This is simple cron management library based on cron4s (cron expression library)
It use single java.util.Timer (which is precise enough) to schedule all jobs and plans only nearest timer tick to ensure that execution of this tick does not shift next ticks.
libraryDependencies += "ru.arigativa" %% "cronicle" % "1.0.1"import java.time.Instant
import java.util.concurrent.Executors
import cron4s.Cron
import ru.arigativa.cronicle.{CronJob, Cronicle}
import scala.concurrent.ExecutionContext
// you can also use global executionContext
val cronicleEc = ExecutionContext.fromExecutor(Executors.newWorkStealingPool())
val cronicle = new Cronicle[String]()(cronicleEc)
val catJob = CronJob(
"print cat",
Cron("*/2 * * * * ?").right.get,
() => println(Instant.now(), "cat")
)
val dogJob = CronJob(
"print dog",
Cron("* * * * * ?").right.get,
() => println(Instant.now(), "dog")
)
cronicle.start() // start cron
cronicle.add(catJob) // add job to schedule
Thread.sleep(2000)
// (2017-05-20T13:14:06.005Z,cat)
cronicle.add(dogJob)
Thread.sleep(2000)
// (2017-05-20T13:14:07Z,dog)
// (2017-05-20T13:14:08.004Z,cat)
// (2017-05-20T13:14:08.004Z,dog)
cronicle.remove(dogJob)
Thread.sleep(2000)
// (2017-05-20T13:14:10.001Z,cat)
cronicle.pause()
Thread.sleep(2000)
// nothing is executed
cronicle.start()
Thread.sleep(2000)
// (2017-05-20T13:14:14.001Z,cat)