abstract class Semaphore[F[_]] extends AnyRef

A purely functional semaphore.

A semaphore has a non-negative number of permits available. Acquiring a permit decrements the current number of permits and releasing a permit increases the current number of permits. An acquire that occurs when there are no permits available results in fiber blocking until a permit becomes available.

Source
Semaphore.scala
Linear Supertypes
AnyRef, Any
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. Semaphore
  2. AnyRef
  3. Any
  1. Hide All
  2. Show All
Visibility
  1. Public
  2. Protected

Instance Constructors

  1. new Semaphore()

Abstract Value Members

  1. abstract def acquireN(n: Long): F[Unit]

    Acquires n permits.

    Acquires n permits.

    The returned effect semantically blocks until all requested permits are available. Note that acquires are statisfied in strict FIFO order, so given s: Semaphore[F] with 2 permits available, an acquireN(3) will always be satisfied before a later call to acquireN(1).

    This method is interruptible, and in case of interruption it will take care of restoring any permits it has acquired. If it does succeed however, managing permits correctly is the user's responsibility. Use permit for a safer but less flexible alternative, when you are using Semaphore merely as a lock.

    n

    number of permits to acquire - must be >= 0

  2. abstract def available: F[Long]

    Returns the number of permits currently available.

    Returns the number of permits currently available. Always non-negative.

    May be out of date the instant after it is retrieved. Use tryAcquire or tryAcquireN if you wish to attempt an acquire, returning immediately if the current count is not high enough to satisfy the request.

  3. abstract def count: F[Long]

    Obtains a snapshot of the current count.

    Obtains a snapshot of the current count. May be negative.

    Like available when permits are available but returns the number of permits callers are waiting for when there are no permits available.

  4. abstract def mapK[G[_]](f: ~>[F, G])(implicit G: kernel.MonadCancel[G, _]): Semaphore[G]

    Modify the context F using natural transformation f.

  5. abstract def permit: kernel.Resource[F, Unit]

    Returns a cats.effect.kernel.Resource that acquires a permit, holds it for the lifetime of the resource, then releases the permit.

  6. abstract def releaseN(n: Long): F[Unit]

    Releases n permits, potentially unblocking up to n outstanding acquires.

    Releases n permits, potentially unblocking up to n outstanding acquires.

    n

    number of permits to release - must be >= 0

  7. abstract def tryAcquireN(n: Long): F[Boolean]

    Acquires n permits now and returns true, or returns false immediately.

    Acquires n permits now and returns true, or returns false immediately. Error if n < 0.

    n

    number of permits to acquire - must be >= 0

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##: Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. def acquire: F[Unit]

    Acquires a single permit.

    Acquires a single permit. Alias for acquireN(1).

  5. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  6. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @native()
  7. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  8. def equals(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef → Any
  9. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable])
  10. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  11. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  12. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  13. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  14. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  15. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  16. def release: F[Unit]

    Releases a single permit.

    Releases a single permit. Alias for releaseN(1).

  17. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  18. def toString(): String
    Definition Classes
    AnyRef → Any
  19. def tryAcquire: F[Boolean]

    Alias for tryAcquireN(1).

  20. def tryPermit(implicit F: Applicative[F]): kernel.Resource[F, Boolean]

    Returns a cats.effect.kernel.Resource that contains a boolean that indicates whether we acquired a permit or not.

    Returns a cats.effect.kernel.Resource that contains a boolean that indicates whether we acquired a permit or not. If the permit was acquired then it is guaranteed to be released at the end of the Resource lifetime

  21. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  22. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  23. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()

Inherited from AnyRef

Inherited from Any

Ungrouped