Add rate limiting filter.

diff --git a/src/main/java/net/pterodactylus/sonitus/data/filter/RateLimitingFilter.java b/src/main/java/net/pterodactylus/sonitus/data/filter/RateLimitingFilter.java
new file mode 100644 (file)
index 0000000..c40f90f
--- /dev/null
+++ b/src/main/java/net/pterodactylus/sonitus/data/filter/RateLimitingFilter.java
@@ -0,0 +1,130 @@
+/*
+ * Sonitus - DelayFilter.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.io.Closeables.close;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.PipedInputStream;
+import java.io.PipedOutputStream;
+import java.util.Arrays;
+import java.util.logging.Logger;
+
+import net.pterodactylus.sonitus.data.ConnectException;
+import net.pterodactylus.sonitus.data.Connection;
+import net.pterodactylus.sonitus.data.Filter;
+import net.pterodactylus.sonitus.data.Format;
+import net.pterodactylus.sonitus.data.Source;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * Rate limiting filter that only passes a specified amount of data per second
+ * from its {@link Source} to its {@link net.pterodactylus.sonitus.data.Sink}.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class RateLimitingFilter implements Filter {
+
+       /** The logger. */
+       private static final Logger logger = Logger.getLogger(RateLimitingFilter.class.getName());
+
+       /** The limiting rate in bytes/second. */
+       private final int rate;
+
+       /** The source’s format. */
+       private Format format;
+
+       /** The input stream to read from. */
+       private PipedInputStream pipedInputStream = new PipedInputStream();
+
+       /**
+        * Creates a new rate limiting filter.
+        *
+        * @param rate
+        *              The limiting rate (in bytes/second)
+        */
+       public RateLimitingFilter(int rate) {
+               this.rate = rate;
+       }
+
+       //
+       // FILTER METHODS
+       //
+
+       @Override
+       public Format format() {
+               return format;
+       }
+
+       @Override
+       public byte[] get(int bufferSize) throws EOFException, IOException {
+               byte[] buffer = new byte[bufferSize];
+               int read = pipedInputStream.read(buffer);
+               if (read == -1) {
+                       throw new EOFException();
+               }
+               return Arrays.copyOf(buffer, read);
+       }
+
+       @Override
+       public void connect(Source source) throws ConnectException {
+               Preconditions.checkNotNull(source, "source must not be null");
+
+               format = source.format();
+               final long start = System.currentTimeMillis();
+               try {
+                       pipedInputStream = new PipedInputStream();
+                       final PipedOutputStream pipedOutputStream = new PipedOutputStream(pipedInputStream);
+                       new Thread(new Connection(source) {
+
+                               @Override
+                               protected int bufferSize() {
+                                       return rate;
+                               }
+
+                               @Override
+                               protected void feed(byte[] buffer) throws IOException {
+                                       long waitTime = 1000 * buffer.length / rate;
+                                       long now = System.currentTimeMillis();
+                                       pipedOutputStream.write(buffer);
+                                       pipedOutputStream.flush();
+                                       while ((System.currentTimeMillis() - now) < waitTime) {
+                                               try {
+                                                       long limitDelay = waitTime - (System.currentTimeMillis() - now);
+                                                       logger.finest(String.format("Waiting %d ms...", limitDelay));
+                                                       Thread.sleep(limitDelay);
+                                               } catch (InterruptedException ie1) {
+                                                       /* ignore, keep looping. */
+                                               }
+                                       }
+                               }
+
+                               @Override
+                               protected void finish() throws IOException {
+                                       close(pipedInputStream, true);
+                                       close(pipedOutputStream, true);
+                               }
+                       }).start();
+               } catch (IOException ioe1) {
+                       throw new ConnectException(ioe1);
+               }
+       }
+
+}