/*
    *  Licensed to the Apache Software Foundation (ASF) under one
    *  or more contributor license agreements.  See the NOTICE file
    *  distributed with this work for additional information
    *  regarding copyright ownership.  The ASF 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.apache.mina.core.session;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.net.SocketAddress;
  import java.nio.channels.FileChannel;
  import java.util.Iterator;
  import java.util.Queue;
  import java.util.Set;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.concurrent.atomic.AtomicInteger;
  import java.util.concurrent.atomic.AtomicLong;
  
  import org.apache.mina.core.buffer.IoBuffer;
  import org.apache.mina.core.file.DefaultFileRegion;
  import org.apache.mina.core.filterchain.IoFilterChain;
  import org.apache.mina.core.future.CloseFuture;
  import org.apache.mina.core.future.DefaultCloseFuture;
  import org.apache.mina.core.future.DefaultReadFuture;
  import org.apache.mina.core.future.DefaultWriteFuture;
  import org.apache.mina.core.future.IoFutureListener;
  import org.apache.mina.core.future.ReadFuture;
  import org.apache.mina.core.future.WriteFuture;
  import org.apache.mina.core.service.AbstractIoService;
  import org.apache.mina.core.service.IoAcceptor;
  import org.apache.mina.core.service.IoProcessor;
  import org.apache.mina.core.service.IoService;
  import org.apache.mina.core.service.TransportMetadata;
  import org.apache.mina.core.write.DefaultWriteRequest;
  import org.apache.mina.core.write.WriteException;
  import org.apache.mina.core.write.WriteRequest;
  import org.apache.mina.core.write.WriteRequestQueue;
  import org.apache.mina.core.write.WriteTimeoutException;
  import org.apache.mina.core.write.WriteToClosedSessionException;
  import org.apache.mina.util.CircularQueue;
  import org.apache.mina.util.ExceptionMonitor;
  
  
  /**
   * Base implementation of {@link IoSession}.
   *
   * @author The Apache MINA Project (dev@mina.apache.org)
   */
  public abstract class AbstractIoSession implements IoSession {
  
      private static final AttributeKey READY_READ_FUTURES_KEY =
          new AttributeKey(AbstractIoSession.class, "readyReadFutures");
      
      private static final AttributeKey WAITING_READ_FUTURES_KEY =
          new AttributeKey(AbstractIoSession.class, "waitingReadFutures");
  
      private static final IoFutureListener<CloseFuture> SCHEDULED_COUNTER_RESETTER =
          new IoFutureListener<CloseFuture>() {
              public void operationComplete(CloseFuture future) {
                  AbstractIoSession session = (AbstractIoSession) future.getSession();
                  session.scheduledWriteBytes.set(0);
                  session.scheduledWriteMessages.set(0);
                  session.readBytesThroughput = 0;
                  session.readMessagesThroughput = 0;
                  session.writtenBytesThroughput = 0;
                  session.writtenMessagesThroughput = 0;
              }
      };
  
      /**
       * An internal write request object that triggers session close.
       * @see #writeRequestQueue
       */
      private static final WriteRequest CLOSE_REQUEST =
          new DefaultWriteRequest(new Object());
  
      private final Object lock = new Object();
  
      private IoSessionAttributeMap attributes;
      private WriteRequestQueue writeRequestQueue;
      private WriteRequest currentWriteRequest;
      
      // The Session creation's time */
      private final long creationTime;
 
     /** An id generator guaranteed to generate unique IDs for the session */
     private static AtomicLong idGenerator = new AtomicLong(0);
     
     /** The session ID */
     private long sessionId;
     
     /**
      * A future that will be set 'closed' when the connection is closed.
      */
     private final CloseFuture closeFuture = new DefaultCloseFuture(this);
 
     private volatile boolean closing;
     
     // traffic control
     private boolean readSuspended=false;
     private boolean writeSuspended=false;
 
     // Status variables
     private final AtomicBoolean scheduledForFlush = new AtomicBoolean();
     private final AtomicInteger scheduledWriteBytes = new AtomicInteger();
     private final AtomicInteger scheduledWriteMessages = new AtomicInteger();
 
     private long readBytes;
     private long writtenBytes;
     private long readMessages;
     private long writtenMessages;
     private long lastReadTime;
     private long lastWriteTime;
 
     private long lastThroughputCalculationTime;
     private long lastReadBytes;
     private long lastWrittenBytes;
     private long lastReadMessages;
     private long lastWrittenMessages;
     private double readBytesThroughput;
     private double writtenBytesThroughput;
     private double readMessagesThroughput;
     private double writtenMessagesThroughput;
 
     private int idleCountForBoth;
     private int idleCountForRead;
     private int idleCountForWrite;
 
     private long lastIdleTimeForBoth;
     private long lastIdleTimeForRead;
     private long lastIdleTimeForWrite;
 
     private boolean deferDecreaseReadBuffer = true;
 
     /**
      * TODO Add method documentation
      */
     protected AbstractIoSession() {
         // Initialize all the Session counters to the current time 
         long currentTime = System.currentTimeMillis();
         creationTime = currentTime;
         lastThroughputCalculationTime = currentTime;
         lastReadTime = currentTime;
         lastWriteTime = currentTime;
         lastIdleTimeForBoth = currentTime;
         lastIdleTimeForRead = currentTime;
         lastIdleTimeForWrite = currentTime;
         
         // TODO add documentation
         closeFuture.addListener(SCHEDULED_COUNTER_RESETTER);
         
         // Set a new ID for this session
         sessionId = idGenerator.incrementAndGet();
     }
 
     /**
      * {@inheritDoc}
      * 
      * We use an AtomicLong to guarantee that the session ID are
      * unique.
      */
     public final long getId() {
         return sessionId;
     }
 
     /**
      * TODO Add method documentation
      */
     public abstract IoProcessor getProcessor();
 
     /**
      * {@inheritDoc}
      */
     public final boolean isConnected() {
         return !closeFuture.isClosed();
     }
 
     /**
      * {@inheritDoc}
      */
     public final boolean isClosing() {
         return closing || closeFuture.isClosed();
     }
 
     /**
      * {@inheritDoc}
      */
     public final CloseFuture getCloseFuture() {
         return closeFuture;
     }
 
     /**
      * TODO Add method documentation
      */
     public final boolean isScheduledForFlush() {
         return scheduledForFlush.get();
     }
 
     /**
      * TODO Add method documentation
      */
     public final boolean setScheduledForFlush(boolean flag) {
         if (flag) {
             return scheduledForFlush.compareAndSet(false, true);
         }
         
         scheduledForFlush.set(false);
         return true;
     }
 
     /**
      * {@inheritDoc}
      */
     public final CloseFuture close(boolean rightNow) {
         if (rightNow) {
             return close();
         }
         
         return closeOnFlush();
     }
 
     /**
      * {@inheritDoc}
      */
     public final CloseFuture close() {
         synchronized (lock) {
             if (isClosing()) {
                 return closeFuture;
             }
             
             closing = true;
         }
 
         getFilterChain().fireFilterClose();
         return closeFuture;
     }
 
     private final CloseFuture closeOnFlush() {
         getWriteRequestQueue().offer(this, CLOSE_REQUEST);
         getProcessor().flush(this);
         return closeFuture;
     }
 
     /**
      * {@inheritDoc}
      */
     public final ReadFuture read() {
         if (!getConfig().isUseReadOperation()) {
             throw new IllegalStateException("useReadOperation is not enabled.");
         }
 
         Queue<ReadFuture> readyReadFutures = getReadyReadFutures();
         ReadFuture future;
         synchronized (readyReadFutures) {
             future = readyReadFutures.poll();
             if (future != null) {
                 if (future.isClosed()) {
                     // Let other readers get notified.
                     readyReadFutures.offer(future);
                 }
             } else {
                 future = new DefaultReadFuture(this);
                 getWaitingReadFutures().offer(future);
             }
         }
 
         return future;
     }
 
     /**
      * TODO Add method documentation
      */
     public final void offerReadFuture(Object message) {
         newReadFuture().setRead(message);
     }
 
     /**
      * TODO Add method documentation
      */
     public final void offerFailedReadFuture(Throwable exception) {
         newReadFuture().setException(exception);
     }
 
     /**
      * TODO Add method documentation
      */
     public final void offerClosedReadFuture() {
         Queue<ReadFuture> readyReadFutures = getReadyReadFutures();
         synchronized (readyReadFutures) {
             newReadFuture().setClosed();
         }
     }
 
     /**
      * TODO Add method documentation
      */
     private ReadFuture newReadFuture() {
         Queue<ReadFuture> readyReadFutures = getReadyReadFutures();
         Queue<ReadFuture> waitingReadFutures = getWaitingReadFutures();
         ReadFuture future;
         synchronized (readyReadFutures) {
             future = waitingReadFutures.poll();
             if (future == null) {
                 future = new DefaultReadFuture(this);
                 readyReadFutures.offer(future);
             }
         }
         return future;
     }
 
     /**
      * TODO Add method documentation
      */
     private Queue<ReadFuture> getReadyReadFutures() {
         Queue<ReadFuture> readyReadFutures =
             (Queue<ReadFuture>) getAttribute(READY_READ_FUTURES_KEY);
         if (readyReadFutures == null) {
             readyReadFutures = new CircularQueue<ReadFuture>();
 
             Queue<ReadFuture> oldReadyReadFutures =
                 (Queue<ReadFuture>) setAttributeIfAbsent(
                         READY_READ_FUTURES_KEY, readyReadFutures);
             if (oldReadyReadFutures != null) {
                 readyReadFutures = oldReadyReadFutures;
             }
         }
         return readyReadFutures;
     }
 
     /**
      * TODO Add method documentation
      */
     private Queue<ReadFuture> getWaitingReadFutures() {
         Queue<ReadFuture> waitingReadyReadFutures =
             (Queue<ReadFuture>) getAttribute(WAITING_READ_FUTURES_KEY);
         if (waitingReadyReadFutures == null) {
             waitingReadyReadFutures = new CircularQueue<ReadFuture>();
 
             Queue<ReadFuture> oldWaitingReadyReadFutures =
                 (Queue<ReadFuture>) setAttributeIfAbsent(
                         WAITING_READ_FUTURES_KEY, waitingReadyReadFutures);
             if (oldWaitingReadyReadFutures != null) {
                 waitingReadyReadFutures = oldWaitingReadyReadFutures;
             }
         }
         return waitingReadyReadFutures;
     }
 
     /**
      * {@inheritDoc}
      */
     public WriteFuture write(Object message) {
         return write(message, null);
     }
 
     /**
      * {@inheritDoc}
      */
     public WriteFuture write(Object message, SocketAddress remoteAddress) {
         if (message == null) {
             throw new NullPointerException("message");
         }
 
         // We can't send a message to a connected session if we don't have 
         // the remote address
         if (!getTransportMetadata().isConnectionless() &&
                 remoteAddress != null) {
             throw new UnsupportedOperationException();
         }
 
         
         // If the session has been closed or is closing, we can't either
         // send a message to the remote side. We generate a future
         // containing an exception.
         if (isClosing() || !isConnected()) {
             WriteFuture future = new DefaultWriteFuture(this);
             WriteRequest request = new DefaultWriteRequest(message, future, remoteAddress);
             WriteException writeException = new WriteToClosedSessionException(request);
             future.setException(writeException);
             return future;
         }
 
         FileChannel openedFileChannel = null;
         
         // TODO: remove this code as soon as we use InputStream
         // instead of Object for the message.
         try {
             if (message instanceof IoBuffer
                     && !((IoBuffer) message).hasRemaining()) {
                 // Nothing to write : probably an error in the user code
                 throw new IllegalArgumentException(
                 "message is empty. Forgot to call flip()?");
             } else if (message instanceof FileChannel) {
                 FileChannel fileChannel = (FileChannel) message;
                 message = new DefaultFileRegion(fileChannel, 0, fileChannel.size());
             } else if (message instanceof File) {
                 File file = (File) message;
                 openedFileChannel = new FileInputStream(file).getChannel();
                 message = new DefaultFileRegion(openedFileChannel, 0, openedFileChannel.size());
             }
         } catch (IOException e) {
             ExceptionMonitor.getInstance().exceptionCaught(e);
             return DefaultWriteFuture.newNotWrittenFuture(this, e);
         }
 
         // Now, we can write the message. First, create a future
         WriteFuture writeFuture = new DefaultWriteFuture(this);
         WriteRequest writeRequest = new DefaultWriteRequest(message, writeFuture, remoteAddress);
         
         // Then, get the chain and inject the WriteRequest into it
         IoFilterChain filterChain = getFilterChain();
         filterChain.fireFilterWrite(writeRequest);
 
         // TODO : This is not our business ! The caller has created a FileChannel,
         // he has to close it !
         if (openedFileChannel != null) {
             // If we opened a FileChannel, it needs to be closed when the write has completed
             final FileChannel finalChannel = openedFileChannel;
             writeFuture.addListener(new IoFutureListener<WriteFuture>() {
                 public void operationComplete(WriteFuture future) {
                     try {
                         finalChannel.close();
                     } catch (IOException e) {
                         ExceptionMonitor.getInstance().exceptionCaught(e);
                     }
                 }
             });
         }
 
         // Return the WriteFuture.
         return writeFuture;
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object getAttachment() {
         return getAttribute("");
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object setAttachment(Object attachment) {
         return setAttribute("", attachment);
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object getAttribute(Object key) {
         return getAttribute(key, null);
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object getAttribute(Object key, Object defaultValue) {
         return attributes.getAttribute(this, key, defaultValue);
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object setAttribute(Object key, Object value) {
         return attributes.setAttribute(this, key, value);
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object setAttribute(Object key) {
         return setAttribute(key, Boolean.TRUE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object setAttributeIfAbsent(Object key, Object value) {
         return attributes.setAttributeIfAbsent(this, key, value);
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object setAttributeIfAbsent(Object key) {
         return setAttributeIfAbsent(key, Boolean.TRUE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object removeAttribute(Object key) {
         return attributes.removeAttribute(this, key);
     }
 
     /**
      * {@inheritDoc}
      */
     public final boolean removeAttribute(Object key, Object value) {
         return attributes.removeAttribute(this, key, value);
     }
 
     /**
      * {@inheritDoc}
      */
     public final boolean replaceAttribute(Object key, Object oldValue, Object newValue) {
         return attributes.replaceAttribute(this, key, oldValue, newValue);
     }
 
     /**
      * {@inheritDoc}
      */
     public final boolean containsAttribute(Object key) {
         return attributes.containsAttribute(this, key);
     }
 
     /**
      * {@inheritDoc}
      */
     public final Set<Object> getAttributeKeys() {
         return attributes.getAttributeKeys(this);
     }
 
     /**
      * TODO Add method documentation
      */
     public final IoSessionAttributeMap getAttributeMap() {
         return attributes;
     }
 
     /**
      * TODO Add method documentation
      */
     public final void setAttributeMap(IoSessionAttributeMap attributes) {
         this.attributes = attributes;
     }
 
     /**
      * Create a new close aware write queue, based on the given write queue.
      * 
      * @param writeRequestQueue The write request queue
      */
     public final void setWriteRequestQueue(WriteRequestQueue writeRequestQueue) {
         this.writeRequestQueue =
             new CloseAwareWriteQueue(writeRequestQueue);
     }
 
 
     /**
      * {@inheritDoc}
      */
     public final void suspendRead() {
         readSuspended = true;
         if (isClosing() || !isConnected()) {
             return;
         }
         getProcessor().updateTrafficControl(this);
     }
 
     /**
      * {@inheritDoc}
      */
     public final void suspendWrite() {
         writeSuspended = true;
         if (isClosing() || !isConnected()) {
             return;
         }
         getProcessor().updateTrafficControl(this);
     }
 
     /**
      * {@inheritDoc}
      */
     @SuppressWarnings("unchecked")
     public final void resumeRead() {
         readSuspended = false;
         if (isClosing() || !isConnected()) {
             return;
         }
         getProcessor().updateTrafficControl(this);
     }
 
     /**
      * {@inheritDoc}
      */
     @SuppressWarnings("unchecked")
     public final void resumeWrite() {
         writeSuspended = false;
         if (isClosing() || !isConnected()) {
             return;
         }
         getProcessor().updateTrafficControl(this);
     }
 
     /**
      * {@inheritDoc}
      */
     public boolean isReadSuspended() {
         return readSuspended;
     }
 
     /**
      * {@inheritDoc}
      */
     public boolean isWriteSuspended() {
         return writeSuspended; 
     }
     
