linux共享内存互斥锁

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>
#include <pthread.h>

#define SHM_NAME "/my_shm"
#define SHM_SIZE 1024

typedef struct {
    int counter;
    pthread_mutex_t mutex;
} SharedData;

int main() {
    int shm_fd = shm_open(SHM_NAME, O_CREAT | O_RDWR, 0666);
    ftruncate(shm_fd, SHM_SIZE);

    SharedData *shared_data = (SharedData *)mmap(0, SHM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
    shared_data->counter = 0;
    pthread_mutex_init(&shared_data->mutex, NULL);

    // Simulate multiple processes accessing the shared memory
    for (int i = 0; i < 10; i++) {
        pthread_t thread;
        pthread_create(&thread, NULL, [](void *arg) {
            SharedData *data = (SharedData *)arg;
            pthread_mutex_lock(&data->mutex);
            data->counter++;
            printf("Counter: %d\n", data->counter);
            pthread_mutex_unlock(&data->mutex);
        }, shared_data);
        pthread_join(thread, NULL);
    }

    pthread_mutex_destroy(&shared_data->mutex);
    munmap(shared_data, SHM_SIZE);
    shm_unlink(SHM_NAME);

    return 0;
}