org.opennms.netmgt.scheduler
Class LegacyScheduler.PeekableFifoQueue<T>

java.lang.Object
  org.opennms.core.queue.FifoQueueImpl<T>
      org.opennms.netmgt.scheduler.LegacyScheduler.PeekableFifoQueue<T>

All Implemented Interfaces:

FifoQueue<T>

Enclosing class:

LegacyScheduler

public static final class LegacyScheduler.PeekableFifoQueue<T>
extends FifoQueueImpl<T>

This queue extends the standard FIFO queue instance so that it is possible to peek at an instance without removing it from the queue.

Method Summary

T	peek() This method allows the caller to peek at the next object that would be returned on a remove call.
T	remove() Removes the next element from the queue and returns it to the caller.
T	remove(long timeout) Removes the next element from the queue and returns it to the caller.

Methods inherited from class org.opennms.core.queue.FifoQueueImpl

add, add, isEmpty, size

Methods inherited from class java.lang.Object

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

Method Detail

peek

public T peek()
       throws InterruptedException,
              FifoQueueException

This method allows the caller to peek at the next object that would be returned on a remove call. If the queue is currently empty then the caller is blocked until an object is put into the queue.

Returns:

The object that would be returned on the next call to remove.

Throws:

InterruptedException - Thrown if the thread is interrupted.

FifoQueueException - Thrown if an error occurs removing an item from the queue.

remove

public T remove()
         throws InterruptedException,
                FifoQueueException

Removes the next element from the queue and returns it to the caller. If there is no objects available then the caller is blocked until an item is available.

Specified by:

remove in interface FifoQueue<T>

Overrides:

remove in class FifoQueueImpl<T>

Returns:

The next element in the queue.

Throws:

InterruptedException - Thrown if the thread is interrupted.

FifoQueueException - Thrown if an error occurs removing an item from the queue.

remove

public T remove(long timeout)
         throws InterruptedException,
                FifoQueueException

Removes the next element from the queue and returns it to the caller. If there is no objects available then the caller is blocked until an item is available. If an object is not available within the time frame specified by timeout.

Specified by:

remove in interface FifoQueue<T>

Overrides:

remove in class FifoQueueImpl<T>

Parameters:

timeout - The maximum time to wait.

Returns:

The next element in the queue.

Throws:

InterruptedException - Thrown if the thread is interrupted.

FifoQueueException - Thrown if an error occurs removing an item from the queue.