     /**
      * {@inheritDoc}
      */
     public final long getReadBytes() {
         return readBytes;
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getWrittenBytes() {
         return writtenBytes;
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getReadMessages() {
         return readMessages;
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getWrittenMessages() {
         return writtenMessages;
     }
 
     /**
      * {@inheritDoc}
      */
     public final double getReadBytesThroughput() {
         return readBytesThroughput;
     }
 
     /**
      * {@inheritDoc}
      */
     public final double getWrittenBytesThroughput() {
         return writtenBytesThroughput;
     }
 
     /**
      * {@inheritDoc}
      */
     public final double getReadMessagesThroughput() {
         return readMessagesThroughput;
     }
 
     /**
      * {@inheritDoc}
      */
     public final double getWrittenMessagesThroughput() {
         return writtenMessagesThroughput;
     }
 
     /**
      * {@inheritDoc}
      */
     public final void updateThroughput(long currentTime, boolean force) {
         int interval = (int) (currentTime - lastThroughputCalculationTime);
 
         long minInterval = getConfig().getThroughputCalculationIntervalInMillis();
         if (minInterval == 0 || interval < minInterval) {
             if (!force) {
                 return;
             }
         }
 
         readBytesThroughput = (readBytes - lastReadBytes) * 1000.0 / interval;
         writtenBytesThroughput = (writtenBytes - lastWrittenBytes) * 1000.0 / interval;
         readMessagesThroughput = (readMessages - lastReadMessages) * 1000.0 / interval;
         writtenMessagesThroughput = (writtenMessages - lastWrittenMessages) * 1000.0 / interval;
 
         lastReadBytes = readBytes;
         lastWrittenBytes = writtenBytes;
         lastReadMessages = readMessages;
         lastWrittenMessages = writtenMessages;
 
         lastThroughputCalculationTime = currentTime;
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getScheduledWriteBytes() {
         return scheduledWriteBytes.get();
     }
 
     /**
      * {@inheritDoc}
      */
     public final int getScheduledWriteMessages() {
         return scheduledWriteMessages.get();
     }
 
     /**
      * TODO Add method documentation
      */
     protected void setScheduledWriteBytes(int byteCount){
         scheduledWriteBytes.set(byteCount);
     }
 
     /**
      * TODO Add method documentation
      */
     protected void setScheduledWriteMessages(int messages) {
         scheduledWriteMessages.set(messages);
     }
 
     /**
      * TODO Add method documentation
      */
     public final void increaseReadBytes(long increment, long currentTime) {
         if (increment <= 0) {
             return;
         }
 
         readBytes += increment;
         lastReadTime = currentTime;
         idleCountForBoth = 0;
         idleCountForRead = 0;
 
         if (getService() instanceof AbstractIoService) {
             ((AbstractIoService) getService()).getStatistics().increaseReadBytes(increment, currentTime);
         }
     }
 
     /**
      * TODO Add method documentation
      */
     public final void increaseReadMessages(long currentTime) {
         readMessages++;
         lastReadTime = currentTime;
         idleCountForBoth = 0;
         idleCountForRead = 0;
 
         if (getService() instanceof AbstractIoService) {
             ((AbstractIoService) getService()).getStatistics().increaseReadMessages(currentTime);
         }
     }
 
     /**
      * TODO Add method documentation
      */
     public final void increaseWrittenBytes(int increment, long currentTime) {
         if (increment <= 0) {
             return;
         }
 
         writtenBytes += increment;
         lastWriteTime = currentTime;
         idleCountForBoth = 0;
         idleCountForWrite = 0;
 
         if (getService() instanceof AbstractIoService) {
             ((AbstractIoService) getService()).getStatistics().increaseWrittenBytes(increment, currentTime);
         }
 
         increaseScheduledWriteBytes(-increment);
     }
 
     /**
      * TODO Add method documentation
      */
     public final void increaseWrittenMessages(
             WriteRequest request, long currentTime) {
         Object message = request.getMessage();
         if (message instanceof IoBuffer) {
             IoBuffer b = (IoBuffer) message;
             if (b.hasRemaining()) {
                 return;
             }
         }
 
         writtenMessages++;
         lastWriteTime = currentTime;
         if (getService() instanceof AbstractIoService) {
             ((AbstractIoService) getService()).getStatistics().increaseWrittenMessages(currentTime);
         }
 
         decreaseScheduledWriteMessages();
     }
 
     /**
      * TODO Add method documentation
      */
     public final void increaseScheduledWriteBytes(int increment) {
         scheduledWriteBytes.addAndGet(increment);
         if (getService() instanceof AbstractIoService) {
             ((AbstractIoService) getService()).getStatistics().increaseScheduledWriteBytes(increment);
         }
     }
 
