/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project 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.handler.traffic;
  
  import org.jboss.netty.channel.Channel;
  import org.jboss.netty.channel.ChannelEvent;
  import org.jboss.netty.channel.ChannelHandlerContext;
  import org.jboss.netty.channel.ChannelState;
  import org.jboss.netty.channel.ChannelStateEvent;
  import org.jboss.netty.channel.MessageEvent;
  import org.jboss.netty.channel.SimpleChannelHandler;
  import org.jboss.netty.logging.InternalLogger;
  import org.jboss.netty.logging.InternalLoggerFactory;
  import org.jboss.netty.util.DefaultObjectSizeEstimator;
  import org.jboss.netty.util.ExternalResourceReleasable;
  import org.jboss.netty.util.ObjectSizeEstimator;
  import org.jboss.netty.util.Timeout;
  import org.jboss.netty.util.Timer;
  import org.jboss.netty.util.TimerTask;
  
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.AtomicBoolean;
  
  /**
   * AbstractTrafficShapingHandler allows to limit the global bandwidth
   * (see {@link GlobalTrafficShapingHandler}) or per session
   * bandwidth (see {@link ChannelTrafficShapingHandler}), as traffic shaping.
   * It allows too to implement an almost real time monitoring of the bandwidth using
   * the monitors from {@link TrafficCounter} that will call back every checkInterval
   * the method doAccounting of this handler.<br>
   * <br>
   *
   * An {@link ObjectSizeEstimator} can be passed at construction to specify what
   * is the size of the object to be read or write accordingly to the type of
   * object. If not specified, it will used the {@link DefaultObjectSizeEstimator} implementation.<br><br>
   *
   * If you want for any particular reasons to stop the monitoring (accounting) or to change
   * the read/write limit or the check interval, several methods allow that for you:<br>
   * <ul>
   * <li><tt>configure</tt> allows you to change read or write limits, or the checkInterval</li>
   * <li><tt>getTrafficCounter</tt> allows you to have access to the TrafficCounter and so to stop
   * or start the monitoring, to change the checkInterval directly, or to have access to its values.</li>
   * <li></li>
   * </ul>
   */
  public abstract class AbstractTrafficShapingHandler extends
          SimpleChannelHandler implements ExternalResourceReleasable {
      /**
       * Internal logger
       */
      static InternalLogger logger = InternalLoggerFactory
              .getInstance(AbstractTrafficShapingHandler.class);
  
      /**
       * Default delay between two checks: 1s
       */
      public static final long DEFAULT_CHECK_INTERVAL = 1000;
  
      /**
       * Default minimal time to wait
       */
      private static final long MINIMAL_WAIT = 10;
  
      /**
       * Traffic Counter
       */
      protected TrafficCounter trafficCounter;
  
      /**
       * ObjectSizeEstimator
       */
      private ObjectSizeEstimator objectSizeEstimator;
  
      /**
       * Timer to associated to any TrafficCounter
       */
      protected Timer timer;
  
      /**
       * used in releaseExternalResources() to cancel the timer
       */
      private volatile Timeout timeout;
  
      /**
       * Limit in B/s to apply to write
       */
     private long writeLimit;
 
     /**
      * Limit in B/s to apply to read
      */
     private long readLimit;
 
     /**
      * Delay between two performance snapshots
      */
     protected long checkInterval = DEFAULT_CHECK_INTERVAL; // default 1 s
 
     /**
      * Boolean associated with the release of this TrafficShapingHandler.
      * It will be true only once when the releaseExternalRessources is called
      * to prevent waiting when shutdown.
      */
     final AtomicBoolean release = new AtomicBoolean(false);
 
      private void init(ObjectSizeEstimator newObjectSizeEstimator,
              Timer newTimer, long newWriteLimit, long newReadLimit,
              long newCheckInterval) {
          objectSizeEstimator = newObjectSizeEstimator;
          timer = newTimer;
          writeLimit = newWriteLimit;
          readLimit = newReadLimit;
          checkInterval = newCheckInterval;
          //logger.warn("TSH: "+writeLimit+":"+readLimit+":"+checkInterval);
      }
 
