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# copyright: (c) 2010 - 2013 by Mahendra M.
# license: BSD, see LICENSE for more details.
"""Zookeeper transport module for kombu.
Zookeeper based transport. This transport uses the built-in kazoo Zookeeper
based queue implementation.
**References**
- https://zookeeper.apache.org/doc/current/recipes.html#sc_recipes_Queues
- https://kazoo.readthedocs.io/en/latest/api/recipe/queue.html
**Limitations**
This queue does not offer reliable consumption. An entry is removed from
the queue prior to being processed. So if an error occurs, the consumer
has to re-queue the item or it will be lost.
Features
========
* Type: Virtual
* Supports Direct: Yes
* Supports Topic: Yes
* Supports Fanout: No
* Supports Priority: Yes
* Supports TTL: No
Connection String
=================
Connects to a zookeeper node as:
.. code-block::
zookeeper://SERVER:PORT/VHOST
The <vhost> becomes the base for all the other znodes. So we can use
it like a vhost.
Transport Options
=================
"""
import os
import socket
from queue import Empty
from kombu.utils.encoding import bytes_to_str, ensure_bytes
from kombu.utils.json import dumps, loads
from . import virtual
try:
import kazoo
from kazoo.client import KazooClient
from kazoo.recipe.queue import Queue
KZ_CONNECTION_ERRORS = (
kazoo.exceptions.SystemErrorException,
kazoo.exceptions.ConnectionLossException,
kazoo.exceptions.MarshallingErrorException,
kazoo.exceptions.UnimplementedException,
kazoo.exceptions.OperationTimeoutException,
kazoo.exceptions.NoAuthException,
kazoo.exceptions.InvalidACLException,
kazoo.exceptions.AuthFailedException,
kazoo.exceptions.SessionExpiredException,
)
KZ_CHANNEL_ERRORS = (
kazoo.exceptions.RuntimeInconsistencyException,
kazoo.exceptions.DataInconsistencyException,
kazoo.exceptions.BadArgumentsException,
kazoo.exceptions.MarshallingErrorException,
kazoo.exceptions.UnimplementedException,
kazoo.exceptions.OperationTimeoutException,
kazoo.exceptions.ApiErrorException,
kazoo.exceptions.NoNodeException,
kazoo.exceptions.NoAuthException,
kazoo.exceptions.NodeExistsException,
kazoo.exceptions.NoChildrenForEphemeralsException,
kazoo.exceptions.NotEmptyException,
kazoo.exceptions.SessionExpiredException,
kazoo.exceptions.InvalidCallbackException,
socket.error,
)
except ImportError:
kazoo = None # noqa
KZ_CONNECTION_ERRORS = KZ_CHANNEL_ERRORS = () # noqa
DEFAULT_PORT = 2181
__author__ = 'Mahendra M <mahendra.m@gmail.com>'
class Channel(virtual.Channel):
"""Zookeeper Channel."""
_client = None
_queues = {}
def __init__(self, connection, **kwargs):
super().__init__(connection, **kwargs)
vhost = self.connection.client.virtual_host
self._vhost = '/{}'.format(vhost.strip('/'))
def _get_path(self, queue_name):
return os.path.join(self._vhost, queue_name)
def _get_queue(self, queue_name):
queue = self._queues.get(queue_name, None)
if queue is None:
queue = Queue(self.client, self._get_path(queue_name))
self._queues[queue_name] = queue
# Ensure that the queue is created
len(queue)
return queue
def _put(self, queue, message, **kwargs):
return self._get_queue(queue).put(
ensure_bytes(dumps(message)),
priority=self._get_message_priority(message, reverse=True),
)
def _get(self, queue):
queue = self._get_queue(queue)
msg = queue.get()
if msg is None:
raise Empty()
return loads(bytes_to_str(msg))
def _purge(self, queue):
count = 0
queue = self._get_queue(queue)
while True:
msg = queue.get()
if msg is None:
break
count += 1
return count
def _delete(self, queue, *args, **kwargs):
if self._has_queue(queue):
self._purge(queue)
self.client.delete(self._get_path(queue))
def _size(self, queue):
queue = self._get_queue(queue)
return len(queue)
def _new_queue(self, queue, **kwargs):
if not self._has_queue(queue):
queue = self._get_queue(queue)
def _has_queue(self, queue):
return self.client.exists(self._get_path(queue)) is not None
def _open(self):
conninfo = self.connection.client
hosts = []
if conninfo.alt:
for host_port in conninfo.alt:
if host_port.startswith('zookeeper://'):
host_port = host_port[len('zookeeper://'):]
if not host_port:
continue
try:
host, port = host_port.split(':', 1)
host_port = (host, int(port))
except ValueError:
if host_port == conninfo.hostname:
host_port = (host_port, conninfo.port or DEFAULT_PORT)
else:
host_port = (host_port, DEFAULT_PORT)
hosts.append(host_port)
host_port = (conninfo.hostname, conninfo.port or DEFAULT_PORT)
if host_port not in hosts:
hosts.insert(0, host_port)
conn_str = ','.join([f'{h}:{p}' for h, p in hosts])
conn = KazooClient(conn_str)
conn.start()
return conn
@property
def client(self):
if self._client is None:
self._client = self._open()
return self._client
class Transport(virtual.Transport):
"""Zookeeper Transport."""
Channel = Channel
polling_interval = 1
default_port = DEFAULT_PORT
connection_errors = (
virtual.Transport.connection_errors + KZ_CONNECTION_ERRORS
)
channel_errors = (
virtual.Transport.channel_errors + KZ_CHANNEL_ERRORS
)
driver_type = 'zookeeper'
driver_name = 'kazoo'
def __init__(self, *args, **kwargs):
if kazoo is None:
raise ImportError('The kazoo library is not installed')
super().__init__(*args, **kwargs)
def driver_version(self):
return kazoo.__version__
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