/**@class java.util.concurrent.ExecutorService implements java.util.concurrent.Executor An {@link java.util.concurrent.Executor} that provides methods to manage termination and methods that can produce a {@link java.util.concurrent.Future} for tracking progress of one or more asynchronous tasks. <p>An {@code ExecutorService} can be shut down, which will cause it to reject new tasks. Two different methods are provided for shutting down an {@code ExecutorService}. The {@link #shutdown} method will allow previously submitted tasks to execute before terminating, while the {@link #shutdownNow} method prevents waiting tasks from starting and attempts to stop currently executing tasks. Upon termination, an executor has no tasks actively executing, no tasks awaiting execution, and no new tasks can be submitted. An unused {@code ExecutorService} should be shut down to allow reclamation of its resources. <p>Method {@code submit} extends base method {@link java.util.concurrent.Executor#execute(Runnable)} by creating and returning a {@link java.util.concurrent.Future} that can be used to cancel execution and/or wait for completion. Methods {@code invokeAny} and {@code invokeAll} perform the most commonly useful forms of bulk execution, executing a collection of tasks and then waiting for at least one, or all, to complete. (Class {@link java.util.concurrent.ExecutorCompletionService} can be used to write customized variants of these methods.) <p>The {@link java.util.concurrent.Executors} class provides factory methods for the executor services provided in this package. <h3>Usage Examples</h3> Here is a sketch of a network service in which threads in a thread pool service incoming requests. It uses the preconfigured {@link java.util.concurrent.Executors#newFixedThreadPool} factory method: <pre> {@code class NetworkService implements Runnable { private final ServerSocket serverSocket; private final ExecutorService pool; public NetworkService(int port, int poolSize) throws IOException { serverSocket = new ServerSocket(port); pool = Executors.newFixedThreadPool(poolSize); } public void run() { // run the service try { for (;;) { pool.execute(new Handler(serverSocket.accept())); } } catch (IOException ex) { pool.shutdown(); } } } class Handler implements Runnable { private final Socket socket; Handler(Socket socket) { this.socket = socket; } public void run() { // read and service request on socket } }}</pre> The following method shuts down an {@code ExecutorService} in two phases, first by calling {@code shutdown} to reject incoming tasks, and then calling {@code shutdownNow}, if necessary, to cancel any lingering tasks: <pre> {@code void shutdownAndAwaitTermination(ExecutorService pool) { pool.shutdown(); // Disable new tasks from being submitted try { // Wait a while for existing tasks to terminate if (!pool.awaitTermination(60, TimeUnit.SECONDS)) { pool.shutdownNow(); // Cancel currently executing tasks // Wait a while for tasks to respond to being cancelled if (!pool.awaitTermination(60, TimeUnit.SECONDS)) System.err.println("Pool did not terminate"); } } catch (InterruptedException ie) { // (Re-)Cancel if current thread also interrupted pool.shutdownNow(); // Preserve interrupt status Thread.currentThread().interrupt(); } }}</pre> <p>Memory consistency effects: Actions in a thread prior to the submission of a {@code Runnable} or {@code Callable} task to an {@code ExecutorService} <a href="package-summary.html#MemoryVisibility"><i>happen-before</i></a> any actions taken by that task, which in turn <i>happen-before</i> the result is retrieved via {@code Future.get()}. @since 1.5 @author Doug Lea */ var ExecutorService = { /**Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted. Invocation has no additional effect if already shut down. <p>This method does not wait for previously submitted tasks to complete execution. Use {@link #awaitTermination awaitTermination} to do that. */ shutdown : function( ) {}, /**Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution. <p>This method does not wait for actively executing tasks to terminate. Use {@link #awaitTermination awaitTermination} to do that. <p>There are no guarantees beyond best-effort attempts to stop processing actively executing tasks. For example, typical implementations will cancel via {@link Thread#interrupt}, so any task that fails to respond to interrupts may never terminate. @return {Object {java.util.List}} list of tasks that never commenced execution */ shutdownNow : function( ) {}, /**Returns {@code true} if this executor has been shut down. @return {Boolean} {@code true} if this executor has been shut down */ isShutdown : function( ) {}, /**Returns {@code true} if all tasks have completed following shut down. Note that {@code isTerminated} is never {@code true} unless either {@code shutdown} or {@code shutdownNow} was called first. @return {Boolean} {@code true} if all tasks have completed following shut down */ isTerminated : function( ) {}, /**Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first. @param {Number} timeout the maximum time to wait @param {Object {TimeUnit}} unit the time unit of the timeout argument @return {Boolean} {@code true} if this executor terminated and {@code false} if the timeout elapsed before termination @throws InterruptedException if interrupted while waiting */ awaitTermination : function( ) {}, /**Submits a value-returning task for execution and returns a Future representing the pending results of the task. The Future's {@code get} method will return the task's result upon successful completion. <p> If you would like to immediately block waiting for a task, you can use constructions of the form {@code result = exec.submit(aCallable).get();} <p>Note: The {@link java.util.concurrent.Executors} class includes a set of methods that can convert some other common closure-like objects, for example, {@link java.security.PrivilegedAction} to {@link java.util.concurrent.Callable} form so they can be submitted. @param {Object {java.util.concurrent.Callable}} task the task to submit @param <T> the type of the task's result @return {Object {java.util.concurrent.Future}} a Future representing pending completion of the task @throws RejectedExecutionException if the task cannot be scheduled for execution @throws NullPointerException if the task is null */ submit : function( ) {}, /**Submits a Runnable task for execution and returns a Future representing that task. The Future's {@code get} method will return the given result upon successful completion. @param {Object {Runnable}} task the task to submit @param {Object {Object}} result the result to return @param <T> the type of the result @return {Object {java.util.concurrent.Future}} a Future representing pending completion of the task @throws RejectedExecutionException if the task cannot be scheduled for execution @throws NullPointerException if the task is null */ submit : function( ) {}, /**Submits a Runnable task for execution and returns a Future representing that task. The Future's {@code get} method will return {@code null} upon <em>successful</em> completion. @param {Object {Runnable}} task the task to submit @return {Object {java.util.concurrent.Future}} a Future representing pending completion of the task @throws RejectedExecutionException if the task cannot be scheduled for execution @throws NullPointerException if the task is null */ submit : function( ) {}, /**Executes the given tasks, returning a list of Futures holding their status and results when all complete. {@link java.util.concurrent.Future#isDone} is {@code true} for each element of the returned list. Note that a <em>completed</em> 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. @param {Object {java.util.Collection}} tasks the collection of tasks @param <T> the type of the values returned from the tasks @return {Object {java.util.List}} 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 InterruptedException if interrupted while waiting, in which case unfinished tasks are cancelled @throws NullPointerException if tasks or any of its elements are {@code null} @throws RejectedExecutionException if any task cannot be scheduled for execution */ invokeAll : function( ) {}, /**Executes the given tasks, returning a list of Futures holding their status and results when all complete or the timeout expires, whichever happens first. {@link java.util.concurrent.Future#isDone} is {@code true} for each element of the returned list. Upon return, tasks that have not completed are cancelled. Note that a <em>completed</em> 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. @param {Object {java.util.Collection}} tasks the collection of tasks @param {Number} timeout the maximum time to wait @param {Object {TimeUnit}} unit the time unit of the timeout argument @param <T> the type of the values returned from the tasks @return {Object {java.util.List}} 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 InterruptedException if interrupted while waiting, in which case unfinished tasks are cancelled @throws NullPointerException if tasks, any of its elements, or unit are {@code null} @throws RejectedExecutionException if any task cannot be scheduled for execution */ invokeAll : function( ) {}, /**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. @param {Object {java.util.Collection}} tasks the collection of tasks @param <T> the type of the values returned from the tasks @return {Object {java.lang.Object}} the result returned by one of the tasks @throws InterruptedException if interrupted while waiting @throws NullPointerException if tasks or any element task subject to execution is {@code null} @throws IllegalArgumentException if tasks is empty @throws ExecutionException if no task successfully completes @throws RejectedExecutionException if tasks cannot be scheduled for execution */ invokeAny : function( ) {}, /**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. @param {Object {java.util.Collection}} tasks the collection of tasks @param {Number} timeout the maximum time to wait @param {Object {TimeUnit}} unit the time unit of the timeout argument @param <T> the type of the values returned from the tasks @return {Object {java.lang.Object}} the result returned by one of the tasks @throws InterruptedException if interrupted while waiting @throws NullPointerException if tasks, or unit, or any element task subject to execution is {@code null} @throws TimeoutException if the given timeout elapses before any task successfully completes @throws ExecutionException if no task successfully completes @throws RejectedExecutionException if tasks cannot be scheduled for execution */ invokeAny : function( ) {}, };