hg: obtain lock when creating share from pooled repo (issue5104)
There are race conditions between clients performing a shared clone
to pooled storage:
1) Clients race to create the new shared repo in the pool directory
2) 1 client is seeding the repo in the pool directory and another goes
to share it before it is fully cloned
We prevent these race conditions by obtaining a lock in the pool
directory that is derived from the name of the repo we will be
accessing.
To test this, a simple generic "lockdelay" extension has been added.
The extension inserts an optional, configurable delay before or after
lock acquisition. In the test, we delay 2 seconds after lock acquisition
in the first process and 1 second before lock acquisition in the 2nd
process. This means the first process has 1s to obtain the lock. There
is a race condition here. If we encounter it in the wild, we could
change the dummy extension to wait on the lock file to appear instead
of relying on timing. But that's more complicated. Let's see what
happens first.
Check that renames are correctly saved by a commit after a merge
Test with the merge on 3 having the rename on the local parent
$ hg init a
$ cd a
$ echo line1 > foo
$ hg add foo
$ hg ci -m '0: add foo'
$ echo line2 >> foo
$ hg ci -m '1: change foo'
$ hg up -C 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg mv foo bar
$ rm bar
$ echo line0 > bar
$ echo line1 >> bar
$ hg ci -m '2: mv foo bar; change bar'
created new head
$ hg merge 1
merging bar and foo to bar
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat bar
line0
line1
line2
$ hg ci -m '3: merge with local rename'
$ hg debugindex bar
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 77 ..... 2 d35118874825 000000000000 000000000000 (re)
1 77 76 ..... 3 5345f5ab8abd 000000000000 d35118874825 (re)
$ hg debugrename bar
bar renamed from foo:9e25c27b87571a1edee5ae4dddee5687746cc8e2
$ hg debugindex foo
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 7 ..... 0 690b295714ae 000000000000 000000000000 (re)
1 7 13 ..... 1 9e25c27b8757 690b295714ae 000000000000 (re)
Revert the content change from rev 2:
$ hg up -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm bar
$ echo line1 > bar
$ hg ci -m '4: revert content change from rev 2'
created new head
$ hg log --template '{rev}:{node|short} {parents}\n'
4:2263c1be0967 2:0f2ff26688b9
3:0555950ead28 2:0f2ff26688b9 1:5cd961e4045d
2:0f2ff26688b9 0:2665aaee66e9
1:5cd961e4045d
0:2665aaee66e9
This should use bar@rev2 as the ancestor:
$ hg --debug merge 3
searching for copies back to rev 1
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: 0f2ff26688b9, local: 2263c1be0967+, remote: 0555950ead28
preserving bar for resolve of bar
bar: versions differ -> m (premerge)
picked tool ':merge' for bar (binary False symlink False changedelete False)
merging bar
my bar@2263c1be0967+ other bar@0555950ead28 ancestor bar@0f2ff26688b9
premerge successful
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat bar
line1
line2
$ hg ci -m '5: merge'
$ hg debugindex bar
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 77 ..... 2 d35118874825 000000000000 000000000000 (re)
1 77 76 ..... 3 5345f5ab8abd 000000000000 d35118874825 (re)
2 153 7 ..... 4 ff4b45017382 d35118874825 000000000000 (re)
3 160 13 ..... 5 3701b4893544 ff4b45017382 5345f5ab8abd (re)
Same thing, but with the merge on 3 having the rename
on the remote parent:
$ cd ..
$ hg clone -U -r 1 -r 2 a b
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 2 files (+1 heads)
$ cd b
$ hg up -C 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg merge 2
merging foo and bar to bar
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat bar
line0
line1
line2
$ hg ci -m '3: merge with remote rename'
$ hg debugindex bar
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 77 ..... 2 d35118874825 000000000000 000000000000 (re)
1 77 76 ..... 3 5345f5ab8abd 000000000000 d35118874825 (re)
$ hg debugrename bar
bar renamed from foo:9e25c27b87571a1edee5ae4dddee5687746cc8e2
$ hg debugindex foo
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 7 ..... 0 690b295714ae 000000000000 000000000000 (re)
1 7 13 ..... 1 9e25c27b8757 690b295714ae 000000000000 (re)
Revert the content change from rev 2:
$ hg up -C 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm bar
$ echo line1 > bar
$ hg ci -m '4: revert content change from rev 2'
created new head
$ hg log --template '{rev}:{node|short} {parents}\n'
4:2263c1be0967 2:0f2ff26688b9
3:3ffa6b9e35f0 1:5cd961e4045d 2:0f2ff26688b9
2:0f2ff26688b9 0:2665aaee66e9
1:5cd961e4045d
0:2665aaee66e9
This should use bar@rev2 as the ancestor:
$ hg --debug merge 3
searching for copies back to rev 1
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: 0f2ff26688b9, local: 2263c1be0967+, remote: 3ffa6b9e35f0
preserving bar for resolve of bar
bar: versions differ -> m (premerge)
picked tool ':merge' for bar (binary False symlink False changedelete False)
merging bar
my bar@2263c1be0967+ other bar@3ffa6b9e35f0 ancestor bar@0f2ff26688b9
premerge successful
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat bar
line1
line2
$ hg ci -m '5: merge'
$ hg debugindex bar
rev offset length ..... linkrev nodeid p1 p2 (re)
0 0 77 ..... 2 d35118874825 000000000000 000000000000 (re)
1 77 76 ..... 3 5345f5ab8abd 000000000000 d35118874825 (re)
2 153 7 ..... 4 ff4b45017382 d35118874825 000000000000 (re)
3 160 13 ..... 5 3701b4893544 ff4b45017382 5345f5ab8abd (re)
$ cd ..