我正在参加「掘金·启航计划」
前言
XXL-JOB是一个分布式任务调度平台，其核心设计目标是开发迅速、学习简单、轻量级、易扩展。
版本：2.3.1
github：github.com/xuxueli/xxl…
执行器
1、入口
XxlJobSpringExecutor类，该类实现了SmartInitializingSingleton接口，在类初始化的时候会执行afterSingletonsInstantiated()方法。该类的afterSingletonsInstantiated方法执行了JobHandler的初始化和其父类XxlJobExecutor.start()。
@Override
public void afterSingletonsInstantiated() {
// init JobHandler Repository
/*initJobHandlerRepository(applicationContext);*/
// init JobHandler Repository (for method)
initJobHandlerMethodRepository(applicationContext);
// refresh GlueFactory
GlueFactory.refreshInstance(1);
// super start
try {
super.start();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
1.1、JobHandler的初始化
通过扫描@XxlJob（以前的版本是@JobHandler）注解，将实例存到ConcurrentHashMap中，key是@XxlJob注解中配置的name，value就是实例。
private void initJobHandlerMethodRepository(ApplicationContext applicationContext) {
if (applicationContext == null) {
return;
}
// init job handler from method
String[] beanDefinitionNames = applicationContext.getBeanNamesForType(Object.class, false, true);
for (String beanDefinitionName : beanDefinitionNames) {
Object bean = applicationContext.getBean(beanDefinitionName);
Map<Method, XxlJob> annotatedMethods = null; // referred to ：org.springframework.context.event.EventListenerMethodProcessor.processBean
try {
annotatedMethods = MethodIntrospector.selectMethods(bean.getClass(),
new MethodIntrospector.MetadataLookup<XxlJob>() {
@Override
public XxlJob inspect(Method method) {
return AnnotatedElementUtils.findMergedAnnotation(method, XxlJob.class);
}
});
} catch (Throwable ex) {
logger.error("xxl-job method-jobhandler resolve error for bean[" + beanDefinitionName + "].", ex);
}
if (annotatedMethods==null || annotatedMethods.isEmpty()) {
continue;
}
for (Map.Entry<Method, XxlJob> methodXxlJobEntry : annotatedMethods.entrySet()) {
Method executeMethod = methodXxlJobEntry.getKey();
XxlJob xxlJob = methodXxlJobEntry.getValue();
// regist
registJobHandler(xxlJob, bean, executeMethod);
}
}
}
// ---------------------- job handler repository ----------------------
private static ConcurrentMap<String, IJobHandler> jobHandlerRepository = new ConcurrentHashMap<String, IJobHandler>();
public static IJobHandler loadJobHandler(String name){
return jobHandlerRepository.get(name);
}
public static IJobHandler registJobHandler(String name, IJobHandler jobHandler){
logger.info(">>>>>>>>>>> xxl-job register jobhandler success, name:{}, jobHandler:{}", name, jobHandler);
return jobHandlerRepository.put(name, jobHandler);
}
1.2、start()
- 初始化日志文件目录
- 初始化调度通信客户端：读取XxlJobConfig中的adminAddresses配置，如果配的是多个，则初始化的客户端也是多个
private static List<AdminBiz> adminBizList;
private void initAdminBizList(String adminAddresses, String accessToken) throws Exception {
if (adminAddresses!=null && adminAddresses.trim().length()>0) {
for (String address: adminAddresses.trim().split(",")) {
if (address!=null && address.trim().length()>0) {
AdminBiz adminBiz = new AdminBizClient(address.trim(), accessToken);
if (adminBizList == null) {
adminBizList = new ArrayList<AdminBiz>();
}
adminBizList.add(adminBiz);
}
}
}
}
- 初始化日志清理线程
- 初始化结果回调线程：启动线程，监听callBackQueue队列，如果有回调消息，则遍历调用上一步初始化的客户端的回调接口/api/callback。
private void doCallback(List<HandleCallbackParam> callbackParamList){
boolean callbackRet = false;
// callback, will retry if error
for (AdminBiz adminBiz: XxlJobExecutor.getAdminBizList()) {
try {
ReturnT<String> callbackResult = adminBiz.callback(callbackParamList);
if (callbackResult!=null && ReturnT.SUCCESS_CODE == callbackResult.getCode()) {
callbackLog(callbackParamList, "<br>----------- xxl-job job callback finish.");
callbackRet = true;
break;
} else {
callbackLog(callbackParamList, "<br>----------- xxl-job job callback fail, callbackResult:" + callbackResult);
}
} catch (Exception e) {
callbackLog(callbackParamList, "<br>----------- xxl-job job callback error, errorMsg:" + e.getMessage());
}
}
if (!callbackRet) {
appendFailCallbackFile(callbackParamList);
}
}
- 初始化执行器服务器：初始化内置的Netty服务，然后遍历客户端，调用客户端的注册接口将执行器信息（读取XxlJobConfig的配置，如果是空，则使用默认的本机ip和9999端口）注册到每个客户端上。
private void initEmbedServer(String address, String ip, int port, String appname, String accessToken) throws Exception {
// fill ip port
port = port>0?port: NetUtil.findAvailablePort(9999);
ip = (ip!=null&&ip.trim().length()>0)?ip: IpUtil.getIp();
// generate address
if (address==null || address.trim().length()==0) {
String ip_port_address = IpUtil.getIpPort(ip, port); // registry-address：default use address to registry , otherwise use ip:port if address is null
address = "http://{ip_port}/".replace("{ip_port}", ip_port_address);
}
// accessToken
if (accessToken==null || accessToken.trim().length()==0) {
logger.warn(">>>>>>>>>>> xxl-job accessToken is empty. To ensure system security, please set the accessToken.");
}
// start
embedServer = new EmbedServer();
embedServer.start(address, port, appname, accessToken);
}
2、任务处理
执行器的Netty接收到任务请求，会交给EmbedServer的内部类EmbedHttpServerHandler的channelRead0处理。
protected void channelRead0(final ChannelHandlerContext ctx, FullHttpRequest msg) throws Exception {
// request parse
//final byte[] requestBytes = ByteBufUtil.getBytes(msg.content()); // byteBuf.toString(io.netty.util.CharsetUtil.UTF_8);
String requestData = msg.content().toString(CharsetUtil.UTF_8);
String uri = msg.uri();
HttpMethod httpMethod = msg.method();
boolean keepAlive = HttpUtil.isKeepAlive(msg);
String accessTokenReq = msg.headers().get(XxlJobRemotingUtil.XXL_JOB_ACCESS_TOKEN);
// invoke
bizThreadPool.execute(new Runnable() {
@Override
public void run() {
// do invoke
Object responseObj = process(httpMethod, uri, requestData, accessTokenReq);
// to json
String responseJson = GsonTool.toJson(responseObj);
// write response
writeResponse(ctx, keepAlive, responseJson);
}
});
}
根据请求的数据参数从之前初始化的JobHandler中获取具体的实例，然后扔到JobThread监听的任务队列triggerQueue中，等待执行。异步执行完成完成后进行回调，调度中心收到回调信息后，更新该任务的执行结果。
结语
这是我学习xxl-job源码的笔记，理解浅显，欢迎掘友指正。本期只介绍了执行器，调度器等我学习完会继续更新。
