/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to you 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.apache.logging.log4j.util;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.BooleanSupplier;

public class LazyBoolean implements BooleanSupplier {
    private final BooleanSupplier supplier;
    private final Lock lock = new ReentrantLock();
    private volatile boolean initialized;
    private volatile boolean value;

    public LazyBoolean(final BooleanSupplier supplier) {
        this.supplier = supplier;
    }

    @Override
    public boolean getAsBoolean() {
        boolean uninitialized = !initialized;
        boolean value = this.value;
        if (uninitialized) {
            lock.lock();
            try {
                uninitialized = !initialized;
                if (uninitialized) {
                    this.value = value = supplier.getAsBoolean();
                    initialized = true;
                }
            } finally {
                lock.unlock();
            }
        }
        return value;
    }

    public void setAsBoolean(final boolean b) {
        lock.lock();
        try {
            initialized = false;
            value = b;
            initialized = true;
        } finally {
            lock.unlock();
        }
    }

    public void reset() {
        initialized = false;
    }
}
