Package org.jboss.netty.handler.traffic

Class ChannelTrafficShapingHandler

java.lang.Object
org.jboss.netty.channel.SimpleChannelHandler
org.jboss.netty.handler.traffic.AbstractTrafficShapingHandler
org.jboss.netty.handler.traffic.ChannelTrafficShapingHandler
All Implemented Interfaces:
ChannelDownstreamHandler, ChannelHandler, ChannelUpstreamHandler, ExternalResourceReleasable
public class ChannelTrafficShapingHandler extends AbstractTrafficShapingHandler

This implementation of the AbstractTrafficShapingHandler is for channel traffic shaping, that is to say a per channel limitation of the bandwidth.

The general use should be as follow:

  • Add in your pipeline a new ChannelTrafficShapingHandler, before a recommended ExecutionHandler (like OrderedMemoryAwareThreadPoolExecutor or MemoryAwareThreadPoolExecutor).

    ChannelTrafficShapingHandler myHandler = new ChannelTrafficShapingHandler(timer);

    timer could be created using HashedWheelTimer

    pipeline.addLast("CHANNEL_TRAFFIC_SHAPING", myHandler);

    Note that this handler has a Pipeline Coverage of "one" which means a new handler must be created for each new channel as the counter cannot be shared among all channels. For instance, if you have a ChannelPipelineFactory, you should create a new ChannelTrafficShapingHandler in this ChannelPipelineFactory each time getPipeline() method is called.

    Other arguments can be passed like write or read limitation (in bytes/s where 0 means no limitation) or the check interval (in millisecond) that represents the delay between two computations of the bandwidth and so the call back of the doAccounting method (0 means no accounting at all).

    A value of 0 means no accounting for checkInterval. If you need traffic shaping but no such accounting, it is recommended to set a positive value, even if it is high since the precision of the Traffic Shaping depends on the period where the traffic is computed. The highest the interval, the less precise the traffic shaping will be. It is suggested as higher value something close to 5 or 10 minutes.

    maxTimeToWait, by default set to 15s, allows to specify an upper bound of time shaping.

  • When you shutdown your application, release all the external resources (except the timer internal itself) by calling:
    myHandler.releaseExternalResources();
  • In your handler, you should consider to use the channel.isWritable() and channelInterestChanged(ctx, event) to handle writability, or through future.addListener(new ChannelFutureListener()) on the future returned by channel.write().

  • You shall also consider to have object size in read or write operations relatively adapted to the bandwidth you required: for instance having 10 MB objects for 10KB/s will lead to burst effect, while having 100 KB objects for 1 MB/s should be smoothly handle by this TrafficShaping handler.

  • Some configuration methods will be taken as best effort, meaning that all already scheduled traffics will not be changed, but only applied to new traffics.

    So the expected usage of those methods are to be used not too often, accordingly to the traffic shaping configuration.