Class TaskManager<WorkerMetricsT>

java.lang.Object

io.aleph0.yap.core.task.TaskManager<WorkerMetricsT>

All Implemented Interfaces:

Measureable<TaskManager.Metrics<WorkerMetricsT>>

public class TaskManager<WorkerMetricsT>
extends Object
implements Measureable<TaskManager.Metrics<WorkerMetricsT>>

TaskManager manages the lifecycle of a logical pipeline task, including starting and stopping workers, handling task actions, and notifying lifecycle listeners. It is designed to be used in a multi-threaded environment and provides methods for managing worker threads and task actions.

The TaskManager delegates decision making to a TaskController instance, which is responsible for deciding what actions to take based on the current state of the task and the workers, and the TaskManager is responsible for executing those actions.

Internally, the TaskManager models the task state as a finite state machine with the following states:

                                  
     READY ─► RUNNING ─► COMPLETED
               │  │               
               │  └────► CANCELLED
               │                  
               └───────► FAILED
 
 

To ensure correctness, it enforces that the task can only perform the above transitions between states. (So, for example, the TaskManager will fail if the controller attempts to transition from COMPLETED to RUNNING or from FAILED to CANCELLED.) Within the boundaries of these constraints, the TaskController is completely free to decide what actions to take.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	TaskManager.LifecycleListener
static final record	TaskManager.Metrics<WorkerMetricsT>
static enum	TaskManager.TaskPhase
static enum	TaskManager.TaskState
static interface	TaskManager.WorkerBody
static interface	TaskManager.WorkerBodyFactory<MetricsT>

Constructor Summary

Constructors

Constructor	Description
TaskManager(String id, Set<String> subscribers, ExecutorService executor, TaskController controller, TaskManager.WorkerBodyFactory<WorkerMetricsT> workerBodyFactory, Queue<?> queue, Topic<?> topic)

Method Summary

Modifier and Type	Method	Description
void	addLifecycleListener(TaskManager.LifecycleListener listener)
TaskManager.Metrics<WorkerMetricsT>	checkMetrics()	Non-destructive check of the metrics.
TaskManager.Metrics<WorkerMetricsT>	flushMetrics()	Destructive read of the metrics.
String	getId()
Set<String>	getSubscribers()
void	removeLifecycleListener(TaskManager.LifecycleListener listener)
void	run()
protected io.aleph0.yap.core.task.TaskManager.StartedWorker<WorkerMetricsT>	startWorker()
protected void	stopAllWorkers()
protected int	stopAnyWorker()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

TaskManager

public TaskManager(String id,
 Set<String> subscribers,
 ExecutorService executor,
 TaskController controller,
 TaskManager.WorkerBodyFactory<WorkerMetricsT> workerBodyFactory,
 Queue<?> queue,
 Topic<?> topic)

Method Details

getId

public String getId()

getSubscribers

public Set<String> getSubscribers()

addLifecycleListener

public void addLifecycleListener(TaskManager.LifecycleListener listener)

removeLifecycleListener

public void removeLifecycleListener(TaskManager.LifecycleListener listener)

run

public void run()
         throws Exception

Throws:

Exception

startWorker

protected io.aleph0.yap.core.task.TaskManager.StartedWorker<WorkerMetricsT> startWorker()
                                                                                 throws RejectedExecutionException

Throws:

RejectedExecutionException

stopAnyWorker

protected int stopAnyWorker()

stopAllWorkers

protected void stopAllWorkers()

checkMetrics

public TaskManager.Metrics<WorkerMetricsT> checkMetrics()

Description copied from interface: Measureable

Non-destructive check of the metrics. This should be used to check the state of metrics without clearing them, for example in a TaskController.

Specified by:

checkMetrics in interface Measureable<WorkerMetricsT>

Returns:

the metrics

flushMetrics

public TaskManager.Metrics<WorkerMetricsT> flushMetrics()

Description copied from interface: Measureable

Destructive read of the metrics. This should be used to check and reset the state of metrics, for example by the metrics checking thread.

Specified by:

flushMetrics in interface Measureable<WorkerMetricsT>

Returns:

the metrics