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Diffstat (limited to 'src/library/scala/concurrent/duration/Deadline.scala')
-rw-r--r-- | src/library/scala/concurrent/duration/Deadline.scala | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/src/library/scala/concurrent/duration/Deadline.scala b/src/library/scala/concurrent/duration/Deadline.scala new file mode 100644 index 0000000000..50e9a75ff7 --- /dev/null +++ b/src/library/scala/concurrent/duration/Deadline.scala @@ -0,0 +1,81 @@ +/* __ *\ +** ________ ___ / / ___ Scala API ** +** / __/ __// _ | / / / _ | (c) 2003-2012, LAMP/EPFL ** +** __\ \/ /__/ __ |/ /__/ __ | http://scala-lang.org/ ** +** /____/\___/_/ |_/____/_/ | | ** +** |/ ** +\* */ + +package 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` aka wall-time; this + * does not take into account changes to the system clock (such as leap + * seconds). + */ +case class Deadline private (time: FiniteDuration) extends Ordered[Deadline] { + /** + * Return a deadline advanced (i.e. moved into the future) by the given duration. + */ + def +(other: FiniteDuration): Deadline = copy(time = time + other) + /** + * Return a deadline moved backwards (i.e. towards the past) by the given duration. + */ + def -(other: FiniteDuration): Deadline = copy(time = time - other) + /** + * Calculate time difference between this and the other deadline, where the result is directed (i.e. may be negative). + */ + def -(other: Deadline): FiniteDuration = time - other.time + /** + * Calculate time difference between this duration and now; the result is negative if the deadline has passed. + * + * '''''Note that on some systems this operation is costly because it entails a system call.''''' + * Check `System.nanoTime` for your platform. + */ + def timeLeft: FiniteDuration = this - Deadline.now + /** + * Determine whether the deadline still lies in the future at the point where this method is called. + * + * '''''Note that on some systems this operation is costly because it entails a system call.''''' + * Check `System.nanoTime` for your platform. + */ + def hasTimeLeft(): Boolean = !isOverdue() + /** + * Determine whether the deadline lies in the past at the point where this method is called. + * + * '''''Note that on some systems this operation is costly because it entails a system call.''''' + * Check `System.nanoTime` for your platform. + */ + def isOverdue(): Boolean = (time.toNanos - System.nanoTime()) < 0 + /** + * The natural ordering for deadline is determined by the natural order of the underlying (finite) duration. + */ + def compare(other: Deadline) = time compare other.time +} + +object Deadline { + /** + * Construct a deadline due exactly at the point where this method is called. Useful for then + * advancing it to obtain a future deadline, or for sampling the current time exactly once and + * then comparing it to multiple deadlines (using subtraction). + */ + def now: Deadline = Deadline(Duration(System.nanoTime, NANOSECONDS)) + + /** + * The natural ordering for deadline is determined by the natural order of the underlying (finite) duration. + */ + implicit object DeadlineIsOrdered extends Ordering[Deadline] { + def compare(a: Deadline, b: Deadline) = a compare b + } + +} |