openstack
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tooz
Code Issues Proposed changes

Implement non-blocking locks with PostgreSQL 

Change-Id: Id0f2f10bf9d284343c19ba395a90aea7b9233124
This commit is contained in:
Julien Danjou 2014-10-26 18:30:47 +01:00
parent 455111284f
commit 33f5d3f497
1 changed files with 20 additions and 6 deletions
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26
tooz/drivers/pgsql.py
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@ -22,6 +22,7 @@ import six
import tooz
from tooz import coordination
from tooz.drivers import _retry
from tooz import locking
@ -39,12 +40,25 @@ class PostgresLock(locking.Lock):
self.key = h.digest()[0:2]
def acquire(self, blocking=True):
if blocking is not True:
raise tooz.NotImplemented(
"This driver does not support non blocking locks")
with self._conn.cursor() as cur:
cur.execute("SELECT pg_advisory_lock(%s, %s);", self.key)
return True
if blocking is True:
with self._conn.cursor() as cur:
cur.execute("SELECT pg_advisory_lock(%s, %s);", self.key)
return True
elif blocking is False:
with self._conn.cursor() as cur:
cur.execute("SELECT pg_try_advisory_lock(%s, %s);", self.key)
return cur.fetchone()[0]
else:
def _acquire():
with self._conn.cursor() as cur:
cur.execute("SELECT pg_try_advisory_lock(%s, %s);",
self.key)
if cur.fetchone()[0] is True:
return True
raise _retry.Retry
kwargs = _retry.RETRYING_KWARGS.copy()
kwargs['stop_max_delay'] = blocking
return _retry.Retrying(**kwargs).call(_acquire)
def release(self):
with self._conn.cursor() as cur: