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Comprehensive Java common library (Java7+)
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/*
 * Copyright (C) 2015-2018 S.Violet
 *
 * 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.
 *
 * Project GitHub: https://github.com/shepherdviolet/thistle
 * Email: [email protected]
 */

package sviolet.thistle.util.concurrent;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

/**
 * ReentrantLock工具
 *
 * @author S.Violet
 */
public class ReentrantLockUtils {

    /**
     * 使用ReentrantLock+Condition阻塞线程等待指定时间, 除了抛出InterruptedException以外, 能够保证等待足够时间(不会提早结束),
     * 即使使用condition.signal()/condition.signalAll()也会继续等待.
     * @param lock ReentrantLock
     * @param condition condition
     * @param timeout 等待时间(ms)
     */
    public static void sleepMillis(ReentrantLock lock, Condition condition, long timeout) {
        final long startMillis = System.currentTimeMillis();
        try {
            lock.lock();
            while (true) {
                final long remainTimeout = timeout - (System.currentTimeMillis() - startMillis);
                if (remainTimeout <= 0) {
                    return;
                }
                try {
                    if (!condition.await(remainTimeout, TimeUnit.MILLISECONDS)) {
                        return;
                    }
                } catch (InterruptedException e) {
                    return;
                }
            }
        } finally {
            lock.unlock();
        }
    }

    /**
     * 使用ReentrantLock+Condition阻塞线程等待信号, 当finishFlag为true, 且condition发出唤醒信号时, 等待结束, 返回true.
     * 当等待超时时, 返回false.
     * @param lock ReentrantLock
     * @param condition condition
     * @param timeout 等待时间(ms)
     * @param finishFlag 结束标记, 只有被置为true, 且condition发出唤醒信号时, 等待才会结束
     * @return false:等待超时 true:在超时前, 线程被唤醒且finishFlag为true
     */
    public static boolean awaitMillis(ReentrantLock lock, Condition condition, long timeout, AtomicBoolean finishFlag) {
        final long startMillis = System.currentTimeMillis();
        try {
            lock.lock();
            while (true) {
                final long remainTimeout = timeout - (System.currentTimeMillis() - startMillis);
                if (remainTimeout <= 0) {
                    return false;
                }
                try {
                    if (!condition.await(remainTimeout, TimeUnit.MILLISECONDS)) {
                        return false;
                    }
                    if (finishFlag.get()){
                        return true;
                    }
                } catch (InterruptedException e) {
                    return false;
                }
            }
        } finally {
            lock.unlock();
        }
    }

}