60 lines
2 KiB
ReStructuredText
60 lines
2 KiB
ReStructuredText
.. _Duration:
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########
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Duration
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########
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Durations are used throughout the Akka library, wherefore this concept is
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represented by a special data type, :class:`scala.concurrent.duration.Duration`.
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Values of this type may represent infinite (:obj:`Duration.Inf`,
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:obj:`Duration.MinusInf`) or finite durations, or be :obj:`Duration.Undefined`.
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Finite vs. Infinite
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===================
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Since trying to convert an infinite duration into a concrete time unit like
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seconds will throw an exception, there are different types available for
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distinguishing the two kinds at compile time:
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* :class:`FiniteDuration` is guaranteed to be finite, calling :meth:`toNanos`
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and friends is safe
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* :class:`Duration` can be finite or infinite, so this type should only be used
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when finite-ness does not matter; this is a supertype of :class:`FiniteDuration`
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Scala
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=====
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In Scala durations are constructable using a mini-DSL and support all expected
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arithmetic operations:
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.. includecode:: code/docs/duration/Sample.scala#dsl
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.. note::
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You may leave out the dot if the expression is clearly delimited (e.g.
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within parentheses or in an argument list), but it is recommended to use it
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if the time unit is the last token on a line, otherwise semi-colon inference
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might go wrong, depending on what starts the next line.
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Java
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====
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Java provides less syntactic sugar, so you have to spell out the operations as
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method calls instead:
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.. includecode:: code/docs/duration/Java.java#import
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.. includecode:: code/docs/duration/Java.java#dsl
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Deadline
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========
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Durations have a brother named :class:`Deadline`, which is a class holding a representation
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of an absolute point in time, and support deriving a duration from this by calculating the
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difference between now and the deadline. This is useful when you want to keep one overall
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deadline without having to take care of the book-keeping wrt. the passing of time yourself:
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.. includecode:: code/docs/duration/Sample.scala#deadline
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In Java you create these from durations:
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.. includecode:: code/docs/duration/Java.java#deadline
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