zulip/zerver/lib/queue.py

317 lines
12 KiB
Python

from django.conf import settings
import pika
from pika.adapters.blocking_connection import BlockingChannel
from pika.spec import Basic
import logging
import ujson
import random
import time
import threading
from collections import defaultdict
from zerver.lib.utils import statsd
from typing import Any, Callable, Dict, List, Mapping, Optional, Set, Union
MAX_REQUEST_RETRIES = 3
Consumer = Callable[[BlockingChannel, Basic.Deliver, pika.BasicProperties, str], None]
# This simple queuing library doesn't expose much of the power of
# rabbitmq/pika's queuing system; its purpose is to just provide an
# interface for external files to put things into queues and take them
# out from bots without having to import pika code all over our codebase.
class SimpleQueueClient(object):
def __init__(self):
# type: () -> None
self.log = logging.getLogger('zulip.queue')
self.queues = set() # type: Set[str]
self.channel = None # type: Optional[BlockingChannel]
self.consumers = defaultdict(set) # type: Dict[str, Set[Consumer]]
# Disable RabbitMQ heartbeats since BlockingConnection can't process them
self.rabbitmq_heartbeat = 0 # type: Optional[int]
self._connect()
def _connect(self):
# type: () -> None
start = time.time()
self.connection = pika.BlockingConnection(self._get_parameters())
self.channel = self.connection.channel()
self.log.info('SimpleQueueClient connected (connecting took %.3fs)' % (time.time() - start,))
def _reconnect(self):
# type: () -> None
self.connection = None
self.channel = None
self.queues = set()
self._connect()
def _get_parameters(self):
# type: () -> pika.ConnectionParameters
# We explicitly disable the RabbitMQ heartbeat feature, since
# it doesn't make sense with BlockingConnection
credentials = pika.PlainCredentials(settings.RABBITMQ_USERNAME,
settings.RABBITMQ_PASSWORD)
return pika.ConnectionParameters(settings.RABBITMQ_HOST,
heartbeat_interval=self.rabbitmq_heartbeat,
credentials=credentials)
def _generate_ctag(self, queue_name):
# type: (str) -> str
return "%s_%s" % (queue_name, str(random.getrandbits(16)))
def _reconnect_consumer_callback(self, queue, consumer):
# type: (str, Consumer) -> None
self.log.info("Queue reconnecting saved consumer %s to queue %s" % (consumer, queue))
self.ensure_queue(queue, lambda: self.channel.basic_consume(consumer,
queue=queue,
consumer_tag=self._generate_ctag(queue)))
def _reconnect_consumer_callbacks(self):
# type: () -> None
for queue, consumers in self.consumers.items():
for consumer in consumers:
self._reconnect_consumer_callback(queue, consumer)
def close(self):
# type: () -> None
if self.connection:
self.connection.close()
def ready(self):
# type: () -> bool
return self.channel is not None
def ensure_queue(self, queue_name, callback):
# type: (str, Callable[[], None]) -> None
'''Ensure that a given queue has been declared, and then call
the callback with no arguments.'''
if not self.connection.is_open:
self._connect()
if queue_name not in self.queues:
self.channel.queue_declare(queue=queue_name, durable=True)
self.queues.add(queue_name)
callback()
def publish(self, queue_name, body):
# type: (str, str) -> None
def do_publish():
# type: () -> None
self.channel.basic_publish(
exchange='',
routing_key=queue_name,
properties=pika.BasicProperties(delivery_mode=2),
body=body)
statsd.incr("rabbitmq.publish.%s" % (queue_name,))
self.ensure_queue(queue_name, do_publish)
def json_publish(self, queue_name, body):
# type: (str, Union[Mapping[str, Any], str]) -> None
# Union because of zerver.middleware.write_log_line uses a str
try:
self.publish(queue_name, ujson.dumps(body))
except (AttributeError, pika.exceptions.AMQPConnectionError):
self.log.warning("Failed to send to rabbitmq, trying to reconnect and send again")
self._reconnect()
self.publish(queue_name, ujson.dumps(body))
def register_consumer(self, queue_name, consumer):
# type: (str, Consumer) -> None
def wrapped_consumer(ch, method, properties, body):
# type: (BlockingChannel, Basic.Deliver, pika.BasicProperties, str) -> None
try:
consumer(ch, method, properties, body)
ch.basic_ack(delivery_tag=method.delivery_tag)
except Exception as e:
ch.basic_nack(delivery_tag=method.delivery_tag)
raise e
self.consumers[queue_name].add(wrapped_consumer)
self.ensure_queue(queue_name,
lambda: self.channel.basic_consume(wrapped_consumer, queue=queue_name,
consumer_tag=self._generate_ctag(queue_name)))
def register_json_consumer(self, queue_name, callback):
# type: (str, Callable[[Dict[str, Any]], None]) -> None
def wrapped_callback(ch, method, properties, body):
# type: (BlockingChannel, Basic.Deliver, pika.BasicProperties, str) -> None
callback(ujson.loads(body))
self.register_consumer(queue_name, wrapped_callback)
def drain_queue(self, queue_name, json=False):
# type: (str, bool) -> List[Dict[str, Any]]
"Returns all messages in the desired queue"
messages = []
def opened():
# type: () -> None
while True:
(meta, _, message) = self.channel.basic_get(queue_name)
if not message:
break
self.channel.basic_ack(meta.delivery_tag)
if json:
message = ujson.loads(message)
