package org.warp.commonutils.concurrency.executor;

import java.util.concurrent.Callable;
import java.util.concurrent.Semaphore;
import javax.annotation.Nonnull;

public final class PermitReleasingCallableDecorator<T> extends CallableDecorator<T> {

	@Nonnull
	private final Runnable queueSizeUpdater;

	@Nonnull
	private final Semaphore semaphore;

	PermitReleasingCallableDecorator(@Nonnull final Callable<T> task,
			@Nonnull final Runnable queueSizeUpdater,
			@Nonnull final Semaphore semaphoreToRelease) {
		super(task);
		this.queueSizeUpdater = queueSizeUpdater;
		this.semaphore = semaphoreToRelease;
	}

	@Override
	public T call() throws Exception {
		try {
			queueSizeUpdater.run();
		} finally {
			// however execution goes, release permit for next task
			this.semaphore.release();

			return super.call();
		}
	}

	@Override
	public final String toString() {
		return String.format("%s[delegate='%s']", getClass().getSimpleName(), super.toString());
	}
}