This document describes an older version of Celery (2.2). For the latest stable version please go here.
Publishes results by sending messages.
Too much state history to fast-forward.
Message consumer.
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End all active queue consumers.
This does not affect already delivered messages, but it does mean the server will not send any more messages for this consumer.
Cancel consumer by queue name.
End all active queue consumers.
This does not affect already delivered messages, but it does mean the server will not send any more messages for this consumer.
Register consumer on server.
Declare queues, exchanges and bindings.
This is done automatically at instantiation if auto_declare is set.
Enable/disable flow from peer.
This is a simple flow-control mechanism that a peer can use to avoid overflowing its queues or otherwise finding itself receiving more messages than it can process.
The peer that receives a request to stop sending content will finish sending the current content (if any), and then wait until flow is reactivated.
Purge messages from all queues.
Warning
This will delete all ready messages, there is no undo operation available.
Specify quality of service.
The client can request that messages should be sent in advance so that when the client finishes processing a message, the following message is already held locally, rather than needing to be sent down the channel. Prefetching gives a performance improvement.
The prefetch window is Ignored if the no_ack option is set.
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Method called when a message is received.
This dispatches to the registered callbacks.
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Redeliver unacknowledged messages.
Asks the broker to redeliver all unacknowledged messages on the specified channel.
Parameters: | requeue – By default the messages will be redelivered to the original recipient. With requeue set to true, the server will attempt to requeue the message, potentially then delivering it to an alternative subscriber. |
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Register a new callback to be called when a message is received.
The signature of the callback needs to accept two arguments: (body, message), which is the decoded message body and the Message instance (a subclass of Message.
Revive consumer after connection loss.
An Exchange declaration.
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Name of the exchange. Default is no name (the default exchange).
AMQP defines four default exchange types (routing algorithms) that covers most of the common messaging use cases. An AMQP broker can also define additional exchange types, so see your broker manual for more information about available exchange types.
direct (default)
Direct match between the routing key in the message, and the routing criteria used when a queue is bound to this exchange.
topic
Wildcard match between the routing key and the routing pattern specified in the exchange/queue binding. The routing key is treated as zero or more words delimited by ”.” and supports special wildcard characters. “*” matches a single word and “#” matches zero or more words.
fanout
Queues are bound to this exchange with no arguments. Hence any message sent to this exchange will be forwarded to all queues bound to this exchange.
headers
Queues are bound to this exchange with a table of arguments containing headers and values (optional). A special argument named “x-match” determines the matching algorithm, where “all” implies an AND (all pairs must match) and “any” implies OR (at least one pair must match).
arguments is used to specify the arguments.
This description of AMQP exchange types was shamelessly stolen from the blog post AMQP in 10 minutes: Part 4 by Rajith Attapattu. This article is recommended reading.
The channel the exchange is bound to (if bound).
Durable exchanges remain active when a server restarts. Non-durable exchanges (transient exchanges) are purged when a server restarts. Default is True.
If set, the exchange is deleted when all queues have finished using it. Default is False.
The default delivery mode used for messages. The value is an integer, or alias string.
1 or “transient”
The message is transient. Which means it is stored in memory only, and is lost if the server dies or restarts.
- 2 or “persistent” (default)
The message is persistent. Which means the message is stored both in-memory, and on disk, and therefore preserved if the server dies or restarts.
The default value is 2 (persistent).
Additional arguments to specify when the exchange is declared.
Create message instance to be sent with publish().
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Declare the exchange.
Creates the exchange on the broker.
Parameters: | nowait – If set the server will not respond, and a response will not be waited for. Default is False. |
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Delete the exchange declaration on server.
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Publish message.
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Message Producer.
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Declare the exchange.
This is done automatically at instantiation if auto_declare is set to True.
Publish message to the specified exchange.
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Revive the producer after connection loss.
A Queue declaration.
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Name of the queue. Default is no name (default queue destination).
The Exchange the queue binds to.
The routing key (if any), also called binding key.
The interpretation of the routing key depends on the Exchange.type.
direct exchange
Matches if the routing key property of the message and the routing_key attribute are identical.
fanout exchange
Always matches, even if the binding does not have a key.
topic exchange
Matches the routing key property of the message by a primitive pattern matching scheme. The message routing key then consists of words separated by dots (”.”, like domain names), and two special characters are available; star (“*”) and hash (“#”). The star matches any word, and the hash matches zero or more words. For example “*.stock.#” matches the routing keys “usd.stock” and “eur.stock.db” but not “stock.nasdaq”.
The channel the Queue is bound to (if bound).
Durable queues remain active when a server restarts. Non-durable queues (transient queues) are purged if/when a server restarts. Note that durable queues do not necessarily hold persistent messages, although it does not make sense to send persistent messages to a transient queue.
Default is True.
Exclusive queues may only be consumed from by the current connection. Setting the ‘exclusive’ flag always implies ‘auto-delete’.
Default is False.
If set, the queue is deleted when all consumers have finished using it. Last consumer can be cancelled either explicitly or because its channel is closed. If there was no consumer ever on the queue, it won’t be deleted.
Additional arguments used when declaring the queue.
Additional arguments used when binding the queue.
Unused in Kombu, but application can take advantage of this. For example to give alternate names to queues with automatically generated queue names.
Cancel a consumer by consumer tag.
Start a queue consumer.
Consumers last as long as the channel they were created on, or until the client cancels them.
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Declares the queue, the exchange and binds the queue to the exchange.
Delete the queue.
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Poll the server for a new message.
Returns the message instance if a message was available, or None otherwise.
Parameters: | no_ack – If set messages received does not have to be acknowledged. |
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This method provides direct access to the messages in a queue using a synchronous dialogue, designed for specific types of applications where synchronous functionality is more important than performance.
Remove all messages from the queue.
Create the queue binding on the server.
Parameters: | nowait – Do not wait for a reply. |
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Declare queue on the server.
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Delete the binding on the server.
Reload taskset result, even if it has been previously fetched.
Get the result of a taskset.
Store the result and status of a task.
Too much state history to fast-forward.