Elastic-Job初始化（1）

版权声明： https://blog.csdn.net/ph3636/article/details/86637762

1. 利用Spring进行配置，配置自己的分布式作业的命名空间处理器，这里主要以simple为主，前提还是要配置META-INF/spring.handlers和spring.schemas

public final class JobNamespaceHandler extends NamespaceHandlerSupport {
    
    @Override
    public void init() {
        registerBeanDefinitionParser("simple", new SimpleJobBeanDefinitionParser());
        registerBeanDefinitionParser("dataflow", new DataflowJobBeanDefinitionParser());
        registerBeanDefinitionParser("script", new ScriptJobBeanDefinitionParser());
    }
}

开始解析xml文件，主要解析代码在AbstractJobBeanDefinitionParser，主要解析类SpringJobScheduler构造函数的属性。属性分别为我们主要实现的job处理器，注册中心即zk，job的配置文件，job记录事件配置，job监听器

 public SpringJobScheduler(final ElasticJob elasticJob, final CoordinatorRegistryCenter regCenter, final LiteJobConfiguration jobConfig, 
                              final JobEventConfiguration jobEventConfig, final ElasticJobListener... elasticJobListeners) {
        super(regCenter, jobConfig, jobEventConfig, getTargetElasticJobListeners(elasticJobListeners));
        this.elasticJob = elasticJob;
    }

2. 实例化JobScheduler，先在任务注册类中注册该类的实例信息，设置监听器的保障服务类

 private JobScheduler(final CoordinatorRegistryCenter regCenter, final LiteJobConfiguration liteJobConfig, final JobEventBus jobEventBus, final ElasticJobListener... elasticJobListeners) {
        JobRegistry.getInstance().addJobInstance(liteJobConfig.getJobName(), new JobInstance());
        this.liteJobConfig = liteJobConfig;
        this.regCenter = regCenter;
        List<ElasticJobListener> elasticJobListenerList = Arrays.asList(elasticJobListeners);
        setGuaranteeServiceForElasticJobListeners(regCenter, elasticJobListenerList);
        schedulerFacade = new SchedulerFacade(regCenter, liteJobConfig.getJobName(), elasticJobListenerList);
        jobFacade = new LiteJobFacade(regCenter, liteJobConfig.getJobName(), Arrays.asList(elasticJobListeners), jobEventBus);
    }

实例化调度程序的门面类SchedulerFacade，里面会初始化各种作用的类，配置服务类，主节点服务类，服务节点类，实例服务类，分片服务类，执行服务类，监控服务类，调解分布式作业不一致状态服务类，各种监听器管理类，

public SchedulerFacade(final CoordinatorRegistryCenter regCenter, final String jobName, final List<ElasticJobListener> elasticJobListeners) {
        this.jobName = jobName;
        configService = new ConfigurationService(regCenter, jobName);
        leaderService = new LeaderService(regCenter, jobName);
        serverService = new ServerService(regCenter, jobName);
        instanceService = new InstanceService(regCenter, jobName);
        shardingService = new ShardingService(regCenter, jobName);
        executionService = new ExecutionService(regCenter, jobName);
        monitorService = new MonitorService(regCenter, jobName);
        reconcileService = new ReconcileService(regCenter, jobName);
        listenerManager = new ListenerManager(regCenter, jobName, elasticJobListeners);
    }

实例化任务门面类LiteJobFacade，和SchedulerFacade的内部属性类似

 public LiteJobFacade(final CoordinatorRegistryCenter regCenter, final String jobName, final List<ElasticJobListener> elasticJobListeners, final JobEventBus jobEventBus) {
        configService = new ConfigurationService(regCenter, jobName);
        shardingService = new ShardingService(regCenter, jobName);
        executionContextService = new ExecutionContextService(regCenter, jobName);
        executionService = new ExecutionService(regCenter, jobName);
        failoverService = new FailoverService(regCenter, jobName);
        this.elasticJobListeners = elasticJobListeners;
        this.jobEventBus = jobEventBus;
    }

增加了发布订阅组件JobEventBus，主要是通过开源框架guava的EventBus来实现。ExecutorServiceObject是个线程池，

public JobEventBus(final JobEventConfiguration jobEventConfig) {
        this.jobEventConfig = jobEventConfig;
        executorServiceObject = new ExecutorServiceObject("job-event", Runtime.getRuntime().availableProcessors() * 2);
        eventBus = new AsyncEventBus(executorServiceObject.createExecutorService());
        register();
    }
    
    private void register() {
        try {
            eventBus.register(jobEventConfig.createJobEventListener());
            isRegistered = true;
        } catch (final JobEventListenerConfigurationException ex) {
            log.error("Elastic job: create JobEventListener failure, error is: ", ex);
        }
    }

jobEventConfig为JobEventRdbConfiguration，创建事件监听器JobEventRdbListener，JobEventRdbStorage会初始化表。

public final class JobEventRdbListener extends JobEventRdbIdentity implements JobEventListener {
    
    private final JobEventRdbStorage repository;
    
    public JobEventRdbListener(final DataSource dataSource) throws SQLException {
        repository = new JobEventRdbStorage(dataSource);
    }
    
