Concurrent

Value Members

1. final def !=(arg0: Any): Boolean

   

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2. final def ##(): Int

   

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3. final def ==(arg0: Any): Boolean

   

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4. def apply[F[_]](implicit instance: Concurrent[F]): Concurrent[F]

   

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   @inline()

5. final def asInstanceOf[T0]: T0

   

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6. def cancelableF[F[_], A](k: ((Either[Throwable, A]) ⇒ Unit) ⇒ F[CancelToken[F]])(implicit F: Concurrent[F]): F[A]

   

   Function that creates an async and cancelable F[A], similar with Concurrent.cancelable, but with the semantics of Async.asyncF.

   Function that creates an async and cancelable F[A], similar with Concurrent.cancelable, but with the semantics of Async.asyncF.

   Example building an asynchronous queue, with the state being kept in cats.effect.concurrent.Ref and thus needing cancelableF:

   import cats.implicits._
   import cats.effect.{CancelToken, Concurrent}
   import cats.effect.concurrent.Ref
   import scala.collection.immutable.Queue
   
   final class AsyncQueue[F[_], A] private (
     ref: Ref[F, AsyncQueue.State[A]])
     (implicit F: Concurrent[F]) {
   
     import AsyncQueue._
   
     def poll: F[A] =
       Concurrent.cancelableF { cb =>
         ref.modify {
           case Await(listeners) =>
             (Await(listeners.enqueue(cb)), F.pure(unregister(cb)))
           case Available(queue) =>
             queue.dequeueOption match {
               case None =>
                 (Await(Queue(cb)), F.pure(unregister(cb)))
               case Some((a, queue2)) =>
                 (Available(queue2), F.delay(cb(a)).as(unregister(cb)))
             }
         }.flatten
       }
   
     def offer(a: A): F[Unit] = {
       // Left as an exercise for the reader ;-)
       ???
     }
   
     private def unregister(cb: Either[Throwable, A] => Unit): CancelToken[F] =
       ref.update {
         case Await(listeners) => Await(listeners.filter(_ != cb))
         case other => other
       }
   }
   
   object AsyncQueue {
     def empty[F[_], A](implicit F: Concurrent[F]): F[AsyncQueue[F, A]] =
       for {
         ref <- Ref.of[F, State[A]](Available(Queue.empty))
       } yield {
         new AsyncQueue[F, A](ref)
       }
   
     private sealed trait State[A]
   
     private case class Await[A](listeners: Queue[Either[Throwable, A] => Unit])
       extends State[A]
   
     private case class Available[A](values: Queue[A])
       extends State[A]
   }

   Contract

   The given generator function will be executed uninterruptedly, via bracket, because due to the possibility of auto-cancellation we can have a resource leak otherwise.

   This means that the task generated by k cannot be cancelled while being evaluated. This is in contrast with Async.asyncF, which does allow cancelable tasks.

   k

   is a function that's going to be injected with a callback, to call on completion, returning an effect that's going to be evaluated to a cancellation token

7. implicit def catsEitherTConcurrent[F[_], L](implicit arg0: Concurrent[F]): Concurrent[[γ$0$]EitherT[F, L, γ$0$]]

   

   Concurrent instance built for cats.data.EitherT values initialized with any F data type that also implements Concurrent.

8. implicit def catsIorTConcurrent[F[_], L](implicit arg0: Concurrent[F], arg1: Semigroup[L]): Concurrent[[γ$4$]IorT[F, L, γ$4$]]

   

   Concurrent instance built for cats.data.IorT values initialized with any F data type that also implements Concurrent.

9. implicit def catsKleisliConcurrent[F[_], R](implicit arg0: Concurrent[F]): Concurrent[[γ$2$]Kleisli[F, R, γ$2$]]

   

   Concurrent instance built for cats.data.Kleisli values initialized with any F data type that also implements Concurrent.

10. implicit def catsOptionTConcurrent[F[_]](implicit arg0: Concurrent[F]): Concurrent[[β$1$]OptionT[F, β$1$]]

    

    Concurrent instance built for cats.data.OptionT values initialized with any F data type that also implements Concurrent.

11. implicit def catsWriterTConcurrent[F[_], L](implicit arg0: Concurrent[F], arg1: Monoid[L]): Concurrent[[γ$3$]WriterT[F, L, γ$3$]]

    

    Concurrent instance built for cats.data.WriterT values initialized with any F data type that also implements Concurrent.

12. def clone(): AnyRef

    

    Attributes

    protected[java.lang]

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    @throws( ... )

13. final def eq(arg0: AnyRef): Boolean

    

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14. def equals(arg0: Any): Boolean

    

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15. def finalize(): Unit

    

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    protected[java.lang]

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    @throws( classOf[java.lang.Throwable] )

16. final def getClass(): Class[_]

    

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17. def hashCode(): Int

    

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18. final def isInstanceOf[T0]: Boolean

    

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19. def liftIO[F[_], A](ioa: IO[A])(implicit F: Concurrent[F]): F[A]

    

    Lifts any IO value into any data type implementing Concurrent.

    Lifts any IO value into any data type implementing Concurrent.

    Compared with Async.liftIO, this version preserves the interruptibility of the given IO value.

    This is the default Concurrent.liftIO implementation.

20. def memoize[F[_], A](f: F[A])(implicit F: Concurrent[F]): F[F[A]]

    

    Lazily memoizes f.

    Lazily memoizes f. For every time the returned F[F[A]] is bound, the effect f will be performed at most once (when the inner F[A] is bound the first time).

    Note: start can be used for eager memoization.

21. final def ne(arg0: AnyRef): Boolean

    

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22. object nonInheritedOps extends ToConcurrentOps

    

23. final def notify(): Unit

    

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24. final def notifyAll(): Unit

    

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25. object ops

    

26. final def synchronized[T0](arg0: ⇒ T0): T0

    

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27. def timeout[F[_], A](fa: F[A], duration: FiniteDuration)(implicit F: Concurrent[F], timer: Timer[F]): F[A]

    

    Returns an effect that either completes with the result of the source within the specified time duration or otherwise raises a TimeoutException.

    Returns an effect that either completes with the result of the source within the specified time duration or otherwise raises a TimeoutException.

    The source is cancelled in the event that it takes longer than the specified time duration to complete.

    duration

    is the time span for which we wait for the source to complete; in the event that the specified time has passed without the source completing, a TimeoutException is raised

28. def timeoutTo[F[_], A](fa: F[A], duration: FiniteDuration, fallback: F[A])(implicit F: Concurrent[F], timer: Timer[F]): F[A]

    

    Returns an effect that either completes with the result of the source within the specified time duration or otherwise evaluates the fallback.

    Returns an effect that either completes with the result of the source within the specified time duration or otherwise evaluates the fallback.

    The source is cancelled in the event that it takes longer than the FiniteDuration to complete, the evaluation of the fallback happening immediately after that.

    duration

    is the time span for which we wait for the source to complete; in the event that the specified time has passed without the source completing, the fallback gets evaluated

    fallback

    is the task evaluated after the duration has passed and the source canceled

29. def toString(): String

    

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30. final def wait(): Unit

    

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    @throws( ... )

31. final def wait(arg0: Long, arg1: Int): Unit

    

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    @throws( ... )

32. final def wait(arg0: Long): Unit

    

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