Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 org.apache.jackrabbit.oak.plugins.segment.standby.client; import static org.apache.jackrabbit.oak.plugins.segment.standby.codec.Messages.newGetHeadReq; import java.io.Closeable; import java.util.concurrent.atomic.AtomicBoolean; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.handler.timeout.ReadTimeoutHandler; import org.apache.jackrabbit.oak.plugins.segment.RecordId; import org.apache.jackrabbit.oak.plugins.segment.standby.codec.RecordIdDecoder; import org.apache.jackrabbit.oak.plugins.segment.standby.codec.ReplyDecoder; import org.apache.jackrabbit.oak.plugins.segment.standby.store.CommunicationObserver; import org.apache.jackrabbit.oak.plugins.segment.standby.store.StandbyStore; import org.slf4j.Logger; import org.slf4j.LoggerFactory; public class StandbyClientHandler extends SimpleChannelInboundHandler<RecordId> implements Closeable { private static final Logger log = LoggerFactory.getLogger(StandbyClientHandler.class); private final StandbyStore store; private final CommunicationObserver observer; private final AtomicBoolean running; private final int readTimeoutMs; private final boolean autoClean; public StandbyClientHandler(final StandbyStore store, CommunicationObserver observer, AtomicBoolean running, int readTimeoutMs, boolean autoClean) { this.store = store; this.observer = observer; this.running = running; this.readTimeoutMs = readTimeoutMs; this.autoClean = autoClean; } @Override public void channelActive(ChannelHandlerContext ctx) throws Exception { log.debug("sending head request"); ctx.writeAndFlush(newGetHeadReq(this.observer.getID())); log.debug("did send head request"); } @Override protected void channelRead0(ChannelHandlerContext ctx, RecordId msg) throws Exception { setHead(ctx, msg); }; @Override public void channelReadComplete(ChannelHandlerContext ctx) { ctx.flush(); } synchronized void setHead(ChannelHandlerContext ctx, RecordId head) { if (store.getHead().getRecordId().equals(head)) { // all sync'ed up log.debug("no changes on sync."); return; } log.debug("updating current head to " + head); ctx.pipeline().remove(ReadTimeoutHandler.class); ctx.pipeline().remove(RecordIdDecoder.class); ctx.pipeline().remove(this); ctx.pipeline().addLast(new ReplyDecoder(store)); ctx.pipeline().addLast( new SegmentLoaderHandler(store, head, this.observer.getID(), running, readTimeoutMs, autoClean)); ctx.pipeline().fireUserEventTriggered("sync"); } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception { log.error("Exception caught, closing channel.", cause); close(); } @Override public void close() { // This handler doesn't own resources to release } }