src/main/java/net/pterodactylus/sonitus/data/source/MultiSource.java

   1 /*
   2  * Sonitus - MultiSource.java - Copyright © 2013 David Roden
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 package net.pterodactylus.sonitus.data.source;
  19
  20 import static com.google.common.base.Preconditions.checkNotNull;
  21
  22 import java.io.EOFException;
  23 import java.io.IOException;
  24 import java.util.Collections;
  25 import java.util.List;
  26 import java.util.concurrent.atomic.AtomicReference;
  27 import java.util.logging.Logger;
  28 import javax.swing.event.EventListenerList;
  29
  30 import net.pterodactylus.sonitus.data.AbstractFilter;
  31 import net.pterodactylus.sonitus.data.Controller;
  32 import net.pterodactylus.sonitus.data.Filter;
  33 import net.pterodactylus.sonitus.data.Metadata;
  34
  35 import com.google.inject.Inject;
  36
  37 /**
  38  * {@link Filter} implementation that simply forwards data from another filter
  39  * and supports changing the source without letting downstream filters know.
  40  *
  41  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  42  */
  43 public class MultiSource extends AbstractFilter {
  44
  45         /** The logger. */
  46         private static final Logger logger = Logger.getLogger(MultiSource.class.getName());
  47
  48         /** The source finished listeners. */
  49         private final EventListenerList sourceFinishedListeners = new EventListenerList();
  50
  51         /** The current source. */
  52         private final AtomicReference<Filter> source = new AtomicReference<Filter>();
  53
  54         /** Whether the source was changed. */
  55         private boolean sourceChanged;
  56
  57         /** Creates a new multi source. */
  58         @Inject
  59         public MultiSource() {
  60                 super("Multisource");
  61         }
  62
  63         //
  64         // LISTENER MANAGEMENT
  65         //
  66
  67         /**
  68          * Adds a source finished listener to the list of registered listeners.
  69          *
  70          * @param sourceFinishedListener
  71          *              The source finished listener to add
  72          */
  73         public void addSourceFinishedListener(SourceFinishedListener sourceFinishedListener) {
  74                 sourceFinishedListeners.add(SourceFinishedListener.class, sourceFinishedListener);
  75         }
  76
  77         /**
  78          * Removes a source finished listener from the list of registered listeners.
  79          *
  80          * @param sourceFinishedListener
  81          *              The source finished listener to remove
  82          */
  83         public void removeSourceFinishedListener(SourceFinishedListener sourceFinishedListener) {
  84                 sourceFinishedListeners.remove(SourceFinishedListener.class, sourceFinishedListener);
  85         }
  86
  87         //
  88         // ACTIONS
  89         //
  90
  91         /**
  92          * Sets the new source to use.
  93          *
  94          * @param source
  95          *              The new source to use
  96          */
  97         public void setSource(Filter source) {
  98                 checkNotNull(source, "source must not be null");
  99
 100                 Filter oldSource = this.source.getAndSet(source);
 101                 if (!source.equals(oldSource)) {
 102                         synchronized (this.source) {
 103                                 sourceChanged = true;
 104                                 this.source.notifyAll();
 105                         }
 106                         metadataUpdated(source.metadata());
 107                         logger.info(String.format("Next Source set: %s", source));
 108                 }
 109         }
 110
 111         //
 112         // EVENT METHODS
 113         //
 114
 115         /**
 116          * Notifies all registered listeners that the current source finished playing
 117          * and that a new source should be {@link #setSource(Filter) set}.
 118          *
 119          * @see SourceFinishedListener
 120          */
 121         private void fireSourceFinished() {
 122                 for (SourceFinishedListener sourceFinishedListener : sourceFinishedListeners.getListeners(SourceFinishedListener.class)) {
 123                         sourceFinishedListener.sourceFinished(this);
 124                 }
 125         }
 126
 127         //
 128         // FILTER METHODS
 129         //
 130
 131         @Override
 132         public List<Controller<?>> controllers() {
 133                 return Collections.emptyList();
 134         }
 135
 136         @Override
 137         public Metadata metadata() {
 138                 if (super.metadata() == null) {
 139                         /* no metadata yet, wait for it. */
 140                         waitForNewSource();
 141                         sourceChanged = false;
 142                 }
 143                 return super.metadata();
 144         }
 145
 146         @Override
 147         public byte[] get(int bufferSize) throws EOFException, IOException {
 148                 while (true) {
 149                         try {
 150                                 return source.get().get(bufferSize);
 151                         } catch (EOFException eofe1) {
 152                                 waitForNewSource();
 153                         } finally {
 154                                 synchronized (source) {
 155                                         sourceChanged = false;
 156                                 }
 157                         }
 158                 }
 159         }
 160
 161         //
 162         // PRIVATE METHODS
 163         //
 164
 165         /** Waits for a new source to be {@link #setSource(Filter) set}. */
 166         private void waitForNewSource() {
 167                 fireSourceFinished();
 168                 synchronized (source) {
 169                         while (!sourceChanged) {
 170                                 try {
 171                                         logger.info("Waiting for next Source...");
 172                                         source.wait();
 173                                         logger.info("Was notified.");
 174                                 } catch (InterruptedException ioe1) {
 175                                         /* ignore: we’ll end up here again if we were interrupted. */
 176                                 }
 177                         }
 178                 }
 179         }
 180
 181 }