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package com.sun.grizzly.connectioncache.spi.concurrent;
/** A class that provides a very simply unbounded queue.
* The main requirement here is that the class support constant time (very fast)
* deletion of arbitrary elements. An instance of this class must be thread safe,
* either by locking or by using a wait-free algorithm (preferred).
* The interface is made as simple is possible to make it easier to produce
* a wait-free implementation.
* @param V object type to be stored in this <code>ConcurrentQueue</code>
*/
public interface ConcurrentQueue<V> {
/** A Handle provides the capability to delete an element of a ConcurrentQueue
* very quickly. Typically, the handle is stored in the element, so that an
* element located from another data structure can be quickly deleted from
* a ConcurrentQueue.
* @param V type of {@link Handle}
*/
public interface Handle<V> {
/** Return the value that corresponds to this handle.
* @return value that corresponds to this handle
*/
V value() ;
/** Delete the element corresponding to this handle
* from the queue. Takes constant time. Returns
* true if the removal succeeded, or false if it failed.
* which can occur if another thread has already called
* poll or remove on this element.
* @return true if the removal succeeded, or false if it failed
*/
boolean remove() ;
}
/** Return the number of elements in the queue.
* @return number of elements in the queue
*/
int size() ;
/** Add a new element to the tail of the queue.
* Returns a handle for the element in the queue.
* @param arg element to add to the queue
* @return a {@link Handle} for the element added to the queue
*/
Handle<V> offer( V arg ) ;
/** Return an element from the head of the queue.
* The element is removed from the queue.
* @return element removed from the queue
*/
V poll() ;
}