Netty realizes Heartbeat sending mechanism

Netty realizes heartbeat sending mechanism
Processing an idle connection is a common task, in order to be able to release resources in a timely manner, it is necessary to detect idle connections and timeouts on the server side, often by sending information to test an inactive link, usually called "Heartbeat," and then at the far end confirming whether it is still alive, Netty provides Idlestatehandler handle this process;
The following is an example implementation controller, at the service end of each interval of 5s (set to 5s only for testing convenience, the actual development can set a longer event interval) to send a heartbeat packet to the client, add a listener, if the client should ring the heartbeat packet, prove that the client connection is valid, If the client does not respond, the client connection is invalid, and the listener obtains the event and shuts down the service-side connection;
Complete sample address (client with sample): Https://gitee.com/assad/netty-test-sample/tree/master/netty-test-sample/src/main/java/heartbeatSample
The following is the implementation of the service-side Heartbeat pack controller, Idlestatehandlerinitializer

public class Idlestatehandlerinitializer extends channelinitializer<channel>{

@Override

protected void Initchannel (Channel ch) throws Exception {

Channelpipeline pipeline = Ch.pipeline ();

Adding an idle state processor, when more than 5s does not receive information about the remote connection, the processor propagates a Idlestatehandler

Pipeline.addlast (New Idlestatehandler (0,0,5, timeunit.seconds));

Add a Idlestatehandler-propagated idlestateevent processor

Pipeline.addlast (New Heartbeathandler ());

Add a normal inbound processor

Pipeline.addlast (New Echoserverhandler ());

  }

Idleevent event Handler

public static final class Heartbeathandler extends channelinboundhandleradapter{

private static final Bytebuf heartbeat_sequence = Unpooled.unreleasablebuffer (

Unpooled.copiedbuffer ("HEARTBEAT", Charset.forname ("UTF-8"));

@Override

public void usereventtriggered (Channelhandlercontext ctx, Object evt) throws Exception {

if (evt instanceof idlestateevent) {

When the idlestateevent is captured, the heartbeat is sent to the far end, and a listener is added, and the server connection is closed if the send fails

Ctx.writeandflush (Heartbeat_sequence.duplicate ()). AddListener (Channelfuturelistener.close_on_failure);

  }else{

If the captured time is not a idlestateevent, the event is passed to the next processor

Super.usereventtriggered (CTX,EVT);

  }

  }

  }

@Sharable

Normal Inbound Processor: Print information that can be sent by the client

public class Echoserverhandler extends channelinboundhandleradapter{

@Override

public void Channelread (Channelhandlercontext ctx, Object msg) throws Exception {

Bytebuf in = (BYTEBUF) msg;

System.out.println ("Server Received:" + in.tostring (charsetutil.utf_8));

  }

@Override

public void Exceptioncaught (Channelhandlercontext ctx, Throwable cause) throws Exception {

Cause.printstacktrace ();

Ctx.close ();

  }

  }

}