com.typesafe.netty

Class HandlerPublisher<T>

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.channel.ChannelDuplexHandler

com.typesafe.netty.HandlerPublisher<T>

All Implemented Interfaces:

io.netty.channel.ChannelHandler, io.netty.channel.ChannelInboundHandler, io.netty.channel.ChannelOutboundHandler, org.reactivestreams.Publisher<T>

public class HandlerPublisher<T>
extends io.netty.channel.ChannelDuplexHandler
implements org.reactivestreams.Publisher<T>

Publisher for a Netty Handler. This publisher supports only one subscriber. All interactions with the subscriber are done from the handlers executor, hence, they provide the same happens before semantics that Netty provides. The handler publishes all messages that match the type as specified by the passed in class. Any non matching messages are forwarded to the next handler. The publisher will signal complete if it receives a channel inactive event. The publisher will release any messages that it drops (for example, messages that are buffered when the subscriber cancels), but other than that, it does not release any messages. It is up to the subscriber to release messages. If the subscriber cancels, the publisher will send a close event up the channel pipeline. All errors will short circuit the buffer, and cause publisher to immediately call the subscribers onError method, dropping the buffer. The publisher can be subscribed to or placed in a handler chain in any order.

Nested Class Summary

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

io.netty.channel.ChannelHandler.Sharable

Constructor Summary

Constructors

Constructor and Description
HandlerPublisher(io.netty.util.concurrent.EventExecutor executor, Class<? extends T> subscriberMessageType) Create a handler publisher.

Method Summary

Modifier and Type	Method and Description
protected boolean	acceptInboundMessage(Object msg) Returns true if the given message should be handled.
protected void	cancelled() Override to handle when a subscriber cancels the subscription.
void	channelActive(io.netty.channel.ChannelHandlerContext ctx)
void	channelInactive(io.netty.channel.ChannelHandlerContext ctx)
void	channelRead(io.netty.channel.ChannelHandlerContext ctx, Object message)
void	channelReadComplete(io.netty.channel.ChannelHandlerContext ctx)
void	channelRegistered(io.netty.channel.ChannelHandlerContext ctx)
void	exceptionCaught(io.netty.channel.ChannelHandlerContext ctx, Throwable cause)
void	handlerAdded(io.netty.channel.ChannelHandlerContext ctx)
void	handlerRemoved(io.netty.channel.ChannelHandlerContext ctx)
protected void	requestDemand() Override to intercept when demand is requested.
void	subscribe(org.reactivestreams.Subscriber<? super T> subscriber)

Methods inherited from class io.netty.channel.ChannelDuplexHandler

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

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelUnregistered, channelWritabilityChanged, 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

Constructor Detail

HandlerPublisher

public HandlerPublisher(io.netty.util.concurrent.EventExecutor executor,
                        Class<? extends T> subscriberMessageType)

Create a handler publisher. The supplied executor must be the same event loop as the event loop that this handler is eventually registered with, if not, an exception will be thrown when the handler is registered.

Parameters:

executor - The executor to execute asynchronous events from the subscriber on.

subscriberMessageType - The type of message this publisher accepts.

Method Detail

acceptInboundMessage

protected boolean acceptInboundMessage(Object msg)
                                throws Exception

Returns true if the given message should be handled. If false it will be passed to the next ChannelInboundHandler in the ChannelPipeline.

Parameters:

msg - The message to check.

Returns:

True if the message should be accepted.

Throws:

Exception

cancelled

protected void cancelled()

Override to handle when a subscriber cancels the subscription. By default, this method will simply close the channel.

requestDemand

protected void requestDemand()

Override to intercept when demand is requested. By default, a channel read is invoked.

subscribe

public void subscribe(org.reactivestreams.Subscriber<? super T> subscriber)

Specified by:

subscribe in interface org.reactivestreams.Publisher<T>

handlerAdded

public void handlerAdded(io.netty.channel.ChannelHandlerContext ctx)
                  throws Exception

Specified by:

handlerAdded in interface io.netty.channel.ChannelHandler

Overrides:

handlerAdded in class io.netty.channel.ChannelHandlerAdapter

Throws:

Exception

channelRegistered

public void channelRegistered(io.netty.channel.ChannelHandlerContext ctx)
                       throws Exception

Specified by:

channelRegistered in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelRegistered in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

Exception

channelActive

public void channelActive(io.netty.channel.ChannelHandlerContext ctx)
                   throws Exception

Specified by:

channelActive in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelActive in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

Exception

channelRead

public void channelRead(io.netty.channel.ChannelHandlerContext ctx,
                        Object message)
                 throws Exception

Specified by:

channelRead in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelRead in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

Exception

channelReadComplete

public void channelReadComplete(io.netty.channel.ChannelHandlerContext ctx)
                         throws Exception

Specified by:

channelReadComplete in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelReadComplete in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

Exception

channelInactive

public void channelInactive(io.netty.channel.ChannelHandlerContext ctx)
                     throws Exception

Specified by:

channelInactive in interface io.netty.channel.ChannelInboundHandler

Overrides:

channelInactive in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

Exception

handlerRemoved

public void handlerRemoved(io.netty.channel.ChannelHandlerContext ctx)
                    throws Exception

Specified by:

handlerRemoved in interface io.netty.channel.ChannelHandler

Overrides:

handlerRemoved in class io.netty.channel.ChannelHandlerAdapter

Throws:

Exception

exceptionCaught

public void exceptionCaught(io.netty.channel.ChannelHandlerContext ctx,
                            Throwable cause)
                     throws Exception

Specified by:

exceptionCaught in interface io.netty.channel.ChannelHandler

Specified by:

exceptionCaught in interface io.netty.channel.ChannelInboundHandler

Overrides:

exceptionCaught in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

Exception