Package org.ow2.clif.util

Class Future

  • All Implemented Interfaces:
    java.lang.Runnable
    Direct Known Subclasses:
    BladeDeploy
    public abstract class Future
extends java.lang.Thread
    Abstract class for running asynchronous tasks. Usage:
    1. derive this class and define the futureExecution() method
    3. create an instance of the derived class
    4. call start() to run the task implemented by the futureExecution() method
    5. then:
      • poll with isComplete() method to know if the task is complete
      • directly get the task result or exception with method futureGet(), waiting for its completion when not completed yet
      • synchronize with the task completion through the optional lock object, to be notified on task completion
    Author:
    Bruno Dillenseger

    • Nested Class Summary

      • Nested classes/interfaces inherited from class java.lang.Thread

        java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

    • Field Summary

      • Fields inherited from class java.lang.Thread

        MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

    • Constructor Summary

      Constructors 
      Constructor Description
      Future​(java.lang.String threadName, java.lang.Object lock)
      Creates an asynchronous task, but does not run it.

    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      protected abstract java.lang.Object futureExecution()
      Define this method to implement the task.
      java.lang.Object futureGet()
      Blocks caller until the task is completed, and get its result or exception.
      boolean isComplete()
      Checks if the task is complete.
      void run()
      Calls abstract method futureExecution() which is supposed to implement (through inheritance) the task, and manages synchronization: on return from futureExecution(): all calls blocked on method futureGet() are resumed method isComplete() definitely returns true instead of false when a lock is provided, all threads waiting on this lock are notified

      • Methods inherited from class java.lang.Thread

        activeCount, checkAccess, clone, countStackFrames, currentThread, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, onSpinWait, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, suspend, toString, yield

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • Future

        public Future​(java.lang.String threadName,
              java.lang.Object lock)
        Creates an asynchronous task, but does not run it. Method start() must be called then, to actually run the task.
        Parameters:
        threadName - an arbitrary convenient name to identify this thread (for debugging purpose)
        lock - an optional lock object to wait on for synchronization with this task completion. When null, just
        See Also:
        Thread.start()

    • Method Detail

      • run

        public final void run()
        Calls abstract method futureExecution() which is supposed to implement (through inheritance) the task, and manages synchronization: on return from futureExecution():
        • all calls blocked on method futureGet() are resumed
        • method isComplete() definitely returns true instead of false
        • when a lock is provided, all threads waiting on this lock are notified
        Specified by:
        run in interface java.lang.Runnable
        Overrides:
        run in class java.lang.Thread

      • futureGet

        public final java.lang.Object futureGet()
                                 throws java.lang.Exception
        Blocks caller until the task is completed, and get its result or exception. A recommended usage is to define an extra method which calls this method and casts the result to the specific result type of the task.
        Returns:
        the task result, i.e. the object returned by method futureExecution()
        Throws:
        java.lang.Exception - if the task defined by method futureExecution() threw an exception

      • isComplete

        public final boolean isComplete()
        Checks if the task is complete.
        Returns:
        true if the task is complete, whatever it is successful or not (i.e. result available or exception thrown), false otherwise.

      • futureExecution

        protected abstract java.lang.Object futureExecution()
                                             throws java.lang.Exception
        Define this method to implement the task.
        Returns:
        the task result, of arbitrary type.
        Throws:
        java.lang.Exception - the task could not complete.