Package net.schmizz.concurrent

Class Promise<V,​T extends java.lang.Throwable>

  • public class Promise<V,​T extends java.lang.Throwable>
extends java.lang.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 Description
      Promise​(java.lang.String name, ExceptionChainer<T> chainer, java.util.concurrent.locks.ReentrantLock lock, LoggerFactory loggerFactory)
      Creates this promise with given name, exception chainer, and associated lock.
      Promise​(java.lang.String name, ExceptionChainer<T> chainer, LoggerFactory loggerFactory)
      Creates this promise with given name and exception chainer.

    • Method Summary

      Modifier and Type Method 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​(java.lang.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()  
      boolean isFulfilled()  
      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, java.util.concurrent.TimeUnit unit)
      Wait for timeout duration for this promise's value to be deliver.
      java.lang.String toString()  
      V tryRetrieve​(long timeout, java.util.concurrent.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​(java.lang.String name,
               ExceptionChainer<T> chainer,
               LoggerFactory loggerFactory)
        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​(java.lang.String name,
               ExceptionChainer<T> chainer,
               java.util.concurrent.locks.ReentrantLock lock,
               LoggerFactory loggerFactory)
        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​(java.lang.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 java.lang.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 java.lang.Throwable

      • retrieve

        public V retrieve​(long timeout,
                  java.util.concurrent.TimeUnit unit)
           throws T extends java.lang.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 java.lang.Throwable

      • tryRetrieve

        public V tryRetrieve​(long timeout,
                     java.util.concurrent.TimeUnit unit)
              throws T extends java.lang.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 java.lang.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.

      • isFulfilled

        public boolean isFulfilled()
        Returns:
        whether this promise was fulfilled with either a value or 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 java.lang.String toString()
        Overrides:
        toString in class java.lang.Object