scmutil: add file object wrapper class to check ambiguity at closing
In Mercurial source tree, opening a file in "a"/"a+" mode like below
doesn't specify atomictemp=True for vfs, and this avoids file stat
ambiguity check by atomictempfile.
- writing changes out in revlog layer uses "a+" mode
- truncation in repair.strip() uses "a" mode
- truncation in transaction._playback() uses "a" mode
If steps below occurs at "the same time in sec", all of mtime, ctime
and size are same between (1) and (3).
1. append data to revlog-style file (and close transaction)
2. discard appended data by truncation (strip or rollback)
3. append same size but different data to revlog-style file again
Therefore, cache validation doesn't work after (3) as expected.
This patch adds file object wrapper class checkambigatclosing to check
(and get rid of) ambiguity at closing. It is used by vfs in subsequent
patch.
This is a part of ExactCacheValidationPlan.
https://www.mercurial-scm.org/wiki/ExactCacheValidationPlan
BTW, checkambigatclosing is tested in test-filecache.py, even though
it doesn't use filecache itself, because filecache assumes that file
stat ambiguity never occurs (and there is no another test-*.py related
to filecache).
$ cat >> $HGRCPATH <<EOF
> [extensions]
> rebase=
>
> [phases]
> publish=False
>
> [alias]
> tglog = log -G --template "{rev}: '{desc}' {branches}\n"
> tglogp = log -G --template "{rev}:{phase} '{desc}' {branches}\n"
> EOF
$ hg init a
$ cd a
$ echo A > A
$ hg ci -Am A
adding A
$ echo B > B
$ hg ci -Am B
adding B
$ echo C >> A
$ hg ci -m C
$ hg up -q -C 0
$ echo D >> A
$ hg ci -m D
created new head
$ echo E > E
$ hg ci -Am E
adding E
$ cd ..
Changes during an interruption - continue:
$ hg clone -q -u . a a1
$ cd a1
$ hg tglog
@ 4: 'E'
|
o 3: 'D'
|
| o 2: 'C'
| |
| o 1: 'B'
|/
o 0: 'A'
Rebasing B onto E:
$ hg rebase -s 1 -d 4
rebasing 1:27547f69f254 "B"
rebasing 2:965c486023db "C"
merging A
warning: conflicts while merging A! (edit, then use 'hg resolve --mark')
unresolved conflicts (see hg resolve, then hg rebase --continue)
[1]
Force a commit on C during the interruption:
$ hg up -q -C 2 --config 'extensions.rebase=!'
$ echo 'Extra' > Extra
$ hg add Extra
$ hg ci -m 'Extra' --config 'extensions.rebase=!'
Force this commit onto secret phase
$ hg phase --force --secret 6
$ hg tglogp
@ 6:secret 'Extra'
|
| o 5:draft 'B'
| |
| o 4:draft 'E'
| |
| o 3:draft 'D'
| |
o | 2:draft 'C'
| |
o | 1:draft 'B'
|/
o 0:draft 'A'
Resume the rebasing:
$ hg rebase --continue
already rebased 1:27547f69f254 "B" as 45396c49d53b
rebasing 2:965c486023db "C"
merging A
warning: conflicts while merging A! (edit, then use 'hg resolve --mark')
unresolved conflicts (see hg resolve, then hg rebase --continue)
[1]
Solve the conflict and go on:
$ echo 'conflict solved' > A
$ rm A.orig
$ hg resolve -m A
(no more unresolved files)
continue: hg rebase --continue
$ hg rebase --continue
already rebased 1:27547f69f254 "B" as 45396c49d53b
rebasing 2:965c486023db "C"
warning: new changesets detected on source branch, not stripping
$ hg tglogp
o 7:draft 'C'
|
| o 6:secret 'Extra'
| |
o | 5:draft 'B'
| |
@ | 4:draft 'E'
| |
o | 3:draft 'D'
| |
| o 2:draft 'C'
| |
| o 1:draft 'B'
|/
o 0:draft 'A'
$ cd ..
Changes during an interruption - abort:
$ hg clone -q -u . a a2
$ cd a2
$ hg tglog
@ 4: 'E'
|
o 3: 'D'
|
| o 2: 'C'
| |
| o 1: 'B'
|/
o 0: 'A'
Rebasing B onto E:
$ hg rebase -s 1 -d 4
rebasing 1:27547f69f254 "B"
rebasing 2:965c486023db "C"
merging A
warning: conflicts while merging A! (edit, then use 'hg resolve --mark')
unresolved conflicts (see hg resolve, then hg rebase --continue)
[1]
Force a commit on B' during the interruption:
$ hg up -q -C 5 --config 'extensions.rebase=!'
$ echo 'Extra' > Extra
$ hg add Extra
$ hg ci -m 'Extra' --config 'extensions.rebase=!'
$ hg tglog
@ 6: 'Extra'
|
o 5: 'B'
|
o 4: 'E'
|
o 3: 'D'
|
| o 2: 'C'
| |
| o 1: 'B'
|/
o 0: 'A'
Abort the rebasing:
$ hg rebase --abort
warning: new changesets detected on target branch, can't strip
rebase aborted
$ hg tglog
@ 6: 'Extra'
|
o 5: 'B'
|
o 4: 'E'
|
o 3: 'D'
|
| o 2: 'C'
| |
| o 1: 'B'
|/
o 0: 'A'
$ cd ..
Changes during an interruption - abort (again):
$ hg clone -q -u . a a3
$ cd a3
$ hg tglogp
@ 4:draft 'E'
|
o 3:draft 'D'
|
| o 2:draft 'C'
| |
| o 1:draft 'B'
|/
o 0:draft 'A'
Rebasing B onto E:
$ hg rebase -s 1 -d 4
rebasing 1:27547f69f254 "B"
rebasing 2:965c486023db "C"
merging A
warning: conflicts while merging A! (edit, then use 'hg resolve --mark')
unresolved conflicts (see hg resolve, then hg rebase --continue)
[1]
Change phase on B and B'
$ hg up -q -C 5 --config 'extensions.rebase=!'
$ hg phase --public 1
$ hg phase --public 5
$ hg phase --secret -f 2
$ hg tglogp
@ 5:public 'B'
|
o 4:public 'E'
|
o 3:public 'D'
|
| o 2:secret 'C'
| |
| o 1:public 'B'
|/
o 0:public 'A'
Abort the rebasing:
$ hg rebase --abort
warning: can't clean up public changesets 45396c49d53b
rebase aborted
$ hg tglogp
@ 5:public 'B'
|
o 4:public 'E'
|
o 3:public 'D'
|
| o 2:secret 'C'
| |
| o 1:public 'B'
|/
o 0:public 'A'
$ cd ..