cats-effect-std
3.6-8a37117
API
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cats-effect-std/cats.effect.std/AtomicCell

AtomicCell

cats.effect.std.AtomicCell
See theAtomicCell companion object
abstract class AtomicCell[F[_], A]

A synchronized, concurrent, mutable reference.

Provides safe concurrent access and modification of its contents, by ensuring only one fiber can operate on them at the time. Thus, all operations except get may semantically block the calling fiber.

final class ParkingLot(data: AtomicCell[IO, Vector[Boolean]], rnd: Random[IO]) {
  def getSpot: IO[Option[Int]] =
    data.evalModify { spots =>
      val availableSpots = spots.zipWithIndex.collect { case (true, idx) => idx }
      rnd.shuffleVector(availableSpots).map { shuffled =>
        val acquired = shuffled.headOption
        val next = acquired.fold(spots)(a => spots.updated(a, false)) // mark the chosen spot as taken
        (next, shuffled.headOption)
      }
    }
}

Attributes

See also

cats.effect.kernel.Ref for a non-blocking alternative.

Companion
object
Source
AtomicCell.scala
Graph
Supertypes
class Object
trait Matchable
class Any

Members list

Value members

Abstract methods

def evalGetAndUpdate(f: A => F[A]): F[A]

Updates the current value using the provided effectual function, and returns the previous value.

Updates the current value using the provided effectual function, and returns the previous value.

Attributes

Source
AtomicCell.scala
def evalModify[B](f: A => F[(A, B)]): F[B]

Like evalUpdate but allows the update function to return an output value.

Like evalUpdate but allows the update function to return an output value.

Attributes

Source
AtomicCell.scala
def evalUpdate(f: A => F[A]): F[Unit]

Like update but using an effectual function; which is guaranteed to run only once.

Like update but using an effectual function; which is guaranteed to run only once.

Attributes

Source
AtomicCell.scala
def evalUpdateAndGet(f: A => F[A]): F[A]

Updates the current value using the provided effectual function, and returns the updated value.

Updates the current value using the provided effectual function, and returns the updated value.

Attributes

Source
AtomicCell.scala
def get: F[A]

Obtains the current value.

Obtains the current value.

Attributes

Source
AtomicCell.scala
def modify[B](f: A => (A, B)): F[B]

Like update but allows the update function to return an output value.

Like update but allows the update function to return an output value.

Attributes

Source
AtomicCell.scala
def set(a: A): F[Unit]

Sets the current value to a.

Sets the current value to a.

Attributes

Source
AtomicCell.scala

Concrete methods

def getAndSet(a: A): F[A]

Replaces the current value with a, returning the previous value.

Replaces the current value with a, returning the previous value.

Attributes

Source
AtomicCell.scala
def getAndUpdate(f: A => A): F[A]

Updates the current value using the provided function, and returns the previous value.

Updates the current value using the provided function, and returns the previous value.

Attributes

Source
AtomicCell.scala
def update(f: A => A): F[Unit]

Modifies the current value using the supplied update function.

Modifies the current value using the supplied update function.

Attributes

Source
AtomicCell.scala
def updateAndGet(f: A => A): F[A]

Updates the current value using the provided function, and returns the updated value.

Updates the current value using the provided function, and returns the updated value.

Attributes

Source
AtomicCell.scala
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