使用显示条件变量的有界缓存

通过使用reetrantlock和condition实现的有界缓存。

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

/**
 * Created by hybian on 2017/4/18.
 */

public class ConditionBoundedBuffer<T> {
    private int tail, head, count;
    private final int BUFFER_SIZE;
    private final T[] items;
    protected final Lock lock = new ReentrantLock();
    //条件谓词
    private final Condition notFull = lock.newCondition();
    private final Condition notEmpty = lock.newCondition();
    public ConditionBoundedBuffer(int buffer_size) {
        this.BUFFER_SIZE = buffer_size;
        items = (T[])new Object[BUFFER_SIZE];
    }
    //阻塞直到notFull
    public void put(T x) throws InterruptedException {
        lock.lockInterruptibly();
        try {
            while (count == items.length)
                notFull.await();
            items[tail] = x;
            if (++tail == items.length)
                tail = 0;
            ++count;
            notEmpty.signal();
        }finally {
            lock.unlock();
        }
    }
    public T take() throws InterruptedException {
        lock.lockInterruptibly();
        try {
            while (count == 0)
                notEmpty.await();
            T x = items[head];
            items[head] = null;
            if (++head == items.length)
                head = 0;
            --count;
            notFull.signal();
            return x;
        }finally {
            lock.unlock();
        }
    }
}