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.
#require svn svn-bindings
$ cat <<EOF >> $HGRCPATH
> [extensions]
> convert =
> mq =
> EOF
$ SVNREPOPATH=`pwd`/svn-repo
#if windows
$ SVNREPOURL=file:///`$PYTHON -c "import urllib, sys; sys.stdout.write(urllib.quote(sys.argv[1]))" "$SVNREPOPATH"`
#else
$ SVNREPOURL=file://`$PYTHON -c "import urllib, sys; sys.stdout.write(urllib.quote(sys.argv[1]))" "$SVNREPOPATH"`
#endif
$ svnadmin create "$SVNREPOPATH"
$ cat > "$SVNREPOPATH"/hooks/pre-revprop-change <<EOF
> #!/bin/sh
>
> REPOS="$1"
> REV="$2"
> USER="$3"
> PROPNAME="$4"
> ACTION="$5"
>
> if [ "$ACTION" = "M" -a "$PROPNAME" = "svn:log" ]; then exit 0; fi
> if [ "$ACTION" = "A" -a "$PROPNAME" = "hg:convert-branch" ]; then exit 0; fi
> if [ "$ACTION" = "A" -a "$PROPNAME" = "hg:convert-rev" ]; then exit 0; fi
>
> echo "Changing prohibited revision property" >&2
> exit 1
> EOF
$ chmod +x "$SVNREPOPATH"/hooks/pre-revprop-change
$ svn co "$SVNREPOURL" "$SVNREPOPATH"-wc
Checked out revision 0.
$ cd "$SVNREPOPATH"-wc
$ echo a > a
$ svn add a
A a
$ svn ci -m'added a' a
Adding a
Transmitting file data .
Committed revision 1.
$ cd ..
initial roundtrip
$ hg convert -s svn -d hg "$SVNREPOPATH"-wc "$SVNREPOPATH"-hg | grep -v initializing
scanning source...
sorting...
converting...
0 added a
$ hg convert -s hg -d svn "$SVNREPOPATH"-hg "$SVNREPOPATH"-wc
scanning source...
sorting...
converting...
second roundtrip should do nothing
$ hg convert -s svn -d hg "$SVNREPOPATH"-wc "$SVNREPOPATH"-hg
scanning source...
sorting...
converting...
$ hg convert -s hg -d svn "$SVNREPOPATH"-hg "$SVNREPOPATH"-wc
scanning source...
sorting...
converting...
new hg rev
$ hg clone "$SVNREPOPATH"-hg "$SVNREPOPATH"-work
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd "$SVNREPOPATH"-work
$ echo b > b
$ hg add b
$ hg ci -mb
adding an empty revision
$ hg qnew -m emtpy empty
$ hg qfinish -a
$ cd ..
echo hg to svn
$ hg --cwd "$SVNREPOPATH"-hg pull -q "$SVNREPOPATH"-work
$ hg convert -s hg -d svn "$SVNREPOPATH"-hg "$SVNREPOPATH"-wc
scanning source...
sorting...
converting...
1 b
0 emtpy
svn back to hg should do nothing
$ hg convert -s svn -d hg "$SVNREPOPATH"-wc "$SVNREPOPATH"-hg
scanning source...
sorting...
converting...
hg back to svn should do nothing
$ hg convert -s hg -d svn "$SVNREPOPATH"-hg "$SVNREPOPATH"-wc
scanning source...
sorting...
converting...
verify which shamap format we are storing and must be able to handle
$ cat svn-repo-hg/.hg/shamap
svn:????????-????-????-????-????????????@1 ???????????????????????????????????????? (glob)
svn:????????-????-????-????-????????????@2 ???????????????????????????????????????? (glob)
svn:????????-????-????-????-????????????@2 ???????????????????????????????????????? (glob)
$ cat svn-repo-wc/.svn/hg-shamap
???????????????????????????????????????? 1 (glob)
???????????????????????????????????????? svn:????????-????-????-????-????????????@2 (glob)
???????????????????????????????????????? svn:????????-????-????-????-????????????@2 (glob)