final class Promise[E, A] extends AnyVal with Serializable
A promise represents an asynchronous variable, of zio.IO type, that can
be set exactly once, with the ability for an arbitrary number of fibers to
suspend (by calling await) and automatically resume when the variable is
set.
Promises can be used for building primitive actions whose completions require the coordinated action of multiple fibers, and for building higher-level concurrent or asynchronous structures.
for { promise <- Promise.make[Nothing, Int] _ <- promise.succeed(42).delay(1.second).fork value <- promise.await // Resumes when forked fiber completes promise } yield value
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final
def
!=(arg0: Any): Boolean
- Definition Classes
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final
def
##(): Int
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final
def
==(arg0: Any): Boolean
- Definition Classes
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final
def
asInstanceOf[T0]: T0
- Definition Classes
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final
def
await: IO[E, A]
Retrieves the value of the promise, suspending the fiber running the action until the result is available.
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final
def
complete(io: IO[E, A]): UIO[Boolean]
Completes the promise with the result of the specified effect.
Completes the promise with the result of the specified effect. If the promise has already been completed, the method will produce false.
Note that Promise.completeWith will be much faster, so consider using that if you do not need to memoize the result of the specified effect.
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final
def
completeWith(io: IO[E, A]): UIO[Boolean]
Completes the promise with the specified effect.
Completes the promise with the specified effect. If the promise has already been completed, the method will produce false.
Note that since the promise is completed with an effect, the effect will be evaluated each time the value of the promise is retrieved through combinators such as
await, potentially producing different results if the effect produces different results on subsequent evaluations. In this case te meaning of the "exactly once" guarantee ofPromiseis that the promise can be completed with exactly one effect. For a version that completes the promise with the result of an effect see Promise.complete. -
final
def
die(e: Throwable): UIO[Boolean]
Kills the promise with the specified error, which will be propagated to all fibers waiting on the value of the promise.
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final
def
done(e: Exit[E, A]): UIO[Boolean]
Exits the promise with the specified exit, which will be propagated to all fibers waiting on the value of the promise.
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final
def
fail(e: E): UIO[Boolean]
Fails the promise with the specified error, which will be propagated to all fibers waiting on the value of the promise.
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def
getClass(): Class[_ <: AnyVal]
- Definition Classes
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final
def
halt(e: Cause[E]): UIO[Boolean]
Halts the promise with the specified cause, which will be propagated to all fibers waiting on the value of the promise.
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final
def
interrupt: UIO[Boolean]
Completes the promise with interruption.
Completes the promise with interruption. This will interrupt all fibers waiting on the value of the promise.
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final
def
isDone: UIO[Boolean]
Checks for completion of this Promise.
Checks for completion of this Promise. Produces true if this promise has already been completed with a value or an error and false otherwise.
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final
def
isInstanceOf[T0]: Boolean
- Definition Classes
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final
def
poll: UIO[Option[IO[E, A]]]
Checks for completion of this Promise.
Checks for completion of this Promise. Returns the result effect if this promise has already been completed or a
Noneotherwise. -
final
def
succeed(a: A): UIO[Boolean]
Completes the promise with the specified value.
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def
toString(): String
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Deprecated Value Members
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final
def
done(io: IO[E, A]): UIO[Boolean]
Alias for Promise.complete
Alias for Promise.complete
- Annotations
- @deprecated
- Deprecated
(Since version 1.0.0) use Promise.complete