org.opendaylight.vtn.manager.internal.util.concurrent

Class FutureSynchronizer<T>

java.lang.Object

java.util.concurrent.locks.AbstractOwnableSynchronizer

java.util.concurrent.locks.AbstractQueuedSynchronizer

org.opendaylight.vtn.manager.internal.util.concurrent.FutureSynchronizer<T>

Type Parameters:

T - The type of the object to be returned.

All Implemented Interfaces:

Serializable

public abstract class FutureSynchronizer<T>
extends AbstractQueuedSynchronizer

An abstract class that provides the synchronization semantics for Future implementation.

This class implements the shared lock using AbstractQueuedSynchronizer. The shared lock is unavailable until the task completes.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class java.util.concurrent.locks.AbstractQueuedSynchronizer

AbstractQueuedSynchronizer.ConditionObject

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	LOCK_ARG An integer value to be passed to shared lock methods.
protected static int	LOCK_FAILED An integer value that indicates the shared lock is unavailable.
protected static int	LOCK_SUCCEEDED An integer value that indicates the shared lock is available for shared lock.
protected static long	serialVersionUID Version number for serialization.
protected static int	STATE_CANCELED Internal state that indicates the task has been canceled.
protected static int	STATE_COMPLETED Internal state that indicates the task has completed.
protected static int	STATE_COMPLETING Internal state that indicates the task is going to complete.
protected static int	STATE_EXECUTING Internal state that indicates the task associated with the future is executing.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	FutureSynchronizer() Construct a new instance.

Method Summary

Modifier and Type	Method and Description
void	awaitCompletion(int state) Await completion of the task only if the task is about to complete.
protected static CancellationException	canceled() Return a CancellationException that indicates the task was canceled.
boolean	done(int expected, int state, T result, Throwable cause) Complete the future.
T	get() Wait for the task to complete, and then return the result of the task.
T	get(long nano) Wait for the task to complete, and then return the result of the task.
T	getResult() Return the result of the task.
Throwable	getTaskCause() Return a Throwable that indicates the cause of failure.
protected static InterruptedException	interrupted() Return an InterruptedException that indicates the task was interrupted.
void	interruptTask() Interrupt the task executing the task.
boolean	isCancelled() Determine whether the task was canceled before it completed normally.
boolean	isDone() Determine whether the task completed or not.
void	setResult(T result, Throwable cause) Set the result of the task.
boolean	setThread(Thread t) Set a thread that is executing the task.
protected int	tryAcquireShared(int arg) Attempts to acquire the shared lock.
protected boolean	tryReleaseShared(int state) Attempts to release the shared lock.
protected static IllegalStateException	unexpectedState(int state) Return an IllegalStateException that indicates the current future is in unexpected state.

Methods inherited from class java.util.concurrent.locks.AbstractQueuedSynchronizer

acquire, acquireInterruptibly, acquireShared, acquireSharedInterruptibly, compareAndSetState, getExclusiveQueuedThreads, getFirstQueuedThread, getQueuedThreads, getQueueLength, getSharedQueuedThreads, getState, getWaitingThreads, getWaitQueueLength, hasContended, hasQueuedPredecessors, hasQueuedThreads, hasWaiters, isHeldExclusively, isQueued, owns, release, releaseShared, setState, toString, tryAcquire, tryAcquireNanos, tryAcquireSharedNanos, tryRelease

Methods inherited from class java.util.concurrent.locks.AbstractOwnableSynchronizer

getExclusiveOwnerThread, setExclusiveOwnerThread

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

protected static final long serialVersionUID

Version number for serialization.

See Also:

Constant Field Values

STATE_EXECUTING

protected static final int STATE_EXECUTING

Internal state that indicates the task associated with the future is executing.

See Also:

Constant Field Values

STATE_COMPLETING

protected static final int STATE_COMPLETING

Internal state that indicates the task is going to complete.

See Also:

Constant Field Values

STATE_COMPLETED

protected static final int STATE_COMPLETED

Internal state that indicates the task has completed.