messages.append(message)
self.ensure_queue(queue_name, opened)
return messages
def start_consuming(self):
# type: () -> None
self.channel.start_consuming()
def stop_consuming(self):
# type: () -> None
self.channel.stop_consuming()
# Patch pika.adapters.TornadoConnection so that a socket error doesn't
# throw an exception and disconnect the tornado process from the rabbitmq
# queue. Instead, just re-connect as usual
class ExceptionFreeTornadoConnection(pika.adapters.TornadoConnection):
def _adapter_disconnect(self):
# type: () -> None
try:
super(ExceptionFreeTornadoConnection, self)._adapter_disconnect()
except (pika.exceptions.ProbableAuthenticationError,
pika.exceptions.ProbableAccessDeniedError,
pika.exceptions.IncompatibleProtocolError) as e:
logging.warning("Caught exception '%r' in ExceptionFreeTornadoConnection when \
calling _adapter_disconnect, ignoring" % (e,))
class TornadoQueueClient(SimpleQueueClient):
# Based on:
# https://pika.readthedocs.io/en/0.9.8/examples/asynchronous_consumer_example.html
def __init__(self):
# type: () -> None
super(TornadoQueueClient, self).__init__()
# Enable rabbitmq heartbeat since TornadoConection can process them
self.rabbitmq_heartbeat = None
self._on_open_cbs = [] # type: List[Callable[[], None]]
def _connect(self, on_open_cb = None):
# type: (Optional[Callable[[], None]]) -> None
self.log.info("Beginning TornadoQueueClient connection")
if on_open_cb is not None:
self._on_open_cbs.append(on_open_cb)
self.connection = ExceptionFreeTornadoConnection(
self._get_parameters(),
on_open_callback = self._on_open,
stop_ioloop_on_close = False)
self.connection.add_on_close_callback(self._on_connection_closed)
def _reconnect(self):
# type: () -> None
self.connection = None
self.channel = None
self.queues = set()
self._connect()
def _on_open(self, connection):
# type: (pika.Connection) -> None
self.connection.channel(
on_open_callback = self._on_channel_open)
def _on_channel_open(self, channel):
# type: (BlockingChannel) -> None
self.channel = channel
for callback in self._on_open_cbs:
callback()
self._reconnect_consumer_callbacks()
self.log.info('TornadoQueueClient connected')
def _on_connection_closed(self, connection, reply_code, reply_text):
# type: (pika.Connection, int, str) -> None
self.log.warning("TornadoQueueClient lost connection to RabbitMQ, reconnecting...")
from tornado import ioloop
# Try to reconnect in two seconds
retry_seconds = 2
def on_timeout():
# type: () -> None
try:
self._reconnect()
except pika.exceptions.AMQPConnectionError:
self.log.critical("Failed to reconnect to RabbitMQ, retrying...")
ioloop.IOLoop.instance().add_timeout(time.time() + retry_seconds, on_timeout)
ioloop.IOLoop.instance().add_timeout(time.time() + retry_seconds, on_timeout)
def ensure_queue(self, queue_name, callback):
# type: (str, Callable[[], None]) -> None
def finish(frame):
# type: (Any) -> None
self.queues.add(queue_name)
callback()
if queue_name not in self.queues:
# If we're not connected yet, send this message
# once we have created the channel
if not self.ready():
self._on_open_cbs.append(lambda: self.ensure_queue(queue_name, callback))
return
self.channel.queue_declare(queue=queue_name, durable=True, callback=finish)
else:
callback()
def register_consumer(self, queue_name, consumer):
# type: (str, Consumer) -> None
def wrapped_consumer(ch, method, properties, body):
# type: (BlockingChannel, Basic.Deliver, pika.BasicProperties, str) -> None
consumer(ch, method, properties, body)
ch.basic_ack(delivery_tag=method.delivery_tag)
if not self.ready():
self.consumers[queue_name].add(wrapped_consumer)
return
self.consumers[queue_name].add(wrapped_consumer)
self.ensure_queue(queue_name,
lambda: self.channel.basic_consume(wrapped_consumer, queue=queue_name,
consumer_tag=self._generate_ctag(queue_name)))
queue_client = None # type: Optional[SimpleQueueClient]
def get_queue_client():
# type: () -> SimpleQueueClient
global queue_client
if queue_client is None:
if settings.RUNNING_INSIDE_TORNADO and settings.USING_RABBITMQ:
queue_client = TornadoQueueClient()
elif settings.USING_RABBITMQ:
queue_client = SimpleQueueClient()
return queue_client
# We using a simple lock to prevent multiple RabbitMQ messages being
# sent to the SimpleQueueClient at the same time; this is a workaround
# for an issue with the pika BlockingConnection where using
# BlockingConnection for multiple queues causes the channel to
# randomly close.
queue_lock = threading.RLock()
def queue_json_publish(queue_name, event, processor):
# type: (str, Union[Mapping[str, Any], str], Callable[[Any], None]) -> None
# most events are dicts, but zerver.middleware.write_log_line uses a str
with queue_lock:
if settings.USING_RABBITMQ:
get_queue_client().json_publish(queue_name, event)
else:
processor(event)
def retry_event(queue_name, event, failure_processor):
# type: (str, Dict[str, Any], Callable[[Dict[str, Any]], None]) -> None
assert 'failed_tries' in event
event['failed_tries'] += 1
if event['failed_tries'] > MAX_REQUEST_RETRIES:
failure_processor(event)
else:
queue_json_publish(queue_name, event, lambda x: None)