Package org.pipecraft.infra.concurrent

Class AbstractCheckedFuture<V,E extends Exception>

java.lang.Object

org.pipecraft.infra.concurrent.AbstractCheckedFuture<V,E>

All Implemented Interfaces:

com.google.common.util.concurrent.ListenableFuture<V>, Future<V>, CheckedFuture<V,E>

Direct Known Subclasses:

ImmediateFuture

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

An abstract decorator on ListenableFuture which adds checkedGet() methods which simplify Future's error handling. Exceptions originating from the future computation are extracted from the ExecutionException wrapper, and passed to the implementation's exception mapper, which is responsible for mapping to the proper exception of type E. Unless really required, it's strongly recommended to handle wrapped runtime exceptions differently than checked exceptions. They should be preserved and thrown unchanged, since they usually denote a bug. This class implements the CheckedFuture interface, which is a replacement for Google's deprecated CheckedFuture.

Author:

Eyal Schneider

Constructor Summary

Constructors

Constructor	Description
AbstractCheckedFuture(com.google.common.util.concurrent.ListenableFuture<V> future)	Constructor

Method Summary

Modifier and Type	Method	Description
void	addListener(Runnable listener, Executor executor)
boolean	cancel(boolean mayInterruptIfRunning)
V	checkedGet()	A simplified version of Future.get() which maps ExecutionException to a more indicative exception type
V	checkedGet(long timeout, TimeUnit unit)	A simplified version of Future.get(long, TimeUnit) which maps ExecutionException to a more indicative exception type
V	get()
V	get(long timeout, TimeUnit unit)
boolean	isCancelled()
boolean	isDone()
protected abstract E	map(Exception e)	Maps a checked exception originating from the underlying computation into the standard exception type E.

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractCheckedFuture

public AbstractCheckedFuture(com.google.common.util.concurrent.ListenableFuture<V> future)

Constructor

Parameters:

future - the listenable future to wrap and add the checked getters functionality to.

Method Detail

checkedGet

public V checkedGet()
             throws InterruptedException,
                    E extends Exception

A simplified version of Future.get() which maps ExecutionException to a more indicative exception type

Specified by:

checkedGet in interface CheckedFuture<V,E extends Exception>

Returns:

the result of executing the future.

Throws:

InterruptedException - When the waiting for completion is interrupted

E - when an execution exception is detected and mapped

CancellationException - if the computation was cancelled

E extends Exception

checkedGet

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

A simplified version of Future.get(long, TimeUnit) which maps ExecutionException to a more indicative exception type

Specified by:

checkedGet in interface CheckedFuture<V,E extends Exception>

Parameters:

timeout - The timeout to apply

unit - The time unit of the timeout parameter

Returns:

the result of executing the future.

Throws:

TimeoutException - In case that the timeout period elapses

InterruptedException - When the waiting for completion is interrupted

E - when an execution exception is detected and mapped

CancellationException - if the computation was cancelled

E extends Exception

map

protected abstract E map(Exception e)

Maps a checked exception originating from the underlying computation into the standard exception type E. In most cases when e is of type RuntimeException, it's recommended to simply throw it here, to avoid hiding a severe error or presenting it as a legitimate error.

Parameters:

e - The original exception

Returns:

The mapped exception of type E

addListener

public void addListener(Runnable listener,
                        Executor executor)

Specified by:

addListener in interface com.google.common.util.concurrent.ListenableFuture<V>

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