play framework 2.1 - scheduling async tasks

Question

In play\'s 2.0.x doc you can see how to schedule asynchronous tasks:

http://www.playframework.org/documentation/2.0.4/ScalaAkka

Akka.system.scheduler         


        

Answer 1

Using sample code and Akka API I made fast test, works for me.

Comparing code between 2.0.4 and 2.1RC1 I can see there're only two changes in case of scheduler:

1. replaced import

   // import akka.util.duration._
   import scala.concurrent.duration._
   

2. added import:

   import play.api.libs.concurrent.Execution.Implicits._
   

app/controllers/Application.scala

package controllers

import play.api._
import play.api.mvc._
import play.libs.Akka

import akka.actor._
import scala.concurrent.duration._
import play.api.libs.concurrent.Execution.Implicits._

object Application extends Controller {

  def index = Action {

    // say hello
    Logger.info("hello, index action started")

    val Tick = "tick"
    val Tack = "tack"

    val tickActor = Akka.system.actorOf(Props(new Actor {
      def receive = {
        case Tick => Logger.info("that still ticks!")
        case Tack => Logger.warn("... 7 seconds after start, only once")
      }
    }))

    // Repeat every 5 seconds, start 5 seconds after start
    Akka.system.scheduler.schedule(
      5 seconds,
      5 seconds,
      tickActor,
      Tick
    )

    // do only once, 7 seconds after start
    Akka.system.scheduler.scheduleOnce(7 seconds, tickActor, Tack)

    Ok(views.html.index("Your new application is ready."))
  }

}

Edit

Nota bene, as I can see from Julien's post on the group, that's enough to import defaultContext only:

import play.api.libs.concurrent.Execution.Implicits.defaultContext

Answer 2

For example run a task every Saturday at 15 AM in java:

DateTime now = new DateTime();

DateTime plannedStart = new DateTime()
    .withDayOfWeek(DateTimeConstants.SATURDAY)
    .withHourOfDay(15)
    .withMinuteOfHour(0)
    .withSecondOfMinute(0)
    .withMillisOfSecond(0);

DateTime nextRun = (now.isAfter(plannedStart))
    ? plannedStart.plusDays(7)
    : plannedStart;

Long nextRunInSeconds = (long) secondsBetween(now, nextRun).getSeconds();

Akka.system().scheduler().schedule(
    Duration.create(nextRunInSeconds, TimeUnit.SECONDS),
    Duration.create(7, TimeUnit.DAYS) ,
    new Runnable() {
        public void run() {
            Logger.info("-------------------------scheduler start : " + new DateTime());
        }
    },
    Akka.system().dispatcher()
);

Answer 3

biesior's answer is great

However, you don't have to go through an actor if you don't want to. Here's the same answer using good old java.lang.Runnable:

Akka.system.scheduler.schedule(5 minutes, 5 minutes, new Runnable {
  def run() {
    Logger.info("that still ticks!")
  }
})
Akka.system.scheduler.scheduleOnce(7 minutes, new Runnable {
  def run() {
    Logger.warn("... 7 seconds after start, only once")
  }
})