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authorStuart Mackie <wsmackie@juniper.net>2016-10-07 12:24:58 -0700
committerStuart Mackie <wsmackie@juniper.net>2016-10-07 12:24:58 -0700
commit4faa7f927149a5c4ef7a03523f7bc14523cb9baa (patch)
tree0be55aa0809cc395e45baeae63db660b4e72fe83 /charms/trusty/cassandra/hooks/coordinator.py
parent82f1a7eb5535b30a95b1e71ff18c315d40d1e6f0 (diff)
Charms for Contrail 3.1 with Mitaka
Change-Id: Id37f3b9743d1974e31fcd7cd9c54be41bb0c47fb Signed-off-by: Stuart Mackie <wsmackie@juniper.net>
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diff --git a/charms/trusty/cassandra/hooks/coordinator.py b/charms/trusty/cassandra/hooks/coordinator.py
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+# Copyright 2015 Canonical Ltd.
+#
+# This file is part of the Cassandra Charm for Juju.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License version 3, as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranties of
+# MERCHANTABILITY, SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR
+# PURPOSE. See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+from charmhelpers.coordinator import BaseCoordinator
+
+
+class CassandraCoordinator(BaseCoordinator):
+ def default_grant(self, lock, unit, granted, queue):
+ '''Grant locks to only one unit at a time, regardless of its name.
+
+ This lets us keep separate locks like repair and restart,
+ while ensuring the operations do not occur on different nodes
+ at the same time.
+ '''
+ # Return True if this unit has already been granted a lock.
+ if self.grants.get(unit):
+ return True
+
+ # Otherwise, return True if the unit is first in the queue.
+ return queue[0] == unit and not granted
+
+
+coordinator = CassandraCoordinator()