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swh/provenance/api/client.py

# Copyright (C) 2021 The Software Heritage developers # Copyright (C) 2021 The Software Heritage developers
# See the AUTHORS file at the top-level directory of this distribution # See the AUTHORS file at the top-level directory of this distribution
# License: GNU General Public License version 3, or any later version # License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information # See top-level LICENSE file for more information
import functools
import inspect
import logging
import queue
import threading
import time
from typing import Any, Dict, Optional
import uuid
import pika
import pika.channel
import pika.connection
import pika.frame
import pika.spec
from swh.core.api.serializers import encode_data_client as encode_data
from swh.core.api.serializers import msgpack_loads as decode_data
from swh.core.statsd import statsd
from .. import get_provenance_storage
from ..interface import ProvenanceStorageInterface
from .serializers import DECODERS, ENCODERS
from .server import ProvenanceStorageRabbitMQServer
LOG_FORMAT = (
"%(levelname) -10s %(asctime)s %(name) -30s %(funcName) "
"-35s %(lineno) -5d: %(message)s"
)
LOGGER = logging.getLogger(__name__)
STORAGE_DURATION_METRIC = "swh_provenance_storage_rabbitmq_duration_seconds"
class ResponseTimeout(Exception):
pass
class TerminateSignal(Exception):
pass
class MetaRabbitMQClient(type):
def __new__(cls, name, bases, attributes):
# For each method wrapped with @remote_api_endpoint in an API backend
# (eg. :class:`swh.indexer.storage.IndexerStorage`), add a new
# method in RemoteStorage, with the same documentation.
#
# Note that, despite the usage of decorator magic (eg. functools.wrap),
# this never actually calls an IndexerStorage method.
backend_class = attributes.get("backend_class", None)
for base in bases:
if backend_class is not None:
break
backend_class = getattr(base, "backend_class", None)
if backend_class:
for meth_name, meth in backend_class.__dict__.items():
if hasattr(meth, "_endpoint_path"):
cls.__add_endpoint(meth_name, meth, attributes)
return super().__new__(cls, name, bases, attributes)
@staticmethod
def __add_endpoint(meth_name, meth, attributes):
wrapped_meth = inspect.unwrap(meth)
@functools.wraps(meth) # Copy signature and doc
def meth_(*args, **kwargs):
with statsd.timed(
metric=STORAGE_DURATION_METRIC, tags={"method": meth_name}
):
# Match arguments and parameters
data = inspect.getcallargs(wrapped_meth, *args, **kwargs)
# Remove arguments that should not be passed
self = data.pop("self")
# Call storage method with remaining arguments
return getattr(self._storage, meth_name)(**data)
@functools.wraps(meth) # Copy signature and doc
def write_meth_(*args, **kwargs):
with statsd.timed(
metric=STORAGE_DURATION_METRIC, tags={"method": meth_name}
):
# Match arguments and parameters
post_data = inspect.getcallargs(wrapped_meth, *args, **kwargs)
try:
# Remove arguments that should not be passed
self = post_data.pop("self")
relation = post_data.pop("relation", None)
assert len(post_data) == 1
if relation is not None:
items = [
(src, rel.dst, rel.path)
for src, dsts in next(iter(post_data.values())).items()
for rel in dsts
]
else:
data = next(iter(post_data.values()))
items = (
list(data.items())
if isinstance(data, dict)
else list({(item,) for item in data})
)
acks_expected = len(items)
self._correlation_id = str(uuid.uuid4())
exchange = ProvenanceStorageRabbitMQServer.get_exchange(
meth_name, relation
)
for item in items:
routing_key = ProvenanceStorageRabbitMQServer.get_routing_key(
item, meth_name, relation
)
# FIXME: this is running in a different thread! Hence, if
# self._connection drops, there is no guarantee that the
# request can be sent for the current elements. This
# situation should be handled properly.
self._connection.ioloop.add_callback_threadsafe(
functools.partial(
ProvenanceStorageRabbitMQClient.request,
channel=self._channel,
reply_to=self._callback_queue,
exchange=exchange,
routing_key=routing_key,
correlation_id=self._correlation_id,
data=item,
)
)
return self.wait_for_acks(acks_expected)
except BaseException as ex:
self.request_termination(str(ex))
return False
if meth_name not in attributes:
attributes[meth_name] = (
write_meth_
if ProvenanceStorageRabbitMQServer.is_write_method(meth_name)
else meth_
)
class ProvenanceStorageRabbitMQClient(threading.Thread, metaclass=MetaRabbitMQClient):
"""This is an example publisher that will handle unexpected interactions
with RabbitMQ such as channel and connection closures.
