--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/com/go/trove/net/DistributedSocketFactory.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,383 @@
+/* ====================================================================
+ * Trove - Copyright (c) 1997-2000 Walt Disney Internet Group
+ * ====================================================================
+ * The Tea Software License, Version 1.1
+ *
+ * Copyright (c) 2000 Walt Disney Internet Group. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The end-user documentation included with the redistribution,
+ *    if any, must include the following acknowledgment:
+ *       "This product includes software developed by the
+ *        Walt Disney Internet Group (http://opensource.go.com/)."
+ *    Alternately, this acknowledgment may appear in the software itself,
+ *    if and wherever such third-party acknowledgments normally appear.
+ *
+ * 4. The names "Tea", "TeaServlet", "Kettle", "Trove" and "BeanDoc" must
+ *    not be used to endorse or promote products derived from this
+ *    software without prior written permission. For written
+ *    permission, please contact opensource@dig.com.
+ *
+ * 5. Products derived from this software may not be called "Tea",
+ *    "TeaServlet", "Kettle" or "Trove", nor may "Tea", "TeaServlet",
+ *    "Kettle", "Trove" or "BeanDoc" appear in their name, without prior
+ *    written permission of the Walt Disney Internet Group.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED.  IN NO EVENT SHALL THE WALT DISNEY INTERNET GROUP OR ITS
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ *
+ * For more information about Tea, please see http://opensource.go.com/.
+ */
+
+package com.go.trove.net;
+
+import java.io.*;
+import java.net.*;
+import java.util.*;
+import java.lang.ref.*;
+import com.go.trove.util.IdentityMap;
+
+/******************************************************************************
+ * A SocketFactory implementation for distributing load among several
+ * SocketFactories. If an exception occurs on a socket, its pool is put into
+ * the "dead" list. A special thread will run in the background, trying to
+ * resurrect the dead SocketSocket. As soon as its able to create sockets
+ * again, its added back into the "live" list.
+ * <p>
+ * Consider wrapping with a {@link LazySocketFactory} for automatic checking
+ * against socket factories that may be dead.
+ *
+ * @author Brian S O'Neill
+ * @version
+ * <!--$$Revision: 1.1 $-->, <!--$$JustDate:--> 01/01/22 <!-- $-->
+ */
+public class DistributedSocketFactory implements SocketFactory {
+    private final long mTimeout;
+
+    private int mFactoryIndex;
+
+    // Contains only the live SocketFactories.
+    private List mFactories;
+
+    // Maps SocketPools to resurrector threads.
+    private Map mResurrectors;
+
+    // Maps CheckedSockets to the SocketPools that they came from.
+    private Map mSocketSources;
+
+    private CheckedSocket.ExceptionListener mListener;
+
+    /**
+     * @param timeout Maximum time to wait (in milliseconds) for new
+     * connections to be established before throwing an exception
+     */
+    public DistributedSocketFactory(long timeout) {
+        mTimeout = timeout;
+        mFactories = Collections.synchronizedList(new ArrayList());
+        mResurrectors = Collections.synchronizedMap(new HashMap());
+        mSocketSources = Collections.synchronizedMap(new IdentityMap());
+
+        mListener = new CheckedSocket.ExceptionListener() {
+            public void exceptionOccurred(CheckedSocket s, Exception e, int count) {
+                if (count == 1) {
+                    deadFactory((SocketFactory)mSocketSources.get(s));
+                }
+            }
+        };
+    }
+
+    public void addSocketFactory(SocketFactory factory) {
+        mFactories.add(factory);
+    }
+
+    public void removeSocketFactory(SocketFactory factory) {
+        mFactories.remove(factory);
+        Thread t = (Thread)mResurrectors.remove(factory);
+        if (t != null) {
+            t.interrupt();
+        }
+    }
+
+    public InetAddressAndPort getInetAddressAndPort() {
+        try {
+            return getFactory(selectFactory(null)).getInetAddressAndPort();
+        }
+        catch (ConnectException e) {
+            return InetAddressAndPort.UNKNOWN;
+        }
+    }
+
+    public InetAddressAndPort getInetAddressAndPort(Object session) {
+        try {
+            return getFactory(selectFactory(session))
+                .getInetAddressAndPort(session);
+        }
+        catch (ConnectException e) {
+            return InetAddressAndPort.UNKNOWN;
+        }
+    }
+
+    public long getDefaultTimeout() {
+        return mTimeout;
+    }
+
+    public CheckedSocket createSocket()
+        throws ConnectException, SocketException
+    {
+        return createSocket(null, mTimeout);
+    }
+
+    public CheckedSocket createSocket(Object session)
+        throws ConnectException, SocketException
+    {
+        return createSocket(session, mTimeout);
+    }
+
+    public CheckedSocket createSocket(long timeout)
+        throws ConnectException, SocketException
+    {
+        return createSocket(null, timeout);
+    }
+
+    public CheckedSocket createSocket(Object session, long timeout)
+        throws ConnectException, SocketException
+    {
+        long startTime = timeout > 0 ? System.currentTimeMillis() : 0;
+        int index = selectFactory(session);
+        int count = mFactories.size();
+
+        for (int i=0; i<count; i++) {
+            SocketFactory factory = null;
+            try {
+                factory = getFactory(index++);
+                CheckedSocket socket = factory.createSocket(session, timeout);
+                socket.addExceptionListener(mListener);
+                mSocketSources.put(socket, factory);
+                return socket;
+            }
+            catch (SocketException e) {
+                deadFactory(factory);
+                
+                if (timeout == 0) {
+                    throw e;
+                }
+                
+                if (timeout > 0) {
+                    timeout -= (System.currentTimeMillis() - startTime);
