diff options
Diffstat (limited to 'src/rabbit_backing_queue.erl')
| -rw-r--r-- | src/rabbit_backing_queue.erl | 97 |
1 files changed, 70 insertions, 27 deletions
diff --git a/src/rabbit_backing_queue.erl b/src/rabbit_backing_queue.erl index 6a21e10f..77278416 100644 --- a/src/rabbit_backing_queue.erl +++ b/src/rabbit_backing_queue.erl @@ -33,26 +33,66 @@ behaviour_info(callbacks) -> {stop, 0}, %% Initialise the backing queue and its state. + %% + %% Takes + %% 1. the amqqueue record + %% 2. a boolean indicating whether the queue is an existing queue + %% that should be recovered + %% 3. an asynchronous callback which accepts a function of type + %% backing-queue-state to backing-queue-state. This callback + %% function can be safely invoked from any process, which + %% makes it useful for passing messages back into the backing + %% queue, especially as the backing queue does not have + %% control of its own mailbox. {init, 3}, %% Called on queue shutdown when queue isn't being deleted. - {terminate, 1}, + {terminate, 2}, %% Called when the queue is terminating and needs to delete all %% its content. - {delete_and_terminate, 1}, + {delete_and_terminate, 2}, %% Remove all messages in the queue, but not messages which have %% been fetched and are pending acks. {purge, 1}, %% Publish a message. - {publish, 3}, + {publish, 4}, %% Called for messages which have already been passed straight %% out to a client. The queue will be empty for these calls %% (i.e. saves the round trip through the backing queue). - {publish_delivered, 4}, + {publish_delivered, 5}, + + %% Return ids of messages which have been confirmed since + %% the last invocation of this function (or initialisation). + %% + %% Message ids should only appear in the result of + %% drain_confirmed under the following circumstances: + %% + %% 1. The message appears in a call to publish_delivered/4 and + %% the first argument (ack_required) is false; or + %% 2. The message is fetched from the queue with fetch/2 and the + %% first argument (ack_required) is false; or + %% 3. The message is acked (ack/2 is called for the message); or + %% 4. The message is fully fsync'd to disk in such a way that the + %% recovery of the message is guaranteed in the event of a + %% crash of this rabbit node (excluding hardware failure). + %% + %% In addition to the above conditions, a message id may only + %% appear in the result of drain_confirmed if + %% #message_properties.needs_confirming = true when the msg was + %% published (through whichever means) to the backing queue. + %% + %% It is legal for the same message id to appear in the results + %% of multiple calls to drain_confirmed, which means that the + %% backing queue is not required to keep track of which messages + %% it has already confirmed. The confirm will be issued to the + %% publisher the first time the message id appears in the result + %% of drain_confirmed. All subsequent appearances of that message + %% id will be ignored. + {drain_confirmed, 1}, %% Drop messages from the head of the queue while the supplied %% predicate returns true. @@ -62,24 +102,9 @@ behaviour_info(callbacks) -> {fetch, 2}, %% Acktags supplied are for messages which can now be forgotten - %% about. Must return 1 guid per Ack, in the same order as Acks. + %% about. Must return 1 msg_id per Ack, in the same order as Acks. {ack, 2}, - %% A publish, but in the context of a transaction. - {tx_publish, 4}, - - %% Acks, but in the context of a transaction. - {tx_ack, 3}, - - %% Undo anything which has been done in the context of the - %% specified transaction. - {tx_rollback, 2}, - - %% Commit a transaction. The Fun passed in must be called once - %% the messages have really been commited. This CPS permits the - %% possibility of commit coalescing. - {tx_commit, 4}, - %% Reinsert messages into the queue which have already been %% delivered and were pending acknowledgement. {requeue, 3}, @@ -107,22 +132,40 @@ behaviour_info(callbacks) -> %% queue. {ram_duration, 1}, - %% Should 'idle_timeout' be called as soon as the queue process + %% Should 'timeout' be called as soon as the queue process %% can manage (either on an empty mailbox, or when a timer %% fires)? - {needs_idle_timeout, 1}, + {needs_timeout, 1}, - %% Called (eventually) after needs_idle_timeout returns - %% 'true'. Note this may be called more than once for each 'true' - %% returned from needs_idle_timeout. - {idle_timeout, 1}, + %% Called (eventually) after needs_timeout returns 'idle' or + %% 'timed'. Note this may be called more than once for each + %% 'idle' or 'timed' returned from needs_timeout. + {timeout, 1}, %% Called immediately before the queue hibernates. {handle_pre_hibernate, 1}, %% Exists for debugging purposes, to be able to expose state via %% rabbitmqctl list_queues backing_queue_status - {status, 1} + {status, 1}, + + %% Passed a function to be invoked with the relevant backing + %% queue's state. Useful for when the backing queue or other + %% components need to pass functions into the backing queue. + {invoke, 3}, + + %% Called prior to a publish or publish_delivered call. Allows + %% the BQ to signal that it's already seen this message (and in + %% what capacity - i.e. was it published previously or discarded + %% previously) and thus the message should be dropped. + {is_duplicate, 2}, + + %% Called to inform the BQ about messages which have reached the + %% queue, but are not going to be further passed to BQ for some + %% reason. Note that this is may be invoked for messages for + %% which BQ:is_duplicate/2 has already returned {'published' | + %% 'discarded', BQS}. + {discard, 3} ]; behaviour_info(_Other) -> undefined. |