    @Override
    public void listen(final JobExecutionEvent executionEvent) {
        repository.addJobExecutionEvent(executionEvent);
    }
    
    @Override
    public void listen(final JobStatusTraceEvent jobStatusTraceEvent) {
        repository.addJobStatusTraceEvent(jobStatusTraceEvent);
    }
}

实现的接口是JobEventListener，EventBus主要是根据注解来解析@Subscribe@AllowConcurrentEvents匹配对应的方法。

public interface JobEventListener extends JobEventIdentity {
    
    /**
     * 作业执行事件监听执行.
     *
     * @param jobExecutionEvent 作业执行事件
     */
    @Subscribe
    @AllowConcurrentEvents
    void listen(JobExecutionEvent jobExecutionEvent);
    
    /**
     * 作业状态痕迹事件监听执行.
     *
     * @param jobStatusTraceEvent 作业状态痕迹事件
     */
    @Subscribe
    @AllowConcurrentEvents
    void listen(JobStatusTraceEvent jobStatusTraceEvent);
}

3. 因为在解析xml文件的时候factory.setInitMethodName("init");设置了init方法。实例化完成后会执行该方法。

 /**
     * 初始化作业.
     */
    public void init() {
        LiteJobConfiguration liteJobConfigFromRegCenter = schedulerFacade.updateJobConfiguration(liteJobConfig);
        JobRegistry.getInstance().setCurrentShardingTotalCount(liteJobConfigFromRegCenter.getJobName(), liteJobConfigFromRegCenter.getTypeConfig().getCoreConfig().getShardingTotalCount());
        JobScheduleController jobScheduleController = new JobScheduleController(
                createScheduler(), createJobDetail(liteJobConfigFromRegCenter.getTypeConfig().getJobClass()), liteJobConfigFromRegCenter.getJobName());
        JobRegistry.getInstance().registerJob(liteJobConfigFromRegCenter.getJobName(), jobScheduleController, regCenter);
        schedulerFacade.registerStartUpInfo(!liteJobConfigFromRegCenter.isDisabled());
        jobScheduleController.scheduleJob(liteJobConfigFromRegCenter.getTypeConfig().getCoreConfig().getCron());
    }

首先把任务配置存储到zk注册中心，具体流程是先检查该节点是否存在，节点的数据是否存在，节点数据的执行类是否一致，配置是否允许重写，最后选择是否替换为新的配置。所有的节点的父节点都是jobName。最后从注册中心中查找最新的配置信息。

 public LiteJobConfiguration updateJobConfiguration(final LiteJobConfiguration liteJobConfig) {
        configService.persist(liteJobConfig);
        return configService.load(false);
    }

 public LiteJobConfiguration load(final boolean fromCache) {
        String result;
        if (fromCache) {
            result = jobNodeStorage.getJobNodeData(ConfigurationNode.ROOT);
            if (null == result) {
                result = jobNodeStorage.getJobNodeDataDirectly(ConfigurationNode.ROOT);
            }
        } else {
            result = jobNodeStorage.getJobNodeDataDirectly(ConfigurationNode.ROOT);
        }
        return LiteJobConfigurationGsonFactory.fromJson(result);
    }

public void persist(final LiteJobConfiguration liteJobConfig) {
        checkConflictJob(liteJobConfig);
        if (!jobNodeStorage.isJobNodeExisted(ConfigurationNode.ROOT) || liteJobConfig.isOverwrite()) {
            jobNodeStorage.replaceJobNode(ConfigurationNode.ROOT, LiteJobConfigurationGsonFactory.toJson(liteJobConfig));
        }
    }
    
    private void checkConflictJob(final LiteJobConfiguration liteJobConfig) {
        Optional<LiteJobConfiguration> liteJobConfigFromZk = find();
        if (liteJobConfigFromZk.isPresent() && !liteJobConfigFromZk.get().getTypeConfig().getJobClass().equals(liteJobConfig.getTypeConfig().getJobClass())) {
            throw new JobConfigurationException("Job conflict with register center. The job '%s' in register center's class is '%s', your job class is '%s'", 
                    liteJobConfig.getJobName(), liteJobConfigFromZk.get().getTypeConfig().getJobClass(), liteJobConfig.getTypeConfig().getJobClass());
        }
    }
    
    private Optional<LiteJobConfiguration> find() {
        if (!jobNodeStorage.isJobNodeExisted(ConfigurationNode.ROOT)) {
            return Optional.absent();
        }
        LiteJobConfiguration result = LiteJobConfigurationGsonFactory.fromJson(jobNodeStorage.getJobNodeDataDirectly(ConfigurationNode.ROOT));
        if (null == result) {
            // TODO 应该删除整个job node,并非仅仅删除config node
            jobNodeStorage.removeJobNodeIfExisted(ConfigurationNode.ROOT);
        }
        return Optional.fromNullable(result);
    }

在任务注册类中注册该任务的分片数量。