     /**
      * TODO Add method documentation
      */
     public final void increaseScheduledWriteMessages() {
         scheduledWriteMessages.incrementAndGet();
         if (getService() instanceof AbstractIoService) {
             ((AbstractIoService) getService()).getStatistics().increaseScheduledWriteMessages();
         }
     }
 
     /**
      * TODO Add method documentation
      */
     private void decreaseScheduledWriteMessages() {
         scheduledWriteMessages.decrementAndGet();
         if (getService() instanceof AbstractIoService) {
             ((AbstractIoService) getService()).getStatistics().decreaseScheduledWriteMessages();
         }
     }
 
     /**
      * TODO Add method documentation
      */
     public final void decreaseScheduledBytesAndMessages(WriteRequest request) {
         Object message = request.getMessage();
         if (message instanceof IoBuffer) {
             IoBuffer b = (IoBuffer) message;
             if (b.hasRemaining()) {
                 increaseScheduledWriteBytes(-((IoBuffer) message).remaining());
             } else {
                 decreaseScheduledWriteMessages();
             }
         } else {
             decreaseScheduledWriteMessages();
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public final WriteRequestQueue getWriteRequestQueue() {
         if (writeRequestQueue == null) {
             throw new IllegalStateException();
         }
         return writeRequestQueue;
     }
 
     /**
      * {@inheritDoc}
      */
     public final WriteRequest getCurrentWriteRequest() {
         return currentWriteRequest;
     }
 
     /**
      * {@inheritDoc}
      */
     public final Object getCurrentWriteMessage() {
         WriteRequest req = getCurrentWriteRequest();
         if (req == null) {
             return null;
         }
         return req.getMessage();
     }
 
     /**
      * {@inheritDoc}
      */
     public final void setCurrentWriteRequest(WriteRequest currentWriteRequest) {
         this.currentWriteRequest = currentWriteRequest;
     }
 
     /**
      * TODO Add method documentation
      */
     public final void increaseReadBufferSize() {
         int newReadBufferSize = getConfig().getReadBufferSize() << 1;
         if (newReadBufferSize <= getConfig().getMaxReadBufferSize()) {
             getConfig().setReadBufferSize(newReadBufferSize);
         } else {
             getConfig().setReadBufferSize(getConfig().getMaxReadBufferSize());
         }
 
         deferDecreaseReadBuffer = true;
     }
 
     /**
      * TODO Add method documentation
      */
     public final void decreaseReadBufferSize() {
         if (deferDecreaseReadBuffer) {
             deferDecreaseReadBuffer = false;
             return;
         }
 
         if (getConfig().getReadBufferSize() > getConfig().getMinReadBufferSize()) {
             getConfig().setReadBufferSize(getConfig().getReadBufferSize() >>> 1);
         }
 
         deferDecreaseReadBuffer = true;
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getCreationTime() {
         return creationTime;
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getLastIoTime() {
         return Math.max(lastReadTime, lastWriteTime);
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getLastReadTime() {
         return lastReadTime;
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getLastWriteTime() {
         return lastWriteTime;
     }
 
     /**
      * {@inheritDoc}
      */
     public final boolean isIdle(IdleStatus status) {
         if (status == IdleStatus.BOTH_IDLE) {
             return idleCountForBoth > 0;
         }
 
         if (status == IdleStatus.READER_IDLE) {
             return idleCountForRead > 0;
         }
 
         if (status == IdleStatus.WRITER_IDLE) {
             return idleCountForWrite > 0;
         }
 
         throw new IllegalArgumentException("Unknown idle status: " + status);
     }
 
     /**
      * {@inheritDoc}
      */
     public final boolean isBothIdle() {
         return isIdle(IdleStatus.BOTH_IDLE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final boolean isReaderIdle() {
         return isIdle(IdleStatus.READER_IDLE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final boolean isWriterIdle() {
         return isIdle(IdleStatus.WRITER_IDLE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final int getIdleCount(IdleStatus status) {
         if (getConfig().getIdleTime(status) == 0) {
             if (status == IdleStatus.BOTH_IDLE) {
                 idleCountForBoth = 0;
             }
 
