This document describes the current stable version of Kombu (5.3). For development docs, go here.
Source code for kombu.pidbox
"""Generic process mailbox."""
from __future__ import annotations
import socket
import warnings
from collections import defaultdict, deque
from contextlib import contextmanager
from copy import copy
from itertools import count
from time import time
from . import Consumer, Exchange, Producer, Queue
from .clocks import LamportClock
from .common import maybe_declare, oid_from
from .exceptions import InconsistencyError
from .log import get_logger
from .matcher import match
from .utils.functional import maybe_evaluate, reprcall
from .utils.objects import cached_property
from .utils.uuid import uuid
REPLY_QUEUE_EXPIRES = 10
W_PIDBOX_IN_USE = """\
A node named {node.hostname} is already using this process mailbox!
Maybe you forgot to shutdown the other node or did not do so properly?
Or if you meant to start multiple nodes on the same host please make sure
you give each node a unique node name!
"""
__all__ = ('Node', 'Mailbox')
logger = get_logger(__name__)
debug, error = logger.debug, logger.error
[docs]
class Node:
"""Mailbox node."""
#: hostname of the node.
hostname = None
#: the :class:`Mailbox` this is a node for.
mailbox = None
#: map of method name/handlers.
handlers = None
#: current context (passed on to handlers)
state = None
#: current channel.
channel = None
def __init__(self, hostname, state=None, channel=None,
handlers=None, mailbox=None):
self.channel = channel
self.mailbox = mailbox
self.hostname = hostname
self.state = state
self.adjust_clock = self.mailbox.clock.adjust
if handlers is None:
handlers = {}
self.handlers = handlers
[docs]
def Consumer(self, channel=None, no_ack=True, accept=None, **options):
queue = self.mailbox.get_queue(self.hostname)
def verify_exclusive(name, messages, consumers):
if consumers:
warnings.warn(W_PIDBOX_IN_USE.format(node=self))
queue.on_declared = verify_exclusive
return Consumer(
channel or self.channel, [queue], no_ack=no_ack,
accept=self.mailbox.accept if accept is None else accept,
**options
)
def on_decode_error(self, message, exc):
error('Cannot decode message: %r', exc, exc_info=1)
[docs]
def listen(self, channel=None, callback=None):
consumer = self.Consumer(channel=channel,
callbacks=[callback or self.handle_message],
on_decode_error=self.on_decode_error)
consumer.consume()
return consumer
[docs]
def dispatch(self, method, arguments=None,
reply_to=None, ticket=None, **kwargs):
arguments = arguments or {}
debug('pidbox received method %s [reply_to:%s ticket:%s]',
reprcall(method, (), kwargs=arguments), reply_to, ticket)
handle = reply_to and self.handle_call or self.handle_cast
try:
reply = handle(method, arguments)
except SystemExit:
raise
except Exception as exc:
error('pidbox command error: %r', exc, exc_info=1)
reply = {'error': repr(exc)}
if reply_to:
self.reply({self.hostname: reply},
exchange=reply_to['exchange'],
routing_key=reply_to['routing_key'],
ticket=ticket)
return reply
[docs]
def handle(self, method, arguments=None):
arguments = {} if not arguments else arguments
return self.handlers[method](self.state, **arguments)
[docs]
def handle_message(self, body, message=None):
destination = body.get('destination')
pattern = body.get('pattern')
matcher = body.get('matcher')
if message:
self.adjust_clock(message.headers.get('clock') or 0)
hostname = self.hostname
run_dispatch = False
if destination:
if hostname in destination:
run_dispatch = True
elif pattern and matcher:
if match(hostname, pattern, matcher):
run_dispatch = True
else:
run_dispatch = True
if run_dispatch:
return self.dispatch(**body)
dispatch_from_message = handle_message
[docs]
def reply(self, data, exchange, routing_key, ticket, **kwargs):
self.mailbox._publish_reply(data, exchange, routing_key, ticket,
channel=self.channel,
serializer=self.mailbox.serializer)
[docs]
class Mailbox:
"""Process Mailbox."""
node_cls = Node
exchange_fmt = '%s.pidbox'
reply_exchange_fmt = 'reply.%s.pidbox'
#: Name of application.
namespace = None
#: Connection (if bound).
connection = None
#: Exchange type (usually direct, or fanout for broadcast).
type = 'direct'
#: mailbox exchange (init by constructor).
exchange = None
#: exchange to send replies to.
reply_exchange = None
#: Only accepts json messages by default.
