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Commit ecc0e8db authored by Shane Hathaway's avatar Shane Hathaway
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Rearranged the sub-connection closing mechanism. The old method was subject 

to database connection leaks when the mount point object was garbage
collected.
parent a051be33
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Showing with 113 additions and 84 deletions
src/ZODB/Mount.py
View file @ ecc0e8db
......@@ -84,8 +84,8 @@
##############################################################################
"""Mounted database support
$Id: Mount.py,v 1.7 2000/11/07 13:03:32 jim Exp $"""
__version__='$Revision: 1.7 $'[11:-2]
$Id: Mount.py,v 1.8 2000/12/30 20:04:49 shane Exp $"""
__version__='$Revision: 1.8 $'[11:-2]
import thread, Persistence, Acquisition
import ExtensionClass, string, time, sys
......@@ -124,7 +124,6 @@ class MountPoint(Persistence.Persistent, Acquisition.Implicit):
# Default values for non-persistent variables.
_v_db = None
_v_data = None
_v_close_db = 0
_v_connect_error = None
def __init__(self, path, params=None, classDefsFromRoot=1):
......@@ -193,50 +192,17 @@ class MountPoint(Persistence.Persistent, Acquisition.Implicit):
dblock.release()
return db, newMount
def __repr__(self):
return "%s %s" % (self.__class__.__name__, self._path)
def _getMountpointId(self):
return self.__mountpoint_id
def _close(self):
# The onCloseCallback handler.
# Closes a single connection to the database
# and possibly the database itself.
t = self._v_data
if t is not None:
self._v_data = None
data = t[0]
if getattr(data, '_v__object_deleted__', 0):
# This mount point has been deleted.
del data._v__object_deleted__
self._v_close_db = 1
if data is not None:
conn = data._p_jar
if conn is not None:
try: del conn._mount_parent_jar
except: pass
if conn._db is not None:
conn.close()
if self._v_close_db:
# Stop using this database. Close it if no other
# MountPoint is using it.
dblock.acquire()
try:
self._v_close_db = 0
self._v_db = None
params = self._params
if dbs.has_key(params):
dbInfo = dbs[params]
db, mounts = dbInfo
try: del mounts[self.__mountpoint_id]
except: pass
if len(mounts) < 1:
# No more mount points are using this database.
del dbs[params]
db.close()
LOG('ZODB', INFO, 'Closed database: %s' % params)
finally:
dblock.release()
def _getMountParams(self):
return self._params
def __repr__(self):
return "%s(%s, %s)" % (self.__class__.__name__, repr(self._path),
self._params)
def __openConnection(self, parent):
def _openMountableConnection(self, parent):
# Opens a new connection to the database.
db = self._v_db
if db is None:
......@@ -249,59 +215,60 @@ class MountPoint(Persistence.Persistent, Acquisition.Implicit):
# Get _p_jar from parent.
self._p_jar = jar = parent._p_jar
conn = db.open(version=jar.getVersion())
# Add an attribute to the connection which
# makes it possible for us to find the primary
# database connection. See ClassFactoryForMount().
conn._mount_parent_jar = jar
try:
jar.onCloseCallback(self._close)
mcc = MountedConnectionCloser(self, conn)
jar.onCloseCallback(mcc)
return conn, newMount
def _getObjectFromConnection(self, conn):
obj = self._getMountRoot(conn.root())
data = getattr(obj, 'aq_base', obj)
# Store the data object in a tuple to hide from acquisition.
self._v_data = (data,)
except:
# Close the connection before processing the exception.
del conn._mount_parent_jar
conn.close()
raise
if newMount:
id = data.id
if callable(id):
id = id()
p = string.join(parent.getPhysicalPath() + (id,), '/')
LOG('ZODB', INFO, 'Mounted database %s at %s' % \
(self._params, p))
return data
def __of__(self, parent):
# Accesses the database, returning an acquisition
# wrapper around the connected object rather than around self.
def _getOrOpenObject(self, parent):
t = self._v_data
if t is None:
self._v_connect_error = None
conn = None
try:
data = self.__openConnection(parent)
conn, newMount = self._openMountableConnection(parent)
data = self._getObjectFromConnection(conn)
if newMount:
id = data.getId()
p = string.join(parent.getPhysicalPath() + (id,), '/')
LOG('ZODB', INFO, 'Mounted database %s at %s' %
(self._getMountParams(), p))
except:
self._v_close_db = 1
# Broken database.
if conn is not None:
conn._close_mounted_db = 1
self._logConnectException()
# Broken database. Wrap around self.
return Acquisition.ImplicitAcquisitionWrapper(self, parent)
raise
else:
data = t[0]
return data.__of__(parent)
def __of__(self, parent):
# Accesses the database, returning an acquisition
# wrapper around the connected object rather than around self.
try:
return self._getOrOpenObject(parent)
except:
return Acquisition.ImplicitAcquisitionWrapper(
self, parent)
def _test(self, parent):
'''Tests the database connection.
'''
if self._v_data is None:
try:
data = self.__openConnection(parent)
except:
self._v_close_db = 1
self._logConnectException()
raise
self._getOrOpenObject(parent)
return 1
def _getMountRoot(self, root):
......@@ -311,22 +278,84 @@ class MountPoint(Persistence.Persistent, Acquisition.Implicit):
try:
app = root['Application']
except:
raise MountedStorageError, \
'No \'Application\' object exists in the mountable database.'
raise MountedStorageError, (
"No 'Application' object exists in the mountable database.")
try:
return app.unrestrictedTraverse(self._path)
except:
raise MountedStorageError, \
('The path \'%s\' was not found in the mountable database.' \
raise MountedStorageError, (
"The path '%s' was not found in the mountable database."
% self._path)
def _logConnectException(self):
'''Records info about the exception that just occurred.
'''
try:
from cStringIO import StringIO
except:
from StringIO import StringIO
import traceback
exc = sys.exc_info()
LOG('ZODB', WARNING, 'Failed to mount database. %s (%s)' % exc[:2])
LOG('ZODB', WARNING, 'Failed to mount database. %s (%s)' % exc[:2],
error=exc)
f=StringIO()
traceback.print_tb(exc[2], 100, f)
self._v_connect_error = (exc[0], exc[1], f.getvalue())
exc = None
class MountedConnectionCloser:
'''Closes the connection used by the mounted database
while performing other cleanup.
'''
def __init__(self, mountpoint, conn):
# conn is the child connection.
self.mp = mountpoint
self.conn = conn
def __call__(self):
# The onCloseCallback handler.
# Closes a single connection to the database
# and possibly the database itself.
conn = self.conn
close_db = 0
if conn is not None:
mp = self.mp
# Remove potential circular references.
self.conn = None
self.mp = None
# Detect whether we should close the database.
close_db = getattr(conn, '_close_mounted_db', 0)
t = mp._v_data
if t is not None:
mp._v_data = None
data = t[0]
if not close_db and getattr(data, '_v__object_deleted__', 0):
# This mount point has been deleted.
del data._v__object_deleted__
close_db = 1
# Close the child connection.
try: del conn._mount_parent_jar
except: pass
conn.close()
if close_db:
# Stop using this database. Close it if no other
# MountPoint is using it.
dblock.acquire()
try:
params = mp._getMountParams()
mp._v_db = None
if dbs.has_key(params):
dbInfo = dbs[params]
db, mounts = dbInfo
try: del mounts[mp._getMountpointId()]
except: pass
if len(mounts) < 1:
# No more mount points are using this database.
del dbs[params]
db.close()
LOG('ZODB', INFO, 'Closed database: %s' % params)
finally:
dblock.release()
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