Class FutureImpl<T>

java.lang.Object

io.vavr.concurrent.FutureImpl<T>

Type Parameters:

T - Result of the computation.

All Implemented Interfaces:

Future<T>, Value<T>, Iterable<T>

final class FutureImpl<T>
extends Object
implements Future<T>

INTERNAL API - This class is subject to change.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static interface	FutureImpl.Computation<T>

Field Summary

Fields

Modifier and Type	Field	Description
private Queue<Consumer<Try<T>>>	actions	The queue of actions is filled when calling onComplete() before the Future is completed or cancelled.
private boolean	cancelled	Indicates if this Future is cancelled GuardedBy("lock")
private final Executor	executor	Used to start new threads.
private final Lock	lock	Used to synchronize state changes.
private Thread	thread	The Thread which runs the computation.
private Option<Try<T>>	value	Once the Future is completed, the value is defined.
private Queue<Thread>	waiters	The queue of waiters is filled when calling await() before the Future is completed or cancelled.

Fields inherited from interface Future

DEFAULT_EXECUTOR, DEFAULT_EXECUTOR_SERVICE

Constructor Summary

Constructors

Modifier	Constructor	Description
private	FutureImpl(Executor executor, Option<Try<T>> value, Queue<Consumer<Try<T>>> actions, Queue<Thread> waiters, FutureImpl.Computation<T> computation)

Method Summary

Modifier and Type	Method	Description
private void	_await(long start, long timeout, TimeUnit unit)	Blocks the current thread.
(package private) static <T> FutureImpl<T>	async(Executor executor, Task<? extends T> task)	Creates a FutureImpl that is eventually completed.
Future<T>	await()	Blocks the current Thread until this Future completed or returns immediately if this Future is already completed.
Future<T>	await(long timeout, TimeUnit unit)	Blocks the current Thread until this Future completed or returns immediately if this Future is already completed.
boolean	cancel(boolean mayInterruptIfRunning)	Cancels the Future.
Executor	executor()	Returns the Executor used by this Future.
ExecutorService	executorService()	Deprecated.
Option<Try<T>>	getValue()	Returns the value of the Future.
private void	handleUncaughtException(Throwable x)
boolean	isCancelled()	Checks if this Future is cancelled, i.e.
boolean	isCompleted()	Checks if this Future is completed, i.e.
(package private) static <T> FutureImpl<T>	of(Executor executor)	Creates a FutureImpl that needs to be automatically completed by calling tryComplete(Try).
(package private) static <T> FutureImpl<T>	of(Executor executor, Try<? extends T> value)	Creates a FutureImpl that is immediately completed with the given value.
Future<T>	onComplete(Consumer<? super Try<T>> action)	Performs the action once the Future is complete.
private void	perform(Consumer<? super Try<T>> action)
(package private) static <T> FutureImpl<T>	sync(Executor executor, Task<? extends T> task)	Creates a FutureImpl that is eventually completed.
String	toString()	Clarifies that values have a proper toString() method implemented.
(package private) boolean	tryComplete(Try<? extends T> value)	INTERNAL METHOD, SHOULD BE USED BY THE CONSTRUCTOR, ONLY.
private void	unlock(Thread waiter)
private void	updateThread()

Methods inherited from class Object

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

Methods inherited from interface Future

andThen, cancel, collect, failed, fallbackTo, filter, filterTry, flatMap, flatMapTry, forEach, get, getCause, isAsync, isEmpty, isFailure, isLazy, isSingleValued, isSuccess, iterator, map, mapTry, onFailure, onSuccess, orElse, orElse, peek, recover, recoverWith, stringPrefix, toCompletableFuture, transform, transformValue, zip, zipWith

Methods inherited from interface Value

collect, collect, contains, corresponds, eq, equals, exists, forAll, getOrElse, getOrElse, getOrElseThrow, getOrElseTry, getOrNull, hashCode, out, out, spliterator, stderr, stdout, toArray, toCharSeq, toEither, toEither, toInvalid, toInvalid, toJavaArray, toJavaArray, toJavaArray, toJavaCollection, toJavaList, toJavaList, toJavaMap, toJavaMap, toJavaMap, toJavaOptional, toJavaParallelStream, toJavaSet, toJavaSet, toJavaStream, toLeft, toLeft, toLinkedMap, toLinkedMap, toLinkedSet, toList, toMap, toMap, toOption, toPriorityQueue, toPriorityQueue, toQueue, toRight, toRight, toSet, toSortedMap, toSortedMap, toSortedMap, toSortedMap, toSortedSet, toSortedSet, toStream, toTree, toTree, toTry, toTry, toValid, toValid, toValidation, toValidation, toVector

Field Details

executor

private final Executor executor

Used to start new threads.

lock

private final Lock lock

Used to synchronize state changes.

cancelled

private volatile boolean cancelled

Indicates if this Future is cancelled GuardedBy("lock")

value

private volatile Option<Try<T>> value

Once the Future is completed, the value is defined. GuardedBy("lock")

actions

private Queue<Consumer<Try<T>>> actions

The queue of actions is filled when calling onComplete() before the Future is completed or cancelled. Otherwise actions = null. GuardedBy("lock")

waiters

private Queue<Thread> waiters

The queue of waiters is filled when calling await() before the Future is completed or cancelled. Otherwise waiters = null. GuardedBy("lock")

thread

private Thread thread

The Thread which runs the computation. GuardedBy("lock")

Constructor Details

FutureImpl

private FutureImpl(Executor executor,
 Option<Try<T>> value,
 Queue<Consumer<Try<T>>> actions,
 Queue<Thread> waiters,
 FutureImpl.Computation<T> computation)

Method Details

of

static <T> FutureImpl<T> of(Executor executor)

Creates a FutureImpl that needs to be automatically completed by calling tryComplete(Try).

Type Parameters:

T - value type of the Future

Parameters:

executor - An Executor to run and control the computation and to perform the actions.

Returns:

a new FutureImpl instance

of

static <T> FutureImpl<T> of(Executor executor,
 Try<? extends T> value)

Creates a FutureImpl that is immediately completed with the given value. No task will be started.

Type Parameters:

T - value type of the Future

Parameters:

executor - An Executor to run and control the computation and to perform the actions.

value - the result of this Future

Returns:

a new FutureImpl instance

sync

static <T> FutureImpl<T> sync(Executor executor,
 Task<? extends T> task)

Creates a FutureImpl that is eventually completed. The given computation is synchronously executed, no thread is started.

Type Parameters:

T - value type of the Future

Parameters:

executor - An Executor to run and control the computation and to perform the actions.

task - A non-blocking computation

Returns:

a new FutureImpl instance

async

static <T> FutureImpl<T> async(Executor executor,
 Task<? extends T> task)

Creates a FutureImpl that is eventually completed. The given computation is asynchronously executed, a new thread is started.

Type Parameters:

T - value type of the Future

Parameters:

executor - An Executor to run and control the computation and to perform the actions.

task - A (possibly blocking) computation

Returns:

a new FutureImpl instance

await

public Future<T> await()

Description copied from interface: Future

Blocks the current Thread until this Future completed or returns immediately if this Future is already completed.

In the case the current thread was interrupted while waiting, a failed Future is returned containing the corresponding InterruptedException.

Specified by:

await in interface Future<T>

Returns:

this Future instance

await

public Future<T> await(long timeout,
 TimeUnit unit)

Description copied from interface: Future

Blocks the current Thread until this Future completed or returns immediately if this Future is already completed.

In the case the current thread was interrupted while waiting, a failed Future is returned containing the corresponding InterruptedException.

If the deadline wasn't met, a failed Future is returned containing a TimeoutException.

Specified by:

await in interface Future<T>

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Returns:

this Future instance

_await

private void _await(long start,
 long timeout,
 TimeUnit unit)

Blocks the current thread.

If timeout = 0 then LockSupport.park() is called (start, timeout and unit are not used), otherwise LockSupport.park(timeout, unit} is called.

If a timeout > -1 is specified and the deadline is not met, this Future fails with a TimeoutException.

If this Thread was interrupted, this Future fails with a InterruptedException.

Parameters:

start - the start time in nanos, based on System.nanoTime()

timeout - a timeout in the given unit of time

unit - a time unit

cancel

public boolean cancel(boolean mayInterruptIfRunning)

Description copied from interface: Future

Cancels the Future. A pending Future may be interrupted, depending on the underlying Executor.

If the Future was successfully cancelled, the result is a Failure(CancellationException).

Specified by:

cancel in interface Future<T>

Parameters:

mayInterruptIfRunning - true if a running thread should be interrupted, otherwise a running thread is allowed to complete its computation.

Returns:

false, if this Future is already completed or could not be cancelled, otherwise true.

See Also:

• Future.isCancelled()
• Future.cancel(boolean)

updateThread

private void updateThread()

executor

public Executor executor()

Description copied from interface: Future

Returns the Executor used by this Future.

Specified by:

executor in interface Future<T>

Returns:

The underlying Executor.

executorService

@Deprecated
public ExecutorService executorService()

Deprecated.

Description copied from interface: Future

This method is deprecated.

THE DEFAULT IMPLEMENTATION (obtained by one of the Future factory methods) MIGHT THROW AN UnsupportedOperationException AT RUNTIME.

Specified by:

executorService in interface Future<T>

Returns:

(never)

getValue

public Option<Try<T>> getValue()

Description copied from interface: Future

Returns the value of the Future.

Specified by:

getValue in interface Future<T>

Returns:

None, if the Future is not yet completed or was cancelled, otherwise Some(Try).

isCancelled

public boolean isCancelled()

Description copied from interface: Future

Checks if this Future is cancelled, i.e. the thread was forced to stop before completion.

Specified by:

isCancelled in interface Future<T>

Returns:

true, if the computation was cancelled, false otherwise

isCompleted

public boolean isCompleted()

Description copied from interface: Future

Checks if this Future is completed, i.e. has a value.

Specified by:

isCompleted in interface Future<T>

Returns:

true, if the computation successfully finished, failed or was cancelled, false otherwise.

onComplete

public Future<T> onComplete(Consumer<? super Try<T>> action)

Description copied from interface: Future

Performs the action once the Future is complete.

Specified by:

onComplete in interface Future<T>

Parameters:

action - An action to be performed when this future is complete.

Returns:

this Future

toString

public String toString()

Description copied from interface: Value

Clarifies that values have a proper toString() method implemented.

See Object.toString().

Specified by:

toString in interface Value<T>

Overrides:

toString in class Object

Returns:

A String representation of this object

tryComplete

boolean tryComplete(Try<? extends T> value)

INTERNAL METHOD, SHOULD BE USED BY THE CONSTRUCTOR, ONLY.

Completes this Future with a value and performs all actions.

This method is idempotent. I.e. it does nothing, if this Future is already completed.

Parameters:

value - A Success containing a result or a Failure containing an Exception.

Throws:

IllegalStateException - if the Future is already completed or cancelled.

NullPointerException - if the given value is null.

perform

private void perform(Consumer<? super Try<T>> action)

unlock

private void unlock(Thread waiter)

handleUncaughtException

private void handleUncaughtException(Throwable x)