com.amazonaws.services.sqs.buffered

Class ReceiveQueueBuffer

java.lang.Object

com.amazonaws.services.sqs.buffered.ReceiveQueueBuffer

public class ReceiveQueueBuffer
extends Object

The ReceiveQueueBuffer class is responsible for dequeueing of messages from a single SQS queue. It uses the provided executor to pre-fetch messages from the server and keeps them in a buffer which it uses to satisfy incoming requests. The number of requests pre-fetched and kept in the buffer, as well as the maximum number of threads used to retrieve the messages are configurable.

Synchronization strategy: - Threads must hold the TaskSpawnSyncPoint object monitor to spawn a new task or modify the number of inflight tasks - Threads must hold the monitor of the "futures" list to modify the list - Threads must hold the monitor of the "finishedTasks" list to modify the list - If you need to lock both futures and finishedTasks, lock futures first and finishedTasks second

Method Summary

Modifier and Type	Method and Description
void	clear() Clears and nacks any pre-fetched messages in this buffer.
com.amazonaws.services.sqs.buffered.QueueBufferFuture<ReceiveMessageRequest,ReceiveMessageResult>	receiveMessageAsync(ReceiveMessageRequest rq, com.amazonaws.services.sqs.buffered.QueueBufferCallback<ReceiveMessageRequest,ReceiveMessageResult> callback) Submits the request for retrieval of messages from the queue and returns a future that will be signalled when the request is satisfied.
void	shutdown() Prevents spawning of new retrieval batches and waits for all in-flight retrieval batches to finish

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

shutdown

public void shutdown()

Prevents spawning of new retrieval batches and waits for all in-flight retrieval batches to finish

receiveMessageAsync

public com.amazonaws.services.sqs.buffered.QueueBufferFuture<ReceiveMessageRequest,ReceiveMessageResult> receiveMessageAsync(ReceiveMessageRequest rq,
                                                                                                                             com.amazonaws.services.sqs.buffered.QueueBufferCallback<ReceiveMessageRequest,ReceiveMessageResult> callback)

Submits the request for retrieval of messages from the queue and returns a future that will be signalled when the request is satisfied. The future may already be signalled by the time it is returned.

Returns:

never null

clear

public void clear()

Clears and nacks any pre-fetched messages in this buffer.