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
  29 import net.pterodactylus.sonitus.data.Controller;
  30 import net.pterodactylus.sonitus.data.Metadata;
  31 import net.pterodactylus.sonitus.data.Source;
  32 import net.pterodactylus.sonitus.data.event.MetadataUpdated;
  33 import net.pterodactylus.sonitus.data.event.SourceFinishedEvent;
  34
  35 import com.google.common.eventbus.EventBus;
  36 import com.google.inject.Inject;
  37
  38 /**
  39  * {@link Source} implementation that simply forwards another source and
  40  * supports changing the source without letting the {@link
  41  * net.pterodactylus.sonitus.data.Sink} know.
  42  *
  43  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  44  */
  45 public class MultiSource implements Source {
  46
  47         /** The logger. */
  48         private static final Logger logger = Logger.getLogger(MultiSource.class.getName());
  49
  50         /** The event bus. */
  51         private final EventBus eventBus;
  52
  53         /** The current source. */
  54         private final AtomicReference<Source> source = new AtomicReference<Source>();
  55
  56         /** Whether the source was changed. */
  57         private boolean sourceChanged;
  58
  59         @Inject
  60         public MultiSource(EventBus eventBus) {
  61                 this.eventBus = eventBus;
  62         }
  63
  64         //
  65         // ACTIONS
  66         //
  67
  68         /**
  69          * Sets the new source to use.
  70          *
  71          * @param source
  72          *              The new source to use
  73          */
  74         public void setSource(Source source) {
  75                 checkNotNull(source, "source must not be null");
  76
  77                 Source oldSource = this.source.getAndSet(source);
  78                 if (oldSource != null) {
  79                         synchronized (this.source) {
  80                                 sourceChanged = true;
  81                                 this.source.notifyAll();
  82                         }
  83                         eventBus.post(new MetadataUpdated(this, source.metadata()));
  84                         logger.info(String.format("Next Source set: %s", source));
  85                 }
  86         }
  87
  88         //
  89         // CONTROLLED METHODS
  90         //
  91
  92         @Override
  93         public String name() {
  94                 return "Multisource";
  95         }
  96
  97         @Override
  98         public List<Controller<?>> controllers() {
  99                 return Collections.emptyList();
 100         }
 101
 102         //
 103         // SOURCE METHODS
 104         //
 105
 106         @Override
 107         public Metadata metadata() {
 108                 return source.get().metadata();
 109         }
 110
 111         @Override
 112         public byte[] get(int bufferSize) throws EOFException, IOException {
 113                 while (true) {
 114                         try {
 115                                 return source.get().get(bufferSize);
 116                         } catch (EOFException eofe1) {
 117                                 eventBus.post(new SourceFinishedEvent(source.get()));
 118                                 synchronized (source) {
 119                                         while (!sourceChanged) {
 120                                                 try {
 121                                                         logger.info("Waiting for next Source...");
 122                                                         source.wait();
 123                                                         logger.info("Was notified.");
 124                                                 } catch (InterruptedException ioe1) {
 125                                                         /* ignore: we’ll end up here again if we were interrupted. */
 126                                                 }
 127                                         }
 128                                 }
 129                         } finally {
 130                                 synchronized (source) {
 131                                         sourceChanged = false;
 132                                 }
 133                         }
 134                 }
 135         }
 136
 137 }