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.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> convert=
> EOF
Prepare orig repo
$ hg init orig
$ cd orig
$ echo foo > foo
$ HGUSER='user name' hg ci -qAm 'foo'
$ cd ..
Explicit --authors
$ cat > authormap.txt <<EOF
> user name = Long User Name
>
> # comment
> this line is ignored
> EOF
$ hg convert --authors authormap.txt orig new
initializing destination new repository
ignoring bad line in author map file authormap.txt: this line is ignored
scanning source...
sorting...
converting...
0 foo
writing author map file $TESTTMP/new/.hg/authormap (glob)
$ cat new/.hg/authormap
user name=Long User Name
$ hg -Rnew log
changeset: 0:d89716e88087
tag: tip
user: Long User Name
date: Thu Jan 01 00:00:00 1970 +0000
summary: foo
$ rm -rf new
Implicit .hg/authormap
$ hg init new
$ mv authormap.txt new/.hg/authormap
$ hg convert orig new
ignoring bad line in author map file $TESTTMP/new/.hg/authormap: this line is ignored (glob)
scanning source...
sorting...
converting...
0 foo
$ hg -Rnew log
changeset: 0:d89716e88087
tag: tip
user: Long User Name
date: Thu Jan 01 00:00:00 1970 +0000
summary: foo