If RabbitMQ closes the connection, it will reopen it. You should
look at the output, as there are limited reasons why the connection may
be closed, which usually are tied to permission related issues or
socket timeouts.
It uses delivery confirmations and illustrates one way to keep track of
messages that have been sent and if they've been confirmed by RabbitMQ.
"""
backend_class = ProvenanceStorageInterface
extra_type_decoders = DECODERS
extra_type_encoders = ENCODERS
def __init__(self, url: str, storage_config: Dict[str, Any]) -> None:
"""Setup the example publisher object, passing in the URL we will use
to connect to RabbitMQ.
:param str url: The URL for connecting to RabbitMQ
:param str routing_key: The routing key name from which this worker will
consume messages
:param str storage_config: Configuration parameters for the underlying
``ProvenanceStorage`` object
"""
super().__init__()
self._connection = None
self._callback_queue: Optional[str] = None
self._channel = None
self._closing = False
self._consumer_tag = None
self._consuming = False
self._correlation_id = str(uuid.uuid4())
self._prefetch_count = 100
self._response_queue: queue.Queue = queue.Queue()
self._storage = get_provenance_storage(**storage_config)
self._url = url
@statsd.timed(metric=STORAGE_DURATION_METRIC, tags={"method": "open"})
def open(self) -> None:
self.start()
while self._callback_queue is None:
time.sleep(0.1)
self._storage.open()
@statsd.timed(metric=STORAGE_DURATION_METRIC, tags={"method": "close"})
def close(self) -> None:
assert self._connection is not None
self._connection.ioloop.add_callback_threadsafe(self.request_termination)
self.join()
self._storage.close()
def request_termination(self, reason: str = "Normal shutdown") -> None:
assert self._connection is not None
def termination_callback():
raise TerminateSignal(reason)
self._connection.ioloop.add_callback_threadsafe(termination_callback)
def connect(self) -> pika.SelectConnection:
"""This method connects to RabbitMQ, returning the connection handle.
When the connection is established, the on_connection_open method
will be invoked by pika.
:rtype: pika.SelectConnection
"""
LOGGER.info("Connecting to %s", self._url)
return pika.SelectConnection(
parameters=pika.URLParameters(self._url),
on_open_callback=self.on_connection_open,
on_open_error_callback=self.on_connection_open_error,
on_close_callback=self.on_connection_closed,
)
def close_connection(self) -> None:
assert self._connection is not None
self._consuming = False
if self._connection.is_closing or self._connection.is_closed:
LOGGER.info("Connection is closing or already closed")
else:
LOGGER.info("Closing connection")
self._connection.close()
def on_connection_open(self, _unused_connection: pika.SelectConnection) -> None:
"""This method is called by pika once the connection to RabbitMQ has
been established. It passes the handle to the connection object in
case we need it, but in this case, we'll just mark it unused.
:param pika.SelectConnection _unused_connection: The connection
"""
LOGGER.info("Connection opened")
self.open_channel()
def on_connection_open_error(
self, _unused_connection: pika.SelectConnection, err: Exception
) -> None:
"""This method is called by pika if the connection to RabbitMQ
can't be established.
:param pika.SelectConnection _unused_connection: The connection
:param Exception err: The error
"""
LOGGER.error("Connection open failed, reopening in 5 seconds: %s", err)
assert self._connection is not None
self._connection.ioloop.call_later(5, self._connection.ioloop.stop)
def on_connection_closed(self, _unused_connection: pika.SelectConnection, reason):
"""This method is invoked by pika when the connection to RabbitMQ is
closed unexpectedly. Since it is unexpected, we will reconnect to
RabbitMQ if it disconnects.
:param pika.connection.Connection connection: The closed connection obj
:param Exception reason: exception representing reason for loss of
connection.
"""
assert self._connection is not None
self._channel = None
if self._closing:
self._connection.ioloop.stop()
else:
LOGGER.warning("Connection closed, reopening in 5 seconds: %s", reason)
self._connection.ioloop.call_later(5, self._connection.ioloop.stop)
def open_channel(self) -> None:
"""Open a new channel with RabbitMQ by issuing the Channel.Open RPC
command. When RabbitMQ responds that the channel is open, the
on_channel_open callback will be invoked by pika.
