Packages

final class AsyncSemaphore extends Serializable

The AsyncSemaphore is an asynchronous semaphore implementation that limits the parallelism on Future execution.

The following example instantiates a semaphore with a maximum parallelism of 10:

val semaphore = AsyncSemaphore(maxParallelism = 10)

def makeRequest(r: HttpRequest): Future[HttpResponse] = ???

// For such a task no more than 10 requests
// are allowed to be executed in parallel.
val future = semaphore.greenLight(() => makeRequest(???))
Source
AsyncSemaphore.scala
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  1. final def !=(arg0: Any): Boolean
    Definition Classes
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  2. final def ##(): Int
    Definition Classes
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  3. final def ==(arg0: Any): Boolean
    Definition Classes
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  4. def acquire(): CancelableFuture[Unit]

    Triggers a permit acquisition, returning a future that will complete when a permit gets acquired.

    Triggers a permit acquisition, returning a future that will complete when a permit gets acquired.

    Annotations
    @tailrec()
  5. def activeCount: Int

    Returns the number of active tasks that are holding on to the available permits.

  6. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  7. def awaitAllReleased(): Future[Unit]

    Returns a future that will be complete when all the currently acquired permits are released, or in other words when the activeCount is zero.

    Returns a future that will be complete when all the currently acquired permits are released, or in other words when the activeCount is zero.

    This also means that we are going to wait for the acquisition and release of all enqueued promises as well.

    Annotations
    @tailrec()
  8. def clone(): AnyRef
    Attributes
    protected[java.lang]
    Definition Classes
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    Annotations
    @throws( ... )
  9. final def eq(arg0: AnyRef): Boolean
    Definition Classes
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  10. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  11. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
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    Annotations
    @throws( classOf[java.lang.Throwable] )
  12. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
  13. def greenLight[A](f: () ⇒ Future[A])(implicit ec: ExecutionContext): Future[A]

    Returns a new future, ensuring that the given source acquires an available permit from the semaphore before it is executed.

    Returns a new future, ensuring that the given source acquires an available permit from the semaphore before it is executed.

    The returned future also takes care of resource handling, releasing its permit after being complete.

    f

    is a function returning the Future instance we want to evaluate after we get the permit from the semaphore

  14. def hashCode(): Int
    Definition Classes
    AnyRef → Any
  15. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  16. final def ne(arg0: AnyRef): Boolean
    Definition Classes
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  17. final def notify(): Unit
    Definition Classes
    AnyRef
  18. final def notifyAll(): Unit
    Definition Classes
    AnyRef
  19. def release(): Unit

    Releases a permit, returning it to the pool.

    Releases a permit, returning it to the pool.

    If there are consumers waiting on permits being available, then the first in the queue will be selected and given a permit immediately.

    Annotations
    @tailrec()
  20. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  21. def toString(): String
    Definition Classes
    AnyRef → Any
  22. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  23. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  24. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

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