# Copyright (C) 2015 Cisco Systems, Inc.
#
# 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 threading
from oslo_messaging._drivers import base
from oslo_messaging._drivers import common as driver_common
from oslo_messaging._drivers import pool as driver_pool
from oslo_messaging._i18n import _LE
from oslo_messaging._i18n import _LW
from oslo_serialization import jsonutils
import kafka
from kafka.common import KafkaError
from oslo_config import cfg
from oslo_log import log as logging
LOG = logging.getLogger(__name__)
PURPOSE_SEND = 'send'
PURPOSE_LISTEN = 'listen'
kafka_opts = [
cfg.StrOpt('kafka_default_host', default='localhost',
deprecated_for_removal=True,
deprecated_reason="Replaced by [DEFAULT]/transport_url",
help='Default Kafka broker Host'),
cfg.PortOpt('kafka_default_port', default=9092,
deprecated_for_removal=True,
deprecated_reason="Replaced by [DEFAULT]/transport_url",
help='Default Kafka broker Port'),
cfg.IntOpt('kafka_max_fetch_bytes', default=1024 * 1024,
help='Max fetch bytes of Kafka consumer'),
cfg.IntOpt('kafka_consumer_timeout', default=1.0,
help='Default timeout(s) for Kafka consumers'),
cfg.IntOpt('pool_size', default=10,
help='Pool Size for Kafka Consumers'),
cfg.IntOpt('conn_pool_min_size', default=2,
help='The pool size limit for connections expiration policy'),
cfg.IntOpt('conn_pool_ttl', default=1200,
help='The time-to-live in sec of idle connections in the pool')
]
CONF = cfg.CONF
def pack_context_with_message(ctxt, msg):
"""Pack context into msg."""
if isinstance(ctxt, dict):
context_d = ctxt
else:
context_d = ctxt.to_dict()
return {'message': msg, 'context': context_d}
def target_to_topic(target, priority=None):
"""Convert target into topic string
:param target: Message destination target
:type target: oslo_messaging.Target
:param priority: Notification priority
:type priority: string
"""
if not priority:
return target.topic
return target.topic + '.' + priority
class Connection(object):
def __init__(self, conf, url, purpose):
driver_conf = conf.oslo_messaging_kafka
self.conf = conf
self.kafka_client = None
self.producer = None
self.consumer = None
self.fetch_messages_max_bytes = driver_conf.kafka_max_fetch_bytes
self.consumer_timeout = float(driver_conf.kafka_consumer_timeout)
self.url = url
self._parse_url()
# TODO(Support for manual/auto_commit functionality)
# When auto_commit is False, consumer can manually notify
# the completion of the subscription.
# Currently we don't support for non auto commit option
self.auto_commit = True
self._consume_loop_stopped = False
def _parse_url(self):
driver_conf = self.conf.oslo_messaging_kafka
self.hostaddrs = []
for host in self.url.hosts:
if host.hostname:
self.hostaddrs.append("%s:%s" % (
host.hostname,
host.port or driver_conf.kafka_default_port))
if not self.hostaddrs:
self.hostaddrs.append("%s:%s" % (driver_conf.kafka_default_host,
driver_conf.kafka_default_port))
def notify_send(self, topic, ctxt, msg, retry):
"""Send messages to Kafka broker.
:param topic: String of the topic
:param ctxt: context for the messages
:param msg: messages for publishing
:param retry: the number of retry
"""
message = pack_context_with_message(ctxt, msg)
self._ensure_connection()
self._send_and_retry(message, topic, retry)
def _send_and_retry(self, message, topic, retry):
current_retry = 0
if not isinstance(message, str):
message = jsonutils.dumps(message)
while message is not None:
try:
self._send(message, topic)
message = None
except Exception:
LOG.warning(_LW("Failed to publish a message of topic %s"),
topic)
current_retry += 1
if retry is not None and current_retry >= retry:
LOG.exception(_LE("Failed to retry to send data "
"with max retry times"))
message = None
def _send(self, message, topic):
self.producer.send_messages(topic, message)
def consume(self, timeout=None):
"""Receive up to 'max_fetch_messages' messages.
:param timeout: poll timeout in seconds
"""
duration = (self.consumer_timeout if timeout is None else timeout)
timer = driver_common.DecayingTimer(duration=duration)
timer.start()
def _raise_timeout():
LOG.debug('Timed out waiting for Kafka response')
raise driver_common.Timeout()
poll_timeout = (self.consumer_timeout if timeout is None
else min(timeout, self.consumer_timeout))
while True:
if self._consume_loop_stopped:
return
try:
next_timeout = poll_timeout * 1000.0
# TODO(use configure() method instead)
# Currently KafkaConsumer does not support for
# the case of updating only fetch_max_wait_ms parameter
self.consumer._config['fetch_max_wait_ms'] = next_timeout
messages = list(self.consumer.fetch_messages())
except Exception as e:
LOG.exception(_LE("Failed to consume messages: %s"), e)
messages = None
if not messages:
poll_timeout = timer.check_return(
_raise_timeout, maximum=self.consumer_timeout)
continue
return messages
def stop_consuming(self):
self._consume_loop_stopped = True
def reset(self):
"""Reset a connection so it can be used again."""
if self.consumer:
self.consumer.close()
self.consumer = None
def close(self):
if self.kafka_client:
self.kafka_client.close()
self.kafka_client = None
if self.producer:
self.producer.stop()
self.consumer = None
def commit(self):
"""Commit is used by subscribers belonging to the same group.
