Module java.base

Class AbstractExecutorService

  • All Implemented Interfaces:
    Executor, ExecutorService
    Direct Known Subclasses:
    ForkJoinPool, ThreadPoolExecutor


    public abstract class AbstractExecutorService
    extends java.lang.Object
    implements ExecutorService
    Provides default implementations of ExecutorService execution methods. This class implements the submit, invokeAny and invokeAll methods using a RunnableFuture returned by newTaskFor, which defaults to the FutureTask class provided in this package. For example, the implementation of submit(Runnable) creates an associated RunnableFuture that is executed and returned. Subclasses may override the newTaskFor methods to return RunnableFuture implementations other than FutureTask.

    Extension example. Here is a sketch of a class that customizes ThreadPoolExecutor to use a CustomTask class instead of the default FutureTask:

     
     public class CustomThreadPoolExecutor extends ThreadPoolExecutor {
    
       static class CustomTask<V> implements RunnableFuture<V> {...}
    
       protected <V> RunnableFuture<V> newTaskFor(Callable<V> c) {
           return new CustomTask<V>(c);
       }
       protected <V> RunnableFuture<V> newTaskFor(Runnable r, V v) {
           return new CustomTask<V>(r, v);
       }
       // ... add constructors, etc.
     }
    Since:
    1.5
    Author:
    Doug Lea
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      <T> java.util.List<Future<T>> invokeAll​(java.util.Collection<? extends Callable<T>> tasks)
      Executes the given tasks, returning a list of Futures holding their status and results when all complete.
      <T> java.util.List<Future<T>> invokeAll​(java.util.Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
      Executes the given tasks, returning a list of Futures holding their status and results when all complete or the timeout expires, whichever happens first.
      <T> T invokeAny​(java.util.Collection<? extends Callable<T>> tasks)
      Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do.
      <T> T invokeAny​(java.util.Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit)
      Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do before the given timeout elapses.
      protected <T> RunnableFuture<T> newTaskFor​(java.lang.Runnable runnable, T value)
      Returns a RunnableFuture for the given runnable and default value.
      protected <T> RunnableFuture<T> newTaskFor​(Callable<T> callable)
      Returns a RunnableFuture for the given callable task.
      Future<?> submit​(java.lang.Runnable task)
      Submits a Runnable task for execution and returns a Future representing that task.
      <T> Future<T> submit​(java.lang.Runnable task, T result)
      Submits a Runnable task for execution and returns a Future representing that task.
      <T> Future<T> submit​(Callable<T> task)
      Submits a value-returning task for execution and returns a Future representing the pending results of the task.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • AbstractExecutorService

        public AbstractExecutorService​()
    • Method Detail

      • newTaskFor

        protected <T> RunnableFuture<T> newTaskFor​(java.lang.Runnable runnable,
                                                   T value)
        Returns a RunnableFuture for the given runnable and default value.
        Type Parameters:
        T - the type of the given value
        Parameters:
        runnable - the runnable task being wrapped
        value - the default value for the returned future
        Returns:
        a RunnableFuture which, when run, will run the underlying runnable and which, as a Future, will yield the given value as its result and provide for cancellation of the underlying task
        Since:
        1.6
      • newTaskFor

        protected <T> RunnableFuture<T> newTaskFor​(Callable<T> callable)
        Returns a RunnableFuture for the given callable task.
        Type Parameters:
        T - the type of the callable's result
        Parameters:
        callable - the callable task being wrapped
        Returns:
        a RunnableFuture which, when run, will call the underlying callable and which, as a Future, will yield the callable's result as its result and provide for cancellation of the underlying task
        Since:
        1.6
      • submit

        public Future<?> submit​(java.lang.Runnable task)
        Description copied from interface: ExecutorService
        Submits a Runnable task for execution and returns a Future representing that task. The Future's get method will return null upon successful completion.
        Specified by:
        submit in interface ExecutorService
        Parameters:
        task - the task to submit
        Returns:
        a Future representing pending completion of the task
        Throws:
        RejectedExecutionException - if the task cannot be scheduled for execution
        java.lang.NullPointerException - if the task is null
      • submit

        public <T> Future<T> submit​(java.lang.Runnable task,
                                    T result)
        Description copied from interface: ExecutorService
        Submits a Runnable task for execution and returns a Future representing that task. The Future's get method will return the given result upon successful completion.
        Specified by:
        submit in interface ExecutorService
        Type Parameters:
        T - the type of the result
        Parameters:
        task - the task to submit
        result - the result to return
        Returns:
        a Future representing pending completion of the task
        Throws:
        RejectedExecutionException - if the task cannot be scheduled for execution
        java.lang.NullPointerException - if the task is null
      • submit

        public <T> Future<T> submit​(Callable<T> task)
        Description copied from interface: ExecutorService
        Submits a value-returning task for execution and returns a Future representing the pending results of the task. The Future's get method will return the task's result upon successful completion.