"""
LOGGER.info("Creating a new channel")
assert self._connection is not None
self._connection.channel(on_open_callback=self.on_channel_open)
def on_channel_open(self, channel: pika.channel.Channel) -> None:
"""This method is invoked by pika when the channel has been opened.
The channel object is passed in so we can make use of it.
Since the channel is now open, we'll declare the exchange to use.
:param pika.channel.Channel channel: The channel object
"""
LOGGER.info("Channel opened")
self._channel = channel
LOGGER.info("Adding channel close callback")
assert self._channel is not None
self._channel.add_on_close_callback(callback=self.on_channel_closed)
self.setup_queue()
def on_channel_closed(
self, channel: pika.channel.Channel, reason: Exception
) -> None:
"""Invoked by pika when RabbitMQ unexpectedly closes the channel.
Channels are usually closed if you attempt to do something that
violates the protocol, such as re-declare an exchange or queue with
different parameters. In this case, we'll close the connection
to shutdown the object.
:param pika.channel.Channel: The closed channel
:param Exception reason: why the channel was closed
"""
LOGGER.warning("Channel %i was closed: %s", channel, reason)
self.close_connection()
def setup_queue(self) -> None:
"""Setup the queue on RabbitMQ by invoking the Queue.Declare RPC
command. When it is complete, the on_queue_declare_ok method will
be invoked by pika.
"""
LOGGER.info("Declaring callback queue")
assert self._channel is not None
self._channel.queue_declare(
queue="", exclusive=True, callback=self.on_queue_declare_ok
)
def on_queue_declare_ok(self, frame: pika.frame.Method) -> None:
"""Method invoked by pika when the Queue.Declare RPC call made in
setup_queue has completed. This method sets up the consumer prefetch
to only be delivered one message at a time. The consumer must
acknowledge this message before RabbitMQ will deliver another one.
You should experiment with different prefetch values to achieve desired
performance.
:param pika.frame.Method method_frame: The Queue.DeclareOk frame
"""
LOGGER.info("Binding queue to default exchanger")
assert self._channel is not None
self._callback_queue = frame.method.queue
self._channel.basic_qos(
prefetch_count=self._prefetch_count, callback=self.on_basic_qos_ok
)
def on_basic_qos_ok(self, _unused_frame: pika.frame.Method) -> None:
"""Invoked by pika when the Basic.QoS method has completed. At this
point we will start consuming messages by calling start_consuming
which will invoke the needed RPC commands to start the process.
:param pika.frame.Method _unused_frame: The Basic.QosOk response frame
"""
LOGGER.info("QOS set to: %d", self._prefetch_count)
self.start_consuming()
def start_consuming(self) -> None:
"""This method sets up the consumer by first calling
add_on_cancel_callback so that the object is notified if RabbitMQ
cancels the consumer. It then issues the Basic.Consume RPC command
which returns the consumer tag that is used to uniquely identify the
consumer with RabbitMQ. We keep the value to use it when we want to
cancel consuming. The on_response method is passed in as a callback pika
will invoke when a message is fully received.
"""
LOGGER.info("Issuing consumer related RPC commands")
LOGGER.info("Adding consumer cancellation callback")
assert self._channel is not None
self._channel.add_on_cancel_callback(callback=self.on_consumer_cancelled)
assert self._callback_queue is not None
self._consumer_tag = self._channel.basic_consume(
queue=self._callback_queue, on_message_callback=self.on_response
)
self._consuming = True
def on_consumer_cancelled(self, method_frame: pika.frame.Method) -> None:
"""Invoked by pika when RabbitMQ sends a Basic.Cancel for a consumer
receiving messages.
:param pika.frame.Method method_frame: The Basic.Cancel frame
"""
LOGGER.info("Consumer was cancelled remotely, shutting down: %r", method_frame)
if self._channel:
self._channel.close()
def on_response(
self,
channel: pika.channel.Channel,
deliver: pika.spec.Basic.Deliver,
properties: pika.spec.BasicProperties,
body: bytes,
) -> None:
"""Invoked by pika when a message is delivered from RabbitMQ. The
channel is passed for your convenience. The deliver object that
is passed in carries the exchange, routing key, delivery tag and
a redelivered flag for the message. The properties passed in is an
instance of BasicProperties with the message properties and the body
is the message that was sent.
