PoolWaitQueue.java

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2010 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package com.sun.enterprise.resource.pool.waitqueue;

import java.util.Collection;

/**
 * Represents the pool wait queue<br>
 * To plug-in multiple implementation of wait-queue<br>
 *
 * @author Jagadish Ramu
 */
public interface PoolWaitQueue {
    String DEFAULT_WAIT_QUEUE = "DEFAULT_WAIT_QUEUE";
    String THREAD_PRIORITY_BASED_WAIT_QUEUE = "THREAD_PRIORITY_BASED_WAIT_QUEUE";

    /**
     * returns the length of wait queue
     * @return length of wait queue.
     */
    int getQueueLength();

    /**
     * resource requesting thread will be added to queue<br>
     * and the object on which it is made to wait is returned
     * @return Object
     */
    Object addToQueue();

    /**
     * removes the specified object (resource request) from the queue
     * @param o Object
     * @return boolean indicating whether the object was removed or not
     */
    boolean removeFromQueue(Object o);

    /**
     * removes the first object (resource request) from the queue
     */
    /*
    Object removeFirst();
    */

    /**
     * removes the first object (resource request) from the queue
     * @return Object first object
     */
    Object remove();

    /**
     * returns (does not remove) the first object (resource request) from the queue
     * @return Object first object
     */
    Object peek();

    /**
     * used to get access to the list of waiting clients<br>
     * Useful in case of rolling over from one pool to another
     * eg: transparent-dynamic-pool-reconfiguration.
     * @return Collection
     */
    Collection getQueueContents();
}