Forked from alexkasko/LimitedExecutorServiceWrapper.java
Created
July 7, 2023 05:18
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ExecutorService wrapper, limits max parallel threads
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| /** | |
| * {@link ExecutorService} wrapper, limit max parallel threads to provided limit. | |
| * May be useful for task with different parrallelism over the same executor. | |
| * | |
| * @author alexkasko | |
| * Date: 7/6/12 | |
| */ | |
| public class LimitedExecutorServiceWrapper implements ExecutorService { | |
| private final ExecutorService target; | |
| private final Semaphore semaphore; | |
| /** | |
| * @param executor executor service to wrap | |
| * @param parallelLimit max parallel threads available in provided executor service through this instance | |
| */ | |
| public LimitedExecutorServiceWrapper(ExecutorService executor, int parallelLimit) { | |
| checkNotNull(executor, "Provided executor is null"); | |
| checkArgument(parallelLimit > 0, "Limit mast be positive but was: '%s'", parallelLimit); | |
| this.target = executor; | |
| this.semaphore = new Semaphore(parallelLimit); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public void shutdown() { | |
| target.shutdown(); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public List<Runnable> shutdownNow() { | |
| return target.shutdownNow(); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public boolean isShutdown() { | |
| return target.isShutdown(); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public boolean isTerminated() { | |
| return target.isTerminated(); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException { | |
| return target.awaitTermination(timeout, unit); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public <T> Future<T> submit(Callable<T> task) { | |
| return target.submit(new SemaphoreCallable<T>(task)); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public <T> Future<T> submit(Runnable task, T result) { | |
| return target.submit(new SemaphoreRunnable(task), result); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public Future<?> submit(Runnable task) { | |
| return target.submit(new SemaphoreRunnable(task)); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks) throws InterruptedException { | |
| return target.invokeAll(Collections2.transform(tasks, new SemaphoreCallableFun<T>())); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public <T> List<Future<T>> invokeAll(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) throws InterruptedException { | |
| return target.invokeAll(Collections2.transform(tasks, new SemaphoreCallableFun<T>()), timeout, unit); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public <T> T invokeAny(Collection<? extends Callable<T>> tasks) throws InterruptedException, ExecutionException { | |
| return target.invokeAny(Collections2.transform(tasks, new SemaphoreCallableFun<T>())); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public <T> T invokeAny(Collection<? extends Callable<T>> tasks, long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException { | |
| return target.invokeAny(Collections2.transform(tasks, new SemaphoreCallableFun<T>()), timeout, unit); | |
| } | |
| /** | |
| * {@inheritDoc} | |
| */ | |
| @Override | |
| public void execute(Runnable command) { | |
| target.execute(new SemaphoreRunnable(command)); | |
| } | |
| private class SemaphoreCallable<T> implements Callable<T> { | |
| private final Callable<T> target; | |
| private SemaphoreCallable(Callable<T> target) { | |
| checkNotNull(target, "Provided callable is null"); | |
| this.target = target; | |
| } | |
| @Override | |
| public T call() throws Exception { | |
| try { | |
| semaphore.acquire(); | |
| return target.call(); | |
| } finally { | |
| semaphore.release(); | |
| } | |
| } | |
| } | |
| private class SemaphoreRunnable implements Runnable { | |
| private final Runnable target; | |
| private SemaphoreRunnable(Runnable target) { | |
| this.target = target; | |
| } | |
| @Override | |
| public void run() { | |
| try { | |
| semaphore.acquire(); | |
| target.run(); | |
| } catch(InterruptedException e) { | |
| throw new UnhandledException(e); | |
| } finally { | |
| semaphore.release(); | |
| } | |
| } | |
| } | |
| private class SemaphoreCallableFun<T> implements Function<Callable<T>, SemaphoreCallable<T>> { | |
| @SuppressWarnings("unchecked") | |
| @Override | |
| public SemaphoreCallable<T> apply(@Nullable Callable<T> input) { | |
| return new SemaphoreCallable<T>(input); | |
| } | |
| } | |
| } |
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