* Added NonReentrantLock

* Replaced ReentrantLock or monitor object with NonReentrantLock

src/main/java/org/jboss/netty/channel/socket/nio/NioDatagramChannel.java

@@ -15,8 +15,7 @@
  */
 package org.jboss.netty.channel.socket.nio;
 
-import static org.jboss.netty.channel.Channels.fireChannelInterestChanged;
-import static org.jboss.netty.channel.Channels.fireChannelOpen;
+import static org.jboss.netty.channel.Channels.*;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -28,7 +27,6 @@ import java.nio.channels.DatagramChannel;
 import java.util.Queue;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
-import java.util.concurrent.locks.ReentrantLock;
 
 import org.jboss.netty.buffer.ChannelBuffer;
 import org.jboss.netty.channel.AbstractChannel;
@@ -41,6 +39,7 @@ import org.jboss.netty.channel.ChannelSink;
 import org.jboss.netty.channel.MessageEvent;
 import org.jboss.netty.channel.socket.DatagramChannelConfig;
 import org.jboss.netty.util.internal.LinkedTransferQueue;
+import org.jboss.netty.util.internal.NonReentrantLock;
 import org.jboss.netty.util.internal.ThreadLocalBoolean;
 
 /**
@@ -76,9 +75,9 @@ class NioDatagramChannel extends AbstractChannel
     final Object interestOpsLock = new Object();
 
     /**
-     * Monitor object for synchronizing access to the {@link WriteBufferQueue}.
+     * Synchronizes access to the {@link WriteBufferQueue}.
      */
-    final ReentrantLock writeLock = new ReentrantLock();
+    final NonReentrantLock writeLock = new NonReentrantLock();
 
     /**
      * WriteTask that performs write operations.

src/main/java/org/jboss/netty/channel/socket/nio/NioDatagramWorker.java

@@ -34,7 +34,6 @@ import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.locks.ReadWriteLock;
-import java.util.concurrent.locks.ReentrantLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 import org.jboss.netty.buffer.ChannelBuffer;
@@ -48,6 +47,7 @@ import org.jboss.netty.logging.InternalLogger;
 import org.jboss.netty.logging.InternalLoggerFactory;
 import org.jboss.netty.util.ThreadRenamingRunnable;
 import org.jboss.netty.util.internal.LinkedTransferQueue;
+import org.jboss.netty.util.internal.NonReentrantLock;
 
 /**
  * A class responsible for registering channels with {@link Selector}.
@@ -443,8 +443,8 @@ class NioDatagramWorker implements Runnable {
             return;
         }
 
-        final ReentrantLock writeLock = channel.writeLock;
-        if (writeLock.isHeldByCurrentThread() || !writeLock.tryLock()) {
+        final NonReentrantLock writeLock = channel.writeLock;
+        if (!writeLock.tryLock()) {
             rescheduleWrite(channel);
             return;
         }

src/main/java/org/jboss/netty/channel/socket/nio/NioSocketChannel.java

@@ -15,7 +15,7 @@
  */
 package org.jboss.netty.channel.socket.nio;
 
-import static org.jboss.netty.channel.Channels.fireChannelInterestChanged;
+import static org.jboss.netty.channel.Channels.*;
 
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
@@ -24,7 +24,6 @@ import java.nio.channels.SocketChannel;
 import java.util.Queue;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
-import java.util.concurrent.locks.ReentrantLock;
 
 import org.jboss.netty.buffer.ChannelBuffer;
 import org.jboss.netty.channel.AbstractChannel;
@@ -35,6 +34,7 @@ import org.jboss.netty.channel.ChannelPipeline;
 import org.jboss.netty.channel.ChannelSink;
 import org.jboss.netty.channel.MessageEvent;
 import org.jboss.netty.util.internal.LinkedTransferQueue;
+import org.jboss.netty.util.internal.NonReentrantLock;
 import org.jboss.netty.util.internal.ThreadLocalBoolean;
 
 /**
@@ -60,7 +60,7 @@ class NioSocketChannel extends AbstractChannel
     private volatile InetSocketAddress remoteAddress;
 
     final Object interestOpsLock = new Object();
-    final ReentrantLock writeLock = new ReentrantLock();
+    final NonReentrantLock writeLock = new NonReentrantLock();
 
     final Runnable writeTask = new WriteTask();
     final AtomicBoolean writeTaskInTaskQueue = new AtomicBoolean();

src/main/java/org/jboss/netty/channel/socket/nio/NioWorker.java

@@ -33,7 +33,6 @@ import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.locks.ReadWriteLock;
-import java.util.concurrent.locks.ReentrantLock;
 import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 import org.jboss.netty.buffer.ChannelBuffer;
@@ -48,6 +47,7 @@ import org.jboss.netty.logging.InternalLoggerFactory;
 import org.jboss.netty.util.ThreadRenamingRunnable;
 import org.jboss.netty.util.internal.IoWorkerRunnable;
 import org.jboss.netty.util.internal.LinkedTransferQueue;
+import org.jboss.netty.util.internal.NonReentrantLock;
 
 /**
  *
@@ -372,8 +372,8 @@ class NioWorker implements Runnable {
             return;
         }
 
