net.schmizz.concurrent

Class Promise<V,T extends Throwable>

java.lang.Object

net.schmizz.concurrent.Promise<V,T>

public class Promise<V,T extends Throwable>
extends Object

Represents promised data of the parameterized type V and allows waiting on it. An exception may also be delivered to a waiter, and will be of the parameterized type T.

For atomic operations on a promise, e.g. checking if a value is delivered and if it is not then setting it, the associated lock for the promise should be acquired while doing so.

Constructor Summary

Constructors

Constructor and Description
Promise(String name, ExceptionChainer<T> chainer) Creates this promise with given name and exception chainer.
Promise(String name, ExceptionChainer<T> chainer, ReentrantLock lock) Creates this promise with given name, exception chainer, and associated lock.

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Clears this promise by setting its value and queued exception to null.
void	deliver(V val) Set this promise's value to val.
void	deliverError(Throwable e) Queues error that will be thrown in any waiting thread or any thread that attempts to wait on this promise hereafter.
boolean	hasWaiters()
boolean	inError()
boolean	isDelivered()
void	lock() Acquire the lock associated with this promise.
V	retrieve() Wait indefinitely for this promise's value to be deliver.
V	retrieve(long timeout, TimeUnit unit) Wait for timeout duration for this promise's value to be deliver.
String	toString()
V	tryRetrieve(long timeout, TimeUnit unit) Wait for timeout duration for this promise's value to be deliver.
void	unlock() Release the lock associated with this promise.

Methods inherited from class java.lang.Object

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

Constructor Detail

Promise

public Promise(String name,
       ExceptionChainer<T> chainer)

Creates this promise with given name and exception chainer. Allocates a new lock object for this promise.

Parameters:

name - name of this promise

chainer - ExceptionChainer that will be used for chaining exceptions

Promise

public Promise(String name,
       ExceptionChainer<T> chainer,
       ReentrantLock lock)

Creates this promise with given name, exception chainer, and associated lock.

Parameters:

name - name of this promise

chainer - ExceptionChainer that will be used for chaining exceptions

lock - lock to use

Method Detail

deliver

public void deliver(V val)

Set this promise's value to val. Any waiters will be delivered this value.

Parameters:

val - the value

deliverError

public void deliverError(Throwable e)

Queues error that will be thrown in any waiting thread or any thread that attempts to wait on this promise hereafter.

Parameters:

e - the error

clear

public void clear()

Clears this promise by setting its value and queued exception to null.

retrieve

public V retrieve()
           throws T extends Throwable

Wait indefinitely for this promise's value to be deliver.

Returns:

the value

Throws:

T - in case another thread informs the promise of an error meanwhile

T extends Throwable

retrieve

public V retrieve(long timeout,
         TimeUnit unit)
           throws T extends Throwable

Wait for timeout duration for this promise's value to be deliver.

Parameters:

timeout - the timeout

unit - time unit for the timeout

Returns:

the value

Throws:

T - in case another thread informs the promise of an error meanwhile, or the timeout expires

T extends Throwable

tryRetrieve

public V tryRetrieve(long timeout,
            TimeUnit unit)
              throws T extends Throwable

Wait for timeout duration for this promise's value to be deliver.

If the value is not deliver by the time the timeout expires, returns null.

Parameters:

timeout - the timeout

unit - time unit for the timeout

Returns:

the value or null

Throws:

T - in case another thread informs the promise of an error meanwhile

T extends Throwable

isDelivered

public boolean isDelivered()

Returns:

whether this promise has a value delivered, and no error waiting to pop.

inError

public boolean inError()

Returns:

whether this promise has been delivered an error.

hasWaiters

public boolean hasWaiters()

Returns:

whether this promise has threads waiting on it.

lock

public void lock()

Acquire the lock associated with this promise.

unlock

public void unlock()

Release the lock associated with this promise.

toString

public String toString()

Overrides:

toString in class Object