Scheduled Tasks

Introduction

Scheduled tasks have always been a point of soreness for many developers in ANY language. Especially choosing where to place them for execution: should it be cron? windows task scheduler? ColdFusion engine? Jenkins, Gitlab? and the list goes on and on.

The ColdBox Scheduled Tasks offers a fresh, programmatic and human approach to scheduling tasks on your server and multi-server application. It allows you to define your tasks in a portable Scheduler we lovingly call the Scheduler.cfc which not only can be used to define your tasks, but also monitor all of their life-cycles and metrics of tasks. Since ColdBox is also hierarchical, it allows for every single ColdBox Module to also define a Scheduler and register their own tasks as well. This is a revolutionary approach to scheduling tasks in an HMVC application.

Global App Scheduler

Every ColdBox application has a global scheduler created for you by convention and registered with a WireBox ID of appScheduler@coldbox. However, you can have complete control of the scheduler by creating the following file: config/Scheduler.cfc. This is a simple CFC with a configure() method where you will define your tasks and several life-cycle methods.

component {

    /**
     * Configure the ColdBox Scheduler
     */
    function configure() {
        /**
         * --------------------------------------------------------------------------
         * Configuration Methods
         * --------------------------------------------------------------------------
         * From here you can set global configurations for the scheduler
         * - setTimezone( ) : change the timezone for ALL tasks
         * - setExecutor( executorObject ) : change the executor if needed
         * - setCacheName( "template" ) : Change the cachename for ALL tasks
         * - setServerFixation( true ) : Set all tasks to run on one server
         */



        /**
         * --------------------------------------------------------------------------
         * Register Scheduled Tasks
         * --------------------------------------------------------------------------
         * You register tasks with the task() method and get back a ColdBoxScheduledTask object
         * that you can use to register your tasks configurations.
         */

        task( "Clear Unregistered Users" )
            .call( () => getInstance( "UserService" ).clearRecentUsers() )
            .everyDayAt( "09:00" );

        task( "Hearbeat" )
            .call( () => runEvent( "main.heartbeat" ) )
            .every( 5, "minutes" )
            .onFailure( ( task, exception ) => {
                getInstance( "System" ).sendBadHeartbeat( exception );
            } );
    }

    /**
     * Called before the scheduler is going to be shutdown
     */
    function onShutdown(){
    }

    /**
     * Called after the scheduler has registered all schedules
     */
    function onStartup(){
    }

    /**
     * Called whenever ANY task fails
     *
     * @task The task that got executed
     * @exception The ColdFusion exception object
     */
    function onAnyTaskError( required task, required exception ){
    }

    /**
     * Called whenever ANY task succeeds
     *
     * @task The task that got executed
     * @result The result (if any) that the task produced
     */
    function onAnyTaskSuccess( required task, result ){
    }

    /**
     * Called before ANY task runs
     *
     * @task The task about to be executed
     */
    function beforeAnyTask( required task ){
    }

    /**
     * Called after ANY task runs
     *
     * @task The task that got executed
     * @result The result (if any) that the task produced
     */
    function afterAnyTask( required task, result ){
    }

}

Life-Cycle Methods

Every Scheduler can create life-cycle methods and monitor the scheduled tasks:

Configuration Methods

The following methods are used to impact the operation of all scheduled tasks managed by the scheduler:

Cachename For All Tasks

By default, all tasks are fixed to use the template cache when doing server fixation. You can override the cachename by a task by task basis or set the global default into the scheduler.

setCacheName( "Redis" )

Server Fixation For All Tasks

By default, all task run on each server/container they are registered with. However, you can also pin them on a specific server using server fixation via the onOneServer() method of the individual scheduled task. However, you can also tell the scheduler to do this for ALL tasks it manages using the setServerFixation() method.

setServerFixation( true )

Timezone For All Tasks

By default, all tasks run under the system default timezone which usually is UTC. However, if you would like to change to a different execution timezone, then you can use the setTimeZone() method and pass in a valid timezone string:

setTimezone( "America/Chicago" )

Custom Executor

By default the scheduler will register a scheduled executor with a default of 20 threads for you with a name of appScheduler@coldbox-scheduler. If you want to add in your own executor as per your configurations, then just call the setExecutor() method.

setExecutor( 
    getAsyncManager().newScheduledExecutor( "mymymy", 50 ) 
);

Scheduler Properties

Every scheduler has the following injections available to you in the variables scope

All module schedulers will have the following extra automatic injections:

Scheduler Methods

Every scheduler has several useful ColdBox interaction methods you can use when registering your tasks callable methods.

Scheduler Utility Methods

Every scheduler has several utility methods:

Scheduling Tasks

Ok, now that we have seen all the capabilities of the scheduler, let's dive deep into scheduling tasks with the task( name ) method.

