com.mattunderscore.executors

Class RepeatingFuture<V>

java.lang.Object

com.mattunderscore.executors.RepeatingFuture<V>

Type Parameters:

V - The type of object returned by get()

All Implemented Interfaces:

IRepeatingFuture<V>, ISettableFuture<V>, Future<V>

public final class RepeatingFuture<V>
extends Object
implements IRepeatingFuture<V>

A base implementation for a Future of a task that is executed repeatedly but a limited number of times.

The get() and get(long, TimeUnit) methods return the result of the most recent execution and only block if the task has not yet run. This implementation does not support changing the number of times to repeat the task.

Since:

0.1.0

Author:

Matt Champion

Constructor Summary

Constructors

Constructor and Description
RepeatingFuture(ITaskCanceller canceller, int repetitions) Constructor for the future.

Method Summary

Modifier and Type	Method and Description
protected void	await() Blocks the thread until the result is set or the task is cancelled.
protected boolean	await(long timeout, TimeUnit unit) Blocks the thread until the result is set or the task is cancelled.
boolean	cancel(boolean mayInterruptIfRunning)
protected void	checkCancellationException() Checks if the CancellationException needs to be thrown.
protected void	checkCancellationException(int index)
protected void	checkExecutionException(TaskExecutionResult<V> result) Checks if a ExecutionException needs to be thrown.
V	get()
V	get(long timeout, TimeUnit unit)
int	getCompletedExecutions() Returns the number of times the task has run this allows progress through the repetitions to be monitored.
int	getExpectedExecutions() Get the number of executions that should happen.
protected TaskExecutionResult<V>	getResult() Return the result of the task execution.
V	getResult(int index) Waits if necessary for the ith computation to complete, and then retrieves its result.
V	getResult(int index, long timeout, TimeUnit unit) Waits if necessary for the ith computation to complete, and then retrieves its result.
protected TaskExecutionResult<V>	getStoredResult(int index) Gets the ith execution result.
boolean	isCancelled()
boolean	isDone()
protected boolean	processCancellation(boolean mayInterruptIfRunning) Process cancellation of the task.
protected void	processResult(TaskExecutionResult<V> result) Process the result being set.
void	setException(Throwable result) Set the result of the task execution.
void	setResult(V result) Set the result of the task execution.
void	setTask(ITaskWrapper wrapper) Set the task
protected boolean	taskDone() Indicate if the task has been executed.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.concurrent.Future

cancel, get, get, isCancelled, isDone

Constructor Detail

RepeatingFuture

public RepeatingFuture(ITaskCanceller canceller,
                       int repetitions)

Constructor for the future. This should be called by the subclass

Parameters:

canceller - A canceller for the future

repetitions - The number of times it is to repeat

Method Detail

getResult

public V getResult(int index)
            throws InterruptedException,
                   ExecutionException,
                   CancellationException,
                   IndexOutOfBoundsException

Description copied from interface: IRepeatingFuture

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

Specified by:

getResult in interface IRepeatingFuture<V>

Parameters:

index - The execution of the task to get the result for

Returns:

The result of the execution

Throws:

InterruptedException - Thrown if the thread was interrupted while the waiting

ExecutionException - Thrown if the execution of the task resulted in an exception

CancellationException - Thrown if the task was cancelled before reaching the ith execution

IndexOutOfBoundsException - Thrown if the ith value is greater than the number of executions or it is less than 0.

getResult

public V getResult(int index,
                   long timeout,
                   TimeUnit unit)
            throws InterruptedException,
                   ExecutionException,
                   CancellationException,
                   TimeoutException,
                   IndexOutOfBoundsException

Description copied from interface: IRepeatingFuture

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

Specified by:

getResult in interface IRepeatingFuture<V>

Parameters:

index - The execution of the task to get the result for

timeout - The maximum time to wait

unit - The time unit of the timeout argument

Returns:

The result of the execution

Throws:

InterruptedException - Thrown if the thread was interrupted while the waiting

ExecutionException - Thrown if the execution of the task resulted in an exception

CancellationException - Thrown if the task was cancelled before reaching the ith execution

TimeoutException - Thrown if the ith execution does not happen within the timeout period

IndexOutOfBoundsException - Thrown if the ith value is greater than the number of executions or it is less than 0.

getExpectedExecutions

public int getExpectedExecutions()

Description copied from interface: IRepeatingFuture

Get the number of executions that should happen.

Specified by:

getExpectedExecutions in interface IRepeatingFuture<V>

Returns:

Number of times the task will try to execute.

getCompletedExecutions

public int getCompletedExecutions()

Description copied from interface: IRepeatingFuture

Returns the number of times the task has run this allows progress through the repetitions to be monitored.

Specified by:

getCompletedExecutions in interface IRepeatingFuture<V>

Returns:

Number of times the task has executed.

checkCancellationException

protected void checkCancellationException(int index)
                                   throws CancellationException

Throws:

CancellationException

processResult

protected void processResult(TaskExecutionResult<V> result)

Process the result being set.

Parameters:

result - The result

processCancellation

protected boolean processCancellation(boolean mayInterruptIfRunning)

Process cancellation of the task.

Parameters:

mayInterruptIfRunning - If the thread should be interrupted if it is running

Returns:

Was the cancellation successful

taskDone

protected boolean taskDone()

Indicate if the task has been executed.

Returns:

True if the task has executed

await

protected void await()
              throws InterruptedException

Blocks the thread until the result is set or the task is cancelled.

Throws:

InterruptedException - The thread was Interrupted while waiting

await

protected boolean await(long timeout,
                        TimeUnit unit)
                 throws InterruptedException

Blocks the thread until the result is set or the task is cancelled. Takes a timeout as the maximum amount of time it will block.

Parameters:

timeout - Duration of the timeout

unit - Unit of the timeout

Returns:

True if the timeout was not reached

Throws:

InterruptedException - The thread was Interrupted while waiting

getResult

protected TaskExecutionResult<V> getResult()

Return the result of the task execution. Assumes that it is set.

Returns:

The result

getStoredResult

protected TaskExecutionResult<V> getStoredResult(int index)

Gets the ith execution result.

Parameters:

index - The result to get

Returns:

The result

setTask

public void setTask(ITaskWrapper wrapper)

Description copied from interface: ISettableFuture

Set the task

Specified by:

setTask in interface ISettableFuture<V>

Parameters:

wrapper - TaskWrapper for task of the future

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,
             CancellationException

Specified by:

get in interface Future<V>

Throws:

InterruptedException

ExecutionException

CancellationException

get

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

Specified by:

get in interface Future<V>

Throws:

InterruptedException

ExecutionException

TimeoutException

CancellationException

checkCancellationException

protected void checkCancellationException()
                                   throws CancellationException

Checks if the CancellationException needs to be thrown.

Throws:

CancellationException - If it needs to be thrown

checkExecutionException

protected void checkExecutionException(TaskExecutionResult<V> result)
                                throws ExecutionException

Checks if a ExecutionException needs to be thrown.

Parameters:

result - The result of the task

Throws:

ExecutionException - If it needs to be thrown

setResult

public void setResult(V result)

Description copied from interface: ISettableFuture

Set the result of the task execution.

Specified by:

setResult in interface ISettableFuture<V>

Parameters:

result - The result of the execution

setException

public void setException(Throwable result)

Description copied from interface: ISettableFuture

Set the result of the task execution.

Specified by:

setException in interface ISettableFuture<V>

Parameters:

result - The execution thrown by the execution