Scheduler

This library provides a simple class to help you manage jobs using one-shot and repeating timers, all of which can be cancelled. It can be used to create multiple jobs that share a single timer — which may be helpful in agent code, where there is a limit on the number of active timers you can set up. This class also allows the user to pass any number of parameters (of any type) to the callbacks that they provide for each job.

You can view the latest version of the library’s source code on GitHub. Click here to see information on other versions of this library.

To include this library, add

#require "Scheduler.lib.nut:0.1.0"

to the top of your agent and/or device code

Note This is a beta release. Please file issues in GitHub to help us improve this library.

Scheduler Usage

This class manages all jobs. Each method for creating a job will return a new Scheduler.Job instance.

Constructor: Scheduler()

The constructor has no parameters.

Example

sch <- Scheduler();

Scheduler Methods

set(duration, callback[, ...])

This method starts a new timer which executes the supplied callback after the specified duration.

Parameters

Parameter	Type	Required	Description
duration	Float	Yes	The period in seconds before the timer fires
callback	Function	Yes	The function to run when the timer finishes
...	Any	No	Optional parameters that will be passed into the callback

Return Value

A Scheduler.Job instance.

Example

function logMsg(message) {
    server.log(message);
}

job1 <- sch.set(5, logMsg, "Timer fired");

at(time, callback[, ...])

This method creates a new job with a callback to execute at the specified time. The time should be provided as an integer representing the number of seconds that have elapsed since midnight on 1 January 1970.

Parameters

Parameter	Type	Required	Description
time	Integer	Yes	The time at which the timer should fire
callback	Function	Yes	The function to run when the timer fires
...	Any	No	Optional parameters that will be passed into the callback

Return Value

A Scheduler.Job instance.

Example

function logMsg(msg) {
    server.log(msg);
}

local inFiveSecs = time() + 5;
job1 <- sch.at(inFiveSecs, logMsg, "Timer fired");

repeat(interval, time, callback[, ...])

This method creates a new job with a callback that will repeat at the specified interval. To create a timer that repeats from a specified time pass in an integer representing the number of seconds that have elapsed since midnight on 1 January 1970, otherwise pass null into the time parameter.

Parameters

Parameter	Type	Required	Description
interval	Integer or float	Yes	The interval between timer firings in seconds
time	Integer or Null	Yes	The time at which the timer should fire, or null if timer should trigger based on the interval
callback	Function	Yes	The function to run when the timer fires
...	Any	No	Optional parameters that will be passed into the callback

Return Value

A Scheduler.Job instance, or an error message if an error was encountered.

Example

function logMsg(msg, jobName) {
    server.log(jobName + ": " + msg);
}

job1 <- sch.repeat(10, null, logMsg, "Repeats every ten seconds...", "Job 1");

local inFiveSecs = time() + 5;
job2 <- sch.repeat(10, inFiveSecs, logMsg, "Repeats every ten seconds...", "Job 2");

Scheduler.Job Usage

You should never call the Scheduler.Job constructor directly. Instead, you should create new jobs (timers) using the Scheduler methods described above.

Scheduler.Job Methods

now()

This method immediately executes the job’s callback. If job repeats, it will be rescheduled to fire based on the repeat interval, otherwise the job will be removed from the queue.

Return Value

The Scheduler.Job instance.

Example

function logMsg(msg) {
    server.log(msg);
}

job1 <- sch.set(20, logMsg, "Timer fired");
job1.now();

cancel()

This method cancels the job. If it is a repeated job it will cancel all repeats.

Return Value

The Scheduler.Job instance.

Example

function logMsg(msg) {
    server.log(msg);
}

job1 <- sch.set(5, logMsg, "Timer fired");
job1.cancel();

getStatus()

This method returns the current status of a job.

Return Value

A job status constant:

Constant	Value	Description
STATUS_NEW	"new"	Job has been created, but not placed in the queue
STATUS_QUEUED	"queued"	Job is in the queue
STATUS_EXPIRED	"expired"	Job has triggered its callback, and is no longer in the queue
STATUS_CANCELED	"canceled"	Job has been deleted from the queue

Example

function logMsg(msg) {
    server.log(msg);
    if (job1.getStatus() == job1.STATUS_EXPIRED) {
        server.log("Job 1 complete.");
        job1 <- null;
    }
}

// Set a job that will fire in 10s
job1 <- sch.set(10, logMsg, "Timer fired");
if (job1.getStatus() == job1.STATUS_QUEUED) {
    server.log("Job 1 scheduled.");
}

Release History

The Electric Imp Dev Center documents the latest version of the library. For past versions, please see the Electric Imp public GitHub repos listed below.

Version	Source Code	Notes
0.1.0	GitHub	Beta release

License

This library is licensed under the MIT License.