org.ardulink.util.Suppliers Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of ardulink-core-util Show documentation

The newest version!

/**
Copyright 2013 project Ardulink http://www.ardulink.org/
 
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
 
    http://www.apache.org/licenses/LICENSE-2.0
 
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package org.ardulink.util;

import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Supplier;

/**
 * [ardulinktitle] [ardulinkversion]
 * 
 * project Ardulink http://www.ardulink.org/
 * 
 * [adsense]
 *
 */
public final class Suppliers {

	private Suppliers() {
		super();
	}

	private static class MemoizingSupplier implements Supplier {

		private final Supplier delegate;
		private final AtomicReference cache = new AtomicReference<>();

		private MemoizingSupplier(Supplier delegate) {
			this.delegate = delegate;
		}

		@Override
		public T get() {
			T value;
			if ((value = cache.get()) == null) {
				synchronized (cache) {
					if ((value = cache.get()) == null) {
						cache.set(value = delegate.get());
					}
				}
			}
			return value;
		}
	}

	public static  Supplier memoize(Supplier delegate) {
		return delegate instanceof MemoizingSupplier ? delegate : new MemoizingSupplier<>(delegate);
	}

}