src/net/pterodactylus/fcp/highlevel/HighLevelContinuousCallback.java

   1 /*
   2  * jFCPlib-high-level-client - HighLevelContinousCallback.java -
   3  * Copyright © 2008 David Roden
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  18  */
  19
  20 package net.pterodactylus.fcp.highlevel;
  21
  22 import java.util.ArrayList;
  23 import java.util.List;
  24
  25 /**
  26  * Callback for an operation that sends progress messages before completion.
  27  *
  28  * @param <R>
  29  *            The type of the continuous result
  30  * @author David ‘Bombe’ Roden &lt;bombe@freenetproject.org&gt;
  31  * @version $Id$
  32  */
  33 public class HighLevelContinuousCallback<R extends HighLevelContinuousResult> extends HighLevelCallback<R> {
  34
  35         /** Callback listeners. */
  36         private final List<HighLevelContinuousCallbackListener<R>> highLevelContinuousCallbackListeners = new ArrayList<HighLevelContinuousCallbackListener<R>>();
  37
  38         /** List of progress results. */
  39         private final List<R> progressQueue = new ArrayList<R>();
  40
  41         /**
  42          * Creates a new continuous callback with the given result.
  43          *
  44          * @see HighLevelCallback#HighLevelCallback(HighLevelResult)
  45          * @param progress
  46          *            The result of the operation
  47          */
  48         HighLevelContinuousCallback(R progress) {
  49                 super(progress);
  50         }
  51
  52         //
  53         // EVENT MANAGEMENT
  54         //
  55
  56         /**
  57          * Adds a callback listener to this callback. If this callback already has
  58          * some progress results, the listener is notified immediately.
  59          *
  60          * @param highLevelContinuousCallbackListener
  61          *            The callback listener to add
  62          */
  63         public void addHighLevelContinuousCallbackListener(HighLevelContinuousCallbackListener<R> highLevelContinuousCallbackListener) {
  64                 highLevelContinuousCallbackListeners.add(highLevelContinuousCallbackListener);
  65                 synchronized (progressQueue) {
  66                         if (!progressQueue.isEmpty()) {
  67                                 fireGotProgress();
  68                         }
  69                 }
  70         }
  71
  72         /**
  73          * Removes a callback listener from this callback.
  74          *
  75          * @param highLevelContinuousCallbackListener
  76          *            The callback listener to remove
  77          */
  78         public void removeHighLevelContinuousCallbackListener(HighLevelContinuousCallbackListener<R> highLevelContinuousCallbackListener) {
  79                 highLevelContinuousCallbackListeners.remove(highLevelContinuousCallbackListener);
  80         }
  81
  82         /**
  83          * Notifies all listeners that progress results have been received.
  84          */
  85         private void fireGotProgress() {
  86                 for (HighLevelContinuousCallbackListener<R> highLevelContinuousCallbackListener: highLevelContinuousCallbackListeners) {
  87                         highLevelContinuousCallbackListener.gotProgress(this);
  88                 }
  89         }
  90
  91         //
  92         // ACCESSORS
  93         //
  94
  95         /**
  96          * Returns the next progress result and removes it from the queue. If no
  97          * progress result is yet available, this method will block.
  98          *
  99          * @return The next progress result
 100          * @throws InterruptedException
 101          *             if {@link Object#wait()} is interrupted
 102          */
 103         public R getProgress() throws InterruptedException {
 104                 return getProgress(0);
 105         }
 106
 107         /**
 108          * Returns the next progress result and removes it from the queue. If no
 109          * progress result is yet available, this method will block until either a
 110          * progress result is available or the given time (in milliseconds) has
 111          * passed.
 112          *
 113          * @param waitTime
 114          *            The maximum time to wait for a progress result
 115          * @return The next progress result
 116          * @throws InterruptedException
 117          *             if {@link Object#wait()} is interrupted
 118          */
 119         public R getProgress(long waitTime) throws InterruptedException {
 120                 synchronized (progressQueue) {
 121                         if (progressQueue.isEmpty()) {
 122                                 progressQueue.wait(waitTime);
 123                         }
 124                         return progressQueue.remove(0);
 125                 }
 126         }
 127
 128         /**
 129          * Returns the latest progress result and clears the queue.
 130          *
 131          * @return The latest progress result, or <code>null</code> if the queue
 132          *         is empty
 133          */
 134         public R getLatestProgress() {
 135                 synchronized (progressQueue) {
 136                         if (progressQueue.isEmpty()) {
 137                                 return null;
 138                         }
 139                         R latestProgress = progressQueue.get(progressQueue.size() - 1);
 140                         progressQueue.clear();
 141                         return latestProgress;
 142                 }
 143         }
 144
 145         /**
 146          * Adds a progress result and notifies all listeners.
 147          *
 148          * @param progress
 149          *            The progress result to add
 150          */
 151         void addProgress(R progress) {
 152                 synchronized (progressQueue) {
 153                         progressQueue.add(progress);
 154                         progressQueue.notify();
 155                 }
 156                 fireGotProgress();
 157         }
 158
 159 }