org.apache.beam.sdk.fn

Class CancellableQueue<T>

java.lang.Object

org.apache.beam.sdk.fn.CancellableQueue<T>

@ThreadSafe
public class CancellableQueue<T>
extends java.lang.Object

A simplified ThreadSafe blocking queue that can be cancelled freeing any blocked Threads and preventing future Threads from blocking.

The queue is able to be reset and re-used.

Constructor Summary

Constructors

Constructor and Description
CancellableQueue(int capacity) Creates a ThreadSafe blocking queue with a maximum capacity.

Method Summary

Modifier and Type	Method and Description
void	cancel(java.lang.Exception exception) Causes any pending and future put(T) and take() invocations to throw an exception.
void	put(T t) Adds an element to this queue.
void	reset() Enables the queue to be re-used after it has been cancelled.
T	take() Takes an element from this queue.

Methods inherited from class java.lang.Object

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

Constructor Detail

CancellableQueue

public CancellableQueue(int capacity)

Creates a ThreadSafe blocking queue with a maximum capacity.

Method Detail

put

public void put(T t)
         throws java.lang.Exception,
                java.lang.InterruptedException

Adds an element to this queue. Will block until the queue is not full or is cancelled.

Throws:

java.lang.InterruptedException - if this thread was interrupted waiting to put the element. The caller must invoke cancel(java.lang.Exception) if the interrupt is unrecoverable.

java.lang.Exception - if the queue is cancelled.

take

public T take()
       throws java.lang.Exception,
              java.lang.InterruptedException

Takes an element from this queue. Will block until the queue is not full or is cancelled.

Throws:

java.lang.InterruptedException - if this thread was interrupted waiting for an element. The caller must invoke cancel(java.lang.Exception) if the interrupt is unrecoverable.

java.lang.Exception - if the queue is cancelled.

cancel

public void cancel(java.lang.Exception exception)

Causes any pending and future put(T) and take() invocations to throw an exception.

The first call to cancel(java.lang.Exception) sets the exception that will be thrown. Resetting the queue clears the exception.

reset

public void reset()

Enables the queue to be re-used after it has been cancelled.