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