accept = ['json']
#: Message serializer
serializer = None
def __init__(self, namespace,
type='direct', connection=None, clock=None,
accept=None, serializer=None, producer_pool=None,
queue_ttl=None, queue_expires=None,
reply_queue_ttl=None, reply_queue_expires=10.0):
self.namespace = namespace
self.connection = connection
self.type = type
self.clock = LamportClock() if clock is None else clock
self.exchange = self._get_exchange(self.namespace, self.type)
self.reply_exchange = self._get_reply_exchange(self.namespace)
self.unclaimed = defaultdict(deque)
self.accept = self.accept if accept is None else accept
self.serializer = self.serializer if serializer is None else serializer
self.queue_ttl = queue_ttl
self.queue_expires = queue_expires
self.reply_queue_ttl = reply_queue_ttl
self.reply_queue_expires = reply_queue_expires
self._producer_pool = producer_pool
def __call__(self, connection):
bound = copy(self)
bound.connection = connection
return bound
[docs]
def Node(self, hostname=None, state=None, channel=None, handlers=None):
hostname = hostname or socket.gethostname()
return self.node_cls(hostname, state, channel, handlers, mailbox=self)
[docs]
def call(self, destination, command, kwargs=None,
timeout=None, callback=None, channel=None):
kwargs = {} if not kwargs else kwargs
return self._broadcast(command, kwargs, destination,
reply=True, timeout=timeout,
callback=callback,
channel=channel)
[docs]
def cast(self, destination, command, kwargs=None):
kwargs = {} if not kwargs else kwargs
return self._broadcast(command, kwargs, destination, reply=False)
[docs]
def abcast(self, command, kwargs=None):
kwargs = {} if not kwargs else kwargs
return self._broadcast(command, kwargs, reply=False)
[docs]
def multi_call(self, command, kwargs=None, timeout=1,
limit=None, callback=None, channel=None):
kwargs = {} if not kwargs else kwargs
return self._broadcast(command, kwargs, reply=True,
timeout=timeout, limit=limit,
callback=callback,
channel=channel)
[docs]
def get_reply_queue(self):
oid = self.oid
return Queue(
f'{oid}.{self.reply_exchange.name}',
exchange=self.reply_exchange,
routing_key=oid,
durable=False,
auto_delete=True,
expires=self.reply_queue_expires,
message_ttl=self.reply_queue_ttl,
)
@cached_property
def reply_queue(self):
return self.get_reply_queue()
[docs]
def get_queue(self, hostname):
return Queue(
f'{hostname}.{self.namespace}.pidbox',
exchange=self.exchange,
durable=False,
auto_delete=True,
expires=self.queue_expires,
message_ttl=self.queue_ttl,
)
@contextmanager
def producer_or_acquire(self, producer=None, channel=None):
if producer:
yield producer
elif self.producer_pool:
with self.producer_pool.acquire() as producer:
yield producer
else:
yield Producer(channel, auto_declare=False)
def _publish_reply(self, reply, exchange, routing_key, ticket,
channel=None, producer=None, **opts):
chan = channel or self.connection.default_channel
exchange = Exchange(exchange, exchange_type='direct',
delivery_mode='transient',
durable=False)
with self.producer_or_acquire(producer, chan) as producer:
try:
producer.publish(
reply, exchange=exchange, routing_key=routing_key,
declare=[exchange], headers={
'ticket': ticket, 'clock': self.clock.forward(),
}, retry=True,
**opts
)
except InconsistencyError:
# queue probably deleted and no one is expecting a reply.
pass
def _publish(self, type, arguments, destination=None,
reply_ticket=None, channel=None, timeout=None,
serializer=None, producer=None, pattern=None, matcher=None):
message = {'method': type,
'arguments': arguments,
'destination': destination,
'pattern': pattern,
'matcher': matcher}
chan = channel or self.connection.default_channel
exchange = self.exchange
if reply_ticket:
maybe_declare(self.reply_queue(chan))
message.update(ticket=reply_ticket,
reply_to={'exchange': self.reply_exchange.name,
'routing_key': self.oid})
serializer = serializer or self.serializer
with self.producer_or_acquire(producer, chan) as producer:
producer.publish(
message, exchange=exchange.name, declare=[exchange],
headers={'clock': self.clock.forward(),
'expires': time() + timeout if timeout else 0},
serializer=serializer, retry=True,
)
def _broadcast(self, command, arguments=None, destination=None,
reply=False, timeout=1, limit=None,
callback=None, channel=None, serializer=None,
pattern=None, matcher=None):
if destination is not None and \
not isinstance(destination, (list, tuple)):
raise ValueError(
'destination must be a list/tuple not {}'.format(
type(destination)))
if (pattern is not None and not isinstance(pattern, str) and
matcher is not None and not isinstance(matcher, str)):
raise ValueError(
'pattern and matcher must be '
'strings not {}, {}'.format(type(pattern), type(matcher))
)
arguments = arguments or {}
reply_ticket = reply and uuid() or None
chan = channel or self.connection.default_channel
# Set reply limit to number of destinations (if specified)
if limit is None and destination:
limit = destination and len(destination) or None
serializer = serializer or self.serializer
self._publish(command, arguments, destination=destination,
reply_ticket=reply_ticket,
channel=chan,
timeout=timeout,
serializer=serializer,
pattern=pattern,
matcher=matcher)
if reply_ticket:
return self._collect(reply_ticket, limit=limit,
timeout=timeout,
callback=callback,
channel=chan)
def _collect(self, ticket,
limit=None, timeout=1, callback=None,
channel=None, accept=None):
if accept is None:
accept = self.accept
chan = channel or self.connection.default_channel
queue = self.reply_queue
consumer = Consumer(chan, [queue], accept=accept, no_ack=True)
responses = []
unclaimed = self.unclaimed
adjust_clock = self.clock.adjust
try:
return unclaimed.pop(ticket)
except KeyError:
pass
def on_message(body, message):
# ticket header added in kombu 2.5
header = message.headers.get
adjust_clock(header('clock') or 0)
expires = header('expires')
if expires and time() > expires:
return
this_id = header('ticket', ticket)
if this_id == ticket:
if callback:
callback(body)
responses.append(body)
else:
unclaimed[this_id].append(body)
consumer.register_callback(on_message)
try:
with consumer:
for i in limit and range(limit) or count():
try:
self.connection.drain_events(timeout=timeout)
except socket.timeout:
break
return responses
finally:
chan.after_reply_message_received(queue.name)
def _get_exchange(self, namespace, type):
return Exchange(self.exchange_fmt % namespace,
type=type,
durable=False,
delivery_mode='transient')
def _get_reply_exchange(self, namespace):
return Exchange(self.reply_exchange_fmt % namespace,
type='direct',
durable=False,
delivery_mode='transient')
@property
def oid(self):
return oid_from(self)
@cached_property
def producer_pool(self):
return maybe_evaluate(self._producer_pool)
