[cloud native] use of Nacos taskmanager task management

Task management class

because Nacos This is used in many places in TaskManager, So we need to know what this class is for , It will not be difficult to read the source code later ;

Say first conclusion :
TaskManager It can be regarded as a set of tasks to be executed , Used to handle tasks that must be performed successfully Single threaded processing of tasks , Ensure that the task is successfully handled ; If the execution fails , The task will be put back into the collection for the next consumption ;

AbstractTask

AbstractTask It's an abstract class , All tasks that need to be executed continue with this class ; This class mainly provides the data and methods needed to perform tasks ; for example

   /*  The interval between two processes of a task , In milliseconds */
    private long taskInterval;
    /* The last time the task was processed , In milliseconds */
    private long lastProcessTime;
/* TaskManager  Determine whether you need to deal with this Task, Subclasses can Override This function implements its own logic  */
    public boolean shouldProcess() {
    
        return (System.currentTimeMillis() - this.lastProcessTime >= this.taskInterval);
    }

TaskProcessor Task processor

TaskProcessor Is the task processor interface , It has a way

boolean process(String taskType, AbstractTask task);

Used to execute the corresponding AbstractTask The task class ; Different types of tasks , You can implement your own execution task logic ;

TaskManager Task management class

TaskManager It is a task management class ;
There are two properties in it to save the tasks to be consumed AbstractTask, And task execution TaskProcessor;

/** Tasks to be consumed AbstractTask**/
private final ConcurrentHashMap<String, AbstractTask> tasks = new ConcurrentHashMap<String, AbstractTask>();
/** Mission AbstractTask Corresponding task executor TaskProcessor**/
 private final ConcurrentHashMap<String, TaskProcessor> taskProcessors =new ConcurrentHashMap<String, TaskProcessor>();

If taskProcessors No corresponding task executor was found in , Then it has a default actuator that will execute

 /** Default actuator **/
 private TaskProcessor defaultTaskProcessor;

Use cases

Nacos An important function of the configuration center module is , During initialization and every other period of time, all data will be stored in the database Dump To disk ;Dump It is a task class AbstractTask; We said that above
AbstractTask It is an information bearing object , Mainly for TaskProcessor Provide the data required for execution ; Let's see. DumpTask;

DumpTask

DumpTask Defines some of its own properties ; Look at other examples DumpAllTask、DumpAllBetaTask

These two task classes only define TASK_ID
Since there are DumpTask The task class , There must be a corresponding task processor class DumpProcessor;

DumpProcessor

DumpProcessor yes DumpTask The executor of the task ; Methods in actuators

public boolean process(String taskType, AbstractTask task)

The code is too long to be analyzed here , Its main operation is Save the configuration file to the local disk , And cache md5
See the article for details 【Nacos Configuration management of source code Four 】DumpService How to complete the configuration file Dump To disk

Corresponding DumpAllTask、DumpAllBetaTask The task executors of the task are DumpAllProcessor、DumpAllBetaProcessor

DumpAllTask Where the task triggers execution

It's on it DumpAllTask The definition and DumpAllTaskProcessor Definition of actuator ; How is it triggered after it is defined ？

DumpService initialization Dump Configuration information

This class is specialized in Dump Service class of configuration information ; As mentioned above DumpAll It is here that is called ; Let's take a look at his main methods ;

    @PostConstruct
    public void init() {
    
        DumpAllProcessor dumpAllProcessor = new DumpAllProcessor(this);
      /** stay new This TaskManager Class time , A thread dedicated to the task has already started , But there is no task at this time Task Add in **/
       dumpAllTaskMgr = new TaskManager( "com.alibaba.nacos.server.DumpAllTaskManager");
dumpAllTaskMgr.setDefaultTaskProcessor(dumpAllProcessor);
      Runnable dumpAll = new Runnable() {
    
            @Override
            public void run() {
    
dumpAllTaskMgr.addTask(DumpAllTask.TASK_ID, new DumpAllTask());
            }
        };
            /** Every time 10 Once per minute DumpAll operation **/
      TimerTaskService.scheduleWithFixedDelay(dumpAll, initialDelay, DUMP_ALL_INTERVAL_IN_MINUTE,
                TimeUnit.MINUTES);
    }

DumpService This is called back during initialization init Method ;
1. First new One. DumpAllProcessor actuator ;
2. Again new One. TaskManager Task manager ; stay new This task manager , A thread will be started to execute all the tasks to be executed ; It's just that no tasks have been added at this time ;
3. Set the default executor of this task manager to DumpAllProcessor;
4. Every ten minutes TaskManager Add a DumpAllTask The task of ; Once added, it will be TaskManager Thread in processingThread perform process Method ;