Registering Tasks

Once you call on this method, the scheduler will create a ColdBoxScheduledTask object for you, configure it, wire it, register it and return it to you.

task( "my-task" )

You can find the API Docs for this object here: https://s3.amazonaws.com/apidocs.ortussolutions.com/coldbox/6.4.0/coldbox/system/web/tasks/ColdBoxScheduledTask.html

Task Closure/Lambda/Object

You register the callable event via the call() method on the task object. You can register a closure/lambda or a invokable CFC. If you register an object, then we will call on the object's run() method by default, but you can change it using the method argument and call any public/remote method.

// Lambda Syntax
task( "my-task" )
    .call( () => getInstance( "myService" ).runcleanup() )
    .everyHour();

// Closure Syntax
task( "my-task" )
    .call( function(){
        // task here
    } )
    .everyHourAt( 45 );

// Object with run() method
task( "my-task" )
    .call( getInstance( "MyTask" ) )
    .everyDay()

// Object with a custom method
task( "my-task" )
    .call( getInstance( "CacheService" ), "reapCache" )
    .everydayAt( "13:00" )

Frequencies

There are many many frequency methods in ColdBox scheduled tasks that will enable the tasks in specific intervals. Every time you see that an argument receives a timeUnit the available options are:

• Nanosecond(s)

• Microsecond(s)

• Millisecond(s) - DEFAULT

• Second(s)

• Minute(s)

• Hour(s)

• Day(s)

Ok, let's go over the frequency methods:

Preventing Overlaps

By default all tasks that have interval rates/periods that will execute on that interval schedule. However, what happens if a task takes longer to execute than the period? Well, by default the task will execute even if the previous one has not executed. If you want to prevent this behavior, then you can use the withNoOverlaps() method and ColdBox will register the tasks with a fixed delay. Meaning the intervals do not start counting until the last task has finished executing.

task( "test" )
    .call( () => getInstance( "CacheService" ).reap() )
    .everyMinute()
    .withNoOverlaps();

Delaying First Execution

Every task can also have an initial delay of first execution by using the delay() method.

/**
 * Set a delay in the running of the task that will be registered with this schedule
 *
 * @delay The delay that will be used before executing the task
 * @timeUnit The time unit to use, available units are: days, hours, microseconds, milliseconds, minutes, nanoseconds, and seconds. The default is milliseconds
 */
ScheduledTask function delay( numeric delay, timeUnit = "milliseconds" )

The delay is numeric and the timeUnit can be:

• days

• hours

• minutes

• seconds

• milliseconds (default)

• microseconds

• nanoseconds

// Lambda Syntax
task( "my-task" )
    .call( () => getInstance( "myService" ).runcleanup() )
    .delay( "5000" )
    .everyHour();

One Off Tasks

A part from registering tasks that have specific intervals/frequencies you can also register tasks that can be executed ONCE ONLY. These are great for warming up caches, registering yourself with control planes, setting up initial data collections and so much more.

Basically, you don't register a frequency just the callable event. Usually, you can also combine them with a delay of execution, if you need them to fire off after certain amount of time has passed.

task( "build-up-cache" )
    .call( () => getInstance( "DataServices" ).buildCache() )
    .delay( 1, "minutes" );

task( "notify-admin-server-is-up" )
    .call( () => getInstance( "SettingService" ).notifyAppIsUp( getUtil().getServerIp() ) )
    .delay( 30, "seconds" );

task( "register-container" )
    .call( () => runEvent( "tasks.registerContainer" ) )
    .delay( 30, "seconds" );

Life-Cycle Methods

We already saw that a scheduler has life-cycle methods, but a task can also have several useful life-cycle methods:

task( "testharness-Heartbeat" )
    .call( function() {
            if ( randRange(1, 5) eq 1 ){
                 throw( message = "I am throwing up randomly!", type="RandomThrowup" );
            }
              writeDump( var='====> I am in a test harness test schedule!', output="console" );
        } )
        .every( "5", "seconds" )
        .before( function( task ) {
              writeDump( var='====> Running before the task!', output="console" );
        } )
        .after( function( task, results ){
              writeDump( var='====> Running after the task!', output="console" );
        } )
        .onFailure( function( task, exception ){
              writeDump( var='====> test schedule just failed!! #exception.message#', output="console" );
        } )
        .onSuccess( function( task, results ){
              writeDump( var="====> Test scheduler success : Stats: #task.getStats().toString()#", output="console" );
        } );

Timezone

By default, all tasks will ask the scheduler for the timezone to run in. However, you can override it on a task-by-task basis using the setTimezone( timezone ) method:

setTimezone( "America/Chicago" )

Truth Test Constraints

There are many ways to constrain the execution of a task. However, you can register a when() closure that will be executed at runtime and boolean evaluated. If true, then the task can run, else it is disabled.

task( "my-task" )
    .call( () => getInstance( "securityService" ).cleanOldUsers() )
    .daily()
    .when( function(){
        // Can we run this task?
        return true;
    );

