/*
* This file is part of the Jikes RVM project (http://jikesrvm.org).
*
* This file is licensed to You under the Common Public License (CPL);
* You may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.opensource.org/licenses/cpl1.0.php
*
* See the COPYRIGHT.txt file distributed with this work for information
* regarding copyright ownership.
*/
package org.jikesrvm.scheduler.greenthreads;
import org.vmmagic.pragma.Uninterruptible;
/**
* Base class for queues of VM_Threads.
*/
@Uninterruptible
public abstract class VM_AbstractThreadQueue {
/** Are any threads on the queue? */
public abstract boolean isEmpty();
/** Add a thread to tail of queue. */
public abstract void enqueue(VM_GreenThread t);
/**
* Remove thread from head of queue.
* @return the thread (null --> queue is empty)
*/
public abstract VM_GreenThread dequeue();
/**
* Number of items on queue (an estimate: queue is not locked during the scan).
*/
public abstract int length();
}