             if (status == IdleStatus.READER_IDLE) {
                 idleCountForRead = 0;
             }
 
             if (status == IdleStatus.WRITER_IDLE) {
                 idleCountForWrite = 0;
             }
         }
 
         if (status == IdleStatus.BOTH_IDLE) {
             return idleCountForBoth;
         }
 
         if (status == IdleStatus.READER_IDLE) {
             return idleCountForRead;
         }
 
         if (status == IdleStatus.WRITER_IDLE) {
             return idleCountForWrite;
         }
 
         throw new IllegalArgumentException("Unknown idle status: " + status);
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getLastIdleTime(IdleStatus status) {
         if (status == IdleStatus.BOTH_IDLE) {
             return lastIdleTimeForBoth;
         }
 
         if (status == IdleStatus.READER_IDLE) {
             return lastIdleTimeForRead;
         }
 
         if (status == IdleStatus.WRITER_IDLE) {
             return lastIdleTimeForWrite;
         }
 
         throw new IllegalArgumentException("Unknown idle status: " + status);
     }
 
     /**
      * TODO Add method documentation
      */
     public final void increaseIdleCount(IdleStatus status, long currentTime) {
         if (status == IdleStatus.BOTH_IDLE) {
             idleCountForBoth++;
             lastIdleTimeForBoth = currentTime;
         } else if (status == IdleStatus.READER_IDLE) {
             idleCountForRead++;
             lastIdleTimeForRead = currentTime;
         } else if (status == IdleStatus.WRITER_IDLE) {
             idleCountForWrite++;
             lastIdleTimeForWrite = currentTime;
         } else {
             throw new IllegalArgumentException("Unknown idle status: " + status);
         }
     }
 
     /**
      * {@inheritDoc}
      */
     public final int getBothIdleCount() {
         return getIdleCount(IdleStatus.BOTH_IDLE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getLastBothIdleTime() {
         return getLastIdleTime(IdleStatus.BOTH_IDLE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getLastReaderIdleTime() {
         return getLastIdleTime(IdleStatus.READER_IDLE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final long getLastWriterIdleTime() {
         return getLastIdleTime(IdleStatus.WRITER_IDLE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final int getReaderIdleCount() {
         return getIdleCount(IdleStatus.READER_IDLE);
     }
 
     /**
      * {@inheritDoc}
      */
     public final int getWriterIdleCount() {
         return getIdleCount(IdleStatus.WRITER_IDLE);
     }
 
     /**
      * {@inheritDoc}
      */
     public SocketAddress getServiceAddress() {
         IoService service = getService();
         if (service instanceof IoAcceptor) {
             return ((IoAcceptor) service).getLocalAddress();
         }
         
         return getRemoteAddress();
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public final int hashCode() {
         return super.hashCode();
     }
 
     /**
      * {@inheritDoc}
      * TODO This is a ridiculous implementation. Need to be replaced.
      */
     @Override
     public final boolean equals(Object o) {
         return super.equals(o);
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public String toString() {
         if (isConnected()||isClosing()) {
             if (getService() instanceof IoAcceptor) {
                 return "(" + getIdAsString() + ": " + getServiceName() + ", server, " +
                         getRemoteAddress() + " => " + getLocalAddress() + ')';
             }
 
             return "(" + getIdAsString() + ": " + getServiceName() + ", client, " +
                         getLocalAddress() + " => " + getRemoteAddress() + ')';
         }
         
         return "Session disconnected ...";
     }
 
     /**
      * TODO Add method documentation
      */
     private String getIdAsString() {
         String id = Long.toHexString(getId()).toUpperCase();
 
