com.sun.spot.service
Class Task

java.lang.Object
  com.sun.spot.service.Task

All Implemented Interfaces:

Runnable

Direct Known Subclasses:

Condition

public abstract class Task
extends Object
implements Runnable

Basic Task class to specify some code to be run starting at a specified time and then repeated periodically. The code will be run in its own Thread and in the context of the Isolate that created it.

Each time the task is run, its doTask() method is called. This method needs to be defined in your child Task class. For example to define a task to display the current temperature in an LED every 10 seconds, your code might look like this:

     // locate a thermometer
     final ITemperatureInput therm = (ITemperatureInput)Resources.lookup(ITemperatureInput.class);
     // get leftmost LED
     final ITriColorLED led = (ITriColorLED)Resources.lookup(ITriColorLED.class, "LED0");
     // define the task - check temperature every 10 seconds
     Task task = new Task(10 * 1000) {
         public void doTask() {
             double temp = therm.getCelsius();
             if (temp <= 5.0) {
                 led.setColor(LEDColor.BLUE);     // indicate cold
             } else if (temp <= 20.0) {
                 led.setColor(LEDColor.GREEN);    // indicate warm
             } else
                 led.setColor(LEDColor.RED);      // indicate hot
             }
         }
     }
     task.start();    // start the task running
  

Scheduling:

Each task will be run periodically. If a start time (hour:minute:second) is specified then the task will first be scheduled to be run at that time everyday. If an end time is specified the task will stop being run at that time. Note if the end time is earlier then the start time then the task will be run until the end time of the next day.

If the start hour is not specified (or set to -1), then the task will be run at min:sec in the current hour, or the next hour if the current time (h:m:s) has m > min. Likewise if both the start hour and minute are not specified then the task will be scheduled to start at :sec in the current or next minute. If the start hour is specified but the start minute or second is not, then the unspecified minute or second defaults to zero. The end time is handled in the same manner.

For example:

• new Task(5 * 60 * 1000) // run task every 5 minutes (= 300000 milliseconds)
• new Task(300000, 9, 0, 15, 00) // every 5 minutes between 9am and 3pm
• new Task(300000, -1, 20, -1, 40) // every 5 minutes each hour between :20 and :40

How to start/stop tasks

Calling task.start() will cause a Task to be scheduled with the TaskManager. Calling task.stop() will cause a Task to be unscheduled by the TaskManager.

Note: if executing the doTask() method throws an exception, only that call will be stopped; the task will still be rescheduled for future execution.

Author:

Ron Goldman

Field Summary

protected boolean	active
protected int	endHour
protected int	endMinute
protected int	endSecond
protected long	maxSleep
protected long	period
protected boolean	respectPhase
protected long	schedEndTime
protected long	schedTime
protected boolean	sleepOk
protected int	startHour
protected int	startMinute
protected int	startSecond

Constructor Summary

Task()
Default constructor.

Task(long period)
Basic Task constructor specifying how often to run task.

Task(long period, int startHour, int startMinute)
Task constructor specifying how often to run task and what time of day (hh:mm) to start it running.

Task(long period, int startHour, int startMinute, int startSecond)
Task constructor specifying how often to run task and what time of day (hh:mm:ss) to start it running.

Task(long period, int startHour, int startMinute, int endHour, int endMinute)
Task constructor specifying how often to run task and what time of day to start and stop it running.

