commands: make commit acquire locks before processing (issue4368)
Before this patch, "hg commit" (process A) executes steps below:
1. get current branch heads via 'repo.branchheads()'
- cache 'repo.changelog'
2. invoke 'repo.commit()'
3. acquire wlock
- invalidate 'repo.dirstate'
4. access 'repo.dirstate'
- re-read '.hg/dirstate'
- check validity of parent revisions with 'repo.changelog'
5. invoke 'repo.commitctx()'
6. acquire store lock (slock)
- invalidate 'repo.changelog'
7. do committing
8. release slock
9. release wlock
10. check new branch head (via 'cmdutil.commitstatus()')
If acquisition of wlock at (3) above waits for another "hg commit"
(process B) or so running parallelly to release wlock, process A
causes creating orphan revision, because:
- '.hg/dirstate' refers the revision, which is newly added by
process B, as its parent
- but already cached 'repo.changelog' doesn't contain such revision
- therefore, validating parents of '.hg/dirstate' at (4) above
replaces such revision with 'nullid'
Then, process A creates "orphan" revision, of which parent is "null"
revision.
In addition to it, "created new head" may be shown at the end of
process A unintentionally, if store is updated parallelly, because
both getting branch heads (1) and checking new branch head (10) are
executed outside slock scope.
To avoid this issue, this patch makes "hg commit" acquire wlock and
slock before processing.
This patch resolves the issue between "hg commit" processes, but not
one between "hg commit" and other commands. Subsequent patches resolve
the latter.
Even after this patch, there are still corner case problems below:
- filecache may overlook changes of '.hg/dirstate', and it causes
similar issue (see below for detail)
https://bz.mercurial-scm.org/show_bug.cgi?id=4368#c10
- 3rd party extension may cause similar issue, if it directly uses
'repo.commit()' without acquisition of wlock and slock
This can be fixed by acquisition of slock at the beginning of
'repo.commit()', but it seems suitable for "default" branch
In fact, acquisition of slock itself is already introduced at
"default" branch by 4414d500604f, but acquisition is not at the
beginning of 'repo.commit()'.
This patch also changes some tests:
- test-fncache.t needs this tricky wrapping, to release (= forced
failure of) wlock certainly
- order of "hg commit" output is changed by widening scope of locks,
because some hooks are fired after releasing wlock
$ . "$TESTDIR/histedit-helpers.sh"
$ cat >> $HGRCPATH <<EOF
> [extensions]
> histedit=
> EOF
$ initrepo ()
> {
> hg init r
> cd r
> for x in a b c d e f ; do
> echo $x > $x
> hg add $x
> hg ci -m $x
> done
> echo a >> e
> hg ci -m 'does not commute with e'
> cd ..
> }
$ initrepo
$ cd r
log before edit
$ hg log --graph
@ changeset: 6:bfa474341cc9
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: does not commute with e
|
o changeset: 5:652413bf663e
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: f
|
o changeset: 4:e860deea161a
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: e
|
o changeset: 3:055a42cdd887
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: d
|
o changeset: 2:177f92b77385
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: c
|
o changeset: 1:d2ae7f538514
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: b
|
o changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
edit the history
$ hg histedit 177f92b77385 --commands - 2>&1 <<EOF | fixbundle
> pick 177f92b77385 c
> pick 055a42cdd887 d
> pick bfa474341cc9 does not commute with e
> pick e860deea161a e
> pick 652413bf663e f
> EOF
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
merging e
warning: conflicts while merging e! (edit, then use 'hg resolve --mark')
Fix up the change and run hg histedit --continue
insert unsupported advisory merge record
$ hg --config extensions.fakemergerecord=$TESTDIR/fakemergerecord.py fakemergerecord -x
$ hg debugmergestate
* version 2 records
local: 8f7551c7e4a2f2efe0bc8c741baf7f227d65d758
other: e860deea161a2f77de56603b340ebbb4536308ae
unrecognized entry: x advisory record
file: e (record type "F", state "u", hash 58e6b3a414a1e090dfc6029add0f3555ccba127f)
local path: e (flags "")
ancestor path: e (node null)
other path: e (node 6b67ccefd5ce6de77e7ead4f5292843a0255329f)
$ hg resolve -l
U e
insert unsupported mandatory merge record
$ hg --config extensions.fakemergerecord=$TESTDIR/fakemergerecord.py fakemergerecord -X
$ hg debugmergestate
* version 2 records
local: 8f7551c7e4a2f2efe0bc8c741baf7f227d65d758
other: e860deea161a2f77de56603b340ebbb4536308ae
file: e (record type "F", state "u", hash 58e6b3a414a1e090dfc6029add0f3555ccba127f)
local path: e (flags "")
ancestor path: e (node null)
other path: e (node 6b67ccefd5ce6de77e7ead4f5292843a0255329f)
unrecognized entry: X mandatory record
$ hg resolve -l
abort: unsupported merge state records: X
(see https://mercurial-scm.org/wiki/MergeStateRecords for more information)
[255]
$ hg resolve -ma
abort: unsupported merge state records: X
(see https://mercurial-scm.org/wiki/MergeStateRecords for more information)
[255]
abort the edit (should clear out merge state)
$ hg histedit --abort 2>&1 | fixbundle
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg debugmergestate
no merge state found
log after abort
$ hg resolve -l
$ hg log --graph
@ changeset: 6:bfa474341cc9
| tag: tip
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: does not commute with e
|
o changeset: 5:652413bf663e
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: f
|
o changeset: 4:e860deea161a
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: e
|
o changeset: 3:055a42cdd887
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: d
|
o changeset: 2:177f92b77385
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: c
|
o changeset: 1:d2ae7f538514
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: b
|
o changeset: 0:cb9a9f314b8b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
$ cd ..