Module stincmale.server

Package stincmale.server.netty4.tcp

Class MonoHandler

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.channel.ChannelDuplexHandler

stincmale.server.netty4.tcp.MonoHandler

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler, ChannelOutboundHandler

@NotThreadSafe
public final class MonoHandler
extends ChannelDuplexHandler

The purpose of this ChannelDuplexHandler is to allow asynchronous processing of inbound messages while preserving the order of outbound response messages (which must correlate to the order of inbound messages) and allowing a client to send a next request before receiving an answer to the previous request. If you want to use the RequestDispatcher functionality, then use this handler indirectly via DispatchMonoHandler.

Disables auto read and controls read operations by itself (auto read is disabled in channelRegistered(ChannelHandlerContext) and is enabled back again in handlerRemoved(ChannelHandlerContext) if it was enabled before disabling). This handler must be placed in the ChannelPipeline above (after in the inbound/upstream evaluation order) any decoders, and above (before in the outbound/downstream evaluation order) any encoders:

  ChannelPipeline p = ...;
  ...
  p.addLast(new MyDecoder());
  ...
  p.addLast(new MyEncoder());
  ...
  p.addLast(new MonoHandler());
  ...
  p.addLast(new MyBusinessLogicHandler());
  ...
  p.addLast(new MyExceptionHandler());
  ...
 

and must not be added to the ChannelPipeline more than once.

The handler guarantees that at any given moment not more than one decoded message is processed by ChannelInboundHandlers which are above (after) this handler in the ChannelPipeline. In order this handler to function properly there must be a single outbound message written per each decoded inbound message that was fired upstream by this handler, and there must not be any other outbound messages. Such an outbound message may later be encoded to an empty message, or just ignored (one should use the VOID_OUTBOUND_MESSAGE to accomplish this).

See Also:

DispatchMonoHandler

Nested Class Summary

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

ChannelHandler.Sharable

Constructor Summary

Constructors

Constructor	Description
MonoHandler()

Method Summary

Modifier and Type	Method	Description
void	channelRead(ChannelHandlerContext ctx, Object msg)
void	channelReadComplete(ChannelHandlerContext ctx)
void	channelRegistered(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.fireChannelRegistered() and then ChannelHandlerContext.read().
void	handlerRemoved(ChannelHandlerContext ctx)	Returns auto read back as it was before channelRegistered(io.netty.channel.ChannelHandlerContext).
void	write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise)	Calls ChannelOutboundInvoker.write(java.lang.Object, io.netty.channel.ChannelPromise) if msg isn't VOID_OUTBOUND_MESSAGE and then either calls ChannelHandlerContext.read() or ChannelHandlerContext.fireChannelRead(java.lang.Object) if this handler has any accumulated inbound messages.

Methods inherited from class io.netty.channel.ChannelDuplexHandler

bind, close, connect, deregister, disconnect, flush, read

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelInactive, channelUnregistered, channelWritabilityChanged, exceptionCaught, userEventTriggered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, handlerAdded, 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

handlerAdded

Constructor Details

MonoHandler

public MonoHandler()

Method Details

channelRegistered

public final void channelRegistered(ChannelHandlerContext ctx) throws Exception

Calls ChannelHandlerContext.fireChannelRegistered() and then ChannelHandlerContext.read(). Disables auto read.

Specified by:

channelRegistered in interface ChannelInboundHandler

Overrides:

channelRegistered in class ChannelInboundHandlerAdapter

Throws:

Exception

channelRead

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

Specified by:

channelRead in interface ChannelInboundHandler

Overrides:

channelRead in class ChannelInboundHandlerAdapter

Throws:

Exception

channelReadComplete

public final void channelReadComplete(ChannelHandlerContext ctx) throws Exception

Specified by:

channelReadComplete in interface ChannelInboundHandler

Overrides:

channelReadComplete in class ChannelInboundHandlerAdapter

Throws:

Exception

write

public final void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception

Calls ChannelOutboundInvoker.write(java.lang.Object, io.netty.channel.ChannelPromise) if msg isn't VOID_OUTBOUND_MESSAGE and then either calls ChannelHandlerContext.read() or ChannelHandlerContext.fireChannelRead(java.lang.Object) if this handler has any accumulated inbound messages.

Specified by:

write in interface ChannelOutboundHandler

Overrides:

write in class ChannelDuplexHandler

Throws:

Exception

handlerRemoved

public final void handlerRemoved(ChannelHandlerContext ctx) throws Exception

Returns auto read back as it was before channelRegistered(io.netty.channel.ChannelHandlerContext).

Specified by:

handlerRemoved in interface ChannelHandler

Overrides:

handlerRemoved in class ChannelHandlerAdapter

Throws:

Exception