代码

#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <assert.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <fstream>
#include <iostream>
#include <sstream>/***  返回一片共享内存标识符，用于后续获取该共享内存，以及销毁该共享内存*  file_name*  md5*/
namespace hhh{namespace hhh{class mutex_function{public:mutex_function() = default;// 定义进程锁结构体
//            typedef struct mutex_struct{
//                pthread_mutex_t lock;
//                pthread_mutexattr_t lock_attr;
//                int memory_addr;
//            }mutex_struct_t;typedef struct mutex_struct{pthread_rwlock_t lock;pthread_rwlockattr_t lock_attr;int memory_addr;}mutex_struct_t;//create memory_addrint create_share_memory_id(const int INDEX_OF_KEY,size_t md5){const char* FILE_PATH = "/home/gsc/Projects";key_t id = ftok(FILE_PATH,md5);const int share_memory_id = shmget(id,md5,IPC_CREAT | 0666);if (share_memory_id == -1){std::cout << "share_memory_id error!\n" << std::endl;exit(EXIT_FAILURE);}else{return share_memory_id;}}// 初始化进程锁结构体
//            int init_mutex_struct(mutex_struct_t* mutex_ptr){
//                pthread_mutexattr_init(&(mutex_ptr->lock_attr));
//                pthread_mutexattr_setpshared(&(mutex_ptr->lock_attr),PTHREAD_PROCESS_SHARED);
//                pthread_mutex_init(&(mutex_ptr->lock),&(mutex_ptr->lock_attr));
//                return 0;
//            }int init_mutex_struct(mutex_struct_t* mutex_ptr){pthread_rwlockattr_init(&(mutex_ptr->lock_attr));pthread_rwlockattr_setpshared(&(mutex_ptr->lock_attr),PTHREAD_PROCESS_SHARED);pthread_rwlock_init(&(mutex_ptr->lock),&(mutex_ptr->lock_attr));return 0;}// 在共享内存上定义进程锁结构体并且返回其位置mutex_struct_t* mutex_struct_addr(const int INDEX){int memory_id = create_share_memory_id(INDEX,sizeof (mutex_struct_t));mutex_struct_t * share_ptr = (mutex_struct_t* )shmat(memory_id, 0, 0);if (share_ptr == (void *)-1){std::cout << "share_ptr error!\n" << std::endl;exit(EXIT_FAILURE);}share_ptr->memory_addr = memory_id;assert(init_mutex_struct(share_ptr)== 0);return share_ptr;}// 销毁进程锁结构体，利用其memory_addr变量索引到其占用的共享内存并销毁
//            const int destory_mutex_struct(mutex_struct_t * mutex_struct){
//                pthread_mutex_destroy(&(mutex_struct->lock));
//                pthread_mutexattr_destroy(&(mutex_struct->lock_attr));
//                assert(shmctl(mutex_struct->memory_addr,IPC_RMID, nullptr) == 0);
//                return 0;
//            }const int destory_mutex_struct(mutex_struct_t * mutex_struct){pthread_rwlock_destroy(&(mutex_struct->lock));pthread_rwlockattr_destroy(&(mutex_struct->lock_attr));assert(shmctl(mutex_struct->memory_addr,IPC_RMID, nullptr) == 0);return 0;}public:size_t share_memory_id;mutex_struct_t* mutex_struct_ptr;};}//namespace hhh
}//namespace hhh//read file
void read_file(const std::string file_name,int id){std::ifstream fp(file_name,std::ios::binary);std::stringstream ss;ss << fp.rdbuf();std::cout << "线程"<< id << "抢占了资源,输出:" << ss.str() << std::endl;sleep(3);std::cout << "线程"<< id << "释放了资源...\n" << std::endl;fp.close();
}int main(){std::string file_name = "/home/gsc/Projects/1.txt";// 创建自定义进程锁hal::hsm::mutex_function mutex_function_object;mutex_function_object.mutex_struct_ptr = mutex_function_object.mutex_struct_addr(111);// 获取一片共享内存空间int memory_addr = mutex_function_object.create_share_memory_id(222,sizeof (int));volatile int* x = (int*)shmat(memory_addr, 0, 0);// 创建新进程int id = fork();assert(id >= 0);// 设置循环次数const int N = 1000000;// 父进程每次加1，子进程每次加2int i;for (i = 0; i < N; ++i) {if (id > 0) {  // 父进程// 加锁
//            pthread_mutex_lock(&(mutex_function_object.mutex_struct_ptr->lock));
//            pthread_rwlock_rdlock(&(mutex_function_object.mutex_struct_ptr->lock));pthread_rwlock_wrlock(&(mutex_function_object.mutex_struct_ptr->lock));//            int temp = *x;
//            *x = temp+1;read_file(file_name,getpid());// 解锁pthread_rwlock_unlock(&(mutex_function_object.mutex_struct_ptr->lock));} else {  // 子进程// 加锁
//            pthread_mutex_lock(&(mutex_function_object.mutex_struct_ptr->lock));
//            pthread_rwlock_rdlock(&(mutex_function_object.mutex_struct_ptr->lock));pthread_rwlock_wrlock(&(mutex_function_object.mutex_struct_ptr->lock));//            int temp = *x;
//            *x = temp+2;read_file(file_name,getpid());// 解锁
//            pthread_mutex_unlock(&(mutex_function_object.mutex_struct_ptr->lock));pthread_rwlock_unlock(&(mutex_function_object.mutex_struct_ptr->lock));}}// 等待循环完毕sleep(1);// 打印
//    printf("pid= %d, x_address= %x, x= %d\n", getpid(), x, *x);// 等待打印完毕sleep(1);// 销毁进程锁,释放申请的共享内存if (id > 0) {  // 父进程mutex_function_object.destory_mutex_struct((mutex_function_object.mutex_struct_ptr));mutex_function_object.mutex_struct_ptr = nullptr;shmctl(memory_addr, IPC_RMID, nullptr);x = nullptr;printf("父进程释放资源完毕\n");}return 0;
}