org.opennms.netmgt.scheduler
Class Scheduler.PeekableFifoQueue

java.lang.Object
  org.opennms.core.queue.FifoQueueImpl
      org.opennms.netmgt.scheduler.Scheduler.PeekableFifoQueue

All Implemented Interfaces:

FifoQueue

Enclosing class:

Scheduler

public static final class Scheduler.PeekableFifoQueue

extends FifoQueueImpl

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

Field Summary

private java.lang.Object

m_hold The object hold.

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

Constructor Summary

(package private)

Scheduler.PeekableFifoQueue() Default constructor.

Method Summary

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

Field Detail

m_hold

private java.lang.Object m_hold

The object hold. This holds the last object peeked at by the application.

Constructor Detail

Scheduler.PeekableFifoQueue

Scheduler.PeekableFifoQueue()

Default constructor.

Method Detail

peek

public java.lang.Object peek()
                      throws java.lang.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:

java.lang.InterruptedException - Thrown if the thread is interrupted.

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

remove

public java.lang.Object remove()
                        throws java.lang.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

Overrides:

remove in class FifoQueueImpl

Returns:

The next element in the queue.

Throws:

java.lang.InterruptedException - Thrown if the thread is interrupted.

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

remove

public java.lang.Object remove(long timeout)
                        throws java.lang.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

Overrides:

remove in class FifoQueueImpl

Parameters:

timeout - The maximum time to wait.

Returns:

The next element in the queue.

Throws:

java.lang.InterruptedException - Thrown if the thread is interrupted.

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