freezer/freezer/utils/streaming.py

111 lines
3.1 KiB
Python

"""
(c) Copyright 2014,2015 Hewlett-Packard Development Company, L.P.
(c) Copyright 2016 Hewlett-Packard Enterprise Development Company, L.P.
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.
Freezer general utils functions
"""
from six.moves import queue
import threading
class Wait(Exception):
pass
class RichQueue(object):
"""
:type data_queue: Queue.Queue
"""
def __init__(self, size=2):
"""
:type size: int
:return:
"""
self.data_queue = queue.Queue(maxsize=size)
# transmission changes in atomic way so no synchronization needed
self.finish_transmission = False
self.is_force_stop = False
def finish(self):
self.finish_transmission = True
def force_stop(self):
self.is_force_stop = True
def empty(self):
return self.data_queue.empty()
def get(self):
try:
res = self.data_queue.get(timeout=1)
self.data_queue.task_done()
return res
except queue.Empty:
raise Wait()
def check_stop(self):
if self.is_force_stop:
raise Exception("Forced stop")
def put_messages(self, messages):
for message in messages:
self.put(message)
self.finish()
def has_more(self):
self.check_stop()
return not self.finish_transmission or not self.data_queue.empty()
def put(self, message):
while True:
try:
self.data_queue.put(message, timeout=1)
break
except queue.Full:
self.check_stop()
def get_messages(self):
while self.has_more():
try:
yield self.get()
except Wait:
self.check_stop()
class QueuedThread(threading.Thread):
def __init__(self, target, rich_queue, exception_queue,
args=(), kwargs=None):
"""
:type args: collections.Iterable
:type kwargs: dict
:type target: () -> ()
:type rich_queue: RichQueue
"""
self.args = args
kwargs = kwargs or {}
self.rich_queue = rich_queue
self._exception_queue = exception_queue
kwargs["rich_queue"] = rich_queue
super(QueuedThread, self).__init__(target=target, args=args,
kwargs=kwargs)
def run(self):
try:
super(QueuedThread, self).run()
except Exception as e:
self._exception_queue.put_nowait(e)
self.rich_queue.force_stop()
# Thread will exit at this point.
raise e