replicate/mdsal-replicate-netty/src/main/java/org/opendaylight/mdsal/replicate/netty/SourceKeepaliveHandler.java

   1 /*
   2  * Copyright (c) 2020 PANTHEON.tech, s.r.o. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.mdsal.replicate.netty;
   9
  10 import io.netty.channel.ChannelHandlerContext;
  11 import io.netty.handler.timeout.IdleStateEvent;
  12 import org.slf4j.Logger;
  13 import org.slf4j.LoggerFactory;
  14
  15 final class SourceKeepaliveHandler extends AbstractKeepaliveHandler {
  16     private static final Logger LOG = LoggerFactory.getLogger(SourceKeepaliveHandler.class);
  17
  18     private final int maxMissedKeepalives;
  19
  20     private int pingsSinceLastContact;
  21
  22     SourceKeepaliveHandler(final int maxMissedKeepalives) {
  23         this.maxMissedKeepalives = maxMissedKeepalives;
  24     }
  25
  26     /**
  27      * Intercept messages from the Sink. Reset the pingsSinceLastContact counter and forward the message.
  28      */
  29     @Override
  30     public void channelRead(final ChannelHandlerContext ctx, final Object msg) {
  31         pingsSinceLastContact = 0;
  32         ctx.fireChannelRead(msg);
  33     }
  34
  35     /**
  36      * If the IdleStateEvent was fired, it means the Source has not written anything to the Sink for the duration
  37      * specified by the keepalive-interval. PING will be sent and pingsSinceLastContact incremented.
  38      * If pingsSinceLastContact reaches max-missed-keepalives a KeepaliveException will be raised and channel closed.
  39      */
  40     @Override
  41     public void userEventTriggered(final ChannelHandlerContext ctx, final Object evt) {
  42         if (evt instanceof IdleStateEvent) {
  43             LOG.trace("IdleStateEvent received. Sending PING to sink");
  44             if (pingsSinceLastContact > maxMissedKeepalives) {
  45                 ctx.fireExceptionCaught(new KeepaliveException(maxMissedKeepalives));
  46             }
  47             ctx.channel().writeAndFlush(Constants.PING);
  48         } else {
  49             ctx.fireUserEventTriggered(evt);
  50         }
  51     }
  52 }