Duration
Durations are used throughout the Akka library, wherefore this concept is represented by a special data type, Duration. Values of this type may represent infinite (Duration.Inf, Duration.MinusInf) or finite durations.
Scala
In Scala durations are constructable using a mini-DSL and support all expected operations:
import akka.util.duration._ // notice the small d
val fivesec = 5.seconds
val threemillis = 3.millis
val diff = fivesec - threemillis
assert (diff < fivesec)
val fourmillis = threemillis * 4 / 3 // though you cannot write it the other way around
val n = threemillis / (1 millisecond)
Note
You may leave out the dot if the expression is clearly delimited (e.g. within parentheses or in an argument list), but it is recommended to use it if the time unit is the last token on a line, otherwise semi-colon inference might go wrong, depending on what starts the next line.
Java
Java provides less syntactic sugar, so you have to spell out the operations as method calls instead:
final Duration fivesec = Duration.create(5, "seconds");
final Duration threemillis = Duration.parse("3 millis");
final Duration diff = fivesec.minus(threemillis);
assert (diff.lt(fivesec));
assert (Duration.Zero().lt(Duration.Inf()));
Deadline
Durations have a brother named Deadline, which is a class holding a representation of an absolute point in time, and support deriving a duration from this by calculating the difference between now and the deadline. This is useful when you want to keep one overall deadline without having to take care of the book-keeping wrt. the passing of time yourself:
val deadline = 10 seconds fromNow
// do something which takes time
awaitCond(..., deadline.timeLeft)
In Java you create these from durations:
final Deadline d = Duration.create(5, "seconds").fromNow();
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