+                    if (timeout < 0) {
+                        throw e;
+                    }
+                }
+            }
+        }
+
+        throw new ConnectException("Unable to create socket");
+    }
+
+    public CheckedSocket getSocket() throws ConnectException, SocketException {
+        return getSocket(null, mTimeout);
+    }
+
+    public CheckedSocket getSocket(Object session)
+        throws ConnectException, SocketException
+    {
+        return getSocket(session, mTimeout);
+    }
+
+    public CheckedSocket getSocket(long timeout)
+        throws ConnectException, SocketException
+    {
+        return getSocket(null, timeout);
+    }
+
+    public CheckedSocket getSocket(Object session, long timeout)
+        throws ConnectException, SocketException
+    {
+        long startTime = timeout > 0 ? System.currentTimeMillis() : 0;
+        int index = selectFactory(session);
+        int count = mFactories.size();
+
+        for (int i=0; i<count; i++) {
+            SocketFactory factory = null;
+            try {
+                factory = getFactory(index++);
+                CheckedSocket socket = factory.getSocket(session, timeout);
+                socket.addExceptionListener(mListener);
+                mSocketSources.put(socket, factory);
+                return socket;
+            }
+            catch (SocketException e) {
+                deadFactory(factory);
+                
+                if (timeout == 0) {
+                    throw e;
+                }
+                
+                if (timeout > 0) {
+                    timeout -= (System.currentTimeMillis() - startTime);
+                    if (timeout < 0) {
+                        throw e;
+                    }
+                }
+            }
+        }
+
+        throw new ConnectException("Unable to get socket");
+    }
+
+    public void recycleSocket(CheckedSocket socket)
+        throws SocketException, IllegalArgumentException
+    {
+        if (socket == null) {
+            return;
+        }
+
+        SocketFactory source = (SocketFactory)mSocketSources.remove(socket);
+
+        if (source == null) {
+            throw new IllegalArgumentException
+                ("Socket did not originate from this pool");
+        }
+
+        socket.removeExceptionListener(mListener);
+        source.recycleSocket(socket);
+    }
+
+    public void clear() {
+        synchronized (mFactories) {
+            for (int i = mFactories.size(); --i >= 0; ) {
+                ((SocketFactory)mFactories.get(i)).clear();
+            }
+        }
+    }
+
+    public int getAvailableCount() {
+        int count = 0;
+        synchronized (mFactories) {
+            for (int i = mFactories.size(); --i >= 0; ) {
+                count += ((SocketFactory)mFactories.get(i))
+                    .getAvailableCount();
+            }
+        }
+        return count;
+    }
+
+    /**
+     * The provided index must be positive, but it can be out of the factory
+     * list bounds.
+     */
+    private SocketFactory getFactory(int index) throws ConnectException {
+        synchronized (mFactories) {
+            int size = mFactories.size();
+            if (size <= 0) {
+                throw new ConnectException("No SocketFactories available");
+            }
+            return (SocketFactory)mFactories.get(index % size);
+        }
+    }
+
+    /**
+     * Returns an index which is positive, but may be out of the factory list
+     * bounds.
+     */
+    private int selectFactory(Object session) throws ConnectException {
+        if (session != null) {
+            return session.hashCode() & 0x7fffffff;
+        }
+        else {
+            synchronized (mFactories) {
+                return mFactoryIndex++ & 0x7fffffff;
+            }
+        }
+    }
+
+    private void deadFactory(SocketFactory factory) {
+        if (factory == null) {
+            return;
+        }
+
+        synchronized (mFactories) {
+            // Only remove factory if its not the last one left.
+            if (mFactories.contains(factory) && mFactories.size() > 1) {
+                mFactories.remove(factory);
+                
+                Resurrector r = new Resurrector(this, factory);
+                Thread t = new Thread(null, r, "Resurrector " +
+                                      factory.getInetAddressAndPort());
+                t.setDaemon(true);
+                t.start();
+                mResurrectors.put(factory, t);
+            }
+        }
+    }
+
+    private static class Resurrector implements Runnable {
+        // Weakly references owner so that this thread won't prevent it from
+        // being garbage collected.
+        private final Reference mOwner;
+        private final SocketFactory mFactory;
+
+        public Resurrector(DistributedSocketFactory owner,
+                           SocketFactory factory) {
+            mOwner = new WeakReference(owner);
+            mFactory = factory;
+        }
+
+        public void run() {
+            DistributedSocketFactory owner = null;
+            try {
+                while (!Thread.interrupted()) {
+                    owner = (DistributedSocketFactory)mOwner.get();
+                    if (owner == null) {
+                        break;
+                    }
+
+                    try {
+                        mFactory.recycleSocket(mFactory.createSocket());
+                        owner.mFactories.add(mFactory);
+                        break;
+                    }
+                    catch (IOException e) {
+                    }
+                    
+                    owner = null;
+
+                    // Wait at 5 seconds before trying again.
+                    try {
+                        Thread.sleep(5000);
+                    }
+                    catch (InterruptedException e) {
+                        break;
+                    }
+                }
+            }
+            finally {
+                owner = (DistributedSocketFactory)mOwner.get();
+                if (owner != null) {
+                    owner.mResurrectors.remove(mFactory);
+                }
+            }
+        }
+    }
+}