        If you would like to immediately block waiting for a task, you can use constructions of the form result = exec.submit(aCallable).get();

        Note: The Executors class includes a set of methods that can convert some other common closure-like objects, for example, PrivilegedAction to Callable form so they can be submitted.

        Specified by:
        submit in interface ExecutorService
        Type Parameters:
        T - the type of the task's result
        Parameters:
        task - the task to submit
        Returns:
        a Future representing pending completion of the task
        Throws:
        RejectedExecutionException - if the task cannot be scheduled for execution
        java.lang.NullPointerException - if the task is null
      • invokeAny

        public <T> T invokeAny​(java.util.Collection<? extends Callable<T>> tasks)
                        throws java.lang.InterruptedException,
                               ExecutionException
        Description copied from interface: ExecutorService
        Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do. Upon normal or exceptional return, tasks that have not completed are cancelled. The results of this method are undefined if the given collection is modified while this operation is in progress.
        Specified by:
        invokeAny in interface ExecutorService
        Type Parameters:
        T - the type of the values returned from the tasks
        Parameters:
        tasks - the collection of tasks
        Returns:
        the result returned by one of the tasks
        Throws:
        java.lang.InterruptedException - if interrupted while waiting
        ExecutionException - if no task successfully completes
      • invokeAny

        public <T> T invokeAny​(java.util.Collection<? extends Callable<T>> tasks,
                               long timeout,
                               TimeUnit unit)
                        throws java.lang.InterruptedException,
                               ExecutionException,
                               TimeoutException
        Description copied from interface: ExecutorService
        Executes the given tasks, returning the result of one that has completed successfully (i.e., without throwing an exception), if any do before the given timeout elapses. Upon normal or exceptional return, tasks that have not completed are cancelled. The results of this method are undefined if the given collection is modified while this operation is in progress.
        Specified by:
        invokeAny in interface ExecutorService
        Type Parameters:
        T - the type of the values returned from the tasks
        Parameters:
        tasks - the collection of tasks
        timeout - the maximum time to wait
        unit - the time unit of the timeout argument
        Returns:
        the result returned by one of the tasks
        Throws:
        java.lang.InterruptedException - if interrupted while waiting
        ExecutionException - if no task successfully completes
        TimeoutException - if the given timeout elapses before any task successfully completes
      • invokeAll

        public <T> java.util.List<Future<T>> invokeAll​(java.util.Collection<? extends Callable<T>> tasks)
                                                throws java.lang.InterruptedException
        Description copied from interface: ExecutorService
        Executes the given tasks, returning a list of Futures holding their status and results when all complete. Future.isDone() is true for each element of the returned list. Note that a completed task could have terminated either normally or by throwing an exception. The results of this method are undefined if the given collection is modified while this operation is in progress.
        Specified by:
        invokeAll in interface ExecutorService
        Type Parameters:
        T - the type of the values returned from the tasks
        Parameters:
        tasks - the collection of tasks
        Returns:
        a list of Futures representing the tasks, in the same sequential order as produced by the iterator for the given task list, each of which has completed
        Throws:
        java.lang.InterruptedException - if interrupted while waiting, in which case unfinished tasks are cancelled
      • invokeAll

        public <T> java.util.List<Future<T>> invokeAll​(java.util.Collection<? extends Callable<T>> tasks,
                                                       long timeout,
                                                       TimeUnit unit)
                                                throws java.lang.InterruptedException
        Description copied from interface: ExecutorService
        Executes the given tasks, returning a list of Futures holding their status and results when all complete or the timeout expires, whichever happens first. Future.isDone() is true for each element of the returned list. Upon return, tasks that have not completed are cancelled. Note that a completed task could have terminated either normally or by throwing an exception. The results of this method are undefined if the given collection is modified while this operation is in progress.
        Specified by:
        invokeAll in interface ExecutorService
        Type Parameters:
        T - the type of the values returned from the tasks
        Parameters:
        tasks - the collection of tasks
        timeout - the maximum time to wait
        unit - the time unit of the timeout argument
        Returns:
        a list of Futures representing the tasks, in the same sequential order as produced by the iterator for the given task list. If the operation did not time out, each task will have completed. If it did time out, some of these tasks will not have completed.
        Throws:
        java.lang.InterruptedException - if interrupted while waiting, in which case unfinished tasks are cancelled