Merge lp:~facundo/ubuntuone-client/fix-getdelta-repetition into lp:ubuntuone-client

[Facundo Batista]

Use PathLockTree to get one GetDelta at a time (LP: #883252).

Use PathLockTree to get one GetDelta at a time.

Actually, two are sent at the same time, but not a zillion as today.

This works with GetDelta rules (don't issue another GetDelta if there's another one with same or less gen number *not running*). The not running part is the trick, so this will happen for a zillion GetDeltas with the same gen number (common case after a move and a lot of operations):

- First GD is queued, and run.

- Second GD is queued (as first is running), but gets locked in the PathLockTree.

- Third and subsequent GDs are not queued, as there's one not running for that gen number.

Test included.

[Curtis Caravone (caravone)]

review: Approve

[Alejandro J. Cura (alecu)]

Looks good

review: Approve

=== modified file 'tests/syncdaemon/test_action_queue.py'
--- tests/syncdaemon/test_action_queue.py	2012-04-19 17:24:57 +0000
+++ tests/syncdaemon/test_action_queue.py	2012-05-09 15:05:24 +0000
@@ -4478,6 +4478,15 @@
         cmd = GetDelta(self.rq, 'vol', 1)
         self.assertEqual(cmd.uniqueness, ('GetDelta', 'vol'))
 
+    def test_path_locking(self):
+        """Test that it acquires correctly the path lock."""
+        t = []
+        self.patch(PathLockingTree, 'acquire',
+                   lambda s, *a, **k: t.extend((a, k)))
+        cmd = GetDelta(self.rq, 'volume_id', 123)
+        cmd._acquire_pathlock()
+        self.assertEqual(t, [('GetDelta', 'volume_id'), {'logger': None}])
+
 
 class GetDeltaFromScratchTestCase(ConnectedBaseTestCase):
     """Test for GetDelta ActionQueueCommand."""

=== modified file 'ubuntuone/syncdaemon/action_queue.py'
--- ubuntuone/syncdaemon/action_queue.py	2012-04-19 17:24:57 +0000
+++ ubuntuone/syncdaemon/action_queue.py	2012-05-09 15:05:24 +0000
@@ -2070,6 +2070,12 @@
         self.log = mklog(logger, 'GetDelta', self.volume_id,
                          None, generation=self.generation)
 
+    def _acquire_pathlock(self):
+        """Acquire pathlock."""
+        pathlock = self.action_queue.pathlock
+        return pathlock.acquire('GetDelta', str(self.volume_id),
+                                logger=self.log)
+
 
 class GetDeltaFromScratch(ActionQueueCommand):
     """Get a delta from scratch."""