Scheduled Tasks Start and End Dates

All scheduled tasks support the ability to seed in the start and end dates via our DSL:

• startOn( date, time = "00:00" )

• endOn( data, time = "00:00" )

This means that you can tell the scheduler when the task will become active on a specific data and time (using the scheduler's timezone), and when the task will become disabled.

task( "restricted-task" )
  .call( () => ... )
  .everyHour()
  .startOn( "2022-01-01", "00:00" )
  .endOn( "2022-04-01" )

Server Fixation

If you are running a cluster of your application and you register tasks they will run at their schedule in EVERY server/container the application has been deployed to. This might not be a great idea if you want only ONE task to run no matter how many servers/containers you have deployed your application on. For this situation you can use the onOneServer() method which tells ColdBox to ONLY run the task once on the first server that wins the race condition.

task( "my-task" )
    .call( () => getInstance( "securityService" ).cleanOldUsers() )
    .daily()
    .onOneServer();

Changing the Cache Provider

By default this feature leverages the template cache provider in CacheBox. However, you can change which cache provider will be used for storing the locking and tracking entries.

task( "my-task" )
    .call( () => getInstance( "securityService" ).cleanOldUsers() )
    .daily()
    .setCacheName( "redis" )
    .onOneServer();

Environment Constraints

All ColdBox applications have a runnable environment stored in the environment setting. You can use that to register a task with constraints of environment using the onEnvironment( environment ) method. This means that the task will ONLY run on those environments. The environment argument can be a single string, a list of environments or an array of environments.

task( "my-task" )
    .call( () => getInstance( "securityService" ).cleanOldUsers() )
    .daily()
    .onEnvironment( "staging" );

task( "my-task" )
    .call( () => getInstance( "securityService" ).cleanOldUsers() )
    .daily()
    .onEnvironment( [ "staging", "production" ] );

task( "my-task" )
    .call( () => getInstance( "securityService" ).cleanOldUsers() )
    .daily()
    .onEnvironment( "staging,production" );

Disabling/Pausing Tasks

Every task is runnable from registration according to the frequency you set. However, you can manually disable a task using the disable() method:

task( "my-task" )
    .call( () => getInstance( "securityService" ).cleanOldUsers() )
    .daily()
    .disable();

Once you are ready to enable the task, you can use the enable() method:

myTask.enable()

xTask() - Easy Disabling of Tasks

Thanks to the inspiration of TestBox where you can mark a spec or test to be skipped from execution by prefixing it with the letter x you can do the same for any task declaration. If they are prefixed with the letter x they will be registered but disabled automatically for you.

function configure(){

	xtask( "Disabled Task" )
		.call ( function(){
			writeDump( var="Disabled", output="console" );
		})
		.every( 1, "second" );

	task( "Scope Test" )
		.call( function(){
			writeDump( var="****************************************************************************", output="console" );
			writeDump( var="Scope Test (application) -> #getThreadName()# #application.keyList()#", output="console" );
			writeDump( var="Scope Test (server) -> #getThreadName()# #server.keyList()#", output="console" );
			writeDump( var="Scope Test (cgi) -> #getThreadName()# #cgi.keyList()#", output="console" );
			writeDump( var="Scope Test (url) -> #getThreadName()# #url.keyList()#", output="console" );
			writeDump( var="Scope Test (form) -> #getThreadName()# #form.keyList()#", output="console" );
			writeDump( var="Scope Test (request) -> #getThreadName()# #request.keyList()#", output="console" );
			writeDump( var="Scope Test (variables) -> #getThreadName()# #variables.keyList()#", output="console" );
			writeDump( var="****************************************************************************", output="console" );
		} )
		.every( 60, "seconds" )
		.onFailure( function( task, exception ){
			writeDump( var='====> Scope test failed (#getThreadName()#)!! #exception.message# #exception.stacktrace.left( 500 )#', output="console" );
		} );
		
}

Task Stats

All tasks keep track of themselves and have lovely metrics. You can use the getStats() method to get a a snapshot structure of the stats in time. Here is what you get in the stats structure:

/**
 * Called after ANY task runs
 *
 * @task The task that got executed
 * @result The result (if any) that the task produced
 */
function afterAnyTask( required task, result ){
    log.info( "task #task.getName()# just ran. Metrics: #task.getStats().toString()# ");
}

Task Helpers

We have created some useful methods that you can use when working with asynchronous tasks:

Schedulers For Modules

Every module in ColdBox also has a convention of config/Scheduler.cfc that if detected will register that scheduler for you with a WireBox ID of cbScheduler@{moduleName}. ColdBox will register the scheduler for you and also store it in the module's configuration struct with a key of scheduler. ColdBox will also manage it's lifecycle and destroy it if the module is unloaded. All the rules for schedulers apply, happy scheduling!

+ MyModule
  + config
     - Router.cfc
     - Scheduler.cfc