net.ninjacat.smooth.concurrent

Class Future<E>

java.lang.Object

net.ninjacat.smooth.concurrent.Future<E>

public class Future<E>
extends Object

Represents long-running operation that should be executed asynchronously.

Result of the operation is either a value or a Throwable. To get the result of operation caller should supply handlers for success and/or failure.

Several operations can be chained by using then(Func) method, for example:

     Future.run(callable).then(transform1).then(transform2).onSuccess(ok).onFailure(boom);
 

This operation can fail at any time, but will never allow any exception escape. In the event that every callable and transform completes successfully then onSuccess(Procedure) will be called, otherwise onFailure(Procedure) will be called with and exception as parameter. All the operations will be performed asynchronously.

Constructor Summary

Constructors

Constructor and Description
Future() Creates a future with a default executor
Future(ExecutorService executor) Creates a future with supplied executor service

Method Summary

Modifier and Type	Method and Description
Future<E>	doIt(Callable<E> callable) Executes block of code in the future.
Try<E>	getResult() Returns the result of the Future.
boolean	isCompleted() Checks if execution is complete
Future<E>	onFailure(Procedure<Throwable> onFailure) Sets failed execution handler.
Future<E>	onSuccess(Procedure<E> onSuccess) Sets successful execution handler.
static <E> Future<E>	run(Callable<E> block) Shortcut for executing a Callable with default parameters.
<T> Future<T>	then(Func<T,E> transform) Allows chaining asynchronous operations.

Methods inherited from class java.lang.Object

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

Constructor Detail

Future

public Future()

Creates a future with a default executor

Future

public Future(ExecutorService executor)

Creates a future with supplied executor service

Parameters:

executor - ExecutorService to be used for asynchronous execution

Method Detail

run

public static <E> Future<E> run(Callable<E> block)

Shortcut for executing a Callable with default parameters.

Will create a new Future and execute it.

Type Parameters:

E - type of the result

Parameters:

block - callable to be executed

Returns:

Future<E>

then

public final <T> Future<T> then(Func<T,E> transform)

Allows chaining asynchronous operations.

Will start new supplied transform function within a new Future as soon as this future succeeds. In case this future fails, failure cause will be propagated to the new Future.

Type Parameters:

T - type of the new future result

Parameters:

transform - function to transform results of this future into result of a new future

Returns:

Future wrapping transform function

onSuccess

public final Future<E> onSuccess(Procedure<E> onSuccess)

Sets successful execution handler.

This handler can be set only once. Will throw IllegalStateException if attempt to set it again will be made

There are no guarantees when the callback will be called

Parameters:

onSuccess - Procedure to handle successful Future execution

Returns:

this future

onFailure

public final Future<E> onFailure(Procedure<Throwable> onFailure)

Sets failed execution handler.

This handler can be set only once. Will throw IllegalStateException if attempt to set it again will be made

There are no guarantees when the callback will be called

Parameters:

onFailure - Procedure to handle failed Future execution

Returns:

this future

doIt

public final Future<E> doIt(Callable<E> callable)

Executes block of code in the future.

Each future can execute code only once. Second attempt ot call this method will throw IllegalStateException

Parameters:

callable - Callable that will be executed asynchronously

Returns:

this future

getResult

public Try<E> getResult()

Returns the result of the Future. This call will block if result is not available yet. Result is returned wrapped in Try so that exceptions during future execution are captured.

Returns:

Result of the Future wrapped in Try

isCompleted

public boolean isCompleted()

Checks if execution is complete

Returns:

true if future is completed, false otherwise