org.hawkular.metrics.tasks.impl

Class TaskServiceImpl

java.lang.Object

org.hawkular.metrics.tasks.impl.TaskServiceImpl

All Implemented Interfaces:

TaskService

public class TaskServiceImpl
extends Object
implements TaskService

Author:

jsanda

Constructor Summary

Constructors

Constructor and Description
TaskServiceImpl(RxSession session, Queries queries, LeaseService leaseService, List<TaskType> taskTypes)

Method Summary

Modifier and Type	Method and Description
rx.Observable<org.hawkular.metrics.tasks.impl.TaskContainer>	findTasks(org.hawkular.metrics.tasks.impl.Lease lease, TaskType taskType)
rx.Observable<org.hawkular.metrics.tasks.impl.TaskContainer>	findTasks(String type, org.joda.time.DateTime timeSlice, int segment)
rx.Observable<Task>	scheduleTask(org.joda.time.DateTime time, Task task) Schedules the task for repeated execution starting in the next time slice after time.
void	setTimeUnit(TimeUnit timeUnit) The time unit determines a couple things.
void	shutdown() Shuts down the internal scheduler.
void	start() Starts the internal scheduler which takes care of running jobs to process the task queue.

Methods inherited from class java.lang.Object

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

Constructor Detail

TaskServiceImpl

public TaskServiceImpl(RxSession session,
                       Queries queries,
                       LeaseService leaseService,
                       List<TaskType> taskTypes)

Method Detail

setTimeUnit

public void setTimeUnit(TimeUnit timeUnit)

The time unit determines a couple things. First, it determines the frequency for scheduling jobs. If TimeUnit.MINUTES is used for instance, then jobs are scheduled every minute. In this context, a job refers to finding and executing tasks in the queue for a particular time slice, which brings up the second thing that timeUnit determines - time slice interval. Time slices are set along fixed intervals, e.g., 13:00, 13:01, 13:02, etc.

Note: This should only be called prior to calling start().

start

public void start()

Description copied from interface: TaskService

Starts the internal scheduler which takes care of running jobs to process the task queue. This method should be called before any calls to TaskService.scheduleTask(DateTime, Task).

Specified by:

start in interface TaskService

shutdown

public void shutdown()

Description copied from interface: TaskService

Shuts down the internal scheduler.

Specified by:

shutdown in interface TaskService

findTasks

public rx.Observable<org.hawkular.metrics.tasks.impl.TaskContainer> findTasks(String type,
                                                                              org.joda.time.DateTime timeSlice,
                                                                              int segment)

findTasks

public rx.Observable<org.hawkular.metrics.tasks.impl.TaskContainer> findTasks(org.hawkular.metrics.tasks.impl.Lease lease,
                                                                              TaskType taskType)

scheduleTask

public rx.Observable<Task> scheduleTask(org.joda.time.DateTime time,
                                        Task task)

Description copied from interface: TaskService

Schedules the task for repeated execution starting in the next time slice after time. If the task scheduler runs jobs for executing tasks every minute and if time is 13:01:22, then the earliest that the task can first get scheduled to execute is at 13:02 and every minute there after. Execution times are determined by Task.getInterval(). If the task has an interval of 30 minutes, then it would be scheduled to run at 13:30, 14:00, 14:30, and so on.

The task is guaranteed to execute at its scheduled time or later, and only one instance of the task will be executed at a time for a given time slice. In other words, if there are 5 machines running TaskService, only one of those TaskService instances will execute the task for a particular time slice.

If task execution fails for whatever reason, it will be rescheduled for execution in the next time slice. If the task runs at 13:30 and fails with some unhandled exception, then TaskService will run the task twice at 14:00. It will first run the task for the 13:30 time slice and then for the 14:00 time slice.

Specified by:

scheduleTask in interface TaskService

Parameters:

time - The starting time from which the initial execution is scheduled. The scheduled execution time depends on Task.getInterval(). Tasks are scheduled to execute on fixed time boundaries. For example, if the task has an interval of 15 minutes, then it will get scheduled to run at 14:00, 14:15, 14:30, 14:45, 15:00, and so on.

task - The task to schedule for execution

Returns:

The task with its scheduled execution time set