Commit 29d95011 authored by Tim Peters's avatar Tim Peters

Close a thread race in Connection.close(), diagnosed by Marius Gedminas.

DB._closeConnection() sets the connection's _db member to None now, under
protection of the lock it holds anyway.  At a deeper level, it's unclear
why _db keeps getting set and unset to begin with, but no time for that
now (and there are already XXX comments about it in the code).

Alas, I wasn't able to write a test that provoked the original bug in
finite time (it's a tiny timing hole), except via calling sleep() between
two lines that don't exist anymore.  Good enough.
parent 66d28f65
......@@ -13,7 +13,7 @@
##############################################################################
"""Database connection support
$Id: Connection.py,v 1.144 2004/04/06 21:47:12 tim_one Exp $"""
$Id: Connection.py,v 1.145 2004/04/08 18:12:25 tim_one Exp $"""
import logging
import sys
......@@ -466,7 +466,9 @@ class Connection(ExportImport, object):
# Return the connection to the pool.
if self._db is not None:
self._db._closeConnection(self)
self._db = None
# _closeConnection() set self._db to None. However, we can't
# assert that here, because self may have been reused (by
# another thread) by the time we get back here.
def commit(self, obj, transaction):
if obj is self:
......
......@@ -13,7 +13,7 @@
##############################################################################
"""Database objects
$Id: DB.py,v 1.72 2004/04/01 03:56:58 jeremy Exp $"""
$Id: DB.py,v 1.73 2004/04/08 18:12:25 tim_one Exp $"""
import cPickle, cStringIO, sys
from thread import allocate_lock
......@@ -72,7 +72,7 @@ class DB(object):
setCacheDeactivateAfter,
getVersionCacheDeactivateAfter, setVersionCacheDeactivateAfter
"""
klass = Connection # Class to use for connections
_activity_monitor = None
......@@ -163,14 +163,21 @@ class DB(object):
return m
def _closeConnection(self, connection):
"""Return a connection to the pool"""
"""Return a connection to the pool.
connection._db must be self on entry.
"""
self._a()
try:
assert connection._db is self
connection._db = None
am = self._activity_monitor
if am is not None:
am.closedConnection(connection)
version=connection._version
pools,pooll=self._pools
version = connection._version
pools, pooll = self._pools
try:
pool, allocated, pool_lock = pools[version]
except KeyError:
......@@ -184,7 +191,7 @@ class DB(object):
return
pool.append(connection)
if len(pool)==1:
if len(pool) == 1:
# Pool now usable again, unlock it.
pool_lock.release()
finally:
......@@ -708,7 +715,7 @@ class AbortVersion(ResourceManager):
def __init__(self, db, version):
super(AbortVersion, self).__init__(db)
self._version = version
def commit(self, ob, t):
tid, oids = self._db._storage.abortVersion(self._version, t)
self._db.invalidate(tid, dict.fromkeys(oids, 1), version=self._version)
......
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