     /**
      *
      * @param newTrafficCounter the TrafficCounter to set
      */
     void setTrafficCounter(TrafficCounter newTrafficCounter) {
         trafficCounter = newTrafficCounter;
     }
 
     /**
      * Constructor using default {@link ObjectSizeEstimator}
      *
      * @param timer
      *          created once for instance like HashedWheelTimer(10, TimeUnit.MILLISECONDS, 1024)
      * @param writeLimit
      *          0 or a limit in bytes/s
      * @param readLimit
      *          0 or a limit in bytes/s
      * @param checkInterval
      *          The delay between two computations of performances for
      *            channels or 0 if no stats are to be computed
      */
     protected AbstractTrafficShapingHandler(Timer timer, long writeLimit,
                                             long readLimit, long checkInterval) {
         init(new DefaultObjectSizeEstimator(), timer, writeLimit, readLimit, checkInterval);
     }
 
     /**
      * Constructor using the specified ObjectSizeEstimator
      *
      * @param objectSizeEstimator
      *            the {@link ObjectSizeEstimator} that will be used to compute
      *            the size of the message
      * @param timer
      *          created once for instance like HashedWheelTimer(10, TimeUnit.MILLISECONDS, 1024)
      * @param writeLimit
      *          0 or a limit in bytes/s
      * @param readLimit
      *          0 or a limit in bytes/s
      * @param checkInterval
      *          The delay between two computations of performances for
      *            channels or 0 if no stats are to be computed
      */
     protected AbstractTrafficShapingHandler(
             ObjectSizeEstimator objectSizeEstimator, Timer timer,
             long writeLimit, long readLimit, long checkInterval) {
         init(objectSizeEstimator, timer, writeLimit, readLimit, checkInterval);
     }
 
     /**
      * Constructor using default {@link ObjectSizeEstimator} and using default Check Interval
      *
      * @param timer
      *          created once for instance like HashedWheelTimer(10, TimeUnit.MILLISECONDS, 1024)
      * @param writeLimit
      *          0 or a limit in bytes/s
      * @param readLimit
      *          0 or a limit in bytes/s
      */
     protected AbstractTrafficShapingHandler(Timer timer, long writeLimit,
                                             long readLimit) {
         init(new DefaultObjectSizeEstimator(), timer, writeLimit, readLimit, DEFAULT_CHECK_INTERVAL);
     }
 
     /**
      * Constructor using the specified ObjectSizeEstimator and using default Check Interval
      *
      * @param objectSizeEstimator
      *            the {@link ObjectSizeEstimator} that will be used to compute
      *            the size of the message
      * @param timer
      *          created once for instance like HashedWheelTimer(10, TimeUnit.MILLISECONDS, 1024)
      * @param writeLimit
      *          0 or a limit in bytes/s
      * @param readLimit
      *          0 or a limit in bytes/s
      */
     protected AbstractTrafficShapingHandler(
             ObjectSizeEstimator objectSizeEstimator, Timer timer,
             long writeLimit, long readLimit) {
         init(objectSizeEstimator, timer, writeLimit, readLimit, DEFAULT_CHECK_INTERVAL);
     }
 
     /**
      * Constructor using default {@link ObjectSizeEstimator} and using NO LIMIT and default Check Interval
      *
      * @param timer
      *          created once for instance like HashedWheelTimer(10, TimeUnit.MILLISECONDS, 1024)
      */
     protected AbstractTrafficShapingHandler(Timer timer) {
         init(new DefaultObjectSizeEstimator(), timer, 0, 0, DEFAULT_CHECK_INTERVAL);
     }
 
     /**
      * Constructor using the specified ObjectSizeEstimator and using NO LIMIT and default Check Interval
      *
      * @param objectSizeEstimator
      *            the {@link ObjectSizeEstimator} that will be used to compute
      *            the size of the message
      * @param timer
      *          created once for instance like HashedWheelTimer(10, TimeUnit.MILLISECONDS, 1024)
      */
     protected AbstractTrafficShapingHandler(
             ObjectSizeEstimator objectSizeEstimator, Timer timer) {
         init(objectSizeEstimator, timer, 0, 0, DEFAULT_CHECK_INTERVAL);
     }
 
