicts during merge.
merging b incomplete! (edit conflicts, then use 'hg resolve --mark')
2 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ hg --cwd b revert -r 2 b
$ hg --cwd b resolve -m b
(no more unresolved files)
$ hg --cwd b ci -d '5 0' -m 'merge'
Expect 4 changes
$ hg convert -d svn b
assuming destination b-hg
initializing svn repository 'b-hg'
initializing svn working copy 'b-hg-wc'
scanning source...
sorting...
converting...
5 base
4 left-1
3 left-2
2 right-1
1 right-2
0 merge
$ svnupanddisplay b-hg-wc 0
4 2 test left-1
4 3 test b
4 3 test left-2
4 4 test .
4 4 test right-1
4 4 test right-2
revision: 4
author: test
msg: merge
A /right-1
A /right-2
revision: 3
author: test
msg: left-2
M /b
A /left-2
revision: 2
author: test
msg: left-1
M /b
A /left-1
revision: 1
author: test
msg: base
A /b
Tags are not supported, but must not break conversion
$ rm -rf a a-hg a-hg-wc
$ hg init a
$ echo a > a/a
$ hg --cwd a ci -d '0 0' -A -m 'Add file a'
adding a
$ hg --cwd a tag -d '1 0' -m 'Tagged as v1.0' v1.0
$ hg convert -d svn a
assuming destination a-hg
initializing svn repository 'a-hg'
initializing svn working copy 'a-hg-wc'
scanning source...
sorting...
converting...
1 Add file a
0 Tagged as v1.0
writing Subversion tags is not yet implemented
$ svnupanddisplay a-hg-wc 2
2 1 test a
2 2 test .
2 2 test .hgtags
revision: 2
author: test
msg: Tagged as v1.0
A /.hgtags
revision: 1
author: test
msg: Add file a
A /a
$ rm -rf a a-hg a-hg-wc