Package org.quartz

Interface InterruptableJob

  • All Superinterfaces:
    Job
    public interface InterruptableJob
extends Job
    The interface to be implemented by Jobs that provide a mechanism for having their execution interrupted. It is NOT a requirement for jobs to implement this interface - in fact, for most people, none of their jobs will.

    Interrupting a Job is very analogous in concept and challenge to normal interruption of a Thread in Java.

    The means of actually interrupting the Job must be implemented within the Job itself (the interrupt() method of this interface is simply a means for the scheduler to inform the Job that a request has been made for it to be interrupted). The mechanism that your jobs use to interrupt themselves might vary between implementations. However the principle idea in any implementation should be to have the body of the job's execute(..) periodically check some flag to see if an interruption has been requested, and if the flag is set, somehow abort the performance of the rest of the job's work. An example of interrupting a job can be found in the java source for the class org.quartz.examples.DumbInterruptableJob. It is legal to use some combination of wait() and notify() synchronization within interrupt() and execute(..) in order to have the interrupt() method block until the execute(..) signals that it has noticed the set flag.

    If the Job performs some form of blocking I/O or similar functions, you may want to consider having the Job.execute(..) method store a reference to the calling Thread as a member variable. Then the Implementation of this interfaces interrupt() method can call interrupt() on that Thread. Before attempting this, make sure that you fully understand what java.lang.Thread.interrupt() does and doesn't do. Also make sure that you clear the Job's member reference to the Thread when the execute(..) method exits (preferably in a finally block.

    See Example 7 (org.quartz.examples.example7.DumbInterruptableJob) for a simple implementation demonstration.

    Author:
    James House
    See Also:
    Job, StatefulJob, Scheduler.interrupt(JobKey), Scheduler.interrupt(String)