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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)
| Method Summary | |
|---|---|
void |
interrupt()
Called by the Scheduler when a user
interrupts the Job. |
| Methods inherited from interface org.quartz.Job |
|---|
execute |
| Method Detail |
|---|
interrupt
void interrupt()
throws UnableToInterruptJobException
Called by the
Schedulerwhen a user interrupts theJob.- Throws:
UnableToInterruptJobException- if there is an exception while interrupting the job.
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