package com.alibaba.otter.canal.common.zookeeper.running;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import org.I0Itec.zkclient.IZkDataListener;
import org.I0Itec.zkclient.exception.ZkException;
import org.I0Itec.zkclient.exception.ZkInterruptedException;
import org.I0Itec.zkclient.exception.ZkNoNodeException;
import org.I0Itec.zkclient.exception.ZkNodeExistsException;
import org.apache.zookeeper.CreateMode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.slf4j.MDC;
import com.alibaba.otter.canal.common.AbstractCanalLifeCycle;
import com.alibaba.otter.canal.common.utils.BooleanMutex;
import com.alibaba.otter.canal.common.utils.JsonUtils;
import com.alibaba.otter.canal.common.zookeeper.ZkClientx;
import com.alibaba.otter.canal.common.zookeeper.ZookeeperPathUtils;
/**
* 针对server的running节点控制
*
* @author jianghang 2012-11-22 下午02:59:42
* @version 1.0.0
*/
public class ServerRunningMonitor extends AbstractCanalLifeCycle {
private static final Logger logger = LoggerFactory.getLogger(ServerRunningMonitor.class);
private ZkClientx zkClient;
private String destination;
private IZkDataListener dataListener;
private BooleanMutex mutex = new BooleanMutex(false);
private volatile boolean release = false;
// 当前服务节点状态信息
private ServerRunningData serverData;
// 当前实际运行的节点状态信息
private volatile ServerRunningData activeData;
private ScheduledExecutorService delayExector = Executors.newScheduledThreadPool(1);
private int delayTime = 5;
private ServerRunningListener listener;
public ServerRunningMonitor(ServerRunningData serverData){
this();
this.serverData = serverData;
}
public ServerRunningMonitor(){
// 创建父节点
dataListener = new IZkDataListener() {
public void handleDataChange(String dataPath, Object data) throws Exception {
MDC.put("destination", destination);
ServerRunningData runningData = JsonUtils.unmarshalFromByte((byte[]) data, ServerRunningData.class);
if (!isMine(runningData.getAddress())) {
mutex.set(false);
}
if (!runningData.isActive() && isMine(runningData.getAddress())) { // 说明出现了主动释放的操作，并且本机之前是active
release = true;
releaseRunning();// 彻底释放mainstem
}
activeData = (ServerRunningData) runningData;
}
public void handleDataDeleted(String dataPath) throws Exception {
MDC.put("destination", destination);
mutex.set(false);
if (!release && isMine(activeData.getAddress())) {
// 如果上一次active的状态就是本机，则即时触发一下active抢占
initRunning();
} else {
// 否则就是等待delayTime，避免因网络瞬端或者zk异常，导致出现频繁的切换操作
delayExector.schedule(new Runnable() {
public void run() {
initRunning();
}
}, delayTime, TimeUnit.SECONDS);
}
}
};
}
public void start() {
super.start();
processStart();
if (zkClient != null) {
String path = ZookeeperPathUtils.getDestinationServerRunning(destination);
zkClient.subscribeDataChanges(path, dataListener);
initRunning();
} else {
processActiveEnter();// 没有zk，直接启动
}
}
public void stop() {
super.stop();
if (zkClient != null) {
String path = ZookeeperPathUtils.getDestinationServerRunning(destination);
zkClient.unsubscribeDataChanges(path, dataListener);
releaseRunning(); // 尝试一下release
} else {
processActiveExit(); // 没有zk，直接启动
}
processStop();
}
public void initRunning() {
if (!isStart()) {
return;
}
String path = ZookeeperPathUtils.getDestinationServerRunning(destination);
// 序列化
byte[] bytes = JsonUtils.marshalToByte(serverData);
try {
mutex.set(false);
zkClient.create(path, bytes, CreateMode.EPHEMERAL);
activeData = serverData;
processActiveEnter();// 触发一下事件
mutex.set(true);
} catch (ZkNodeExistsException e) {
bytes = zkClient.readData(path, true);
if (bytes == null) {// 如果不存在节点，立即尝试一次
initRunning();
} else {
activeData = JsonUtils.unmarshalFromByte(bytes, ServerRunningData.class);
}
} catch (ZkNoNodeException e) {
zkClient.createPersistent(ZookeeperPathUtils.getDestinationPath(destination), true); // 尝试创建父节点
initRunning();
}
}
/**
* 阻塞等待自己成为active，如果自己成为active，立马返回
*
* @throws InterruptedException
*/
public void waitForActive() throws InterruptedException {
initRunning();
mutex.get();
}
/**
* 检查当前的状态
*/
public boolean check() {
String path = ZookeeperPathUtils.getDestinationServerRunning(destination);
try {
byte[] bytes = zkClient.readData(path);
ServerRunningData eventData = JsonUtils.unmarshalFromByte(bytes, ServerRunningData.class);
activeData = eventData;// 更新下为最新值
// 检查下nid是否为自己
boolean result = isMine(activeData.getAddress());
if (!result) {
logger.warn("canal is running in node[{}] , but not in node[{}]", activeData.getCid(),
serverData.getCid());
}
return result;
} catch (ZkNoNodeException e) {
logger.warn("canal is not run any in node");
return false;
} catch (ZkInterruptedException e) {
logger.warn("canal check is interrupt");
Thread.interrupted();// 清除interrupt标记
return check();
} catch (ZkException e) {
logger.warn("canal check is failed");
return false;
}
}
public boolean releaseRunning() {
if (check()) {
String path = ZookeeperPathUtils.getDestinationServerRunning(destination);
zkClient.delete(path);
mutex.set(false);
processActiveExit();
return true;
}
return false;
}
// ====================== helper method ======================
private boolean isMine(String address) {
return address.equals(serverData.getAddress());
}
private void processStart() {
if (listener != null) {
try {
listener.processStart();
} catch (Exception e) {
logger.error("processStart failed", e);
}
}
}
private void processStop() {
if (listener != null) {
try {
listener.processStop();
} catch (Exception e) {
logger.error("processStop failed", e);
}
}
}
private void processActiveEnter() {
if (listener != null) {
try {
listener.processActiveEnter();
} catch (Exception e) {
logger.error("processSwitchActive failed", e);
}
}
}
private void processActiveExit() {
if (listener != null) {
try {
listener.processActiveExit();
} catch (Exception e) {
logger.error("processSwitchActive failed", e);
}
}
}
public void setListener(ServerRunningListener listener) {
this.listener = listener;
}
// ===================== setter / getter =======================
public void setDelayTime(int delayTime) {
this.delayTime = delayTime;
}
public void setServerData(ServerRunningData serverData) {
this.serverData = serverData;
}
public void setDestination(String destination) {
this.destination = destination;
}
public void setZkClient(ZkClientx zkClient) {
this.zkClient = zkClient;
}
}