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.
Attributes
- Companion:
- object
- Source:
- Semaphore.scala
- Graph
- Supertypes
- class Objecttrait Matchableclass Any
Members list
Value members
Abstract methods
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.
Attributes
- n
number of permits to acquire - must be >= 0
- Source:
- Semaphore.scala
Returns the number of permits currently available. Always non-negative.
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May be out of date the instant after it is retrieved.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.
Attributes
- Source:
- Semaphore.scala
Obtains a snapshot of the current count. May be negative.
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.
Attributes
- Source:
- Semaphore.scala
Modify the context F using natural transformation f.
Returns a cats.effect.kernel.Resource that acquires a permit, holds it for the lifetime of the resource, then releases the permit.
Returns a cats.effect.kernel.Resource that acquires a permit, holds it for the lifetime of the resource, then releases the permit.
Attributes
- Source:
- Semaphore.scala
Releases n permits, potentially unblocking up to n outstanding acquires.
Releases n permits, potentially unblocking up to n outstanding acquires.
Attributes
- n
number of permits to release - must be >= 0
- Source:
- Semaphore.scala
Acquires n permits now and returns true, or returns false immediately. Error if n < 0.
Acquires n permits now and returns true, or returns false immediately. Error if n < 0.
Attributes
- n
number of permits to acquire - must be >= 0
- Source:
- Semaphore.scala
Concrete methods
Acquires a single permit. Alias for [[acquireN]](1).
Releases a single permit. Alias for [[releaseN]](1).
Alias for [[tryAcquireN]](1).
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
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
Attributes
- Source:
- Semaphore.scala