操作系统实验 C++实现生产者-消费者问题

实验目的

1、进一步加深理解进程同步的概念

2、加深对进程通信的理解

3、了解Linux下共享内存的使用方法

实验内容

1、按照下面要求，写两个c程序，分别是生产者producer.c以及customer.c

2、一组生产者和一组消费者进程共享一块环形缓冲区

使用共享内存+信号量实现生产者-消费者

1、生产者进程：在第0个缓冲区写入a，第1个写入b，……，第9个写入j，并在屏幕上打印:“Producer-pid：write Y”，其中Y为写入字符，pid为生产者进程的进程ID；

2、消费者进程：依次从缓冲区中读出写入字符，读出后，将该缓冲区置为X，并在屏幕上打印：“Customer：read Y”，其中Y为读出字符，pid为消费者进程的进程ID；

基本思路

定义一个数据结构：

typedef struct{

int write;//当前要写的缓冲区 i

nt read;//当前要读的缓冲区

char buf[10];//10个缓冲区

}shared_buf;

创建一个大小为sizeof(shared_buf)的共享内存
Producer：在buf[write]写字符‘a’+ write，然后write = （++write）% 10;
Customer：读buf[read]中字符，并置buf[read] = ‘X’，然后read = （++read）% 10；
使用信号量：full、empty、mutex来进行同步及互斥

参考：共享内存

Linux POSIX共享内存

Linux System V共享内存

实验代码

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <process.h>

// 定义共享数据结构
typedef struct {
    int write;
    int read;
    char buf[10];
} shared_buf;

// 信号量句柄
HANDLE empty_semaphore;
HANDLE full_semaphore;
HANDLE mutex_semaphore;

// 共享内存句柄
HANDLE shared_memory_handle;
shared_buf* shared_memory_ptr;

// 生产者函数
unsigned __stdcall producer(void* arg) {
    int pid = _getpid();
    for (int i = 0; i < 20; i++) {
        // 等待有空缓冲区
        WaitForSingleObject(empty_semaphore, INFINITE);
        // 互斥访问共享内存
        WaitForSingleObject(mutex_semaphore, INFINITE);

        char ch = 'a' + i;
        shared_memory_ptr->buf[shared_memory_ptr->write] = ch;
        printf("Producer - %d: write %c\n", pid, ch);
        shared_memory_ptr->write = (shared_memory_ptr->write + 1) % 10;

        ReleaseSemaphore(mutex_semaphore, 1, NULL);
        ReleaseSemaphore(full_semaphore, 1, NULL);
    }
    return 0;
}

// 消费者函数
unsigned __stdcall consumer(void* arg) {
    int pid = _getpid();
    for (int i = 0; i < 20; i++) {
        // 等待有满缓冲区
        WaitForSingleObject(full_semaphore, INFINITE);
        // 互斥访问共享内存
        WaitForSingleObject(mutex_semaphore, INFINITE);

        char ch = shared_memory_ptr->buf[shared_memory_ptr->read];
        shared_memory_ptr->buf[shared_memory_ptr->read] = 'X';
        printf("Consumer - %d: read %c\n", pid, ch);
        shared_memory_ptr->read = (shared_memory_ptr->read + 1) % 10;

        ReleaseSemaphore(mutex_semaphore, 1, NULL);
        ReleaseSemaphore(empty_semaphore, 1, NULL);
    }
    return 0;
}

int main() {
    // 创建信号量
    empty_semaphore = CreateSemaphore(NULL, 10, 10, NULL);
    full_semaphore = CreateSemaphore(NULL, 0, 10, NULL);
    mutex_semaphore = CreateSemaphore(NULL, 1, 1, NULL);

    // 创建共享内存
    shared_memory_handle = CreateFileMapping(
        INVALID_HANDLE_VALUE,
        NULL,
        PAGE_READWRITE,
        0,
        sizeof(shared_buf),
        "SharedMemory"
    );
    if (shared_memory_handle == NULL) {
        perror("CreateFileMapping");
        return 1;
    }
    shared_memory_ptr = (shared_buf*)MapViewOfFile(
        shared_memory_handle,
        FILE_MAP_ALL_ACCESS,
        0,
        0,
        sizeof(shared_buf)
    );
    if (shared_memory_ptr == NULL) {
        perror("MapViewOfFile");
        CloseHandle(shared_memory_handle);
        return 1;
    }

    // 初始化共享内存
    shared_memory_ptr->write = 0;
    shared_memory_ptr->read = 0;
    for (int i = 0; i < 20; i++) {
        shared_memory_ptr->buf[i] = 'X';
    }

    // 创建生产者和消费者线程
    unsigned thread_id_producer;
    unsigned thread_id_consumer;
    HANDLE producer_thread = (HANDLE)_beginthreadex(NULL, 0, producer, NULL, 0, &thread_id_producer);
    HANDLE consumer_thread = (HANDLE)_beginthreadex(NULL, 0, consumer, NULL, 0, &thread_id_consumer);

    // 等待线程结束
    WaitForSingleObject(producer_thread, INFINITE);
    WaitForSingleObject(consumer_thread, INFINITE);

    // 清理资源
    UnmapViewOfFile(shared_memory_ptr);
    CloseHandle(shared_memory_handle);
    CloseHandle(empty_semaphore);
    CloseHandle(full_semaphore);
    CloseHandle(mutex_semaphore);
    CloseHandle(producer_thread);
    CloseHandle(consumer_thread);

    return 0;
}