Method Summary

protected void	computeScheduledTime()
void	deferToDeepSleep(boolean defer, long maxSleepTime) Specify if this task should defer to deep sleep and if so for how long.
abstract void	doTask() Method called when Task is run.
int	getEndHour() Get what hour of day to stop running this task.
int	getEndMinute() Get what minute of the hour to stop running this task.
int	getEndSecond() Get what second of the minute to stop running this task.
long	getPeriod() Get the interval to reschedule the task.
long	getScheduledTime() Get the time the task is next scheduled to be run.
int	getStartHour() Get what hour of day to start running this task.
int	getStartMinute() Get what minute of the hour to start running this task.
int	getStartSecond() Get what second of the minute to start running this task.
protected void	init()
boolean	isActive() Check if the task is currently scheduled for execution.
protected void	reschedule()
void	run() Internal method.
void	setEndHour(int endHour) Set what hour of day to stop running this task.
void	setEndMinute(int endMinute) Set what minute of the hour to stop running this task.
void	setEndSecond(int endSecond) Set what second of the minute to stop running this task.
void	setEndTime(int endHour, int endMinute) Set what time of day (hh:mm) to stop running this task.
void	setEndTime(int endHour, int endMinute, int endSecond) Set what time of day (hh:mm:ss) to stop running this task.
void	setPeriod(long t) Set the interval to reschedule the task.
void	setScheduledTime(long t) Set the time when the task is next scheduled to be run.
void	setStartHour(int startHour) Set what hour of day to start running this task.
void	setStartMinute(int startMinute) Set what minute of the hour to start running this task.
void	setStartSecond(int startSecond) Set what second of the minute to start running this task.
void	setStartTime(int startHour, int startMinute) Set what time of day (hh:mm) to start running this task.
void	setStartTime(int startHour, int startMinute, int startSecond) Set what time of day (hh:mm:ss) to start running this task.
void	start() Schedule the task for subsequent execution.
void	stop() Remove the task from subsequent execution.

Methods inherited from class java.lang.Object

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

Field Detail

period

protected long period

startHour

protected int startHour

startMinute

protected int startMinute

startSecond

protected int startSecond

endHour

protected int endHour

endMinute

protected int endMinute

endSecond

protected int endSecond

schedTime

protected long schedTime

schedEndTime

protected long schedEndTime

active

protected boolean active

sleepOk

protected boolean sleepOk

respectPhase

protected boolean respectPhase

maxSleep

protected long maxSleep

Constructor Detail

Task

public Task()

Default constructor.

Task

public Task(long period)

Basic Task constructor specifying how often to run task.

Parameters:

period - run task interval in milliseconds

Task

public Task(long period,
            int startHour,
            int startMinute)

Task constructor specifying how often to run task and what time of day (hh:mm) to start it running.

Parameters:

period - time interval in milliseconds to wait before rescheduling this task

startHour - hour of the day (0-23) to start running task (-1 = unspecified)

startMinute - minute of the hour (0-59) to start running task (-1 = unspecified)

Task

public Task(long period,
            int startHour,
            int startMinute,
            int startSecond)

Task constructor specifying how often to run task and what time of day (hh:mm:ss) to start it running.

Parameters:

period - time interval in milliseconds to wait before rescheduling this task

startHour - hour of the day (0-23) to start running task (-1 = unspecified)

startMinute - minute of the hour (0-59) to start running task (-1 = unspecified)

startSecond - second of the minute (0-59) to start running task (-1 = unspecified)

Task

public Task(long period,
            int startHour,
            int startMinute,
            int endHour,
            int endMinute)

Task constructor specifying how often to run task and what time of day to start and stop it running.

Parameters:

period - time interval in milliseconds to wait before rescheduling this task

startHour - hour of the day (0-23) to start running task (-1 = unspecified)

startMinute - minute of the hour (0-59) to start running task (-1 = unspecified)

endHour - hour of the day (0-23) to stop running task (-1 = unspecified)

endMinute - minute of the hour (0-59) to stop running task (-1 = unspecified)

Method Detail

doTask

public abstract void doTask()
                     throws Exception

Method called when Task is run. User must define it.

Throws:

Exception

init

protected void init()

setStartTime

public void setStartTime(int startHour,
                         int startMinute)

Set what time of day (hh:mm) to start running this task.

Parameters:

startHour - hour of the day (0-23) to start running task

startMinute - minute of the hour (0-59) to start running task

setStartTime

public void setStartTime(int startHour,
                         int startMinute,
                         int startSecond)

Set what time of day (hh:mm:ss) to start running this task.

