前面讲了xxl-job的搭建，现在来粗略的解析下该分布式调度系统的源码，先来客户点代码
客户端源码
- 客户端开启的时候会向服务中心进行注册，其实现用的是jetty连接，且每隔半分钟会发送一次心跳，来告诉服务中心该执行器是否正常
- 查看源码可以从配置文件入手
@Bean(initMethod = "start", destroyMethod = "destroy")
public XxlJobExecutor xxlJobExecutor() {
logger.info(">>>>>>>>>>> xxl-jobhandler config init.");
XxlJobExecutor xxlJobExecutor = new XxlJobExecutor();
xxlJobExecutor.setAdminAddresses(adminAddresses);
xxlJobExecutor.setAppName(appName);
xxlJobExecutor.setIp(ip);
xxlJobExecutor.setPort(port);
xxlJobExecutor.setAccessToken(accessToken);
xxlJobExecutor.setLogPath(logPath);
xxlJobExecutor.setLogRetentionDays(logRetentionDays);
return xxlJobExecutor;
}很明显，在把配置信息注入以后，该配置执行了start方法，进入其中
- 可以看到以下代码，英文注释我斗胆翻译下~
// ---------------------- start stop ----------------------
public void start() throws Exception {
// init admin-client 初始化服务中心
initAdminBizList(adminAddresses, accessToken);
// init executor-jobHandlerRepository
// 初始化jobHandler也就是继承了该类的所有定时方法，模仿spring ioc，把实例化对象都保存了起来
initJobHandlerRepository(applicationContext);
// init logpath 初始化日志文件，设置文件路径
XxlJobFileAppender.initLogPath(logPath);
// init executor-server 初始化执行器服务，看参数知道这里就是jetty连接的主要地方了
initExecutorServer(port, ip, appName, accessToken);
// init JobLogFileCleanThread 看名字也知道 初始化日志清理线程，应该是用来定时清理日志的
JobLogFileCleanThread.getInstance().start(logRetentionDays);
}国人编写的代码就是有国人自己的风格，至少比国外的开源代码好看懂点
- 这里主要深入执行器部分吧，其他还是容易看懂的，继续深入
private void initExecutorServer(int port, String ip, String appName, String accessToken) throws Exception {
// valid param 可以看到，我们不配置jetty端口，它默认也是9999
port = port>0?port: NetUtil.findAvailablePort(9999);
// start server
NetComServerFactory.putService(ExecutorBiz.class, new ExecutorBizImpl()); // rpc-service, base on jetty
NetComServerFactory.setAccessToken(accessToken);
//主要就是这个方法了
serverFactory.start(port, ip, appName); // jetty registry
}继续深入
代码语言：javascript复制// ---------------------- server start ----------------------
//可以看到用到了jetty服务
JettyServer server = new JettyServer();
public void start(int port, String ip, String appName) throws Exception {
server.start(port, ip, appName);
}继续深入
代码语言：javascript复制public void start(final int port, final String ip, final String appName) throws Exception {
thread = new Thread(new Runnable() {
@Override
public void run() {
// The Server
server = new Server(new ExecutorThreadPool()); // 非阻塞
// HTTP connector
ServerConnector connector = new ServerConnector(server);
if (ip!=null && ip.trim().length()>0) {
connector.setHost(ip); // The network interface this connector binds to as an IP address or a hostname. If null or 0.0.0.0, then bind to all interfaces.
}
connector.setPort(port);
server.setConnectors(new Connector[]{connector});
// Set a handler
HandlerCollection handlerc =new HandlerCollection();
handlerc.setHandlers(new Handler[]{new JettyServerHandler()});
server.setHandler(handlerc);
try {
// Start server
server.start();
logger.info(">>>>>>>>>>> xxl-job jetty server start success at port:{}.", port);
// Start Registry-Server 注册到服务中心方法，单独线程执行
ExecutorRegistryThread.getInstance().start(port, ip, appName);
// Start Callback-Server 定时任务回调方法，单独线程执行
TriggerCallbackThread.getInstance().start();
server.join(); // block until thread stopped
logger.info(">>>>>>>>>>> xxl-rpc server join success, netcon={}, port={}", JettyServer.class.getName(), port);
} catch (Exception e) {
logger.error(e.getMessage(), e);
} finally {
//destroy();
}
}
});
thread.setDaemon(true); // daemon, service jvm, user thread leave >>> daemon leave >>> jvm leave
thread.start();
}可以看出这里主要关注
代码语言：javascript复制ExecutorRegistryThread.getInstance().start(port, ip, appName);
TriggerCallbackThread.getInstance().start();这两个方法 继续深入
代码语言：javascript复制public void start(final int port, final String ip, final String appName){
// valid
if (appName==null || appName.trim().length()==0) {
logger.warn(">>>>>>>>>>> xxl-job, executor registry config fail, appName is null.");
return;
}
if (XxlJobExecutor.getAdminBizList() == null) {
logger.warn(">>>>>>>>>>> xxl-job, executor registry config fail, adminAddresses is null.");
return;
}
// executor address (generate addredd = ip:port)
final String executorAddress;
if (ip != null && ip.trim().length()>0) {
executorAddress = ip.trim().concat(":").concat(String.valueOf(port));
} else {
executorAddress = IpUtil.getIpPort(port);
}
registryThread = new Thread(new Runnable() {
@Override
public void run() {
// registry 此线程为守护线程，不销毁，循环执行
while (!toStop) {
try {
RegistryParam registryParam = new RegistryParam(RegistryConfig.RegistType.EXECUTOR.name(), appName, executorAddress);
for (AdminBiz adminBiz: XxlJobExecutor.getAdminBizList()) {
try {
ReturnT<String> registryResult = adminBiz.registry(registryParam);
if (registryResult!=null && ReturnT.SUCCESS_CODE == registryResult.getCode()) {
registryResult = ReturnT.SUCCESS;
logger.info(">>>>>>>>>>> xxl-job registry success, registryParam:{}, registryResult:{}", new Object[]{registryParam, registryResult});
break;
} else {
logger.info(">>>>>>>>>>> xxl-job registry fail, registryParam:{}, registryResult:{}", new Object[]{registryParam, registryResult});
}
} catch (Exception e) {
logger.info(">>>>>>>>>>> xxl-job registry error, registryParam:{}", registryParam, e);
}
}
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
// 睡眠30秒
try {
TimeUnit.SECONDS.sleep(RegistryConfig.BEAT_TIMEOUT);
} catch (InterruptedException e) {
logger.error(e.getMessage(), e);
}
}
// registry remove 服务中心移除此任务起效果
try {
RegistryParam registryParam = new RegistryParam(RegistryConfig.RegistType.EXECUTOR.name(), appName, executorAddress);
for (AdminBiz adminBiz: XxlJobExecutor.getAdminBizList()) {
try {
ReturnT<String> registryResult = adminBiz.registryRemove(registryParam);
if (registryResult!=null && ReturnT.SUCCESS_CODE == registryResult.getCode()) {
registryResult = ReturnT.SUCCESS;
logger.info(">>>>>>>>>>> xxl-job registry-remove success, registryParam:{}, registryResult:{}", new Object[]{registryParam, registryResult});
break;
} else {
logger.info(">>>>>>>>>>> xxl-job registry-remove fail, registryParam:{}, registryResult:{}", new Object[]{registryParam, registryResult});
}
} catch (Exception e) {
logger.info(">>>>>>>>>>> xxl-job registry-remove error, registryParam:{}", registryParam, e);
}
}
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
logger.info(">>>>>>>>>>> xxl-job, executor registry thread destory.");
}
});
registryThread.setDaemon(true);
registryThread.start();
}继续
代码语言：javascript复制public void start() {
// valid
if (XxlJobExecutor.getAdminBizList() == null) {
logger.warn(">>>>>>>>>>> xxl-job, executor callback config fail, adminAddresses is null.");
return;
}
triggerCallbackThread = new Thread(new Runnable() {
@Override
public void run() {
// normal callback
while(!toStop){
try {
//这里采用了阻塞队列，可以看出，当服务中心发送任务到此队列，就会被消费
HandleCallbackParam callback = getInstance().callBackQueue.take();
if (callback != null) {
// callback list param
List<HandleCallbackParam> callbackParamList = new ArrayList<HandleCallbackParam>();
int drainToNum = getInstance().callBackQueue.drainTo(callbackParamList);
callbackParamList.add(callback);
// callback, will retry if error
if (callbackParamList!=null && callbackParamList.size()>0) {
doCallback(callbackParamList);
}
}
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
}
// last callback
try {
List<HandleCallbackParam> callbackParamList = new ArrayList<HandleCallbackParam>();
int drainToNum = getInstance().callBackQueue.drainTo(callbackParamList);
if (callbackParamList!=null && callbackParamList.size()>0) {
doCallback(callbackParamList);
}
} catch (Exception e) {
logger.error(e.getMessage(), e);
}
logger.info(">>>>>>>>>>> xxl-job, executor callback thread destory.");
}
});
triggerCallbackThread.setDaemon(true);
triggerCallbackThread.start();
}可以看到此方法放入任务
public static void pushCallBack(HandleCallbackParam callback){
getInstance().callBackQueue.add(callback);
logger.debug(">>>>>>>>>>> xxl-job, push callback request, logId:{}", callback.getLogId());
}后面可以追溯好多层级，最顶上发现
代码语言：javascript复制private RpcResponse doInvoke(HttpServletRequest request) {
try {
// deserialize request
byte[] requestBytes = HttpClientUtil.readBytes(request);
if (requestBytes == null || requestBytes.length==0) {
RpcResponse rpcResponse = new RpcResponse();
rpcResponse.setError("RpcRequest byte[] is null");
return rpcResponse;
}
RpcRequest rpcRequest = (RpcRequest) HessianSerializer.deserialize(requestBytes, RpcRequest.class);
// invoke 主要就是这个调用了，调用一次会执行一次对应任务
RpcResponse rpcResponse = NetComServerFactory.invokeService(rpcRequest, null);
return rpcResponse;
} catch (Exception e) {
logger.error(e.getMessage(), e);
RpcResponse rpcResponse = new RpcResponse();
rpcResponse.setError("Server-error:" e.getMessage());
return rpcResponse;
}
}而这个对象实际在JettyServer服务类中已经加入
代码语言：javascript复制// Set a handler
HandlerCollection handlerc =new HandlerCollection();
handlerc.setHandlers(new Handler[]{new JettyServerHandler()});
server.setHandler(handlerc);
