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