After subscribing messages, commit is called to prevent
the other subscribers which belong to the same group
from re-subscribing the same messages.
Currently self.auto_commit option is always True,
so we don't need to call this function.
"""
self.consumer.commit()
def _ensure_connection(self):
if self.kafka_client:
return
try:
self.kafka_client = kafka.KafkaClient(
self.hostaddrs)
self.producer = kafka.SimpleProducer(self.kafka_client)
except KafkaError as e:
LOG.exception(_LE("Kafka Connection is not available: %s"), e)
self.kafka_client = None
def declare_topic_consumer(self, topics, group=None):
self._ensure_connection()
for topic in topics:
self.kafka_client.ensure_topic_exists(topic)
self.consumer = kafka.KafkaConsumer(
*topics, group_id=group,
bootstrap_servers=self.hostaddrs,
fetch_message_max_bytes=self.fetch_messages_max_bytes)
self._consume_loop_stopped = False
class OsloKafkaMessage(base.RpcIncomingMessage):
def __init__(self, ctxt, message):
super(OsloKafkaMessage, self).__init__(ctxt, message)
def requeue(self):
LOG.warning(_LW("requeue is not supported"))
def reply(self, reply=None, failure=None):
LOG.warning(_LW("reply is not supported"))
class KafkaListener(base.PollStyleListener):
def __init__(self, conn):
super(KafkaListener, self).__init__()
self._stopped = threading.Event()
self.conn = conn
self.incoming_queue = []
@base.batch_poll_helper
def poll(self, timeout=None):
while not self._stopped.is_set():
if self.incoming_queue:
return self.incoming_queue.pop(0)
try:
messages = self.conn.consume(timeout=timeout)
for msg in messages:
message = msg.value
LOG.debug('poll got message : %s', message)
message = jsonutils.loads(message)
self.incoming_queue.append(OsloKafkaMessage(
ctxt=message['context'], message=message['message']))
except driver_common.Timeout:
return None
def stop(self):
self._stopped.set()
self.conn.stop_consuming()
def cleanup(self):
self.conn.close()
def commit(self):
# TODO(Support for manually/auto commit functionality)
# It's better to allow users to commit manually and support for
# self.auto_commit = False option. For now, this commit function
# is meaningless since user couldn't call this function and
# auto_commit option is always True.
self.conn.commit()
class KafkaDriver(base.BaseDriver):
"""Note: Current implementation of this driver is experimental.
We will have functional and/or integrated testing enabled for this driver.
"""
def __init__(self, conf, url, default_exchange=None,
allowed_remote_exmods=None):
opt_group = cfg.OptGroup(name='oslo_messaging_kafka',
title='Kafka driver options')
conf.register_group(opt_group)
conf.register_opts(kafka_opts, group=opt_group)
super(KafkaDriver, self).__init__(
conf, url, default_exchange, allowed_remote_exmods)
# the pool configuration properties
max_size = self.conf.oslo_messaging_kafka.pool_size
min_size = self.conf.oslo_messaging_kafka.conn_pool_min_size
ttl = self.conf.oslo_messaging_kafka.conn_pool_ttl
self.connection_pool = driver_pool.ConnectionPool(
self.conf, max_size, min_size, ttl,
self._url, Connection)
self.listeners = []
def cleanup(self):
for c in self.listeners:
c.close()
self.listeners = []
def send(self, target, ctxt, message, wait_for_reply=None, timeout=None,
retry=None):
raise NotImplementedError(
'The RPC implementation for Kafka is not implemented')
def send_notification(self, target, ctxt, message, version, retry=None):
"""Send notification to Kafka brokers
:param target: Message destination target
:type target: oslo_messaging.Target
:param ctxt: Message context
:type ctxt: dict
:param message: Message payload to pass
:type message: dict
:param version: Messaging API version (currently not used)
:type version: str
:param retry: an optional default kafka consumer retries configuration
None means to retry forever
0 means no retry
N means N retries
:type retry: int
"""
with self._get_connection(purpose=PURPOSE_SEND) as conn:
conn.notify_send(target_to_topic(target), ctxt, message, retry)
def listen(self, target, batch_size, batch_timeout):
raise NotImplementedError(
'The RPC implementation for Kafka is not implemented')
def listen_for_notifications(self, targets_and_priorities, pool,
batch_size, batch_timeout):
"""Listen to a specified list of targets on Kafka brokers
:param targets_and_priorities: List of pairs (target, priority)
priority is not used for kafka driver
target.exchange_target.topic is used as
a kafka topic
:type targets_and_priorities: list
:param pool: consumer group of Kafka consumers
:type pool: string
"""
conn = self._get_connection(purpose=PURPOSE_LISTEN)
topics = set()
for target, priority in targets_and_priorities:
topics.add(target_to_topic(target, priority))
conn.declare_topic_consumer(topics, pool)
listener = KafkaListener(conn)
return base.PollStyleListenerAdapter(listener, batch_size,
batch_timeout)
def _get_connection(self, purpose):
return driver_common.ConnectionContext(self.connection_pool, purpose)