         // Somewhat inefficient, but it won't happen that often
         // because an ID is often a big integer.
         while (id.length() < 8) {
             id = '0' + id; // padding
         }
         id = "0x" + id;
 
         return id;
     }
 
     /**
      * TODO Add method documentation
      */
     private String getServiceName() {
         TransportMetadata tm = getTransportMetadata();
         if (tm == null) {
             return "null";
         }
         
         return tm.getProviderName() + ' ' + tm.getName();
     }
 
     /**
      * Fires a {@link IoEventType#SESSION_IDLE} event to any applicable
      * sessions in the specified collection.
      *
      * @param currentTime the current time (i.e. {@link System#currentTimeMillis()})
      */
     public static void notifyIdleness(Iterator<? extends IoSession> sessions, long currentTime) {
         IoSession s = null;
         while (sessions.hasNext()) {
             s = sessions.next();
             notifyIdleSession(s, currentTime);
         }
     }
 
     /**
      * Fires a {@link IoEventType#SESSION_IDLE} event if applicable for the
      * specified {@code session}.
      *
      * @param currentTime the current time (i.e. {@link System#currentTimeMillis()})
      */
     public static void notifyIdleSession(IoSession session, long currentTime) {
         notifyIdleSession0(
                 session, currentTime,
                 session.getConfig().getIdleTimeInMillis(IdleStatus.BOTH_IDLE),
                 IdleStatus.BOTH_IDLE, Math.max(
                     session.getLastIoTime(),
                     session.getLastIdleTime(IdleStatus.BOTH_IDLE)));
 
         notifyIdleSession0(
                 session, currentTime,
                 session.getConfig().getIdleTimeInMillis(IdleStatus.READER_IDLE),
                 IdleStatus.READER_IDLE, Math.max(
                     session.getLastReadTime(),
                     session.getLastIdleTime(IdleStatus.READER_IDLE)));
 
         notifyIdleSession0(
                 session, currentTime,
                 session.getConfig().getIdleTimeInMillis(IdleStatus.WRITER_IDLE),
                 IdleStatus.WRITER_IDLE, Math.max(
                     session.getLastWriteTime(),
                     session.getLastIdleTime(IdleStatus.WRITER_IDLE)));
 
         notifyWriteTimeout(session, currentTime);
     }
 
     private static void notifyIdleSession0(
             IoSession session, long currentTime,
             long idleTime, IdleStatus status, long lastIoTime) {
         if (idleTime > 0 && lastIoTime != 0
                 && currentTime - lastIoTime >= idleTime) {
             session.getFilterChain().fireSessionIdle(status);
         }
     }
 
     private static void notifyWriteTimeout(
             IoSession session, long currentTime) {
 
         long writeTimeout = session.getConfig().getWriteTimeoutInMillis();
         if (writeTimeout > 0 &&
                 currentTime - session.getLastWriteTime() >= writeTimeout &&
                 !session.getWriteRequestQueue().isEmpty(session)) {
             WriteRequest request = session.getCurrentWriteRequest();
             if (request != null) {
                 session.setCurrentWriteRequest(null);
                 WriteTimeoutException cause = new WriteTimeoutException(request);
                 request.getFuture().setException(cause);
                 session.getFilterChain().fireExceptionCaught(cause);
                 // WriteException is an IOException, so we close the session.
                 session.close(true);
             }
         }
     }
 
     
     
     /**
      * A queue which handles the CLOSE request.
      * 
      * TODO : Check that when closing a session, all the pending
      * requests are correctly sent.
      */
     private class CloseAwareWriteQueue implements WriteRequestQueue {
 
         private final WriteRequestQueue q;
 
         /**
          * {@inheritDoc}
          */
         public CloseAwareWriteQueue(WriteRequestQueue q) {
             this.q = q;
         }
 
         /**
          * {@inheritDoc}
          */
         public synchronized WriteRequest poll(IoSession session) {
             WriteRequest answer = q.poll(session);
             
             if (answer == CLOSE_REQUEST) {
                 AbstractIoSession.this.close();
                 dispose(session);
                 answer = null;
             }
             
             return answer;
         }
 
         /**
          * {@inheritDoc}
          */
         public void offer(IoSession session, WriteRequest e) {
             q.offer(session, e);
         }
 
         /**
          * {@inheritDoc}
          */
         public boolean isEmpty(IoSession session) {
             return q.isEmpty(session);
         }
 
         /**
          * {@inheritDoc}
          */
         public void clear(IoSession session) {
             q.clear(session);
         }
 
         /**
          * {@inheritDoc}
          */
         public void dispose(IoSession session) {
             q.dispose(session);
         }
     }
 }