me.joeycumines.javapromises.v1

Class PromiseBase<T>

java.lang.Object

me.joeycumines.javapromises.v1.PromiseBase<T>

All Implemented Interfaces:

Promise<T>

Direct Known Subclasses:

PromiseRunnable, PromiseStage

public abstract class PromiseBase<T>
extends java.lang.Object
implements Promise<T>

A simple thread-safe Promise implementation sans then, except, and always.

Field Summary

Fields

Modifier and Type	Field and Description
protected java.lang.Object	lock Use this as a lock against which you can synchronize the state.

Constructor Summary

Constructors

Constructor and Description
PromiseBase()

Method Summary

Modifier and Type	Method and Description
java.lang.Throwable	exceptSync() Calling this method will block until the promise is resolved, returning a value if it resolved with REJECTED, otherwise returning null.
protected PromiseBase<T>	fulfill(T value)
protected java.lang.Throwable	getException()
PromiseState	getState() Get the current state of the promise.
protected T	getValue()
protected PromiseBase<T>	reject(java.lang.Throwable exception)
protected PromiseBase<T>	resolve(Promise<? extends T> promise) Resolve this promise with the same value/exception and state as another promise.
void	sync() Calling this method will block the current thread until this is resolved (not PENDING).
T	thenSync() Calling this method will block until the promise is resolved, returning a value if it resolved with FULFILLED, otherwise returning null.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface me.joeycumines.javapromises.core.Promise

always, except, except, then, then

Field Detail

lock

protected final java.lang.Object lock

Use this as a lock against which you can synchronize the state.

This used to be another object instanced by the constructor, but it has been changed to this, for now, since there is not any real need for a separate lock object.

Constructor Detail

PromiseBase

public PromiseBase()

Method Detail

getState

public PromiseState getState()

Description copied from interface: Promise

Get the current state of the promise.

A promise's initial state is PENDING, will change at most once, to either resolved states, FULFILLED or REJECTED.

Specified by:

getState in interface Promise<T>

Returns:

The state of the promise.

getValue

protected T getValue()

getException

protected java.lang.Throwable getException()

reject

protected PromiseBase<T> reject(java.lang.Throwable exception)
                         throws MutatedStateException,
                                java.lang.NullPointerException

Throws:

MutatedStateException

java.lang.NullPointerException

fulfill

protected PromiseBase<T> fulfill(T value)
                          throws SelfResolutionException,
                                 MutatedStateException

Throws:

SelfResolutionException

MutatedStateException

resolve

protected PromiseBase<T> resolve(Promise<? extends T> promise)
                          throws SelfResolutionException,
                                 MutatedStateException

Resolve this promise with the same value/exception and state as another promise. Resolving null will fulfill this with null.

Note that this may happen asynchronously, subsequent calls to resolve may fail silently. Take this into consideration especially if exposing this method externally.

Circular references are not checked, but we do take care not to directly resolve this.

Parameters:

promise - The promise to resolve.

Returns:

This promise.

Throws:

SelfResolutionException - If promise is this, or the promise is resolved to this.

MutatedStateException - If this was already resolved, at the time of this call. Not triggered immediately if promise is PENDING.

sync

public void sync()

Description copied from interface: Promise

Calling this method will block the current thread until this is resolved (not PENDING).

All responsibility for sane use of this method lies with the caller.

Specified by:

sync in interface Promise<T>

thenSync

public T thenSync()

Description copied from interface: Promise

Calling this method will block until the promise is resolved, returning a value if it resolved with FULFILLED, otherwise returning null.

Specified by:

thenSync in interface Promise<T>

Returns:

The resolved value, or null if REJECTED.

See Also:

Promise.sync()

exceptSync

public java.lang.Throwable exceptSync()

Description copied from interface: Promise

Calling this method will block until the promise is resolved, returning a value if it resolved with REJECTED, otherwise returning null.

Specified by:

exceptSync in interface Promise<T>

Returns:

The reason for rejection, or null if FULFILLED.

See Also:

Promise.sync()