Question

在生成SIZE项之后，生产者进程应该写入fd_pipe_p2c管道并由消费者进程读取，然后消费者进程输出它正在消耗的内容。之后，消费者应该通过pipe_fd_c2p管道回写给生产者，让它知道缓冲区中有更多的空间。

cnt int似乎没有达到SIZE，我希望它在生成器函数生成SIZE项后执行。因此，消费者功能永远不会收到所产生的东西。

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#define SIZE 10

int shared_arr[SIZE];
int cnt = 0, in = 0, out = 0;
int fd_pipe_c2p[2], fd_pipe_p2c[2];

void consumer();
void producer();

int main() {
    pipe(fd_pipe_c2p); // consumer to producer
    pipe(fd_pipe_p2c); // producer to consumer

    if (fork() == 0) {
        // child process
        consumer();
    } else {
        // parent process
        producer();
        sleep(3);
    }

    exit(0);
}

void consumer() {
    // consumer process
    close(fd_pipe_c2p[0]);
    while (1) {
        while (cnt == 0) {
            // give up everything
            write(fd_pipe_c2p[1], &cnt, 1);
            write(fd_pipe_c2p[1], shared_arr, sizeof(shared_arr));

            // read in cnt?
            read(fd_pipe_p2c[0], &cnt, 1);
            if (cnt > 0) { // if we have something, break out of inner loop
                break;
            }
        }

        read(fd_pipe_p2c[0], shared_arr, sizeof(shared_arr)); // read in array

        int n = shared_arr[out]; // get value to consume

        fprintf(stderr, "I am consuming.......%d\n", n, out);

        out = (out + 1) % SIZE; // move out forward?
        cnt--; // decrease count
    }
}

void producer() {
    // producer process
    close(fd_pipe_p2c[0]);
    while (1) {
        // read in cnt, if it's not == SIZE then produce something
        read(fd_pipe_c2p[0], &cnt, 1);
        while (cnt == SIZE)  {
            // write to consumer, we've produced something for it:
            write(fd_pipe_p2c[1], &cnt, 1);
            write(fd_pipe_p2c[1], shared_arr, sizeof(shared_arr));
        }

        // cnt != SIZE, so let's produce something:
        shared_arr[in] = rand() % 100;
        fprintf(stderr, "I am producing......%d...%d\n", shared_arr[in], in);
        in = (in + 1) % SIZE;
        cnt++;
    }
}


}

也许预期输出的一个例子可以更好地解释：

I am producing......26...0.

I am producing......34...1.

I am producing......6...2.

I am producing......1...3.

I am producing......84...4.

I am producing......35...5.

I am producing......89...6.

I am producing......38...7.

I am producing......65...8.

I am producing......78...9.

 Check to see something available.

I am producing......80...0.

I am consuming......26  0       

I am producing......67...1.

I am consuming......34  1       

I am producing......59...2.

I am consuming......6   2       

I am producing......52...3.

I am consuming......1   3       

I am producing......85...4.

I am consuming......84  4       

I am producing......79...5.

I am consuming......35  5       

I am producing......94...6.

I am consuming......89  6       

I am producing......58...7.

I am consuming......38  7       

I am producing......74...8.

I am consuming......65  8       

I am producing......67...9.

I am consuming......78  9       

 Check to see something available.

相反，这是我当前的输出：

I am producing......83...0
I am producing......86...1
I am producing......77...2
I am producing......15...3
I am producing......93...4
I am producing......35...5
I am producing......86...6
I am producing......92...7
I am producing......49...8
I am producing......21...9
I am producing......62...0
I am producing......27...1
I am producing......90...2
I am producing......59...3
I am producing......63...4
I am producing......26...5
I am producing......40...6
I am producing......26...7
I am producing......72...8
I am producing......36...9
I am producing......11...0
I am producing......68...1
I am producing......67...2
I am producing......29...3
I am producing......82...4
I am producing......30...5
I am producing......62...6
I am producing......23...7
I am producing......67...8
I am producing......35...9
I am producing......29...0
I am producing......2...1
I am producing......22...2
I am producing......58...3
I am producing......69...4
I am producing......67...5
I am producing......93...6
I am producing......56...7
I am producing......11...8
I am producing......42...9
I am producing......29...0

生产者/消费者有两个管道 - 消费者没有写任何东西

0 个答案: