Java tutorial
/* * Copyright (c) 2015 Intellectual Reserve, Inc. All rights reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * */ package cf.dropsonde.metron; import com.squareup.wire.Wire; import control.ControlMessage; import events.Heartbeat; import events.UUID; import io.netty.buffer.ByteBufInputStream; import io.netty.channel.ChannelDuplexHandler; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.socket.DatagramPacket; import io.netty.util.ReferenceCounted; /** * @author Mike Heath */ class ControlMessageHandler extends ChannelDuplexHandler { private final Wire wire = new Wire(); private long errorCount = 0; private long messagesReceived = 0; private long messagesSent = 0; @Override public void channelRead(ChannelHandlerContext context, Object message) throws Exception { try { messagesReceived++; final ByteBufInputStream input = new ByteBufInputStream(((DatagramPacket) message).content()); final ControlMessage controlMessage = wire.parseFrom(input, ControlMessage.class); final control.UUID identifier = controlMessage.identifier; switch (controlMessage.controlType) { case HeartbeatRequest: final Heartbeat heartbeat = new Heartbeat.Builder() .controlMessageIdentifier(new UUID(identifier.low, identifier.high)) .receivedCount(messagesReceived).errorCount(errorCount).sentCount(messagesSent).build(); context.writeAndFlush(heartbeat); break; default: throw new IllegalStateException( "Don't know how to handle messages of type: " + controlMessage.controlType); } } finally { if (message instanceof ReferenceCounted) { ((ReferenceCounted) message).release(); } } } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { errorCount++; } @Override public void flush(ChannelHandlerContext ctx) throws Exception { super.flush(ctx); messagesSent++; } }