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bookmark: add a test for a race condition on push...
bookmark: add a test for a race condition on push Bookmark pointing to unknown nodes are ignored. Later these ignored bookmarks are dropped when writing the file back on disk. On paper, this behavior should be fine, but with the current implementation, it can lead to unexpected bookmark deletions. In theory, to make sure writer as a consistent view, taking the lock also invalidate bookmark data we already loaded into memory. However this invalidation is incomplete. The data are stored in a `filecache` that preserve them if the bookmark related file are untouched. In practice, the bookmark data in memory also depends of the changelog content, because of the step checking if the bookmarks refers to a node known to the changelog. So if the bookmark data were loaded from an up to date bookmark file but filtered with an outdated changelog file this go undetected. This condition is fairly specific, but can occurs very often in practice. We introduce a test recreating the situation. The test comes in an independant changeset to show it actually reproduce the situation. The fix will come soon after. A large share of the initial investigation of this race condition was made by Valentin Gatien-Baron <valentin.gatienbaron@gmail.com>.

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test-bookmarks-corner-case.t
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/ tests / test-bookmarks-corner-case.t
bookmark: add a test for a race condition on push...
r42538 ================================
Test corner case around bookmark
================================
This test file is meant to gather test around bookmark that are specific
enough to not find a place elsewhere.
Test bookmark/changelog race condition
======================================
The data from the bookmark file are filtered to only contains bookmark with
node known to the changelog. If the cache invalidation between these two bits
goes wrong, bookmark can be dropped.
global setup
------------
$ cat >> $HGRCPATH << EOF
> [ui]
> ssh = "$PYTHON" "$TESTDIR/dummyssh"
> [server]
> concurrent-push-mode=check-related
> EOF
Setup
-----
initial repository setup
$ hg init bookrace-server
$ cd bookrace-server
$ echo a > a
$ hg add a
$ hg commit -m root
$ echo a >> a
$ hg bookmark book-A
$ hg commit -m A0
$ hg up 'desc(root)'
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(leaving bookmark book-A)
$ echo b > b
$ hg add b
$ hg bookmark book-B
$ hg commit -m B0
created new head
$ hg up null
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
(leaving bookmark book-B)
$ hg phase --public --rev 'all()'
$ hg log -G
o changeset: 2:c79985706978
| bookmark: book-B
| tag: tip
| parent: 0:6569b5a81c7e
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: B0
|
| o changeset: 1:39c28d785860
|/ bookmark: book-A
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: A0
|
o changeset: 0:6569b5a81c7e
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
$ hg book
book-A 1:39c28d785860
book-B 2:c79985706978
$ cd ..
Add new changeset on each bookmark in distinct clones
$ hg clone ssh://user@dummy/bookrace-server client-A
requesting all changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 2 files (+1 heads)
new changesets 6569b5a81c7e:c79985706978
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -R client-A update book-A
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(activating bookmark book-A)
$ echo a >> client-A/a
$ hg -R client-A commit -m A1
$ hg clone ssh://user@dummy/bookrace-server client-B
requesting all changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 2 files (+1 heads)
new changesets 6569b5a81c7e:c79985706978
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -R client-B update book-B
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
(activating bookmark book-B)
$ echo b >> client-B/b
$ hg -R client-B commit -m B1
extension to reproduce the race
-------------------------------
If two process are pushing we want to make sure the following happens:
* process A read changelog
* process B to its full push
* process A read bookmarks
* process A proceed with rest of the push
We build a server side extension for this purpose
$ cat > bookrace.py << EOF
> import os
> import time
> import atexit
> from mercurial import error, extensions, bookmarks
> def wrapinit(orig, self, repo):
> if not os.path.exists('push-A-started'):
> print('setting raced push up')
> with open('push-A-started', 'w'):
> pass
> clock = 300
> while not os.path.exists('push-B-done'):
> clock -= 1
> if clock <= 0:
> raise error.Abort("race scenario timed out")
> time.sleep(0.1)
> return orig(self, repo)
>
> repo.__class__ = racedrepo
> def uisetup(ui):
> extensions.wrapfunction(bookmarks.bmstore, '__init__', wrapinit)
> def e():
> with open('push-A-done', 'w'):
> pass
> atexit.register(e)
> EOF
Actual test
-----------
Start the raced push.
$ cat >> bookrace-server/.hg/hgrc << EOF
> [extensions]
> bookrace=$TESTTMP/bookrace.py
> EOF
$ hg push -R client-A -r book-A >push-output.txt 2>&1 &
Wait up to 30 seconds for that push to start.
$ clock=30
$ while [ ! -f push-A-started ] && [ $clock -gt 0 ] ; do
> clock=`expr $clock - 1`
> sleep 1
> done
Do the other push.
$ cat >> bookrace-server/.hg/hgrc << EOF
> [extensions]
> bookrace=!
> EOF
$ hg push -R client-B -r book-B
pushing to ssh://user@dummy/bookrace-server
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
updating bookmark book-B
Signal the raced put that we are done (it waits up to 30 seconds).
$ touch push-B-done
Wait for the raced push to finish (with the remaning of the initial 30 seconds).
$ while [ ! -f push-A-done ] && [ $clock -gt 0 ] ; do
> clock=`expr $clock - 1`
> sleep 1
> done
Check raced push output.
$ cat push-output.txt
pushing to ssh://user@dummy/bookrace-server
searching for changes
remote: setting raced push up
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
updating bookmark book-A
Check result of the push.
$ hg -R bookrace-server log -G
o changeset: 4:9ce3b28c16de
| bookmark: book-A
| tag: tip
| parent: 1:39c28d785860
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: A1
|
| o changeset: 3:f26c3b5167d1
| | bookmark: book-B (false !)
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: B1
| |
| o changeset: 2:c79985706978
| | parent: 0:6569b5a81c7e
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: B0
| |
o | changeset: 1:39c28d785860
|/ user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: A0
|
o changeset: 0:6569b5a81c7e
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
$ hg -R bookrace-server book
book-A 4:9ce3b28c16de
book-B 3:f26c3b5167d1 (false !)