Add filter that supports changing sources.

diff --git a/src/main/java/net/pterodactylus/sonitus/data/filter/MultiSourceFilter.java b/src/main/java/net/pterodactylus/sonitus/data/filter/MultiSourceFilter.java
new file mode 100644 (file)
index 0000000..57c313e
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sonitus/data/filter/MultiSourceFilter.java
@@ -0,0 +1,182 @@
+/*
+ * Sonitus - MultiSource.java - Copyright © 2013 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.sonitus.data.filter;
+
+import static com.google.common.base.Preconditions.*;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.PipedInputStream;
+import java.io.PipedOutputStream;
+import java.util.Arrays;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+import net.pterodactylus.sonitus.data.ConnectException;
+import net.pterodactylus.sonitus.data.Filter;
+import net.pterodactylus.sonitus.data.Format;
+import net.pterodactylus.sonitus.data.ReusableSink;
+import net.pterodactylus.sonitus.data.Source;
+
+/**
+ * {@link ReusableSink} implementation that supports changing the source without
+ * letting the {@link net.pterodactylus.sonitus.data.Sink} know.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class MultiSourceFilter implements Filter, ReusableSink {
+
+       /** The logger. */
+       private static final Logger logger = Logger.getLogger(MultiSourceFilter.class.getName());
+
+       /** Object used for synchronization. */
+       private final Object syncObject = new Object();
+
+       /** The connection. */
+       private Connection connection;
+
+       /** The format. */
+       private Format format;
+
+       @Override
+       public Format format() {
+               return format;
+       }
+
+       @Override
+       public byte[] get(int bufferSize) throws EOFException, IOException {
+               byte[] buffer = new byte[bufferSize];
+               InputStream inputStream;
+               synchronized (syncObject) {
+                       inputStream = connection.pipedInputStream;
+               }
+               int read = inputStream.read(buffer);
+               return Arrays.copyOf(buffer, read);
+       }
+
+       @Override
+       public void connect(Source source) throws ConnectException {
+               checkNotNull(source, "source must not be null");
+               if (format != null) {
+                       checkArgument(format.equals(source.format()), "source’s format must equal this sink’s format");
+               } else {
+                       format = source.format();
+               }
+
+               if (connection == null) {
+                       connection = new Connection();
+                       new Thread(connection).start();
+               }
+               try {
+                       connection.source(source);
+               } catch (IOException ioe1) {
+                       throw new ConnectException(ioe1);
+               }
+       }
+
+       /**
+        * The connection feeds the input from the currently connected source to the
+        * input stream that {@link #get(int)} will get its data from.
+        *
+        * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+        */
+       private class Connection implements Runnable {
+
+               /** The currently connected source. */
+               /* synchronized by syncObject. */
+               private Source source;
+
+               /** The input stream that {@link #get(int)} will read from. */
+               /* synchronized by syncObject. */
+               private PipedInputStream pipedInputStream;
+
+               /** The output stream that the source will be fed into. */
+               /* synchronized by syncObject. */
+               private PipedOutputStream pipedOutputStream;
+
+               /**
+                * Changes the source of the connection.
+                *
+                * @param source
+                *              The new source of the connection
+                * @return This connection
+                * @throws IOException
+                *              if an I/O error occurs
+                */
+               public Connection source(Source source) throws IOException {
+                       synchronized (syncObject) {
+                               this.source = source;
+                               pipedInputStream = new PipedInputStream();
+                               pipedOutputStream = new PipedOutputStream(pipedInputStream);
+                               syncObject.notifyAll();
+                       }
+                       return this;
+               }
+
+               @Override
+               public void run() {
+                       while (true) {
+                               /* wait for source to be set. */
+                               OutputStream outputStream;
+                               logger.finest("Entering synchronized block...");
+                               synchronized (syncObject) {
+                                       logger.finest("Entered synchronized block.");
+                                       while (source == null) {
+                                               try {
+                                                       logger.finest("Waiting for source to connect...");
+                                                       syncObject.wait();
+                                               } catch (InterruptedException ie1) {
+                                                       /* ignore, keep waiting. */
+                                               }
+                                       }
+                                       outputStream = pipedOutputStream;
+                               }
+                               logger.finest("Exited synchronized block.");
+
+                               byte[] buffer = null;
+                               boolean readSuccessful = false;
+                               while (!readSuccessful) {
+                                       try {
+                                               buffer = source.get(4096);
+                                               logger.finest(String.format("Read %d Bytes.", buffer.length));
+                                               if (buffer.length > 0) {
+                                                       readSuccessful = true;
+                                               }
+                                       } catch (IOException e) {
+                                               /* TODO - notify & wait */
+                                       }
+                               }
+
+                               try {
+                                       outputStream.write(buffer);
+                                       logger.finest(String.format("Wrote %d Bytes.", buffer.length));
+                               } catch (IOException ioe1) {
+                                       /* okay, the sink has died, exit. */
+                                       logger.log(Level.WARNING, "Could not write to pipe!", ioe1);
+                                       break;
+                               }
+                       }
+
+                       logger.info("Exiting.");
+               }
+
+       }
+
+}