scala.concurrent.duration

This class stores a deadline, as obtained via Deadline.now or the duration DSL:

import scala.concurrent.duration._
3.seconds.fromNow

Its main purpose is to manage repeated attempts to achieve something (like awaiting a condition) by offering the methods hasTimeLeft and timeLeft. All durations are measured according to System.nanoTime; this does not take into account changes to the system clock (such as leap seconds).

Utility for working with java.util.concurrent.TimeUnit durations.

This class is not meant as a general purpose representation of time, it is optimized for the needs of scala.concurrent.

Basic Usage

Examples:

import scala.concurrent.duration._

val duration = Duration(100, MILLISECONDS)
val duration = Duration(100, "millis")

duration.toNanos
duration < 1.second
duration <= Duration.Inf

Invoking inexpressible conversions (like calling toSeconds on an infinite duration) will throw an IllegalArgumentException.

Implicits are also provided for Int, Long and Double. Example usage:

import scala.concurrent.duration._

val duration = 100.millis

The DSL provided by the implicit conversions always allows construction of finite durations, even for infinite Double inputs; use Duration.Inf instead.

Extractors, parsing and arithmetic are also included:

val d = Duration("1.2 µs")
val Duration(length, unit) = 5 millis
val d2 = d * 2.5
val d3 = d2 + 1.millisecond

Handling of Time Units

Calculations performed on finite durations always retain the more precise unit of either operand, no matter whether a coarser unit would be able to exactly express the same duration. This means that Duration can be used as a lossless container for a (length, unit) pair if it is constructed using the corresponding methods and no arithmetic is performed on it; adding/subtracting durations should in that case be done with care.

Correspondence to Double Semantics

The semantics of arithmetic operations on Duration are two-fold:

- exact addition/subtraction with nanosecond resolution for finite durations, independent of the summands' magnitude - isomorphic to java.lang.Double when it comes to infinite or undefined values

The conversion between Duration and Double is done using Duration.toUnit (with unit NANOSECONDS) and Duration.fromNanos(Double)

Ordering

The default ordering is consistent with the ordering of Double numbers, which means that Undefined is considered greater than all other durations, including Duration.Inf.

This object can be used as closing token for declaring a deadline at some future point in time:

import scala.concurrent.duration._

val deadline = 3 seconds fromNow

This object can be used as closing token if you prefer dot-less style but do not want to enable language.postfixOps:

import scala.concurrent.duration._

val duration = 2 seconds span