/*
 * 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 io.trino.execution.executor.scheduler;

import com.google.errorprone.annotations.ThreadSafe;

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

@ThreadSafe
final class Gate
{
    private final Lock lock = new ReentrantLock();
    private final Condition opened = lock.newCondition();
    private boolean open;

    public Gate(boolean opened)
    {
        this.open = opened;
    }

    public void close()
    {
        lock.lock();
        try {
            open = false;
        }
        finally {
            lock.unlock();
        }
    }

    public void open()
    {
        lock.lock();
        try {
            open = true;
            opened.signalAll();
        }
        finally {
            lock.unlock();
        }
    }

    public void awaitOpen()
            throws InterruptedException
    {
        lock.lock();
        try {
            while (!open) {
                opened.await();
            }
        }
        finally {
            lock.unlock();
        }
    }
}
