class AsyncSemaphore extends AnyRef

An AsyncSemaphore is a traditional semaphore but with asynchronous execution.

Grabbing a permit returns a Future[Permit].

Basic usage:

val semaphore = new AsyncSemaphore(n)
...
semaphore.acquireAndRun() {
  somethingThatReturnsFutureT()
}

Calls to acquire() and acquireAndRun are serialized, and tickets are given out fairly (in order of arrival).

Self Type
AsyncSemaphore
See also

AsyncMutex for a mutex version.

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Instance Constructors

  1. new AsyncSemaphore(initialPermits: Int, maxWaiters: Int)

    Constructs a semaphore with maxWaiters as the limit on the number of waiters for permits.

    Constructs a semaphore with maxWaiters as the limit on the number of waiters for permits.

    initialPermits

    must be positive

    maxWaiters

    must be non-negative

  2. new AsyncSemaphore(initialPermits: Int)

    Constructs a semaphore with no limit on the max number of waiters for permits.

    Constructs a semaphore with no limit on the max number of waiters for permits.

    initialPermits

    must be positive

  3. new AsyncSemaphore(initialPermits: Int, maxWaiters: Option[Int])
    Attributes
    protected

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 acquire(): Future[Permit]

    Acquire a Permit, asynchronously.

    Acquire a Permit, asynchronously. Be sure to permit.release() in a

    - finally block of your onSuccess callback - ensure block of your future chain

    Interrupting this future is only advisory, and will not release the permit if the future has already been satisfied.

    returns

    a Future[Permit] when the Future is satisfied, computation can proceed, or a Future.Exception[RejectedExecutionException] if the configured maximum number of waiters would be exceeded.

    Note

    This method always return the same instance of Permit.

  5. def acquireAndRun[T](func: ⇒ Future[T]): Future[T]

    Execute the function asynchronously when a permit becomes available.

    Execute the function asynchronously when a permit becomes available.

    If the function throws a non-fatal exception, the exception is returned as part of the Future. For all exceptions, the permit would be released before returning.

    returns

    a Future[T] equivalent to the return value of the input function. If the configured maximum value of waitq is reached, Future.Exception[RejectedExecutionException] is returned.

  6. def acquireAndRunSync[T](func: ⇒ T): Future[T]

    Execute the function when a permit becomes available.

    Execute the function when a permit becomes available.

    If the function throws an exception, the exception is returned as part of the Future. For all exceptions, the permit would be released before returning.

    returns

    a Future[T] equivalent to the return value of the input function. If the configured maximum value of waitq is reached, Future.Exception[RejectedExecutionException] is returned.

  7. final def asInstanceOf[T0]: T0
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  8. def clone(): AnyRef
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  9. final def eq(arg0: AnyRef): Boolean
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  10. def equals(arg0: Any): Boolean
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  11. def fail(exc: Throwable): Unit

    Fail the semaphore and stop it from distributing further permits.

    Fail the semaphore and stop it from distributing further permits. Subsequent attempts to acquire a permit fail with exc. This semaphore's queued waiters are also failed with exc.

  12. def finalize(): Unit
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  13. final def getClass(): Class[_]
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  14. def hashCode(): Int
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  15. final def isInstanceOf[T0]: Boolean
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  16. final def ne(arg0: AnyRef): Boolean
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  17. final def notify(): Unit
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    @native()
  18. final def notifyAll(): Unit
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    @native()
  19. def numInitialPermits: Int
  20. def numPermitsAvailable: Int
  21. def numWaiters: Int
  22. final def synchronized[T0](arg0: ⇒ T0): T0
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  23. def toString(): String
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  24. final def wait(): Unit
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    @throws( ... )
  25. final def wait(arg0: Long, arg1: Int): Unit
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    @throws( ... )
  26. final def wait(arg0: Long): Unit
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