mirror of
https://git.anonymousland.org/anonymousland/synapse-product.git
synced 2024-09-07 23:11:59 +00:00
Merge pull request #2804 from matrix-org/erikj/file_consumer
Add decent impl of a FileConsumer
This commit is contained in:
commit
b6dc7044a9
139
synapse/util/file_consumer.py
Normal file
139
synapse/util/file_consumer.py
Normal file
@ -0,0 +1,139 @@
|
||||
# -*- coding: utf-8 -*-
|
||||
# Copyright 2018 New Vector Ltd
|
||||
#
|
||||
# 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.
|
||||
|
||||
from twisted.internet import threads, reactor
|
||||
|
||||
from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
|
||||
|
||||
import Queue
|
||||
|
||||
|
||||
class BackgroundFileConsumer(object):
|
||||
"""A consumer that writes to a file like object. Supports both push
|
||||
and pull producers
|
||||
|
||||
Args:
|
||||
file_obj (file): The file like object to write to. Closed when
|
||||
finished.
|
||||
"""
|
||||
|
||||
# For PushProducers pause if we have this many unwritten slices
|
||||
_PAUSE_ON_QUEUE_SIZE = 5
|
||||
# And resume once the size of the queue is less than this
|
||||
_RESUME_ON_QUEUE_SIZE = 2
|
||||
|
||||
def __init__(self, file_obj):
|
||||
self._file_obj = file_obj
|
||||
|
||||
# Producer we're registered with
|
||||
self._producer = None
|
||||
|
||||
# True if PushProducer, false if PullProducer
|
||||
self.streaming = False
|
||||
|
||||
# For PushProducers, indicates whether we've paused the producer and
|
||||
# need to call resumeProducing before we get more data.
|
||||
self._paused_producer = False
|
||||
|
||||
# Queue of slices of bytes to be written. When producer calls
|
||||
# unregister a final None is sent.
|
||||
self._bytes_queue = Queue.Queue()
|
||||
|
||||
# Deferred that is resolved when finished writing
|
||||
self._finished_deferred = None
|
||||
|
||||
# If the _writer thread throws an exception it gets stored here.
|
||||
self._write_exception = None
|
||||
|
||||
def registerProducer(self, producer, streaming):
|
||||
"""Part of IConsumer interface
|
||||
|
||||
Args:
|
||||
producer (IProducer)
|
||||
streaming (bool): True if push based producer, False if pull
|
||||
based.
|
||||
"""
|
||||
if self._producer:
|
||||
raise Exception("registerProducer called twice")
|
||||
|
||||
self._producer = producer
|
||||
self.streaming = streaming
|
||||
self._finished_deferred = preserve_fn(threads.deferToThread)(self._writer)
|
||||
if not streaming:
|
||||
self._producer.resumeProducing()
|
||||
|
||||
def unregisterProducer(self):
|
||||
"""Part of IProducer interface
|
||||
"""
|
||||
self._producer = None
|
||||
if not self._finished_deferred.called:
|
||||
self._bytes_queue.put_nowait(None)
|
||||
|
||||
def write(self, bytes):
|
||||
"""Part of IProducer interface
|
||||
"""
|
||||
if self._write_exception:
|
||||
raise self._write_exception
|
||||
|
||||
if self._finished_deferred.called:
|
||||
raise Exception("consumer has closed")
|
||||
|
||||
self._bytes_queue.put_nowait(bytes)
|
||||
|
||||
# If this is a PushProducer and the queue is getting behind
|
||||
# then we pause the producer.
|
||||
if self.streaming and self._bytes_queue.qsize() >= self._PAUSE_ON_QUEUE_SIZE:
|
||||
self._paused_producer = True
|
||||
self._producer.pauseProducing()
|
||||
|
||||
def _writer(self):
|
||||
"""This is run in a background thread to write to the file.
|
||||
"""
|
||||
try:
|
||||
while self._producer or not self._bytes_queue.empty():
|
||||
# If we've paused the producer check if we should resume the
|
||||
# producer.
|
||||
if self._producer and self._paused_producer:
|
||||
if self._bytes_queue.qsize() <= self._RESUME_ON_QUEUE_SIZE:
|
||||
reactor.callFromThread(self._resume_paused_producer)
|
||||
|
||||
bytes = self._bytes_queue.get()
|
||||
|
||||
# If we get a None (or empty list) then that's a signal used
|
||||
# to indicate we should check if we should stop.
|
||||
if bytes:
|
||||
self._file_obj.write(bytes)
|
||||
|
||||
# If its a pull producer then we need to explicitly ask for
|
||||
# more stuff.
|
||||
if not self.streaming and self._producer:
|
||||
reactor.callFromThread(self._producer.resumeProducing)
|
||||
except Exception as e:
|
||||
self._write_exception = e
|
||||
raise
|
||||
finally:
|
||||
self._file_obj.close()
|
||||
|
||||
def wait(self):
|
||||
"""Returns a deferred that resolves when finished writing to file
|
||||
"""
|
||||
return make_deferred_yieldable(self._finished_deferred)
|
||||
|
||||
def _resume_paused_producer(self):
|
||||
"""Gets called if we should resume producing after being paused
|
||||
"""
|
||||
if self._paused_producer and self._producer:
|
||||
self._paused_producer = False
|
||||
self._producer.resumeProducing()
