From: David ‘Bombe’ Roden <bombe@pterodactylus.net>
Date: Sat, 16 Mar 2013 17:22:57 +0000 (+0100)
Subject: Add filter that supports changing sources.
X-Git-Url: https://git.pterodactylus.net/?a=commitdiff_plain;h=e1c3f4db2b1eadd90bdadc4781d91b18b1337cf0;p=sonitus.git

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
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.");
+		}
+
+	}
+
+}