     /**
      * Constructor using default {@link ObjectSizeEstimator} and using NO LIMIT
      *
      * @param timer
      *          created once for instance like HashedWheelTimer(10, TimeUnit.MILLISECONDS, 1024)
      * @param checkInterval
      *          The delay between two computations of performances for
      *            channels or 0 if no stats are to be computed
      */
     protected AbstractTrafficShapingHandler(Timer timer, long checkInterval) {
         init(new DefaultObjectSizeEstimator(), timer, 0, 0, checkInterval);
     }
 
     /**
      * Constructor using the specified ObjectSizeEstimator and using NO LIMIT
      *
      * @param objectSizeEstimator
      *            the {@link ObjectSizeEstimator} that will be used to compute
      *            the size of the message
      * @param timer
      *          created once for instance like HashedWheelTimer(10, TimeUnit.MILLISECONDS, 1024)
      * @param checkInterval
      *          The delay between two computations of performances for
      *            channels or 0 if no stats are to be computed
      */
     protected AbstractTrafficShapingHandler(
             ObjectSizeEstimator objectSizeEstimator, Timer timer,
             long checkInterval) {
         init(objectSizeEstimator, timer, 0, 0, checkInterval);
     }
 
     /**
      * Change the underlying limitations and check interval.
      */
     public void configure(long newWriteLimit, long newReadLimit,
             long newCheckInterval) {
         configure(newWriteLimit, newReadLimit);
         configure(newCheckInterval);
     }
 
     /**
      * Change the underlying limitations.
      */
     public void configure(long newWriteLimit, long newReadLimit) {
         writeLimit = newWriteLimit;
         readLimit = newReadLimit;
         if (trafficCounter != null) {
             trafficCounter.resetAccounting(System.currentTimeMillis() + 1);
         }
     }
 
     /**
      * Change the check interval.
      */
     public void configure(long newCheckInterval) {
         checkInterval = newCheckInterval;
         if (trafficCounter != null) {
             trafficCounter.configure(checkInterval);
         }
     }
 
     /**
      * Called each time the accounting is computed from the TrafficCounters.
      * This method could be used for instance to implement almost real time accounting.
      *
      * @param counter
      *            the TrafficCounter that computes its performance
      */
     protected void doAccounting(TrafficCounter counter) {
         // NOOP by default
     }
 
     /**
      * Class to implement setReadable at fix time
      */
     private class ReopenReadTimerTask implements TimerTask {
         final ChannelHandlerContext ctx;
         ReopenReadTimerTask(ChannelHandlerContext ctx) {
             this.ctx = ctx;
         }
         public void run(Timeout timeoutArg) throws Exception {
             //logger.warn("Start RRTT: "+release.get());
             if (release.get()) {
                 return;
             }
             /*
             logger.warn("WAKEUP! "+
                     (ctx != null && ctx.getChannel() != null &&
                             ctx.getChannel().isConnected()));
              */
             if (ctx != null && ctx.getChannel() != null &&
                     ctx.getChannel().isConnected()) {
                 //logger.warn(" setReadable TRUE: ");
                 // readSuspended = false;
                 ctx.setAttachment(null);
                 ctx.getChannel().setReadable(true);
             }
         }
     }
 
     /**
     *
     * @return the time that should be necessary to wait to respect limit. Can
     *         be negative time
     */
     private static long getTimeToWait(long limit, long bytes, long lastTime,
             long curtime) {
         long interval = curtime - lastTime;
         if (interval == 0) {
             // Time is too short, so just lets continue
             return 0;
         }
         return (bytes * 1000 / limit - interval) / 10 * 10;
     }
 
