--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/com/go/trove/net/InetAddressResolver.java	Sat Mar 21 11:00:06 2009 +0000
@@ -0,0 +1,211 @@
+/* ====================================================================
+ * 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.net.*;
+import java.util.*;
+import java.lang.ref.*;
+import com.go.trove.util.SoftHashMap;
+
+/******************************************************************************
+ * Allows network host names to resolve to inet addresses via event
+ * notification.
+ * <p>
+ * Note: This class makes use of the java.util.Timer class, available only in
+ * Java 2, version 1.3. 
+ *
+ * @author Brian S O'Neill
+ * @version
+ * <!--$$Revision: 1.1 $-->, <!--$$JustDate:--> 01/01/23 <!-- $-->
+ */
+public class InetAddressResolver {
+    // Wait for 10 minutes before trying to resolve again.
+    private static final long RESOLVE_PERIOD = 10 * 60 * 1000;
+    private static Timer cResolveTimer;
+
+    private static Map cResolvers = new SoftHashMap();
+
+    private static Timer getResolveTimer() {
+        Timer timer = cResolveTimer;
+        if (timer == null) {
+            timer = new Timer(true);
+            timer.schedule(new TimerTask() {
+                public void run() {
+                    Thread.currentThread().setName("InetAddressResolver");
+                }
+            }, 0);
+            cResolveTimer = timer;
+        }
+        return timer;
+    }
+
+    /**
+     * Resolve the host name into InetAddresses and listen for changes.
+     * The caller must save a reference to the resolver to prevent it from
+     * being reclaimed by the garbage collector.
+     *
+     * @param host host to resolve into InetAddresses
+     * @param listener listens for InetAddresses
+     */    
+    public static InetAddressResolver listenFor(String host,
+                                                InetAddressListener listener) {
+        synchronized (cResolvers) {
+            InetAddressResolver resolver = 
+                (InetAddressResolver)cResolvers.get(host);
+            if (resolver == null) {
+                resolver = new InetAddressResolver(host);
+                cResolvers.put(host, resolver);
+            }
+            resolver.addListener(listener);
+            return resolver;
+        }
+    }
+
+    private final String mHost;
+
+    private List mListeners = new ArrayList();
+    
+    // Is either an instance of UnknownHostException or InetAddress[].
+    private Object mResolutionResults;
+
+    private InetAddressResolver(String host) {
+        mHost = host;
+
+        // Initial delay is random so that requests against other hosts are
+        // staggered.
+        long delay = (long)(Math.random() * RESOLVE_PERIOD);
+        getResolveTimer().schedule(new Resolver(this), delay, RESOLVE_PERIOD);
+    }
+
+    private synchronized void addListener(InetAddressListener listener) {
+        mListeners.add(listener);
+        if (!resolveAddresses()) {
+            // Ensure that new listener is called the first time.
+            notifyListener(listener);
+        }
+    }
+
+    private synchronized void notifyListener(InetAddressListener listener) {
+        if (mResolutionResults instanceof UnknownHostException) {
+            listener.unknown((UnknownHostException)mResolutionResults);
+        }
+        else {
+            InetAddress[] addresses = (InetAddress[])mResolutionResults;
+            addresses = (InetAddress[])addresses.clone();
+            listener.resolved(addresses);
+        }
+    }
+
+    // Returns true if anything changed from the last time this was invoked.
+    private synchronized boolean resolveAddresses() {
+        boolean changed;
+        try {
+            InetAddress[] addresses = InetAddress.getAllByName(mHost);
+            if (mResolutionResults instanceof UnknownHostException) {
+                changed = true;
+            }
+            else {
+                // Results may be ordered differently, so keep them sorted.
+                Arrays.sort(addresses, new Comparator() {
+                    public int compare(Object a, Object b) {
+                        return ((InetAddress)a).getHostAddress()
+                            .compareTo(((InetAddress)b).getHostAddress());
+                    }
+                });
+
+                changed = !Arrays.equals
+                    (addresses, (InetAddress[])mResolutionResults);
+            }
+            mResolutionResults = addresses;
+        }
+        catch (UnknownHostException e) {
+            changed = !(mResolutionResults instanceof UnknownHostException);
+            mResolutionResults = e;
+        }
+
+        if (changed) {
+            int size = mListeners.size();
+            for (int i=0; i<size; i++) {
+                notifyListener((InetAddressListener)mListeners.get(i));
+            }
+        }
+
+        return changed;
+    }
+
+    private class Resolver extends TimerTask {
+        // Weakly references owner so that the timer won't prevent it from
+        // being garbage collected.
+        private final Reference mOwner;
+
+        public Resolver(InetAddressResolver owner) {
+            mOwner = new WeakReference(owner);
+        }
+
+        public void run() {
+            InetAddressResolver owner = (InetAddressResolver)mOwner.get();
+            if (owner == null) {
+                cancel();
+            }
+            Thread t = Thread.currentThread();
+            String originalName = t.getName();
+            t.setName("InetAddressResolver:" + owner.mHost);
+            try {
+                owner.resolveAddresses();
+            }
+            finally {
+                t.setName(originalName);
+            }
+        }
+    }
+}