Pat Garrity
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54 lines
1.5 KiB
Scala
54 lines
1.5 KiB
Scala
package gs.timing.v0
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import cats.Functor
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import cats.syntax.all.*
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import java.util.concurrent.TimeUnit
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import scala.concurrent.duration.FiniteDuration
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/** Timer based on monotonic time expressed as nanoseconds. Each timer is based
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* on a fixed start point, and calculates [[ElapsedTime]] based on that point.
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*
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* This class should be instantiated by [[Timing]], which will inject an
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* appropriate function for calculating elapsed time.
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*
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* ## Usage
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*
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* {{{
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* import gs.timing.v0.Timing
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* import cats.effect.IO
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*
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* val timing = Timing.system[IO]
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*
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* val program: IO[List[ElapsedTime]] =
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* for
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* timer <- timing.start()
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* elapsed1 <- timer.checkpoint()
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* elapsed2 <- timer.checkpoint()
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* elapsed3 <- timer.checkpoint()
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* yield
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* List(elapsed1, elapsed2, elapsed3)
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* }}}
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*
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* @param start
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* The fixed start point, expressed as monotonic time (nanoseconds, tick
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* count).
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* @param checkpointFunction
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* The checkpoint function used to evaluate the current time.
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*/
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final class MonotonicTimer[F[_]: Functor](
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val start: Long,
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private val checkpointFunction: () => F[Long]
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):
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/** @return
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* The [[ElapsedTime]] (in nanoseconds) based on the fixed start point and
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* checking the current monotonic time.
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*/
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def checkpoint(): F[ElapsedTime] =
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checkpointFunction().map(end =>
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ElapsedTime(
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start = start,
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end = end,
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duration = new FiniteDuration(end - start, TimeUnit.NANOSECONDS)
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)
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)
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