:param pika.channel.Channel channel: The channel object
:param pika.spec.Basic.Deliver: deliver method
:param pika.spec.BasicProperties: properties
:param bytes body: The message body
"""
LOGGER.info(
"Received message # %s from %s: %s",
deliver.delivery_tag,
properties.app_id,
body,
)
self._response_queue.put(
(
properties.correlation_id,
decode_data(body, extra_decoders=self.extra_type_decoders),
)
)
LOGGER.info("Acknowledging message %s", deliver.delivery_tag)
channel.basic_ack(delivery_tag=deliver.delivery_tag)
def stop_consuming(self) -> None:
"""Tell RabbitMQ that you would like to stop consuming by sending the
Basic.Cancel RPC command.
"""
if self._channel:
LOGGER.info("Sending a Basic.Cancel RPC command to RabbitMQ")
self._channel.basic_cancel(self._consumer_tag, self.on_cancel_ok)
def on_cancel_ok(self, _unused_frame: pika.frame.Method) -> None:
"""This method is invoked by pika when RabbitMQ acknowledges the
cancellation of a consumer. At this point we will close the channel.
This will invoke the on_channel_closed method once the channel has been
closed, which will in-turn close the connection.
:param pika.frame.Method _unused_frame: The Basic.CancelOk frame
:param str|unicode consumer_tag: Tag of the consumer to be stopped
"""
self._consuming = False
LOGGER.info(
"RabbitMQ acknowledged the cancellation of the consumer: %s",
self._consumer_tag,
)
LOGGER.info("Closing the channel")
assert self._channel is not None
self._channel.close()
def run(self) -> None:
"""Run the example code by connecting and then starting the IOLoop."""
while not self._closing:
try:
self._connection = self.connect()
assert self._connection is not None
self._connection.ioloop.start()
except KeyboardInterrupt:
LOGGER.info("Connection closed by keyboard interruption, reopening")
if self._connection is not None:
self._connection.ioloop.stop()
except TerminateSignal as ex:
LOGGER.info("Termination requested: %s", ex)
self.stop()
if self._connection is not None and not self._connection.is_closed:
# Finish closing
self._connection.ioloop.start()
except BaseException as ex:
LOGGER.warning("Unexpected exception, terminating: %s", ex)
self.stop()
if self._connection is not None and not self._connection.is_closed:
# Finish closing
self._connection.ioloop.start()
LOGGER.info("Stopped")
def stop(self) -> None:
"""Cleanly shutdown the connection to RabbitMQ by stopping the consumer
with RabbitMQ. When RabbitMQ confirms the cancellation, on_cancel_ok
will be invoked by pika, which will then closing the channel and
connection. The IOLoop is started again because this method is invoked
by raising a TerminateSignal exception. This exception stops the IOLoop
which needs to be running for pika to communicate with RabbitMQ. All of
the commands issued prior to starting the IOLoop will be buffered but
not processed.
"""
assert self._connection is not None
if not self._closing:
self._closing = True
LOGGER.info("Stopping")
if self._consuming:
self.stop_consuming()
self._connection.ioloop.start()
else:
self._connection.ioloop.stop()
LOGGER.info("Stopped")
@staticmethod
def request(
channel: pika.channel.Channel,
reply_to: str,
exchange: str,
routing_key: str,
correlation_id: str,
**kwargs,
) -> None:
channel.basic_publish(
exchange=exchange,
routing_key=routing_key,
properties=pika.BasicProperties(
content_type="application/msgpack",
correlation_id=correlation_id,
reply_to=reply_to,
),
body=encode_data(
kwargs,
extra_encoders=ProvenanceStorageRabbitMQClient.extra_type_encoders,
),
)
def wait_for_acks(self, acks_expected: int) -> bool:
acks_received = 0
while acks_received < acks_expected:
try:
acks_received += self.wait_for_response()
except ResponseTimeout:
LOGGER.warning(
"Timed out waiting for acks, %s received, %s expected",
acks_received,
acks_expected,
)
return False
return acks_received == acks_expected
def wait_for_response(self, timeout: float = 60.0) -> Any:
while True:
try:
correlation_id, response = self._response_queue.get(timeout=timeout)
if correlation_id == self._correlation_id:
return response
except queue.Empty:
raise ResponseTimeout
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