fullsync / fullsync

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor,

 * Boston, MA 02110-1301, USA.

 *

 * For information about the authors of this project Have a look

 * at the AUTHORS file in the root of this project.

 */

package net.sourceforge.fullsync.ui;

import java.util.concurrent.CompletableFuture;

import java.util.concurrent.ScheduledExecutorService;

import java.util.function.Consumer;

import java.util.function.Supplier;

import javax.inject.Inject;

import org.eclipse.swt.widgets.Display;

import net.sourceforge.fullsync.ThrowingSupplier;

public class BackgroundExecutor {

	private final ScheduledExecutorService scheduledExecutorService;

	private final Display display;

	@Inject

	public BackgroundExecutor(ScheduledExecutorService scheduledExecutorService, Display display) {

		this.scheduledExecutorService = scheduledExecutorService;

		this.display = display;

	}

		CompletableFuture<R> future = CompletableFuture.supplyAsync(unchecked(supplier), scheduledExecutorService);

		UIUpdateTask<R> task = new UIUpdateTask<>(display, future, successConsumer, errorConsumer);

		future.thenRun(task);

	}

	// from http://4comprehension.com/sneakily-throwing-exceptions-in-lambda-expressions-in-java/

	static <R> Supplier<R> unchecked(ThrowingSupplier<R> f) {

		return () -> {

			try {

				return f.get();

			}

			catch (Exception ex) {

				return sneakyThrow(ex);

			}

		};

	}

	// from http://4comprehension.com/sneakily-throwing-exceptions-in-lambda-expressions-in-java/

	@SuppressWarnings("unchecked")

	static <T extends Exception, R> R sneakyThrow(Exception t) throws T {

		throw (T) t; // ( ͡° ͜ʖ ͡°)

	}

	private static class UIUpdateTask<T> implements Runnable {

		private final Display display;

		private final CompletableFuture<T> future;

		private final Consumer<T> successConsumer;

		private final Consumer<Exception> errorConsumer;

		public UIUpdateTask(Display display, CompletableFuture<T> future, Consumer<T> successConsumer, Consumer<Exception> errorConsumer) {

			this.display = display;

			this.future = future;

			this.successConsumer = successConsumer;

			this.errorConsumer = errorConsumer;

		}

		@Override

		public void run() {

			display.asyncExec(this::notifyOnUiThread);

		}

		}

	}

}