src/main/java/net/pterodactylus/sonitus/data/filter/MultiSourceFilter.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.filter;
  19
  20 import static com.google.common.base.Preconditions.*;
  21
  22 import java.io.EOFException;
  23 import java.io.IOException;
  24 import java.io.InputStream;
  25 import java.io.OutputStream;
  26 import java.io.PipedInputStream;
  27 import java.io.PipedOutputStream;
  28 import java.util.Arrays;
  29 import java.util.logging.Level;
  30 import java.util.logging.Logger;
  31
  32 import net.pterodactylus.sonitus.data.ConnectException;
  33 import net.pterodactylus.sonitus.data.Filter;
  34 import net.pterodactylus.sonitus.data.Format;
  35 import net.pterodactylus.sonitus.data.Metadata;
  36 import net.pterodactylus.sonitus.data.ReusableSink;
  37 import net.pterodactylus.sonitus.data.Source;
  38 import net.pterodactylus.sonitus.data.event.SourceFinishedEvent;
  39
  40 import com.google.common.eventbus.EventBus;
  41 import com.google.inject.Inject;
  42
  43 /**
  44  * {@link ReusableSink} implementation that supports changing the source without
  45  * letting the {@link net.pterodactylus.sonitus.data.Sink} know.
  46  *
  47  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  48  */
  49 public class MultiSourceFilter implements Filter, ReusableSink {
  50
  51         /** The logger. */
  52         private static final Logger logger = Logger.getLogger(MultiSourceFilter.class.getName());
  53
  54         /** Object used for synchronization. */
  55         private final Object syncObject = new Object();
  56
  57         /** The event bus. */
  58         private final EventBus eventBus;
  59
  60         /** The connection. */
  61         private Connection connection;
  62
  63         @Inject
  64         public MultiSourceFilter(EventBus eventBus) {
  65                 this.eventBus = eventBus;
  66         }
  67
  68         @Override
  69         public Format format() {
  70                 synchronized (syncObject) {
  71                         return connection.source.format();
  72                 }
  73         }
  74
  75         @Override
  76         public Metadata metadata() {
  77                 synchronized (syncObject) {
  78                         return connection.source.metadata();
  79                 }
  80         }
  81
  82         @Override
  83         public byte[] get(int bufferSize) throws EOFException, IOException {
  84                 byte[] buffer = new byte[bufferSize];
  85                 InputStream inputStream;
  86                 synchronized (syncObject) {
  87                         inputStream = connection.pipedInputStream;
  88                 }
  89                 int read = inputStream.read(buffer);
  90                 return Arrays.copyOf(buffer, read);
  91         }
  92
  93         @Override
  94         public void connect(Source source) throws ConnectException {
  95                 checkNotNull(source, "source must not be null");
  96                 if ((connection != null) && (connection.source != null)) {
  97                         checkArgument(connection.source.format().equals(source.format()), "source’s format must equal this sink’s format");
  98                 }
  99
 100                 if (connection == null) {
 101                         connection = new Connection();
 102                         new Thread(connection).start();
 103                 }
 104                 try {
 105                         connection.source(source);
 106                 } catch (IOException ioe1) {
 107                         throw new ConnectException(ioe1);
 108                 }
 109         }
 110
 111         @Override
 112         public void metadataUpdated() {
 113                 /* ignore. */
 114         }
 115
 116         /**
 117          * The connection feeds the input from the currently connected source to the
 118          * input stream that {@link #get(int)} will get its data from.
 119          *
 120          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 121          */
 122         private class Connection implements Runnable {
 123
 124                 /** The currently connected source. */
 125                 /* synchronized by syncObject. */
 126                 private Source source;
 127
 128                 /** The input stream that {@link #get(int)} will read from. */
 129                 /* synchronized by syncObject. */
 130                 private PipedInputStream pipedInputStream;
 131
 132                 /** The output stream that the source will be fed into. */
 133                 /* synchronized by syncObject. */
 134                 private PipedOutputStream pipedOutputStream;
 135
 136                 /**
 137                  * Changes the source of the connection.
 138                  *
 139                  * @param source
 140                  *              The new source of the connection
 141                  * @return This connection
 142                  * @throws IOException
 143                  *              if an I/O error occurs
 144                  */
 145                 public Connection source(Source source) throws IOException {
 146                         synchronized (syncObject) {
 147                                 if (this.source != null) {
 148                                         eventBus.post(new SourceFinishedEvent(this.source));
 149                                 }
 150                                 this.source = source;
 151                                 pipedInputStream = new PipedInputStream();
 152                                 pipedOutputStream = new PipedOutputStream(pipedInputStream);
 153                                 syncObject.notifyAll();
 154                         }
 155                         return this;
 156                 }
 157
 158                 @Override
 159                 public void run() {
 160                         while (true) {
 161                                 /* wait for source to be set. */
 162                                 OutputStream outputStream;
 163                                 Source source;
 164                                 logger.finest("Entering synchronized block...");
 165                                 synchronized (syncObject) {
 166                                         logger.finest("Entered synchronized block.");
 167                                         source = this.source;
 168                                         while (source == null) {
 169                                                 try {
 170                                                         logger.finest("Waiting for source to connect...");
 171                                                         syncObject.wait();
 172                                                 } catch (InterruptedException ie1) {
 173                                                         /* ignore, keep waiting. */
 174                                                 }
 175                                                 source = this.source;
 176                                         }
 177                                         outputStream = pipedOutputStream;
 178                                 }
 179                                 logger.finest("Exited synchronized block.");
 180
 181                                 byte[] buffer = null;
 182                                 boolean readSuccessful = false;
 183                                 while (!readSuccessful) {
 184                                         try {
 185                                                 buffer = source.get(4096);
 186                                                 logger.finest(String.format("Read %d Bytes.", buffer.length));
 187                                                 if (buffer.length > 0) {
 188                                                         readSuccessful = true;
 189                                                 }
 190                                         } catch (IOException e) {
 191                                                 /* TODO - notify & wait */
 192                                         }
 193                                 }
 194
 195                                 try {
 196                                         outputStream.write(buffer);
 197                                         logger.finest(String.format("Wrote %d Bytes.", buffer.length));
 198                                 } catch (IOException ioe1) {
 199                                         /* okay, the sink has died, exit. */
 200                                         logger.log(Level.WARNING, "Could not write to pipe!", ioe1);
 201                                         break;
 202                                 }
 203                         }
 204
 205                         logger.info("Exiting.");
 206                 }
 207
 208         }
 209
 210 }