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.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init a
$ cd a
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qrename mqbase renamed
$ mkdir .hg/patches/foo
$ hg qrename renamed foo
$ hg qseries
foo/renamed
$ ls .hg/patches/foo
renamed
$ mkdir .hg/patches/bar
$ hg qrename foo/renamed bar
$ hg qseries
bar/renamed
$ ls .hg/patches/bar
renamed
$ hg qrename bar/renamed baz
$ hg qseries
baz
$ ls .hg/patches/baz
.hg/patches/baz
$ hg qrename baz new/dir
$ hg qseries
new/dir
$ ls .hg/patches/new/dir
.hg/patches/new/dir
$ cd ..
Test patch being renamed before committed:
$ hg init b
$ cd b
$ hg qinit -c
$ hg qnew x
$ hg qrename y
$ hg qcommit -m rename
$ cd ..
Test overlapping renames (issue2388)
$ hg init c
$ cd c
$ hg qinit -c
$ echo a > a
$ hg add
adding a
$ hg qnew patcha
$ echo b > b
$ hg add
adding b
$ hg qnew patchb
$ hg ci --mq -m c1
$ hg qrename patchb patchc
$ hg qrename patcha patchb
$ hg st --mq
M patchb
M series
A patchc
R patcha
$ cd ..
Test renames with mq repo (issue2097)
$ hg init issue2097
$ cd issue2097
$ hg qnew p0
$ (cd .hg/patches && hg init)
$ hg qren p0 p1
$ hg debugstate --mq
$ hg ci --mq -mq0
nothing changed
[1]
$ cd ..
Test renaming to a folded patch (issue3058)
$ hg init issue3058
$ cd issue3058
$ hg init --mq
$ echo a > a
$ hg add a
$ hg qnew adda
$ echo b >> a
$ hg qnew addb
$ hg qpop
popping addb
now at: adda
$ hg ci --mq -m "save mq"
$ hg qfold addb
$ hg qmv addb
$ cat .hg/patches/addb
# HG changeset patch
# Parent 0000000000000000000000000000000000000000
diff -r 000000000000 a
--- /dev/null * (glob)
+++ b/a * (glob)
@@ -0,0 +1,2 @@
+a
+b
$ cd ..