-        final ReentrantLock writeLock = channel.writeLock;
-        if (writeLock.isHeldByCurrentThread() || !writeLock.tryLock()) {
+        final NonReentrantLock writeLock = channel.writeLock;
+        if (!writeLock.tryLock()) {
             rescheduleWrite(channel);
             return;
         }

src/main/java/org/jboss/netty/handler/ssl/SslHandler.java

@@ -50,6 +50,7 @@ import org.jboss.netty.channel.MessageEvent;
 import org.jboss.netty.handler.codec.frame.FrameDecoder;
 import org.jboss.netty.logging.InternalLogger;
 import org.jboss.netty.logging.InternalLoggerFactory;
+import org.jboss.netty.util.internal.NonReentrantLock;
 
 /**
  * Adds <a href="http://en.wikipedia.org/wiki/Transport_Layer_Security">SSL
@@ -174,6 +175,7 @@ public class SslHandler extends FrameDecoder
     final Object ignoreClosedChannelExceptionLock = new Object();
     private final Queue<PendingWrite> pendingUnencryptedWrites = new LinkedList<PendingWrite>();
     private final Queue<MessageEvent> pendingEncryptedWrites = new LinkedList<MessageEvent>();
+    private final NonReentrantLock pendingEncryptedWritesLock = new NonReentrantLock();
 
     /**
      * Creates a new instance.
@@ -658,36 +660,35 @@ public class SslHandler extends FrameDecoder
     }
 
     private void offerEncryptedWriteRequest(MessageEvent encryptedWrite) {
-        boolean offered;
-        if (Thread.holdsLock(pendingEncryptedWrites)) {
-            offered = pendingEncryptedWrites.offer(encryptedWrite);
-        } else {
-            synchronized (pendingEncryptedWrites) {
-                offered = pendingEncryptedWrites.offer(encryptedWrite);
+        final boolean locked = pendingEncryptedWritesLock.tryLock();
+        try {
+            pendingEncryptedWrites.offer(encryptedWrite);
+        } finally {
+            if (locked) {
+                pendingEncryptedWritesLock.unlock();
             }
         }
-        assert offered;
     }
 
     private void flushPendingEncryptedWrites(ChannelHandlerContext ctx) {
         // Avoid possible dead lock and data integrity issue
         // which is caused by cross communication between more than one channel
         // in the same VM.
-        if (Thread.holdsLock(pendingEncryptedWrites)) {
+        if (!pendingEncryptedWritesLock.tryLock()) {
             return;
         }
 
-        synchronized (pendingEncryptedWrites) {
+        try {
             if (pendingEncryptedWrites.isEmpty()) {
                 return;
             }
-        }
 
-        synchronized (pendingEncryptedWrites) {
             MessageEvent e;
             while ((e = pendingEncryptedWrites.poll()) != null) {
                 ctx.sendDownstream(e);
             }
+        } finally {
+            pendingEncryptedWritesLock.unlock();
         }
     }
 
@@ -827,7 +828,7 @@ public class SslHandler extends FrameDecoder
                 // There is also a same issue between pendingEncryptedWrites
                 // and pendingUnencryptedWrites.
                 if (!Thread.holdsLock(handshakeLock) &&
-                    !Thread.holdsLock(pendingEncryptedWrites)) {
+                    !pendingEncryptedWritesLock.isHeldByCurrentThread()) {
                     wrap(ctx, channel);
                 }
             }

src/main/java/org/jboss/netty/util/internal/NonReentrantLock.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2010 Red Hat, Inc.
+ *
+ * Red Hat licenses this file to you under the Apache License, version 2.0
+ * (the "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at:
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+package org.jboss.netty.util.internal;
+
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.AbstractQueuedSynchronizer;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.Lock;
+
+/**
+ * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
+ * @author <a href="http://gleamynode.net/">Trustin Lee</a>
+ * @version $Rev$, $Date$
+ */
+public final class NonReentrantLock extends AbstractQueuedSynchronizer
+                             implements Lock {
+
+    private static final long serialVersionUID = -833780837233068610L;
+
+    private Thread owner;
+
+    public void lock() {
+        acquire(1);
+    }
+
+    public void lockInterruptibly() throws InterruptedException {
+        acquireInterruptibly(1);
+    }
+
+    public boolean tryLock() {
+        return tryAcquire(1);
+    }
+
+    public boolean tryLock(long time, TimeUnit unit)
+            throws InterruptedException {
+        return tryAcquireNanos(1, unit.toNanos(time));
+    }
+
+    public void unlock() {
+        release(1);
+    }
+
+    public boolean isHeldByCurrentThread() {
+        return isHeldExclusively();
+    }
+
+    public Condition newCondition() {
+        return new ConditionObject();
+    }
+
+    @Override
+    protected final boolean tryAcquire(int acquires) {
+        if (compareAndSetState(0, 1)) {
+            owner = Thread.currentThread();
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    protected final boolean tryRelease(int releases) {
+        if (Thread.currentThread() != owner) {
+            throw new IllegalMonitorStateException();
+        }
+        owner = null;
+        setState(0);
+        return true;
+    }
+
+    @Override
+    protected final boolean isHeldExclusively() {
+        return getState() != 0 && owner == Thread.currentThread();
+    }
+}