org.jumpi.impl.taskscheduler
Class TaskSchedulerImpl

java.lang.Object
  |
  +--org.jumpi.impl.taskscheduler.TaskSchedulerImpl

All Implemented Interfaces:

Component, Configurable, Manageable, java.lang.Runnable, TaskScheduler

public class TaskSchedulerImpl

extends java.lang.Object

implements java.lang.Runnable, TaskScheduler

A TaskSchedulerImpl implementation using an internal Thread pool to run concurrent Tasks.

Constructor Summary

TaskSchedulerImpl()

Method Summary

void	configure(java.lang.String name, Properties props) Configure the TaskSchedulerImpl.
java.lang.String	getName() Get the fully qualified name of the instance.
void	manage(Component root, Component parent, java.lang.String operation, java.util.Hashtable parameters) Perform a recursive management operation through the Jumpi component tree, using the parameters provided.
void	run() All thread pool threads call run() to take the next available tasks for running, and run them until the task is no longer schedulable.
void	schedule(Task task) Schedule the given Task to run as soon as possible, using one of the threads in the TaskSchedulerImpl's internal thread pool.

Methods inherited from class java.lang.Object

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

Constructor Detail

TaskSchedulerImpl

public TaskSchedulerImpl()

Method Detail

configure

public void configure(java.lang.String name,
                      Properties props)
               throws java.lang.Exception

Configure the TaskSchedulerImpl.

The following configuration attributes are defined:

• minthreads - optional integer [0..MAX-INT] default 1

  The number of threads to run continuously to service tasks regardless of the number of tasks ready to be scheduled.

• maxthreads - optional integer [$minthreads..MAX-INT] default 10

  The maximum number of threads to run concurrently to service tasks.

• maxschedules - optional integer [1..MAX-INT] default 10

  The maximum number of tasks which can be expected to be scheduled simultaneously.

• keepaliveinterval - optional integer [1000..MAX-INT] default 1000

  The time to keep threads running in the absence of schedulable tasks, before allowing the thread to finish.

• jointestinterval - optional integer [1000..MAX-INT] default 1000

  The time in milliseconds to check if the controller has finished during shutdown.

• joinfailinterval - integer[$jointestinterval..MAX-INT] - optional[30000].

  The time in milliseconds to before shutdown must complete, regardless if the controller are still running.

Specified by:

configure in interface Configurable

Parameters:

name - the fully qualified instance name.

props - the read-only properties to configure the instance with.

Throws:

java.lang.Exception - when configuration is unsuccessful.

java.lang.IllegalArgumentException - if name or props are missing.

manage

public void manage(Component root,
                   Component parent,
                   java.lang.String operation,
                   java.util.Hashtable parameters)
            throws java.lang.Exception

Perform a recursive management operation through the Jumpi component tree, using the parameters provided.

The following management actions are handled:

• LINK. Link the instance with a Jumpi instance.
• STARTUP. Add the minimum number of threads to the pool.
• SHUTDOWN. Signal all the threads to stop working at the next opportunity.
• JOIN. Wait for all the threads to stop.
• UNLINK. Remove the link to the Jumpi instance.
• INFO. Adds an empty result to the Parameters.INFO_RESULT_SET using the component's fully qualified name as key.
• MANAGE. No operations defined.

Specified by:

manage in interface Manageable

Parameters:

root - the Jumpi instance at the root of the component tree.

parent - the immediate parent of the component.

operation - the operation.

parameters - the operation parameters.

Throws:

java.lang.Exception - if any failure to perform management occurs.

java.lang.IllegalArgumentException - when parameters are missing.

schedule

public void schedule(Task task)

Schedule the given Task to run as soon as possible, using one of the threads in the TaskSchedulerImpl's internal thread pool.

A Task is run as long as it is schedulable once a thread has been assigned to handle it. Even if the run method exits or exits through a runtime exception , the assigned thread re-runs the method.

A Task should never call schedule for itself from a synchronized block which shares a synchronization with isSchedulable(). This could cause deadlock.

Specified by:

schedule in interface TaskScheduler

Parameters:

task - the Task to schedule.

Throws:

java.lang.IllegalArgumentException - if task is null.

java.lang.IllegalStateException - if scheduler not started.

run

public void run()

All thread pool threads call run() to take the next available tasks for running, and run them until the task is no longer schedulable.

If a Task is long running, then the thread pool thread is taken out of the pool and allowed to run the task until completion. Threads for long running tasks exit after the task is no longer schedulable, and are not reclaimed to the thread pool.

Specified by:

run in interface java.lang.Runnable

getName

public java.lang.String getName()

Get the fully qualified name of the instance. Identical to the name used in configure.

Specified by:

getName in interface Configurable

Returns:

the fully qualified name of the instance.

See Also:

configure(java.lang.String, org.jumpi.spi.Properties)