org.opennms.netmgt.scheduler

Class LegacyScheduler

java.lang.Object

org.opennms.netmgt.scheduler.LegacyScheduler

All Implemented Interfaces:

Runnable, Fiber, PausableFiber, Scheduler, ScheduleTimer, Timer

public class LegacyScheduler
extends Object
implements Runnable, PausableFiber, Scheduler

This class implements a simple scheduler to ensure the polling occurs at the expected intervals. The scheduler employees a dynamic thread pool that adjust to the load until a maximum thread count is reached.

Author:

Mike Davidson , Brian Weaver , OpenNMS

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LegacyScheduler.PeekableFifoQueue<T> This queue extends the standard FIFO queue instance so that it is possible to peek at an instance without removing it from the queue.

Field Summary

Fields inherited from interface org.opennms.core.fiber.PausableFiber

PAUSE_PENDING, PAUSED, RESUME_PENDING

Fields inherited from interface org.opennms.core.fiber.Fiber

RUNNING, START_PENDING, STARTING, STATUS_NAMES, STOP_PENDING, STOPPED

Constructor Summary

Constructors

Constructor and Description
LegacyScheduler(String parent, int maxSize) Constructs a new instance of the scheduler.
LegacyScheduler(String parent, int maxSize, float lowMark, float hiMark) Constructs a new instance of the scheduler.

Method Summary

Methods

Modifier and Type	Method and Description
long	getCurrentTime() getCurrentTime
String	getName() Returns the name of this fiber.
long	getNumTasksExecuted() Returns the total number of scheduled tasks (ReadyRunnables) that have been executed since the scheduler was initialized.
ExecutorService	getRunner() Returns the pool of threads that are used to executed the runnable instances scheduled by the class' instance.
int	getScheduled() Returns total number of elements currently scheduled.
int	getStatus() getStatus
void	pause() pause
void	resume() resume
void	run() The main method of the scheduler.
void	schedule(long interval, ReadyRunnable runnable) schedule
void	schedule(ReadyRunnable runnable, long interval) This method is used to schedule a ready runnable in the system.
void	start() start
void	stop() stop

Methods inherited from class java.lang.Object

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

Constructor Detail

LegacyScheduler

public LegacyScheduler(String parent,
               int maxSize)

Constructs a new instance of the scheduler. The maximum number of executable threads is specified in the constructor. The executable threads are part of a runnable thread pool where the scheduled runnables are executed.

Parameters:

parent - String prepended to "Scheduler" to create fiber name

maxSize - The maximum size of the thread pool.

LegacyScheduler

public LegacyScheduler(String parent,
               int maxSize,
               float lowMark,
               float hiMark)

Constructs a new instance of the scheduler. The maximum number of executable threads is specified in the constructor. The executable threads are part of a runnable thread pool where the scheduled runnables are executed.

Parameters:

parent - String prepended to "Scheduler" to create fiber name

maxSize - The maximum size of the thread pool.

lowMark - The low water mark ratios of thread size to threads when threads are stopped.

hiMark - The high water mark ratio of thread size to threads when threads are started.

Method Detail

schedule

public void schedule(ReadyRunnable runnable,
            long interval)

This method is used to schedule a ready runnable in the system. The interval is used as the key for determining which queue to add the runnable.

Parameters:

runnable - The element to run when interval expires.

interval - The queue to add the runnable to.

Throws:

RuntimeException - Thrown if an error occurs adding the element to the queue.

schedule

public void schedule(long interval,
            ReadyRunnable runnable)

schedule

This method is used to schedule a ready runnable in the system. The interval is used as the key for determining which queue to add the runnable.

Specified by:

schedule in interface Scheduler

Specified by:

schedule in interface ScheduleTimer

Parameters:

interval - a long.

runnable - a ReadyRunnable object.

getCurrentTime

public long getCurrentTime()

getCurrentTime

Specified by:

getCurrentTime in interface Scheduler

Specified by:

getCurrentTime in interface Timer

Returns:

a long.

start

public void start()

start

Specified by:

start in interface Fiber

Specified by:

start in interface Scheduler

stop

public void stop()

stop

Specified by:

stop in interface Fiber

Specified by:

stop in interface Scheduler

pause

public void pause()

pause

Specified by:

pause in interface PausableFiber

Specified by:

pause in interface Scheduler

resume

public void resume()

resume

Specified by:

resume in interface PausableFiber

Specified by:

resume in interface Scheduler

getStatus

public int getStatus()

getStatus

Specified by:

getStatus in interface Fiber

Specified by:

getStatus in interface Scheduler

Returns:

a int.

getName

public String getName()

Returns the name of this fiber.

Specified by:

getName in interface Fiber

Returns:

a String object.

getScheduled

public int getScheduled()

Returns total number of elements currently scheduled.

Returns:

the sum of all the elements in the various queues

getRunner

public ExecutorService getRunner()

Returns the pool of threads that are used to executed the runnable instances scheduled by the class' instance.

Returns:

thread pool

run

public void run()

The main method of the scheduler. This method is responsible for checking the runnable queues for ready objects and then enqueuing them into the thread pool for execution.

Specified by:

run in interface Runnable

getNumTasksExecuted

public long getNumTasksExecuted()

Returns the total number of scheduled tasks (ReadyRunnables) that have been executed since the scheduler was initialized.

Specified by:

getNumTasksExecuted in interface Scheduler

Returns:

the number of task executed