Class ResolvedPromiseImpl<T>

  • Type Parameters:
    T - The result type associated with the Promise.
    All Implemented Interfaces:
    Promise<T>

    final class ResolvedPromiseImpl<T>
    extends PromiseImpl<T>
    Resolved Promise implementation.

    This class is not used directly by clients. Clients should use PromiseFactory.resolved(Object) to create a resolved Promise.

    Since:
    1.1
    • Field Detail

      • value

        private final T value
        The value of this resolved Promise.
    • Constructor Detail

      • ResolvedPromiseImpl

        ResolvedPromiseImpl​(T value,
                            PromiseFactory factory)
        Initialize this resolved Promise.
        Parameters:
        value - The value of this resolved Promise.
        factory - The factory to use for callbacks and scheduled operations.
    • Method Detail

      • isDone

        public boolean isDone()
        Returns whether this Promise has been resolved.

        This Promise may be successfully resolved or resolved with a failure.

        Returns:
        true if this Promise was resolved either successfully or with a failure; false if this Promise is unresolved.
      • getValue

        public T getValue()
        Returns the value of this Promise.

        If this Promise is not resolved, this method must block and wait for this Promise to be resolved before completing.

        If this Promise was successfully resolved, this method returns with the value of this Promise. If this Promise was resolved with a failure, this method must throw an InvocationTargetException with the failure exception as the cause.

        Returns:
        The value of this resolved Promise.
      • getFailure

        public java.lang.Throwable getFailure()
        Returns the failure of this Promise.

        If this Promise is not resolved, this method must block and wait for this Promise to be resolved before completing.

        If this Promise was resolved with a failure, this method returns with the failure of this Promise. If this Promise was successfully resolved, this method must return null.

        Returns:
        The failure of this resolved Promise or null if this Promise was successfully resolved.
      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object
      • onFailure

        public Promise<T> onFailure​(Consumer<? super java.lang.Throwable> failure)
        Register a callback to be called with the failure for this Promise when this Promise is resolved with a failure. The callback will not be called if this Promise is resolved successfully.

        This method may be called at any time including before and after this Promise has been resolved.

        Resolving this Promise happens-before any registered callback is called. That is, in a registered callback, Promise.isDone() must return true and Promise.getValue() and Promise.getFailure() must not block.

        A callback may be called on a different thread than the thread which registered the callback. So the callback must be thread safe but can rely upon that the registration of the callback happens-before the registered callback is called.

        Specified by:
        onFailure in interface Promise<T>
        Overrides:
        onFailure in class PromiseImpl<T>
        Parameters:
        failure - The Consumer callback that receives the failure of this Promise. Must not be null.
        Returns:
        This Promise.
      • then

        public <R> Promise<R> then​(Success<? super T,​? extends R> success,
                                   Failure failure)
        Chain a new Promise to this Promise with Success and Failure callbacks.

        The specified Success callback is called when this Promise is successfully resolved and the specified Failure callback is called when this Promise is resolved with a failure.

        This method returns a new Promise which is chained to this Promise. The returned Promise must be resolved when this Promise is resolved after the specified Success or Failure callback is executed. The result of the executed callback must be used to resolve the returned Promise. Multiple calls to this method can be used to create a chain of promises which are resolved in sequence.

        If this Promise is successfully resolved, the Success callback is executed and the result Promise, if any, or thrown exception is used to resolve the returned Promise from this method. If this Promise is resolved with a failure, the Failure callback is executed and the returned Promise from this method is failed.

        This method may be called at any time including before and after this Promise has been resolved.

        Resolving this Promise happens-before any registered callback is called. That is, in a registered callback, Promise.isDone() must return true and Promise.getValue() and Promise.getFailure() must not block.

        A callback may be called on a different thread than the thread which registered the callback. So the callback must be thread safe but can rely upon that the registration of the callback happens-before the registered callback is called.

