def __init__(self, dbhost, dbuser, dbpass, dbname):
# reset event
if EVENT_MCX_UPDATES_AVAILABLE.isSet():
EVENT_MCX_UPDATES_AVAILABLE.clear()
self.__cursor = None
"""The cursor of MySQLdb library retrieved from the mcxPersistent object."""
self.__updates = {}
"""All updates, that are available since last time. Defaults to an empty dict."""
self.__getUpdateMethods()
# initiate base class
mcxDatabaseThread.__init__(self, dbhost, dbuser, dbpass, dbname)
def __checkForUpdates(self):
"""The base method that's actually checking for new updates by running all marked methods."""
if len(self.__updateMethods):
updatesAvailable = False
for method in self.__updateMethods:
# get new cursor
self.__cursor = self.persistent.getCursor()
# execute check update method
updatesAvailable = updatesAvailable or getattr(self, method)()
# close and reset cursor
self.__cursor.close()
self.__cursor = None
if updatesAvailable:
# needs to be cleared by another thread
EVENT_MCX_UPDATES_AVAILABLE.set()
def run(self):
"""
@requires: self.isDaemon() == True
@summary: This thread serves forever.
As long as EVENT_MCX_UPDATES_AVAILABLE is not set this thread will look every CONFIG_CHECKUPDATE_INTERVAL seconds for new updates until found.
If updates were found, it will fire EVENT_MCX_UPDATES_AVAILABLE and wait until this event becomes cleared.
"""
# serve forever
while self.isDaemon():
# and event flag not cleared by now
if not EVENT_MCX_UPDATES_AVAILABLE.isSet():
# ensure we do not operate on an invalid object
self.__cursor = None
self.__clearUpdates()
try:
# make sure connection is established
self.persistent.connect()
# check for updates only, if connection is established
if self.persistent.connected():
self.__cursor = self.persistent.getCursor()
# check for updates
self.__checkForUpdates()
# disconnect properly
self.persistent.disconnect()
else:
raise ConnectionException(DATABASE_SERVER_NOT_AVAILABLE)
# no database available
# let's handle the recover thread and wait for it
except ConnectionException, (error):
print "%s fired EVENT_MCX_DATABASE_LOST caused by: %s" % (self.getName(), error)
# handle events
EVENT_MCX_DATABASE_RECOVERED.clear()
EVENT_MCX_DATABASE_LOST.set()
EVENT_MCX_DATABASE_RECOVERED.wait()
# repeat this in a given interval and sleep in the meantime :)
sleep(CONFIG_CHECKUPDATE_INTERVAL)