|
176
tests/util/test_file_consumer.py
Normal file
176
tests/util/test_file_consumer.py
Normal file
@ -0,0 +1,176 @@
|
||||
# -*- coding: utf-8 -*-
|
||||
# Copyright 2018 New Vector Ltd
|
||||
#
|
||||
# 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.
|
||||
|
||||
|
||||
from twisted.internet import defer, reactor
|
||||
from mock import NonCallableMock
|
||||
|
||||
from synapse.util.file_consumer import BackgroundFileConsumer
|
||||
|
||||
from tests import unittest
|
||||
from StringIO import StringIO
|
||||
|
||||
import threading
|
||||
|
||||
|
||||
class FileConsumerTests(unittest.TestCase):
|
||||
|
||||
@defer.inlineCallbacks
|
||||
def test_pull_consumer(self):
|
||||
string_file = StringIO()
|
||||
consumer = BackgroundFileConsumer(string_file)
|
||||
|
||||
try:
|
||||
producer = DummyPullProducer()
|
||||
|
||||
yield producer.register_with_consumer(consumer)
|
||||
|
||||
yield producer.write_and_wait("Foo")
|
||||
|
||||
self.assertEqual(string_file.getvalue(), "Foo")
|
||||
|
||||
yield producer.write_and_wait("Bar")
|
||||
|
||||
self.assertEqual(string_file.getvalue(), "FooBar")
|
||||
finally:
|
||||
consumer.unregisterProducer()
|
||||
|
||||
yield consumer.wait()
|
||||
|
||||
self.assertTrue(string_file.closed)
|
||||
|
||||
@defer.inlineCallbacks
|
||||
def test_push_consumer(self):
|
||||
string_file = BlockingStringWrite()
|
||||
consumer = BackgroundFileConsumer(string_file)
|
||||
|
||||
try:
|
||||
producer = NonCallableMock(spec_set=[])
|
||||
|
||||
consumer.registerProducer(producer, True)
|
||||
|
||||
consumer.write("Foo")
|
||||
yield string_file.wait_for_n_writes(1)
|
||||
|
||||
self.assertEqual(string_file.buffer, "Foo")
|
||||
|
||||
consumer.write("Bar")
|
||||
yield string_file.wait_for_n_writes(2)
|
||||
|
||||
self.assertEqual(string_file.buffer, "FooBar")
|
||||
finally:
|
||||
consumer.unregisterProducer()
|
||||
|
||||
yield consumer.wait()
|
||||
|
||||
self.assertTrue(string_file.closed)
|
||||
|
||||
@defer.inlineCallbacks
|
||||
def test_push_producer_feedback(self):
|
||||
string_file = BlockingStringWrite()
|
||||
consumer = BackgroundFileConsumer(string_file)
|
||||
|
||||
try:
|
||||
producer = NonCallableMock(spec_set=["pauseProducing", "resumeProducing"])
|
||||
|
||||
resume_deferred = defer.Deferred()
|
||||
producer.resumeProducing.side_effect = lambda: resume_deferred.callback(None)
|
||||
|
||||
consumer.registerProducer(producer, True)
|
||||
|
||||
number_writes = 0
|
||||
with string_file.write_lock:
|
||||
for _ in range(consumer._PAUSE_ON_QUEUE_SIZE):
|
||||
consumer.write("Foo")
|
||||
number_writes += 1
|
||||
|
||||
producer.pauseProducing.assert_called_once()
|
||||
|
||||
yield string_file.wait_for_n_writes(number_writes)
|
||||
|
||||
yield resume_deferred
|
||||
producer.resumeProducing.assert_called_once()
|
||||
finally:
|
||||
consumer.unregisterProducer()
|
||||
|
||||
yield consumer.wait()
|
||||
|
||||
self.assertTrue(string_file.closed)
|
||||
|
||||
|
||||
class DummyPullProducer(object):
|
||||
def __init__(self):
|
||||
self.consumer = None
|
||||
self.deferred = defer.Deferred()
|
||||
|
||||
def resumeProducing(self):
|
||||
d = self.deferred
|
||||
self.deferred = defer.Deferred()
|
||||
d.callback(None)
|
||||
|
||||
def write_and_wait(self, bytes):
|
||||
d = self.deferred
|
||||
self.consumer.write(bytes)
|
||||
return d
|
||||
|
||||
def register_with_consumer(self, consumer):
|
||||
d = self.deferred
|
||||
self.consumer = consumer
|
||||
self.consumer.registerProducer(self, False)
|
||||
return d
|
||||
|
||||
|
||||
class BlockingStringWrite(object):
|
||||
def __init__(self):
|
||||
self.buffer = ""
|
||||
self.closed = False
|
||||
self.write_lock = threading.Lock()
|
||||
|
||||
self._notify_write_deferred = None
|
||||
self._number_of_writes = 0
|
||||
|
||||
def write(self, bytes):
|
||||
with self.write_lock:
|
||||
self.buffer += bytes
|
||||
self._number_of_writes += 1
|
||||
|
||||
reactor.callFromThread(self._notify_write)
|
||||
|
||||
def close(self):
|
||||
self.closed = True
|
||||
|
||||
def _notify_write(self):
|
||||
"Called by write to indicate a write happened"
|
||||
with self.write_lock:
|
||||
if not self._notify_write_deferred:
|
||||
return
|
||||
d = self._notify_write_deferred
|
||||
self._notify_write_deferred = None
|
||||
d.callback(None)
|
||||
|
||||
@defer.inlineCallbacks
|
||||
def wait_for_n_writes(self, n):
|
||||
"Wait for n writes to have happened"
|
||||
while True:
|
||||
with self.write_lock:
|
||||
if n <= self._number_of_writes:
|
||||
return
|
||||
|
||||
if not self._notify_write_deferred:
|
||||
self._notify_write_deferred = defer.Deferred()
|
||||
|
||||
d = self._notify_write_deferred
|
||||
|
||||
yield d
|
Loading…
Reference in New Issue
Block a user