Play Framework - Schedule a task at precise time [duplicate] - scala

Question

This question already has answers here:
scala - How to run a task every day a 11PM
(2 answers)
Closed 6 years ago.
I'm doing a Scala - Play application and I want to schedule a task to sending mail everyday at 3 A.M, so I create a class for that but i'ts not working:
class ManageSendInvalidateDaemon #Inject() (app: Application, emailSender: EmailSender, mailer: MailerClient) {
Akka.system(app).scheduler.schedule(
scala.concurrent.duration.Duration.create(20,TimeUnit.SECONDS),
scala.concurrent.duration.Duration.create(60, TimeUnit.SECONDS),
new Runnable(){
override def run()={
//Function to send the mail
}
}
);
};
I think the problem is here:
scala.concurrent.duration.Duration.create(20,TimeUnit.SECONDS),
scala.concurrent.duration.Duration.create(60, TimeUnit.SECONDS),
I don't really understand what it's the use of these 2 lines

Answer 1

That will not work as you expect. Akka scheduler just lets you specify the recurrency of the task, but not the day, hour etc when it will run (ex: you can tell it to run a task every 10 minutes, but not run this at 15:30 each Monday).
Those two lines instruct Akka to run that task every 60 seconds, and run the first time 20 seconds after you define it (so if the schedule call is executed at 12h30m that task will run the first time at 12:30:20 and then 12:31:20, 12:32:20, etc).
To overcome this, you just need to run a task periodically (in your case, each minute for example), and check the current hour. If it is 3AM send those emails (and eventually store anywere that this task was executed).
Another option is to use something like akka-quartz-scheduler, that lets you specify that type of scheduling

Answer 2

I had the same problem. So I created a method to calculate how much time from now until the time I want to run my
schedule = Akka.system().scheduler().schedule(
Duration.create(nextRunTime(), TimeUnit.MILLISECONDS),
Duration.create(DAY_IN_MS, TimeUnit.MILLISECONDS),
...,);
The nextRunTime() method calculates how much time in milliseconds will be until the next 3 AM and after that I set an interval of one day (DAY_IN_MS)
private int nextRunTime() {
String runTimeValue = "03:00";
LocalTime now = new LocalTime();
LocalTime runTime = new LocalTime(runTimeValue);
int timeUntilRun;
if (runTime.isAfter(now)) { // From now until the run time
timeUntilRun = runTime.getMillisOfDay() - now.getMillisOfDay();
} else { // From now until midnight, plus from midnight until the run time
timeUntilRun = DAY_IN_MS - now.getMillisOfDay() + runTime.getMillisOfDay();
}
Logger.info("nextRunTime(): next run in " + timeUntilRun + " ms");
return timeUntilRun;
}