See Also:

Constant Field Values

STATE_CANCELED

protected static final int STATE_CANCELED

Internal state that indicates the task has been canceled.

See Also:

Constant Field Values

LOCK_ARG

protected static final int LOCK_ARG

An integer value to be passed to shared lock methods.

See Also:

Constant Field Values

LOCK_SUCCEEDED

protected static final int LOCK_SUCCEEDED

An integer value that indicates the shared lock is available for shared lock.

See Also:

Constant Field Values

LOCK_FAILED

protected static final int LOCK_FAILED

An integer value that indicates the shared lock is unavailable.

See Also:

Constant Field Values

Constructor Detail

FutureSynchronizer

protected FutureSynchronizer()

Construct a new instance.

Method Detail

interrupted

protected static final InterruptedException interrupted()

Return an InterruptedException that indicates the task was interrupted.

Returns:

An InterruptedException instance.

canceled

protected static final CancellationException canceled()

Return a CancellationException that indicates the task was canceled.

Returns:

A CancellationException instance.

unexpectedState

protected static final IllegalStateException unexpectedState(int state)

Return an IllegalStateException that indicates the current future is in unexpected state.

Parameters:

state - The current internal state value.

Returns:

A IllegalStateException instance.

setThread

public final boolean setThread(Thread t)

Set a thread that is executing the task.

Parameters:

t - A Thread instance.

Returns:

true only if the task has already been canceled.

isCancelled

public final boolean isCancelled()

Determine whether the task was canceled before it completed normally.

Returns:

true only if the task was canceled.

isDone

public final boolean isDone()

Determine whether the task completed or not.

Returns:

true only if the task completed.

setResult

public final void setResult(T result,
                            Throwable cause)

Set the result of the task.

Note that this method never changes the state of this future.

Parameters:

result - The result of the task.

cause - The cause of the task failure.

interruptTask

public final void interruptTask()

Interrupt the task executing the task.

getTaskCause

public final Throwable getTaskCause()

Return a Throwable that indicates the cause of failure.

Returns:

A Throwable instance.

getResult

public final T getResult()
                  throws ExecutionException

Return the result of the task.

Returns:

The result of the task.

Throws:

CancellationException - The task was canceled.

ExecutionException - The task caught an exception.

awaitCompletion

public final void awaitCompletion(int state)

Await completion of the task only if the task is about to complete.

Parameters:

state - The current state of the future.

done

public final boolean done(int expected,
                          int state,
                          T result,
                          Throwable cause)

Complete the future.

Parameters:

expected - The expected internal state.

state - The internal state to be set.

result - The result of the target task.

cause - The Throwable that indicates the cause of failure.

Returns:

true on success. false if another thread completed the task.

get

public final T get()
            throws InterruptedException,
                   ExecutionException

Wait for the task to complete, and then return the result of the task.

Returns:

The result of the task.

Throws:

CancellationException - The task was canceled.

InterruptedException - The current thread was interrupted while waiting.

ExecutionException - The task caught an exception.

get

public final T get(long nano)
            throws InterruptedException,
                   ExecutionException,
                   TimeoutException

Wait for the task to complete, and then return the result of the task.

Parameters:

nano - The number of nanoseconds to wait.

Returns:

The result of the task.

Throws:

CancellationException - The task was canceled.

InterruptedException - The current thread was interrupted while waiting.

ExecutionException - The task caught an exception.

TimeoutException - The task did not complete within the given timeout.

tryAcquireShared

protected final int tryAcquireShared(int arg)

Attempts to acquire the shared lock.

Overrides:

tryAcquireShared in class AbstractQueuedSynchronizer

Parameters:

arg - Unused.

Returns:

A positive value if the task associated with this future has already completed. Otherwise a negative value is returned.

tryReleaseShared

protected final boolean tryReleaseShared(int state)

Attempts to release the shared lock.

Overrides:

tryReleaseShared in class AbstractQueuedSynchronizer

Parameters:

state - The internal state to be set.

Returns:

true is always returned.