com.tangosol.util
Class TaskDaemon

java.lang.Object
  com.tangosol.util.Base
      com.tangosol.util.Daemon
          com.tangosol.util.TaskDaemon

All Implemented Interfaces:

Runnable

Direct Known Subclasses:

SessionHelper.SessionReaperDaemon

public class TaskDaemon
extends Daemon

A Daemon thread handler that asynchronously executes Runnable tasks, either at a scheduled time or "as soon as possible".

Author:

cp 2003.10.09, cp 2006.02.23 (Coherence 3.2) bulletproofing for use in the CQC

Nested Class Summary

class

TaskDaemon.PeriodicTask A PeriodicTask is a task that automatically reschedules itself so that it executes on a periodic basis.

Nested classes/interfaces inherited from class com.tangosol.util.Daemon

Daemon.DaemonWorker

Constructor Summary

TaskDaemon()
Default constructor.

TaskDaemon(String sName)
Creates a TaskDaemon with the specified name.

TaskDaemon(String sName, int nPriority, boolean fStart)
Creates a TaskDaemon with a specified name and priority.

TaskDaemon(String sName, int nPriority, boolean fStart, boolean fFinish, int cMillisTimeout)
Creates a TaskDaemon with a specified name and priority.

Method Summary

void	executePeriodicTask(Runnable task, long cMillisInterval) Schedule a periodic task to be run "as soon as possible", and to repeat at the specified interval.
void	executeTask(Runnable task) Schedule a task to be run by the daemon "as soon as possible".
protected String	getDescription() Format the Daemon attributes into a String for inclusion in the String returned from the Daemon.toString() method.
long	getIdleTimeout() Determine the length of time that the daemon will live without any activity before it stops itself.
protected long	getMostRecentTaskTime() Determine when the most recent task was run.
protected LongArray	getTasks() Obtain the pending tasks.
protected Runnable	instantiatePeriodicTask(Runnable task, long cMillisInterval) Create a task that will automatically be run on a periodic basis.
boolean	isFinishing() Determine if the daemon will finish those scheduled tasks that are ripe (presently due to be run) before stopping.
protected void	onException(Throwable e, Runnable task) Process an exception that is thrown during a task execution.
void	run() The task processing loop.
protected void	run(Runnable task) Execute a Runnable task.
void	schedulePeriodicTask(Runnable task, long ldtFirst, long cMillisInterval) Schedule a periodic task to be run at the specified time, and to repeat at the specified interval.
void	scheduleTask(Runnable task, long ldt) Schedule a task to be run at the specified time, or as soon after as possible.
void	setFinishing(boolean fFinish) Specify whether the daemon will finish scheduled tasks before stopping.
void	setIdleTimeout(long cMillis) Configure the daemon's timeout.
void	stop(boolean fFinish) Request the daemon to stop, optionally completing tasks that have already been scheduled and are ready to be run.
protected Runnable	takeNextRipeTask() Wait for the next scheduled task is ripe (due or overdue), then remove it from the pending schedule and return it.
String	toString() Return a human-readable String representation of the Daemon.
protected void	updateMostRecentTaskTime() Set the time that the most recent task was run to the current time.

Methods inherited from class com.tangosol.util.Daemon

changeState, configureWorker, getConfiguredName, getConfiguredPriority, getState, getThread, getThreadContextClassLoader, getWorker, instantiateWorker, isOnWorkerThread, isRunning, isStopping, setConfiguredName, setConfiguredPriority, setThreadContextClassLoader, start, stop, toStateString

Constructor Detail

TaskDaemon

public TaskDaemon()

Default constructor. Creates a TaskDaemon using default settings. The daemon will not be automatically started.

TaskDaemon

public TaskDaemon(String sName)

Creates a TaskDaemon with the specified name. The daemon will not be automatically started.

Parameters:

sName - the thread name (may be null)

TaskDaemon

public TaskDaemon(String sName,
                  int nPriority,
                  boolean fStart)

Creates a TaskDaemon with a specified name and priority.

Parameters:

sName - the thread name (may be null)

nPriority - the thread priority, between Thread.MIN_PRIORITY and Thread.MAX_PRIORITY inclusive

fStart - pass true to start the thread immediately

TaskDaemon

public TaskDaemon(String sName,
                  int nPriority,
                  boolean fStart,
                  boolean fFinish,
                  int cMillisTimeout)

Creates a TaskDaemon with a specified name and priority.

