io.netty.handler.flow

Class FlowControlHandler

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.channel.ChannelDuplexHandler

io.netty.handler.flow.FlowControlHandler

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler, ChannelOutboundHandler

public class FlowControlHandler
extends ChannelDuplexHandler

The FlowControlHandler ensures that only one message per read() is sent downstream. Classes such as ByteToMessageDecoder or MessageToByteEncoder are free to emit as many events as they like for any given input. A channel's auto reading configuration doesn't usually apply in these scenarios. This is causing problems in downstream ChannelHandlers that would like to hold subsequent events while they're processing one event. It's a common problem with the HttpObjectDecoder that will very often fire an HttpRequest that is immediately followed by a LastHttpContent event.

{@code
 ChannelPipeline pipeline = ...;

 pipeline.addLast(new HttpServerCodec());
 pipeline.addLast(new FlowControlHandler());

 pipeline.addLast(new MyExampleHandler());

 class MyExampleHandler extends ChannelInboundHandlerAdapter {

See Also:

ChannelConfig.setAutoRead(boolean)

Nested Class Summary

Nested classes/interfaces inherited from interface io.netty.channel.ChannelHandler

ChannelHandler.Sharable

Constructor Summary

Constructors

Constructor and Description
FlowControlHandler()
FlowControlHandler(boolean releaseMessages)

Method Summary

Modifier and Type	Method and Description
void	channelInactive(ChannelHandlerContext ctx) Calls ChannelHandlerContext.fireChannelInactive() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	channelRead(ChannelHandlerContext ctx, Object msg) Calls ChannelHandlerContext.fireChannelRead(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	channelReadComplete(ChannelHandlerContext ctx) Calls ChannelHandlerContext.fireChannelReadComplete() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	handlerAdded(ChannelHandlerContext ctx) Do nothing by default, sub-classes may override this method.
void	handlerRemoved(ChannelHandlerContext ctx) Do nothing by default, sub-classes may override this method.
void	read(ChannelHandlerContext ctx) Calls ChannelHandlerContext.read() to forward to the next ChannelOutboundHandler in the ChannelPipeline.

Methods inherited from class io.netty.channel.ChannelDuplexHandler

bind, close, connect, deregister, disconnect, flush, write

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaught, userEventTriggered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, isSharable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.netty.channel.ChannelHandler

exceptionCaught

Constructor Detail

FlowControlHandler

public FlowControlHandler()

FlowControlHandler

public FlowControlHandler(boolean releaseMessages)

Method Detail

handlerAdded

public void handlerAdded(ChannelHandlerContext ctx)
                  throws Exception

Description copied from class: ChannelHandlerAdapter

Do nothing by default, sub-classes may override this method.

Specified by:

handlerAdded in interface ChannelHandler

Overrides:

handlerAdded in class ChannelHandlerAdapter

Throws:

Exception

handlerRemoved

public void handlerRemoved(ChannelHandlerContext ctx)
                    throws Exception

Description copied from class: ChannelHandlerAdapter

Do nothing by default, sub-classes may override this method.

Specified by:

handlerRemoved in interface ChannelHandler

Overrides:

handlerRemoved in class ChannelHandlerAdapter

Throws:

Exception

channelInactive

public void channelInactive(ChannelHandlerContext ctx)
                     throws Exception

Description copied from class: ChannelInboundHandlerAdapter

Calls ChannelHandlerContext.fireChannelInactive() to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

channelInactive in interface ChannelInboundHandler

Overrides:

channelInactive in class ChannelInboundHandlerAdapter

Throws:

Exception

read

public void read(ChannelHandlerContext ctx)
          throws Exception

Description copied from class: ChannelDuplexHandler

Calls ChannelHandlerContext.read() to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

read in interface ChannelOutboundHandler

Overrides:

read in class ChannelDuplexHandler

Throws:

Exception

channelRead

public void channelRead(ChannelHandlerContext ctx,
                        Object msg)
                 throws Exception

Description copied from class: ChannelInboundHandlerAdapter

Calls ChannelHandlerContext.fireChannelRead(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

channelRead in interface ChannelInboundHandler

Overrides:

channelRead in class ChannelInboundHandlerAdapter

Throws:

Exception

channelReadComplete

public void channelReadComplete(ChannelHandlerContext ctx)
                         throws Exception

Description copied from class: ChannelInboundHandlerAdapter

Calls ChannelHandlerContext.fireChannelReadComplete() to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

channelReadComplete in interface ChannelInboundHandler

Overrides:

channelReadComplete in class ChannelInboundHandlerAdapter

Throws:

Exception