Version: 2.0.x

Clock

Clock service contains some functionality related to time and scheduling.

To get the current time in a specific time unit, the currentTime function takes a unit as TimeUnit and returns UIO[Long]:

import zio._
import java.util.concurrent.TimeUnit

val inMilliseconds: UIO[Long] = Clock.currentTime(TimeUnit.MILLISECONDS)
val inDays        : UIO[Long] = Clock.currentTime(TimeUnit.DAYS)

To get current date time in the current timezone the currentDateTime function returns a ZIO effect containing OffsetDateTime.

Also, the Clock service has a very useful functionality for sleeping and creating a delay between jobs. The sleep takes a Duration and sleeps for the specified duration. It is analogous to java.lang.Thread.sleep function, but it doesn't block any underlying thread. It's completely non-blocking.

In the following example we are going to print the current time periodically by placing a one second sleep between each print call:

import zio._

def printTimeForever: ZIO[Any, Throwable, Nothing] =
  Clock.currentDateTime.flatMap(Console.printLine(_)) *>
    ZIO.sleep(1.seconds) *> printTimeForever

For scheduling purposes like retry and repeats, ZIO has a great data type called Schedule.

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