SpotRef

Obtains a snapshot of the current value, and a setter for updating it.

The setter attempts to modify the contents from the snapshot to the new value (and return true). If it cannot do this (because the contents changed since taking the snapshot), the setter is a noop and returns false.

Satisfies: r.access.map(_._1) == r.get and r.access.flatMap { case (v, setter) => setter(f(v)) } == r.tryUpdate(f).map(_.isDefined).

Obtains the current value.

Since Ref is always guaranteed to have a value, the returned action completes immediately after being bound.

Like tryModify but retries until the update has been successfully made.

Like tryModifyState but retries the modification until successful.

Sets the current value to a.

The returned action completes after the reference has been successfully set.

Like tryUpdate but allows the update function to return an output value of type B. The returned action completes with None if the value is not updated successfully and Some(b) otherwise.

Update the value of this Ref with a state computation.

The current value of this Ref is used as the initial state and the computed output state is stored in this Ref after computation completes. If a concurrent modification occurs, None is returned.

Attempts to modify the current value once, returning false if another concurrent modification completes between the time the variable is read and the time it is set.

Modifies the current value using the supplied update function. If another modification occurs between the time the current value is read and subsequently updated, the modification is retried using the new value. Hence, f may be invoked multiple times.

Satisfies: r.update(_ => a) == r.set(a)

Like modify but schedules resulting effect right after modification.

Useful for implementing effectful transition of a state machine, in which an effect is performed based on current state and the state must be updated to reflect that this effect will be performed.

Both modification and finalizer are within a single uncancelable region, to prevent canceled finalizers from leaving the Ref's value permanently out of sync with effects actually performed. if you need cancellation mechanic in finalizer please see flatModifyFull.

Like modify but schedules resulting effect right after modification.

Unlike flatModify finalizer cancellation could be unmasked via supplied Poll. Modification itself is still uncancelable.

When used as part of a state machine, cancelable regions should usually have an onCancel finalizer to update the state to reflect that the effect will not be performed.

Like modifyState but schedules resulting effect right after state computation & update.

Both modification and finalizer are uncancelable, if you need cancellation mechanic in finalizer please see flatModifyStateFull.

Like modifyState but schedules resulting effect right after modification.

Unlike flatModifyState finalizer cancellation could be masked via supplied Poll[F]. Modification itself is still uncancelable.

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

Updates the current value using f and returns the previous value.

In case of retries caused by concurrent modifications, the returned value will be the last one before a successful update.

Modify the context F using transformation f.

Updates the current value using f, and returns the updated value.