java - 当我们在消费者和生产者缓冲区中使用信号量时

Question

我正在消费者和生产者中研究 BoundedBuffer 类，我们希望在该类中使用信号量我们这样做了，但是每次使用 acquire() 时都会出现错误错误是:

未报告的异常 java.lang.InterruptedException;必须被捕获或宣布被抛出

这是代码:

import java.util.concurrent.Semaphore;

public class BoundedBuffer implements Buffer { 
    private static final int   BUFFER_SIZE = 4;

    /**
     * volatile does not appear in the printed text. A discussion of
     * volatile is in chapter 7.
     */
    private volatile int count;
    private Object[] buffer;
    private int in;   // points to the next free position in the buffer
    private int out;  // points to the next full position in the buffer

    private Semaphore  mutex;
    private Semaphore  empty;
    private Semaphore full;

    public BoundedBuffer() { //constractur
        // buffer is initially empty
        //count = 0;
        in = 0;
        out = 0;

        buffer = new Object[BUFFER_SIZE];

        mutex = new Semaphore(1);
        empty = new Semaphore(BUFFER_SIZE);
        full = new Semaphore(0);
    }

    // producer calls this method
    public void insert(Object item) {
        //while (count == BUFFER_SIZE) 
        // ; // do nothing the brach full

        // add an item to the buffer
        // ++count;

        empty.acquire();
        mutex.acquire();
        buffer[in] = item;
        in = (in + 1) % BUFFER_SIZE;//that to do cyrcle or to go to the begining againe
/*
        if (count == BUFFER_SIZE)
            System.out.println("Baker put " + item + " Shelf FULL");
        else
            System.out.println("Baker put " + item + " Shelf Size = " +  count);
*/


        mutex.release();
        full.release();

    }

    // consumer calls this method
    public Object remove() {
        //Object item;
        full.acquire();
        mutex.acquire();

        //while (count == 0) 
            ; // do nothing the buffer is empty

        // remove an item from the buffer
        //--count;

        Object item = buffer[out];
        out = (out + 1) % BUFFER_SIZE;
        mutex.release();
        empty.release();
        return item;
    }
}

Answer 1

也许我不完全理解你的应用程序，但你不能只使用 java.util.concurrent 包中已经提供的有界缓冲区类( ArrayBlockingQueue )吗？

This is a classic "bounded buffer", in which a fixed-sized array holds elements inserted by producers and extracted by consumers. Once created, the capacity cannot be increased. Attempts to put an element to a full queue will result in the put operation blocking; attempts to retrieve an element from an empty queue will similarly block.