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 java.io.Closeable; import java.lang.management.ManagementFactory; import java.util.UUID; import java.util.concurrent.TimeUnit; import java.util.concurrent.atomic.AtomicBoolean; import javax.management.MBeanServer; import javax.management.ObjectName; import javax.management.StandardMBean; import javax.net.ssl.SSLException; import io.netty.bootstrap.Bootstrap; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelInitializer; import io.netty.channel.ChannelOption; import io.netty.channel.ChannelPipeline; import io.netty.channel.EventLoopGroup; import io.netty.channel.nio.NioEventLoopGroup; import io.netty.channel.socket.SocketChannel; import io.netty.channel.socket.nio.NioSocketChannel; import io.netty.handler.codec.compression.SnappyFramedDecoder; import io.netty.handler.codec.string.StringEncoder; import io.netty.handler.ssl.SslContext; import io.netty.handler.ssl.util.InsecureTrustManagerFactory; import io.netty.handler.timeout.ReadTimeoutHandler; import io.netty.util.CharsetUtil; import org.apache.jackrabbit.oak.plugins.segment.SegmentStore; import org.apache.jackrabbit.oak.plugins.segment.standby.codec.RecordIdDecoder; import org.apache.jackrabbit.oak.plugins.segment.standby.jmx.ClientStandbyStatusMBean; import org.apache.jackrabbit.oak.plugins.segment.standby.jmx.StandbyStatusMBean; 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 final class StandbyClient implements ClientStandbyStatusMBean, Runnable, Closeable { public static final String CLIENT_ID_PROPERTY_NAME = "standbyID"; private static final Logger log = LoggerFactory.getLogger(StandbyClient.class); private final String host; private final int port; private final int readTimeoutMs; private final boolean autoClean; private final StandbyStore store; private final CommunicationObserver observer; private StandbyClientHandler handler; private EventLoopGroup group; private SslContext sslContext; private boolean active = false; private int failedRequests; private long lastSuccessfulRequest; private volatile String state; private final Object sync = new Object(); private final AtomicBoolean running = new AtomicBoolean(true); private long syncStartTimestamp; private long syncEndTimestamp; public StandbyClient(String host, int port, SegmentStore store, boolean secure, int readTimeoutMs, boolean autoClean) throws SSLException { this.state = STATUS_INITIALIZING; this.lastSuccessfulRequest = -1; this.syncStartTimestamp = -1; this.syncEndTimestamp = -1; this.failedRequests = 0; this.host = host; this.port = port; if (secure) { this.sslContext = SslContext.newClientContext(InsecureTrustManagerFactory.INSTANCE); } this.readTimeoutMs = readTimeoutMs; this.autoClean = autoClean; this.store = new StandbyStore(store); String s = System.getProperty(CLIENT_ID_PROPERTY_NAME); this.observer = new CommunicationObserver( (s == null || s.length() == 0) ? UUID.randomUUID().toString() : s); final MBeanServer jmxServer = ManagementFactory.getPlatformMBeanServer(); try { jmxServer.registerMBean(new StandardMBean(this, ClientStandbyStatusMBean.class), new ObjectName(this.getMBeanName())); } catch (Exception e) { log.error("can register standby status mbean", e); } } public String getMBeanName() { return StandbyStatusMBean.JMX_NAME + ",id=\"" + this.observer.getID() + "\""; } public void close() { stop(); state = STATUS_CLOSING; final MBeanServer jmxServer = ManagementFactory.getPlatformMBeanServer(); try { jmxServer.unregisterMBean(new ObjectName(this.getMBeanName())); } catch (Exception e) { log.error("can unregister standby status mbean", e); } observer.unregister(); shutdownNetty(); state = STATUS_CLOSED; } public void run() { if (!isRunning()) { // manually stopped return; } Bootstrap b; synchronized (this.sync) { if (this.active) { return; } state = STATUS_STARTING; handler = new StandbyClientHandler(this.store, observer, running, readTimeoutMs, autoClean); group = new NioEventLoopGroup(); b = new Bootstrap(); b.group(group); b.channel(NioSocketChannel.class); b.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, readTimeoutMs); b.option(ChannelOption.TCP_NODELAY, true); b.option(ChannelOption.SO_REUSEADDR, true); b.option(ChannelOption.SO_KEEPALIVE, true); b.handler(new ChannelInitializer<SocketChannel>() { @Override public void initChannel(SocketChannel ch) throws Exception { ChannelPipeline p = ch.pipeline(); if (sslContext != null) { p.addLast(sslContext.newHandler(ch.alloc())); } p.addLast("readTimeoutHandler", new ReadTimeoutHandler(readTimeoutMs, TimeUnit.MILLISECONDS)); p.addLast(new StringEncoder(CharsetUtil.UTF_8)); p.addLast(new SnappyFramedDecoder(true)); p.addLast(new RecordIdDecoder(store)); p.addLast(handler); } }); state = STATUS_RUNNING; this.active = true; } try { long startTimestamp = System.currentTimeMillis(); // Start the client. ChannelFuture f = b.connect(host, port).sync(); // Wait until the connection is closed. f.channel().closeFuture().sync(); this.failedRequests = 0; this.syncStartTimestamp = startTimestamp; this.syncEndTimestamp = System.currentTimeMillis(); this.lastSuccessfulRequest = syncEndTimestamp / 1000; } catch (Exception e) { this.failedRequests++; log.error("Failed synchronizing state.", e); } finally { synchronized (this.sync) { this.active = false; shutdownNetty(); } } } private void shutdownNetty() { if (handler != null) { handler.close(); handler = null; } if (group != null && !group.isShuttingDown()) { group.shutdownGracefully(0, 1, TimeUnit.SECONDS).syncUninterruptibly(); group = null; } } @Override public String getMode() { return "client: " + this.observer.getID(); } @Override public boolean isRunning() { return running.get(); } @Override public void start() { running.set(true); state = STATUS_RUNNING; } @Override public void stop() { running.set(false); state = STATUS_STOPPED; } @Override public String getStatus() { return this.state; } @Override public int getFailedRequests() { return this.failedRequests; } @Override public int getSecondsSinceLastSuccess() { if (this.lastSuccessfulRequest < 0) return -1; return (int) (System.currentTimeMillis() / 1000 - this.lastSuccessfulRequest); } @Override public int calcFailedRequests() { return this.getFailedRequests(); } @Override public int calcSecondsSinceLastSuccess() { return this.getSecondsSinceLastSuccess(); } @Override public void cleanup() { store.cleanup(); } @Override public long getSyncStartTimestamp() { return syncStartTimestamp; } @Override public long getSyncEndTimestamp() { return syncEndTimestamp; } }