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 semantic blocking until a permit becomes available.
- Companion
- object
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.
- Value Params
- n
number of permits to acquire - must be >= 0
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May be out of date the instant after it is retrieved.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.
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.
Modify the context F using natural transformation f.
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.
Releases n permits, potentially unblocking up to n outstanding acquires.
Releases n permits, potentially unblocking up to n outstanding acquires.
- Value Params
- n
number of permits to release - must be >= 0