《JAVA程序性能优化》-ArrayBlockingQueue的简单实现

/**
 * @author shujun.xiong
 * @date 2019/7/18 9:32
 */

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

public class ConditionTest {
    private final Integer[] items;
    private final ReentrantLock lock;
    private final Condition notEmpty;
    private final Condition notFull;
    private int putIndex, takeIndex, count;

    public ConditionTest() {
        this.items = new Integer[Integer.MAX_VALUE];
        lock = new ReentrantLock(true);
        this.notEmpty = lock.newCondition();
        this.notFull = lock.newCondition();
        putIndex = 0;
        takeIndex = 0;
        count = 0;
    }

    public void put(Integer number) throws InterruptedException {
        if (number == null) {
            throw new NullPointerException();
        }
        final Integer[] items = this.items;
        final ReentrantLock lock = this.lock;
        lock.lockInterruptibly();
        try {
            try {
                while (count == items.length) {
                    notFull.await();
                }
            } catch (InterruptedException e) {
                notFull.signal();
                throw e;
            }

            insert(number);
        } finally {
            lock.unlock();
        }
        
    }

    private void insert(Integer e) {
        items[putIndex] = e;
        putIndex++;
        ++count;
        notEmpty.signal();
    }

    public Integer take() throws InterruptedException {
        final ReentrantLock lock = this.lock;
        lock.lockInterruptibly();
        try {
            try {
                while (count == 0) {
                    notEmpty.await();
                }
            } catch (InterruptedException e) {
                notEmpty.signal();
                throw e;
            }
            Integer x = extract();
            return x;
        } finally {
            lock.unlock();
        }
    }

    private Integer extract() {
        final Integer[] items = this.items;
        Integer x = items[takeIndex];
        takeIndex++;
        --count;
        notFull.signal();
        return x;
    }
}