com.google.common.util.concurrent
Class AbstractCheckedFuture<V,E extends Exception>

java.lang.Object
  com.google.common.util.concurrent.AbstractCheckedFuture<V,E>

All Implemented Interfaces:

CheckedFuture<V,E>, ListenableFuture<V>, Future<V>

@Beta
public abstract class AbstractCheckedFuture<V,E extends Exception>
extends Object
implements CheckedFuture<V,E>

A delegating wrapper around a ListenableFuture that adds support for the checkedGet() and checkedGet(long, TimeUnit) methods.

Since:

1

Author:

Sven Mawson

delegate

protected final ListenableFuture<V> delegate

The delegate, used to pass along all our methods.

AbstractCheckedFuture

protected AbstractCheckedFuture(ListenableFuture<V> delegate)

Constructs an AbstractCheckedFuture that wraps a delegate.

mapException

protected abstract E mapException(Exception e)

Translate from an InterruptedException, CancellationException or ExecutionException to an exception of type E. Subclasses must implement the mapping themselves. The e parameter can be an instance of InterruptedException, CancellationException, or ExecutionException.

checkedGet

public V checkedGet()
             throws E extends Exception

Description copied from interface: CheckedFuture

Exception checking version of Future.get() that will translate InterruptedException, CancellationException and ExecutionException into application-specific exceptions.

Specified by:

checkedGet in interface CheckedFuture<V,E extends Exception>

Returns:

the result of executing the future.

Throws:

E - on interruption, cancellation or execution exceptions.

E extends Exception

checkedGet

public V checkedGet(long timeout,
                    TimeUnit unit)
             throws TimeoutException,
                    E extends Exception

Description copied from interface: CheckedFuture

Exception checking version of Future.get(long, TimeUnit) that will translate InterruptedException, CancellationException and ExecutionException into application-specific exceptions. On timeout this method throws a normal TimeoutException.

Specified by:

checkedGet in interface CheckedFuture<V,E extends Exception>

Returns:

the result of executing the future.

Throws:

TimeoutException - if retrieving the result timed out.

E - on interruption, cancellation or execution exceptions.

E extends Exception

cancel

public boolean cancel(boolean mayInterruptIfRunning)

Description copied from interface: java.util.concurrent.Future

Attempts to cancel execution of this task. This attempt will fail if the task has already completed, has already been cancelled, or could not be cancelled for some other reason. If successful, and this task has not started when cancel is called, this task should never run. If the task has already started, then the mayInterruptIfRunning parameter determines whether the thread executing this task should be interrupted in an attempt to stop the task.

After this method returns, subsequent calls to Future.isDone() will always return true. Subsequent calls to Future.isCancelled() will always return true if this method returned true.

Specified by:

cancel in interface Future<V>

Parameters:

mayInterruptIfRunning - true if the thread executing this task should be interrupted; otherwise, in-progress tasks are allowed to complete

Returns:

false if the task could not be cancelled, typically because it has already completed normally; true otherwise

isCancelled

public boolean isCancelled()

Description copied from interface: java.util.concurrent.Future

Returns true if this task was cancelled before it completed normally.

Specified by:

isCancelled in interface Future<V>

Returns:

true if this task was cancelled before it completed

isDone

public boolean isDone()

Description copied from interface: java.util.concurrent.Future

Returns true if this task completed. Completion may be due to normal termination, an exception, or cancellation -- in all of these cases, this method will return true.

Specified by:

isDone in interface Future<V>

Returns:

true if this task completed

get

public V get()
      throws InterruptedException,
             ExecutionException

Description copied from interface: java.util.concurrent.Future

Waits if necessary for the computation to complete, and then retrieves its result.

Specified by:

get in interface Future<V>

Returns:

the computed result

Throws:

InterruptedException - if the current thread was interrupted while waiting

ExecutionException - if the computation threw an exception

get

public V get(long timeout,
             TimeUnit unit)
      throws InterruptedException,
             ExecutionException,
             TimeoutException

Description copied from interface: java.util.concurrent.Future

Waits if necessary for at most the given time for the computation to complete, and then retrieves its result, if available.

Specified by:

get in interface Future<V>

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Returns:

the computed result

Throws:

InterruptedException - if the current thread was interrupted while waiting

ExecutionException - if the computation threw an exception

TimeoutException - if the wait timed out

addListener

public void addListener(Runnable listener,
                        Executor exec)

Description copied from interface: ListenableFuture

Adds a listener and executor to the ListenableFuture. The listener will be passed to the executor for execution when the Future's computation is complete.

There is no guaranteed ordering of execution of listeners, they may get called in the order they were added and they may get called out of order, but any listener added through this method is guaranteed to be called once the computation is complete.

Specified by:

addListener in interface ListenableFuture<V>

Parameters:

listener - the listener to run when the computation is complete.

exec - the executor to run the listener in.