     @Override
     public void messageReceived(ChannelHandlerContext ctx, MessageEvent evt)
             throws Exception {
         try {
             long curtime = System.currentTimeMillis();
             long size = objectSizeEstimator.estimateSize(evt.getMessage());
             if (trafficCounter != null) {
                 trafficCounter.bytesRecvFlowControl(size);
                 if (readLimit == 0) {
                     // no action
                     return;
                 }
                 // compute the number of ms to wait before reopening the channel
                 long wait = getTimeToWait(readLimit,
                         trafficCounter.getCurrentReadBytes(),
                         trafficCounter.getLastTime(), curtime);
                 if (wait >= MINIMAL_WAIT) { // At least 10ms seems a minimal
                                             // time in order to
                     Channel channel = ctx.getChannel();
                     // try to limit the traffic
                     if (channel != null && channel.isConnected()) {
                         // Channel version
                         if (timer == null) {
                             // Sleep since no executor
                             // logger.warn("Read sleep since no timer for "+wait+" ms for "+this);
                             if (release.get()) {
                                 return;
                             }
                             Thread.sleep(wait);
                             return;
                         }
                         if (ctx.getAttachment() == null) {
                             // readSuspended = true;
                             ctx.setAttachment(Boolean.TRUE);
                             channel.setReadable(false);
                             // logger.warn("Read will wakeup after "+wait+" ms "+this);
                             TimerTask timerTask = new ReopenReadTimerTask(ctx);
                             timeout = timer.newTimeout(timerTask, wait,
                                     TimeUnit.MILLISECONDS);
                         } else {
                             // should be waiting: but can occurs sometime so as
                             // a FIX
                             // logger.warn("Read sleep ok but should not be here: "+wait+" "+this);
                             if (release.get()) {
                                 return;
                             }
                             Thread.sleep(wait);
                         }
                     } else {
                         // Not connected or no channel
                         // logger.warn("Read sleep "+wait+" ms for "+this);
                         if (release.get()) {
                             return;
                         }
                         Thread.sleep(wait);
                     }
                 }
             }
         } finally {
             // The message is then just passed to the next handler
             super.messageReceived(ctx, evt);
         }
     }
 
     @Override
     public void writeRequested(ChannelHandlerContext ctx, MessageEvent evt)
             throws Exception {
         try {
             long curtime = System.currentTimeMillis();
             long size = objectSizeEstimator.estimateSize(evt.getMessage());
             if (trafficCounter != null) {
                 trafficCounter.bytesWriteFlowControl(size);
                 if (writeLimit == 0) {
                     return;
                 }
                 // compute the number of ms to wait before continue with the
                 // channel
                 long wait = getTimeToWait(writeLimit,
                         trafficCounter.getCurrentWrittenBytes(),
                         trafficCounter.getLastTime(), curtime);
                 if (wait >= MINIMAL_WAIT) {
                     // Global or Channel
                     if (release.get()) {
                         return;
                     }
                     Thread.sleep(wait);
                 }
             }
         } finally {
             // The message is then just passed to the next handler
             super.writeRequested(ctx, evt);
         }
     }
     @Override
     public void handleDownstream(ChannelHandlerContext ctx, ChannelEvent e)
             throws Exception {
         if (e instanceof ChannelStateEvent) {
             ChannelStateEvent cse = (ChannelStateEvent) e;
             if (cse.getState() == ChannelState.INTEREST_OPS &&
                     (((Integer) cse.getValue()).intValue() & Channel.OP_READ) != 0) {
 
                 // setReadable(true) requested
                 boolean readSuspended = ctx.getAttachment() != null;
                 if (readSuspended) {
                     // Drop the request silently if this handler has
                     // set the flag.
                     e.getFuture().setSuccess();
                     return;
                 }
             }
         }
         super.handleDownstream(ctx, e);
     }
 
     /**
      *
      * @return the current TrafficCounter (if
      *         channel is still connected)
      */
     public TrafficCounter getTrafficCounter() {
         return trafficCounter;
     }
 
     public void releaseExternalResources() {
         if (trafficCounter != null) {
             trafficCounter.stop();
         }
         release.set(true);
         if (timeout != null) {
             timeout.cancel();
         }
     }
 
     @Override
     public String toString() {
         return "TrafficShaping with Write Limit: " + writeLimit +
                 " Read Limit: " + readLimit + " and Counter: " +
                 (trafficCounter != null? trafficCounter.toString() : "none");
     }
 }