Trait Promise.Promise

trait Promise[T]

Promise is an object which can be completed with a value or failed with an exception.

A promise should always eventually be completed, whether for success or failure, in order to avoid unintended resource retention for any associated Futures' callbacks or transformations.

Supertypes	class Object trait Matchable class Any

Abstract methods

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def future: Future[T]

Future containing the value of this promise.

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def isCompleted: Boolean

Returns whether the promise has already been completed with a value or an exception.

Note: Using this method may result in non-deterministic concurrent programs.

Returns	true if the promise is already completed, false otherwise

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def tryComplete(result: Try[T]): Boolean

Tries to complete the promise with either a value or the exception.

Note: Using this method may result in non-deterministic concurrent programs.

Returns	If the promise has already been completed returns false, or true otherwise.

Concrete methods

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def complete(result: Try[T]): Promise.this.type

Completes the promise with either an exception or a value.

Value parameters	result Either the value or the exception to complete the promise with. If the promise has already been fulfilled, failed or has timed out, calling this method will throw an IllegalStateException.

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def completeWith(other: Future[T]): Promise.this.type

Completes this promise with the specified future, once that future is completed.

Returns	This promise

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def failure(cause: Throwable): Promise.this.type

Completes the promise with an exception.

Value parameters	cause The throwable to complete the promise with. If the throwable used to fail this promise is an error, a control exception or an interrupted exception, it will be wrapped as a cause within an ExecutionException which will fail the promise. If the promise has already been fulfilled, failed or has timed out, calling this method will throw an IllegalStateException.

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def success(value: T): Promise.this.type

Completes the promise with a value.

Value parameters	value The value to complete the promise with. If the promise has already been fulfilled, failed or has timed out, calling this method will throw an IllegalStateException.

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def tryFailure(cause: Throwable): Boolean

Tries to complete the promise with an exception.

Note: Using this method may result in non-deterministic concurrent programs.

Returns	If the promise has already been completed returns false, or true otherwise.

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def trySuccess(value: T): Boolean

Tries to complete the promise with a value.

Note: Using this method may result in non-deterministic concurrent programs.

Returns	If the promise has already been completed returns false, or true otherwise.