Parameters:

startHour - hour of the day (0-23) to start running task

startMinute - minute of the hour (0-59) to start running task

startSecond - second of the minute (0-59) to start running task

setEndTime

public void setEndTime(int endHour,
                       int endMinute)

Set what time of day (hh:mm) to stop running this task.

Parameters:

endHour - hour of the day (0-23) to stop running task

endMinute - minute of the hour (0-59) to stop running task

setEndTime

public void setEndTime(int endHour,
                       int endMinute,
                       int endSecond)

Set what time of day (hh:mm:ss) to stop running this task.

Parameters:

endHour - hour of the day (0-23) to stop running task

endMinute - minute of the hour (0-59) to stop running task

endSecond - second of the minute (0-59) to stop running task

setStartHour

public void setStartHour(int startHour)

Set what hour of day to start running this task.

Parameters:

startHour - hour of the day (0-23) to start running task

setStartMinute

public void setStartMinute(int startMinute)

Set what minute of the hour to start running this task.

Parameters:

startMinute - minute of the hour (0-59) to start running task

setStartSecond

public void setStartSecond(int startSecond)

Set what second of the minute to start running this task.

Parameters:

startSecond - second of the minute (0-59) to start running task

setEndHour

public void setEndHour(int endHour)

Set what hour of day to stop running this task.

Parameters:

endHour - hour of the day (0-23) to stop running task

setEndMinute

public void setEndMinute(int endMinute)

Set what minute of the hour to stop running this task.

Parameters:

endMinute - minute of the hour (0-59) to stop running task

setEndSecond

public void setEndSecond(int endSecond)

Set what second of the minute to stop running this task.

Parameters:

endSecond - second of the minute (0-59) to stop running task

getScheduledTime

public long getScheduledTime()

Get the time the task is next scheduled to be run.

Returns:

time in milliseconds when task is to be run

setScheduledTime

public void setScheduledTime(long t)

Set the time when the task is next scheduled to be run.

Parameters:

t - time in milliseconds when task is to be run

getPeriod

public long getPeriod()

Get the interval to reschedule the task.

Returns:

the interval to reschedule the task in milliseconds

setPeriod

public void setPeriod(long t)

Set the interval to reschedule the task.

Parameters:

t - the interval to reschedule the task in milliseconds

getStartHour

public int getStartHour()

Get what hour of day to start running this task.

Returns:

hour of the day (0-23) to start running task

getStartMinute

public int getStartMinute()

Get what minute of the hour to start running this task.

Returns:

minute of the hour (0-59) to start running task

getStartSecond

public int getStartSecond()

Get what second of the minute to start running this task.

Returns:

second of the minute (0-59) to start running task

getEndHour

public int getEndHour()

Get what hour of day to stop running this task.

Returns:

hour of the day (0-23) to stop running task

getEndMinute

public int getEndMinute()

Get what minute of the hour to stop running this task.

Returns:

minute of the hour (0-59) to stop running task

getEndSecond

public int getEndSecond()

Get what second of the minute to stop running this task.

Returns:

second of the minute (0-59) to stop running task

deferToDeepSleep

public void deferToDeepSleep(boolean defer,
                             long maxSleepTime)

Specify if this task should defer to deep sleep and if so for how long. Currently this has no effect.

Parameters:

defer - true if task will defer

maxSleepTime - maximum time before task will be run (<=0 means no limit)

start

public void start()

Schedule the task for subsequent execution. Ignored if the task has already been started.

stop

public void stop()

Remove the task from subsequent execution. Ignored if the task has already been stopped.

isActive

public boolean isActive()

Check if the task is currently scheduled for execution.

Returns:

true if the task is currently active, false if it is stopped

computeScheduledTime

protected void computeScheduledTime()

reschedule

protected void reschedule()

run

public void run()

Internal method. Do not call explicitly.

Specified by:

run in interface Runnable

See Also:

Thread.run()