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