producerbiasedqueue.java

JXTA&#8482 is a set of open, generalized peer-to-peer (P2P) protocols that allow any networked devi

/*
 * Copyright (c) 2001-2007 Sun Microsystems, Inc.  All rights reserved.
 *  
 *  The Sun Project JXTA(TM) Software License
 *  
 *  Redistribution and use in source and binary forms, with or without 
 *  modification, are permitted provided that the following conditions are met:
 *  
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
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 *     include the following acknowledgment: "This product includes software 
 *     developed by Sun Microsystems, Inc. for JXTA(TM) technology." 
 *     Alternately, this acknowledgment may appear in the software itself, if 
 *     and wherever such third-party acknowledgments normally appear.
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 *  ====================================================================
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 *  This software consists of voluntary contributions made by many individuals 
 *  on behalf of Project JXTA. For more information on Project JXTA, please see 
 *  http://www.jxta.org.
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 *  This license is based on the BSD license adopted by the Apache Foundation. 
 */

package net.jxta.impl.util;


import java.util.logging.Logger;
import java.util.logging.Level;
import net.jxta.logging.Logging;

import java.util.List;
import java.util.ArrayList;

import net.jxta.impl.util.TimeUtils;


/**
 *  A queue who's implementation is biased towards effciency in adding elements
 *  to the queue.
 *
 *  @deprecated Please convert all code to use the java.util.concurrent BlockingQueue instead.
 *
 **/
@Deprecated
public class ProducerBiasedQueue extends UnbiasedQueue {
    
    /**
     *  Log4J
     **/
    private static final Logger LOG = Logger.getLogger(ProducerBiasedQueue.class.getName());
    
    /**
     * Default constructor. 100 element FIFO queue which drops oldest element
     * when full.
     */
    public ProducerBiasedQueue() {
        this(DEFAULT_MAX_OBJECTS, DROP_OLDEST_OBJECT);
    }
    
    /**
     * Full featured constructor for creating a new ConsumerBiasedQueue.
     *
     * @param size    Queue will be not grow larger than this size. Use
     *    Integer.MAX_VALUE for "unbounded" queue size.
     * @param dropOldest  Controls behaviour of element insertion when the queue is
     * full. If "true" and the queue is full upon a push operation then the
     * oldest element will be dropped to be replaced with the element currently
     * being pushed. If "false" then then newest item will be dropped.
     */
    public ProducerBiasedQueue(int size, boolean dropOldest) {
        super(size, dropOldest, new ArrayList<Object>());
    }
    
    /**
     *  Flush the queue of all pending objects.
     **/
    @Override
    public void clear() {
        synchronized (queue) {
            super.clear();
        }
    }
    
    @Override
    public boolean push(Object obj) {
        synchronized (queue) {
            boolean pushed;

            pushed = super.push(obj);
            queue.notify(); // inform someone who is waiting. we dont have to tell everyone though.
            return pushed;
        }
    }
    
    /* The pop methods of this queue, unlike the "push" method. This creates a
     *  bottleneck for producers seperate from the primary lock on the "queue"
     *  member. This reduces contention on the primary lock which benefits users
     *  who are popping items from the queue (Consumers).
     *
     */
    
    /**
     * Return next obj in the queue if there is one.
     *
     * @return Object, null if the queue is empty
     **/
    @Override
    public synchronized Object pop() {
        synchronized (queue) {
            return super.pop();
        }
    }
    
    /**
     * Gets a Object from the queue. If no Object is immediately available,
     * then wait the specified amount of time. Per Java convention, a timeout
     * of zero (0) means wait an infinite amount of time. Negative values mean
     * do not wait at all.
     *
     * @param timeout amount of time to wait in milliseconds for an object to
     * be available. Per Java convention, a timeout of zero (0) means wait an
     * infinite amount of time. Negative values mean do not wait at all.
     * @return The next object in the queue.
     * @throws InterruptedException    if the operation is interrupted before
     *     the timeout interval is completed.
     */
    @Override
    public synchronized Object pop(long timeout) throws InterruptedException {
        synchronized (queue) {
            return super.pop(timeout);
        }
    }
    
    /**
     *  Returns an array of objects, possibly empty, from the queue.
     *
     *  @param maxObjs  the maximum number of items to return.
     *  @return an array of objects, possibly empty containing the returned
     *  queue elements.
     **/
    @Override
    public synchronized Object[] popMulti(int maxObjs) {
        synchronized (queue) {
            return super.popMulti(maxObjs);
        }
    }
    
    /**
     *  Set how many objects this queue may store. Note that if there are more
     *  objects already in the queue than the specified amount then the queue
     *  will retain its current capacity.
     *
     *  @param maxObjs  The number of objects which the queue must be able to
     *  store.
     **/
    @Override
    public void setMaxQueueSize(int maxObjs) {
        synchronized (queue) {
            super.setMaxQueueSize(maxObjs);
        }
    }
    
    /**
     *  Return the number of elements currently in the queue. This method is
     *  useful for statistical sampling, but should not be used to determine
     *  program logic due to the multi-threaded behaviour of these queues. You
     *  should use the return values and timeout behaviour of the push() and
     * pop() methods to regulate how you use the queue.
     *
     *  @return the number of elements currently in the queue. Be warned that
     *  even two sequential calls to this method may return different answers
     *  due to activity on other threads.
     *
     **/
    @Override
    public int getCurrentInQueue() {
        synchronized (queue) {
            return super.getCurrentInQueue();
        }
    }
    
    /**
     *  Return the average number of elements in the queue at Enqueue time.
     *
     *  @return average number of elements which were in the queue at during all
     *  of the "push" operations which returned a "true" result. Does not
     *  include the item being pushed. If no elements have ever been enqueued
     *  then "NaN" will be returned.
     **/
    @Override
    public double getAvgInQueueAtEnqueue() {
        synchronized (queue) {
            return super.getAvgInQueueAtEnqueue();
        }
    }
    
    /**
     *  Return the average number of elements in the queue at dequeue time.
     *
     *  @return average number of elements which were in the queue at during all
     *  of the "pop" operations which returned a non-null result. Includes the
     * item being "pop"ed in the average. If no elements have ever been dequeued
     *  then "NaN" will be returned.
     **/
    @Override
    public double getAvgInQueueAtDequeue() {
        synchronized (queue) {
            return super.getAvgInQueueAtDequeue();
        }
    }
}