Parameters:

sName - the thread name (may be null)

nPriority - the thread priority, between Thread.MIN_PRIORITY and Thread.MAX_PRIORITY inclusive

fStart - pass true to start the thread immediately

fFinish - pass true to makes sure ripe tasks are run before the daemon shuts down

cMillisTimeout - the number of milliseconds to wait after the previous task finsished for a new task to be submitted before automatically shutting down the daemon thread

Method Detail

run

public void run()

The task processing loop.

Specified by:

run in interface Runnable

Specified by:

run in class Daemon

stop

public void stop(boolean fFinish)

Request the daemon to stop, optionally completing tasks that have already been scheduled and are ready to be run.

Parameters:

fFinish - pass true if the daemon should finish any tasks that have already been scheduled before stopping

isFinishing

public boolean isFinishing()

Determine if the daemon will finish those scheduled tasks that are ripe (presently due to be run) before stopping.

Returns:

true if the daemon is configured to finish any ripe scheduled tasks before stopping

setFinishing

public void setFinishing(boolean fFinish)

Specify whether the daemon will finish scheduled tasks before stopping.

Parameters:

fFinish - pass true to force the daemon to finish any scheduled tasks before stopping

getIdleTimeout

public long getIdleTimeout()

Determine the length of time that the daemon will live without any activity before it stops itself.

Returns:

the timeout for the TaskDaemon's thread to live before being shut down

setIdleTimeout

public void setIdleTimeout(long cMillis)

Configure the daemon's timeout. Note that if the daemon shuts itself down, it will automatically restart when something is added to the queue.

Parameters:

cMillis - if greater than zero, the number of milliseconds that the daemon will wait with nothing in the queue before shutting itself down

executeTask

public void executeTask(Runnable task)

Schedule a task to be run by the daemon "as soon as possible".

Parameters:

task - a Runnable object to invoke

scheduleTask

public void scheduleTask(Runnable task,
                         long ldt)

Schedule a task to be run at the specified time, or as soon after as possible.

Parameters:

task - a Runnable object to invoke

ldt - a datetime value at which to run the task

executePeriodicTask

public void executePeriodicTask(Runnable task,
                                long cMillisInterval)

Schedule a periodic task to be run "as soon as possible", and to repeat at the specified interval.

Parameters:

task - a Runnable object to invoke

cMillisInterval - the number of milliseconds to wait after the task is run before running it again

schedulePeriodicTask

public void schedulePeriodicTask(Runnable task,
                                 long ldtFirst,
                                 long cMillisInterval)

Schedule a periodic task to be run at the specified time, and to repeat at the specified interval.

Parameters:

task - a Runnable object to invoke

ldtFirst - a datetime value at which to first run the task

cMillisInterval - the number of milliseconds to wait after the task is run before running it again

getTasks

protected LongArray getTasks()

Obtain the pending tasks.

Returns:

a LongArray keyed by SafeTimeMillis with a corresponding value being a List of tasks scheduled at that time

takeNextRipeTask

protected Runnable takeNextRipeTask()
                             throws InterruptedException

Wait for the next scheduled task is ripe (due or overdue), then remove it from the pending schedule and return it.

Returns:

a task that is ripe to be run, or null if the TaskDaemon is shutting down and no task should be run

Throws:

InterruptedException

run

protected void run(Runnable task)

Execute a Runnable task.

Parameters:

task - a Runnable object

getMostRecentTaskTime

protected long getMostRecentTaskTime()

Determine when the most recent task was run.

Returns:

the date/time at which the most recent task was run

updateMostRecentTaskTime

protected void updateMostRecentTaskTime()

Set the time that the most recent task was run to the current time.

instantiatePeriodicTask

protected Runnable instantiatePeriodicTask(Runnable task,
                                           long cMillisInterval)

Create a task that will automatically be run on a periodic basis.

Parameters:

task - the actual task to run

cMillisInterval - the period of time, in milliseconds, to wait between runs of the task

Returns:

a task that will run itself periodically

toString

public String toString()

Return a human-readable String representation of the Daemon.

Overrides:

toString in class Daemon

Returns:

a String describing the Daemon

getDescription

protected String getDescription()

Format the Daemon attributes into a String for inclusion in the String returned from the Daemon.toString() method.

Overrides:

getDescription in class Daemon

Returns:

a String listing the attributes of the Daemon

onException

protected void onException(Throwable e,
                           Runnable task)

Process an exception that is thrown during a task execution. The default implementation logs the exception and continues.

Parameters:

e - Throwable object (a RuntimeException or an Error)

task - the task that caused the exception