This document describes the current stable version of Kombu (5.0). For development docs, go here.

Source code for kombu.simple

"""Simple messaging interface."""

import socket

from collections import deque
from queue import Empty
from time import monotonic

from . import entity
from . import messaging
from .connection import maybe_channel

__all__ = ('SimpleQueue', 'SimpleBuffer')


class SimpleBase:
    Empty = Empty
    _consuming = False

    def __enter__(self):
        return self

    def __exit__(self, *exc_info):
        self.close()

    def __init__(self, channel, producer, consumer, no_ack=False):
        self.channel = maybe_channel(channel)
        self.producer = producer
        self.consumer = consumer
        self.no_ack = no_ack
        self.queue = self.consumer.queues[0]
        self.buffer = deque()
        self.consumer.register_callback(self._receive)

    def get(self, block=True, timeout=None):
        if not block:
            return self.get_nowait()

        self._consume()

        time_start = monotonic()
        remaining = timeout
        while True:
            if self.buffer:
                return self.buffer.popleft()

            if remaining is not None and remaining <= 0.0:
                raise self.Empty()

            try:
                # The `drain_events` method will
                # block on the socket connection to rabbitmq. if any
                # application-level messages are received, it will put them
                # into `self.buffer`.
                # * The method will block for UP TO `timeout` milliseconds.
                # * The method may raise a socket.timeout exception; or...
                # * The method may return without having put anything on
                #    `self.buffer`.  This is because internal heartbeat
                #    messages are sent over the same socket; also POSIX makes
                #    no guarantees against socket calls returning early.
                self.channel.connection.client.drain_events(timeout=remaining)
            except socket.timeout:
                raise self.Empty()

            if remaining is not None:
                elapsed = monotonic() - time_start
                remaining = timeout - elapsed

    def get_nowait(self):
        m = self.queue.get(no_ack=self.no_ack)
        if not m:
            raise self.Empty()
        return m

    def put(self, message, serializer=None, headers=None, compression=None,
            routing_key=None, **kwargs):
        self.producer.publish(message,
                              serializer=serializer,
                              routing_key=routing_key,
                              headers=headers,
                              compression=compression,
                              **kwargs)

    def clear(self):
        return self.consumer.purge()

    def qsize(self):
        _, size, _ = self.queue.queue_declare(passive=True)
        return size

    def close(self):
        self.consumer.cancel()

    def _receive(self, message_data, message):
        self.buffer.append(message)

    def _consume(self):
        if not self._consuming:
            self.consumer.consume(no_ack=self.no_ack)
            self._consuming = True

    def __len__(self):
        """`len(self) -> self.qsize()`."""
        return self.qsize()

    def __bool__(self):
        return True
    __nonzero__ = __bool__


[docs]class SimpleQueue(SimpleBase): """Simple API for persistent queues.""" no_ack = False queue_opts = {} queue_args = {} exchange_opts = {'type': 'direct'} def __init__(self, channel, name, no_ack=None, queue_opts=None, queue_args=None, exchange_opts=None, serializer=None, compression=None, **kwargs): queue = name queue_opts = dict(self.queue_opts, **queue_opts or {}) queue_args = dict(self.queue_args, **queue_args or {}) exchange_opts = dict(self.exchange_opts, **exchange_opts or {}) if no_ack is None: no_ack = self.no_ack if not isinstance(queue, entity.Queue): exchange = entity.Exchange(name, **exchange_opts) queue = entity.Queue(name, exchange, name, queue_arguments=queue_args, **queue_opts) routing_key = name else: exchange = queue.exchange routing_key = queue.routing_key consumer = messaging.Consumer(channel, queue) producer = messaging.Producer(channel, exchange, serializer=serializer, routing_key=routing_key, compression=compression) super().__init__(channel, producer, consumer, no_ack, **kwargs)
[docs]class SimpleBuffer(SimpleQueue): """Simple API for ephemeral queues.""" no_ack = True queue_opts = {'durable': False, 'auto_delete': True} exchange_opts = {'durable': False, 'delivery_mode': 'transient', 'auto_delete': True}