131 lines
3.9 KiB
Python
131 lines
3.9 KiB
Python
# Licensed under the Apache License, Version 2.0 (the "License"); you may
|
|
# not use this file except in compliance with the License. You may obtain
|
|
# a copy of the License at
|
|
#
|
|
# http://www.apache.org/licenses/LICENSE-2.0
|
|
#
|
|
# Unless required by applicable law or agreed to in writing, software
|
|
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
# License for the specific language governing permissions and limitations
|
|
# under the License.
|
|
|
|
import abc
|
|
import atexit
|
|
import logging
|
|
import threading
|
|
|
|
import six
|
|
from six.moves import queue as Queue
|
|
|
|
LOG = logging.getLogger(__name__)
|
|
STOP_EVENT = ("STOP", None, None, None)
|
|
|
|
|
|
@six.add_metaclass(abc.ABCMeta)
|
|
class RowEvent(object):
|
|
ROW_CREATE = "create"
|
|
ROW_UPDATE = "update"
|
|
ROW_DELETE = "delete"
|
|
ONETIME = False
|
|
event_name = 'RowEvent'
|
|
|
|
def __init__(self, events, table, conditions, old_conditions=None):
|
|
self.table = table
|
|
self.events = events
|
|
self.conditions = conditions
|
|
self.old_conditions = old_conditions
|
|
|
|
@property
|
|
def key(self):
|
|
return (self.__class__, self.table, self.events, self.conditions)
|
|
|
|
def __hash__(self):
|
|
return hash(self.key)
|
|
|
|
def __eq__(self, other):
|
|
try:
|
|
return self.key == other.key
|
|
except AttributeError:
|
|
return False
|
|
|
|
def __ne__(self, other):
|
|
return not self == other
|
|
|
|
@abc.abstractmethod
|
|
def matches(self, event, row, old=None):
|
|
"""Test that `event` on `row` matches watched events
|
|
|
|
:param event: event type
|
|
:type event: ROW_CREATE, ROW_UPDATE, or ROW_DELETE
|
|
:param row:
|
|
:param old:
|
|
:returns: boolean, True if match else False
|
|
"""
|
|
|
|
@abc.abstractmethod
|
|
def run(self, event, row, old):
|
|
"""Method to run when the event matches"""
|
|
|
|
|
|
class RowEventHandler(object):
|
|
def __init__(self):
|
|
self.__watched_events = set()
|
|
self.__lock = threading.Lock()
|
|
self.notifications = Queue.Queue()
|
|
self.notify_thread = threading.Thread(target=self.notify_loop)
|
|
self.notify_thread.daemon = True
|
|
atexit.register(self.shutdown)
|
|
self.start()
|
|
|
|
def start(self):
|
|
self.notify_thread.start()
|
|
|
|
def matching_events(self, event, row, updates):
|
|
with self.__lock:
|
|
return tuple(t for t in self.__watched_events
|
|
if t.matches(event, row, updates))
|
|
|
|
def watch_event(self, event):
|
|
with self.__lock:
|
|
self.__watched_events.add(event)
|
|
|
|
def watch_events(self, events):
|
|
with self.__lock:
|
|
for event in events:
|
|
self.__watched_events.add(event)
|
|
|
|
def unwatch_event(self, event):
|
|
with self.__lock:
|
|
self.__watched_events.discard(event)
|
|
|
|
def unwatch_events(self, events):
|
|
with self.__lock:
|
|
for event in events:
|
|
self.__watched_events.discard(event)
|
|
|
|
def shutdown(self):
|
|
self.notifications.put(STOP_EVENT)
|
|
|
|
def notify_loop(self):
|
|
while True:
|
|
try:
|
|
match, event, row, updates = self.notifications.get()
|
|
if (match, event, row, updates) == STOP_EVENT:
|
|
self.notifications.task_done()
|
|
break
|
|
match.run(event, row, updates)
|
|
if match.ONETIME:
|
|
self.unwatch_event(match)
|
|
self.notifications.task_done()
|
|
except Exception:
|
|
# If any unexpected exception happens we don't want the
|
|
# notify_loop to exit.
|
|
LOG.exception('Unexpected exception in notify_loop')
|
|
|
|
def notify(self, event, row, updates=None):
|
|
matching = self.matching_events(
|
|
event, row, updates)
|
|
for match in matching:
|
|
self.notifications.put((match, event, row, updates))
|