        Specified by:
        then in interface Promise<T>
        Overrides:
        then in class PromiseImpl<T>
        Type Parameters:
        R - The value type associated with the returned Promise.
        Parameters:
        success - The Success callback to be called when this Promise is successfully resolved. May be null if no Success callback is required. In this case, the returned Promise must be resolved with the value null when this Promise is successfully resolved.
        failure - The Failure callback to be called when this Promise is resolved with a failure. May be null if no Failure callback is required.
        Returns:
        A new Promise which is chained to this Promise. The returned Promise must be resolved when this Promise is resolved after the specified Success or Failure callback, if any, is executed.
      • recover

        public Promise<T> recover​(Function<Promise<?>,​? extends T> recovery)
        Recover from a failure of this Promise with a recovery value.

        If this Promise is successfully resolved, the returned Promise must be resolved with the value of this Promise.

        If this Promise is resolved with a failure, the specified Function is applied to this Promise to produce a recovery value.

        • If the recovery value is not null, the returned Promise must be resolved with the recovery value.
        • If the recovery value is null, the returned Promise must be failed with the failure of this Promise.
        • If the specified Function throws an exception, the returned Promise must be failed with that exception.

        To recover from a failure of this Promise with a recovery value of null, the Promise.recoverWith(Function) method must be used. The specified Function for Promise.recoverWith(Function) can return Promises.resolved(null) to supply the desired null value.

        This method may be called at any time including before and after this Promise has been resolved.

        Specified by:
        recover in interface Promise<T>
        Overrides:
        recover in class PromiseImpl<T>
        Parameters:
        recovery - If this Promise resolves with a failure, the specified Function is called to produce a recovery value to be used to resolve the returned Promise. Must not be null.
        Returns:
        A Promise that resolves with the value of this Promise or recovers from the failure of this Promise.
      • recoverWith

        public Promise<T> recoverWith​(Function<Promise<?>,​Promise<? extends T>> recovery)
        Recover from a failure of this Promise with a recovery Promise.

        If this Promise is successfully resolved, the returned Promise must be resolved with the value of this Promise.

        If this Promise is resolved with a failure, the specified Function is applied to this Promise to produce a recovery Promise.

        • If the recovery Promise is not null, the returned Promise must be resolved with the recovery Promise.
        • If the recovery Promise is null, the returned Promise must be failed with the failure of this Promise.
        • If the specified Function throws an exception, the returned Promise must be failed with that exception.

        This method may be called at any time including before and after this Promise has been resolved.

        Specified by:
        recoverWith in interface Promise<T>
        Overrides:
        recoverWith in class PromiseImpl<T>
        Parameters:
        recovery - If this Promise resolves with a failure, the specified Function is called to produce a recovery Promise to be used to resolve the returned Promise. Must not be null.
        Returns:
        A Promise that resolves with the value of this Promise or recovers from the failure of this Promise.
      • fallbackTo

        public Promise<T> fallbackTo​(Promise<? extends T> fallback)
        Fall back to the value of the specified Promise if this Promise fails.

        If this Promise is successfully resolved, the returned Promise must be resolved with the value of this Promise.

        If this Promise is resolved with a failure, the successful result of the specified Promise is used to resolve the returned Promise. If the specified Promise is resolved with a failure, the returned Promise must be failed with the failure of this Promise rather than the failure of the specified Promise.

        This method may be called at any time including before and after this Promise has been resolved.

        Specified by:
        fallbackTo in interface Promise<T>
        Overrides:
        fallbackTo in class PromiseImpl<T>
        Parameters:
        fallback - The Promise whose value must be used to resolve the returned Promise if this Promise resolves with a failure. Must not be null.
        Returns:
        A Promise that returns the value of this Promise or falls back to the value of the specified Promise.
      • timeout

        public Promise<T> timeout​(long millis)
        Time out the resolution of this Promise.

        If this Promise is successfully resolved before the timeout, the returned Promise is resolved with the value of this Promise. If this Promise is resolved with a failure before the timeout, the returned Promise is resolved with the failure of this Promise. If the timeout is reached before this Promise is resolved, the returned Promise is failed with a TimeoutException.

        Specified by:
        timeout in interface Promise<T>
        Overrides:
        timeout in class PromiseImpl<T>
        Parameters:
        millis - The time to wait in milliseconds. Zero and negative time is treated as an immediate timeout.
        Returns:
        A Promise that is resolved when either this Promise is resolved or the specified timeout is reached.