hugegraph-common/src/main/java/com/baidu/hugegraph/concurrent/BarrierEvent.java

/*
 *
 *  Copyright 2017 HugeGraph Authors
 *
 *  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 com.baidu.hugegraph.concurrent;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import com.baidu.hugegraph.util.E;

public class BarrierEvent {

    private final Lock lock = new ReentrantLock();
    private final Condition cond = lock.newCondition();
    private volatile boolean signaled = false;

    /**
     * Wait forever until the signal is received.
     * @return true if signal is received
     * @throws InterruptedException if interrupted.
     */
    public void await() throws InterruptedException {
        this.lock.lock();
        try {
            while (!this.signaled) {
                this.cond.await();
            }
        } finally {
            this.lock.unlock();
        }
    }

    /**
     * Wait specified time in milliseconds.
     * @param timeout: the time in millisecond to wait.
     * @return true if signal is received, false if time out.
     */
    public boolean await(long timeout) throws InterruptedException {
        E.checkArgument(timeout >= 0L,
                        "The time must be >= 0, but got '%d'.",
                        timeout);
        long deadline = System.currentTimeMillis() + timeout;
        this.lock.lock();
        try {
            while (!this.signaled) {
                timeout = deadline - System.currentTimeMillis();
                if (timeout > 0) {
                    this.cond.await(timeout, TimeUnit.MILLISECONDS);
                }
                if (System.currentTimeMillis() >= deadline) {
                    return this.signaled;
                }
            }
        } finally {
            this.lock.unlock();
        }
        return true;
    }

    public void reset() {
        this.lock.lock();
        try {
            this.signaled = false;
        } finally {
            this.lock.unlock();
        }
    }

    public void signal() {
        this.lock.lock();
        try {
            this.signaled = true;
            this.cond.signal();
        } finally {
            this.lock.unlock();
        }
    }

    public void signalAll() {
        this.lock.lock();
        try {
            this.signaled = true;
            this.cond.signalAll();
        } finally {
            this.lock.unlock();
        }
    }
}