com.google.common.util.concurrent

Class AbstractCheckedFuture<V,X extends Exception>

java.lang.Object

com.google.common.util.concurrent.AbstractCheckedFuture<V,X>

All Implemented Interfaces:

CheckedFuture<V,X>, ListenableFuture<V>, Future<V>

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

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

Since:

1

Author:

Sven Mawson

Field Summary

Fields

Modifier and Type	Field and Description
protected ListenableFuture<V>	delegate The delegate, used to pass along all our methods.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractCheckedFuture(ListenableFuture<V> delegate) Constructs an AbstractCheckedFuture that wraps a delegate.

Method Summary

Methods

Modifier and Type	Method and Description
void	addListener(Runnable listener, Executor exec) Registers a listener to be run on the given executor.
boolean	cancel(boolean mayInterruptIfRunning)
V	checkedGet() Exception checking version of Future.get() that will translate InterruptedException, CancellationException and ExecutionException into application-specific exceptions.
V	checkedGet(long timeout, TimeUnit unit) Exception checking version of Future.get(long, TimeUnit) that will translate InterruptedException, CancellationException and ExecutionException into application-specific exceptions.
V	get()
V	get(long timeout, TimeUnit unit)
boolean	isCancelled()
boolean	isDone()
protected abstract X	mapException(Exception e) Translates from an InterruptedException, CancellationException or ExecutionException thrown by get to an exception of type X to be thrown by checkedGet.

Methods inherited from class java.lang.Object

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

Field Detail

delegate

protected final ListenableFuture<V> delegate

The delegate, used to pass along all our methods.

Constructor Detail

AbstractCheckedFuture

protected AbstractCheckedFuture(ListenableFuture<V> delegate)

Constructs an AbstractCheckedFuture that wraps a delegate.

Method Detail

mapException

protected abstract X mapException(Exception e)

Translates from an InterruptedException, CancellationException or ExecutionException thrown by get to an exception of type X to be thrown by checkedGet. Subclasses must implement this method.

If e is an InterruptedException, the calling checkedGet method has already restored the interrupt after catching the exception. If an implementation of mapException(Exception) wishes to swallow the interrupt, it can do so by calling Thread.interrupted().

checkedGet

public V checkedGet()
             throws X extends Exception

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

This implementation calls get() and maps that method's standard exceptions to instances of type X using mapException(java.lang.Exception).

In addition, if get throws an InterruptedException, this implementation will set the current thread's interrupt status before calling mapException.

Specified by:

checkedGet in interface CheckedFuture<V,X extends Exception>

Returns:

the result of executing the future.

Throws:

X - if get() throws an InterruptedException, CancellationException, or ExecutionException

X extends Exception

checkedGet

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

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.

This implementation calls get(long, TimeUnit) and maps that method's standard exceptions (excluding TimeoutException, which is propagated) to instances of type X using mapException(java.lang.Exception).

In addition, if get throws an InterruptedException, this implementation will set the current thread's interrupt status before calling mapException.

Specified by:

checkedGet in interface CheckedFuture<V,X extends Exception>

Returns:

the result of executing the future.

Throws:

X - if get() throws an InterruptedException, CancellationException, or ExecutionException

TimeoutException - if retrieving the result timed out.

X extends Exception

cancel

public boolean cancel(boolean mayInterruptIfRunning)

Specified by:

cancel in interface Future<V>

isCancelled

public boolean isCancelled()

Specified by:

isCancelled in interface Future<V>

isDone

public boolean isDone()

Specified by:

isDone in interface Future<V>

get

public V get()
      throws InterruptedException,
             ExecutionException

Specified by:

get in interface Future<V>

Throws:

InterruptedException

ExecutionException

get

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

Specified by:

get in interface Future<V>

Throws:

InterruptedException

ExecutionException

TimeoutException

addListener

public void addListener(Runnable listener,
               Executor exec)

Description copied from interface: ListenableFuture

Registers a listener to be run on the given executor. The listener will run when the Future's computation is complete or, if the computation is already complete, immediately.

There is no guaranteed ordering of execution of listeners, but any listener added through this method is guaranteed to be called once the computation is complete.

Listeners cannot throw checked exceptions and should not throw RuntimeException unless their executors are prepared to handle it. Listeners that will execute in MoreExecutors.sameThreadExecutor() should take special care, since they may run during the call to addListener or during the call that sets the future's value.

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