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.concurrent.atomic.AtomicReference;
  25 import java.util.logging.Logger;
  26
  27 import net.pterodactylus.sonitus.data.Metadata;
  28 import net.pterodactylus.sonitus.data.Source;
  29 import net.pterodactylus.sonitus.data.event.SourceFinishedEvent;
  30
  31 import com.google.common.eventbus.EventBus;
  32 import com.google.inject.Inject;
  33
  34 /**
  35  * {@link Source} implementation that simply forwards another source and
  36  * supports changing the source without letting the {@link
  37  * net.pterodactylus.sonitus.data.Sink} know.
  38  *
  39  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  40  */
  41 public class MultiSource implements Source {
  42
  43         /** The logger. */
  44         private static final Logger logger = Logger.getLogger(MultiSource.class.getName());
  45
  46         /** The event bus. */
  47         private final EventBus eventBus;
  48
  49         /** The current source. */
  50         private final AtomicReference<Source> source = new AtomicReference<Source>();
  51
  52         /** Whether the source was changed. */
  53         private boolean sourceChanged;
  54
  55         @Inject
  56         public MultiSource(EventBus eventBus) {
  57                 this.eventBus = eventBus;
  58         }
  59
  60         //
  61         // ACTIONS
  62         //
  63
  64         /**
  65          * Sets the new source to use.
  66          *
  67          * @param source
  68          *              The new source to use
  69          */
  70         public void setSource(Source source) {
  71                 checkNotNull(source, "source must not be null");
  72
  73                 Source oldSource = this.source.getAndSet(source);
  74                 if (oldSource != null) {
  75                         synchronized (this.source) {
  76                                 sourceChanged = true;
  77                                 this.source.notifyAll();
  78                         }
  79                         logger.info(String.format("Next Source set: %s", source));
  80                 }
  81         }
  82
  83         //
  84         // SOURCE METHODS
  85         //
  86
  87         @Override
  88         public Metadata metadata() {
  89                 return source.get().metadata();
  90         }
  91
  92         @Override
  93         public byte[] get(int bufferSize) throws EOFException, IOException {
  94                 while (true) {
  95                         try {
  96                                 return source.get().get(bufferSize);
  97                         } catch (EOFException eofe1) {
  98                                 eventBus.post(new SourceFinishedEvent(source.get()));
  99                                 synchronized (source) {
 100                                         while (!sourceChanged) {
 101                                                 try {
 102                                                         logger.info("Waiting for next Source...");
 103                                                         source.wait();
 104                                                         logger.info("Was notified.");
 105                                                 } catch (InterruptedException ioe1) {
 106                                                         /* ignore: we’ll end up here again if we were interrupted. */
 107                                                 }
 108                                         }
 109                                 }
 110                         } finally {
 111                                 synchronized (source) {
 112                                         sourceChanged = false;
 113                                 }
 114                         }
 115                 }
 116         }
 117
 118 }