GB28181系统设计(三)-进程通信让python获取共享内存数据

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	message_queue::remove("message_queue");

		//Create a message_queue.
	message_queue mq(create_only    //only create
			, "message_queue"           //name
			, 100                       //max message number
			, sizeof(int)               //max message size
		);

	//删除之前创建
	shared_memory_object::remove("RGB_MEMORY_1");

	//创建RGB共享内存段
	shared_memory_object shm(create_only, "RGB_MEMORY_1", read_write);

	//设置共享内存大小,RGB 1080p 图像
	shm.truncate(1920*1080*3);

	//映射共享内存
	mapped_region region(shm, read_write);

	//清零，这一步可以删除
	std::memset(region.get_address(), 0, region.get_size());

	//往内存里写数据，测试先用string
	string *strTest = static_cast<string*>(region.get_address());

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	shared_memory_object shm(open_only, "RGB_MEMORY_1", read_only);
	//映射共享内存
	mapped_region region(shm, read_only);

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 我们什么时候读呢，使用消息队列或者udp来发送短信息提醒

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	message_queue::remove("message_queue");

		//Create a message_queue.
	message_queue mq(create_only    //only create
			, "message_queue"           //name
			, 100                       //max message number
			, sizeof(int)               //max message size
		);
	int num = 0;
	mq.send(&num++, sizeof(int), 0);

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	int number;
	mq.receive(&number, sizeof(number), recvd_size, priority);
	if (recvd_size != sizeof(number))
		return 1;
	cout<<"recv " << number << endl;
	//接下去就可以读取共享内存了，先用字符串测试
	char *mem = static_cast<char*>(region.get_address());
	string str(mem, region.get_size());

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//发送端
int main()
{
	
	message_queue::remove("message_queue");

		//Create a message_queue.
	message_queue mq(create_only    //only create
			, "message_queue"           //name
			, 100                       //max message number
			, sizeof(int)               //max message size
		);

	//1 先删除之前创建的
	shared_memory_object::remove("MySharedMemory_Name");

	//2 创建共享内存段
	shared_memory_object shm(create_only, "MySharedMemory_Name", read_write);

	//3 设置共享内存大小
	shm.truncate(1024);

	//4 映射共享内存片段
	mapped_region region(shm, read_write);

	//5 初始化为0
	std::memset(region.get_address(), 0, region.get_size());

	//6 往内存里写入数据
	string *strTest = static_cast<string*>(region.get_address());
	for (int i = 0; i < 100; i++)
	{
		
		*strTest = "this is test for " + std::to_string(i);
		cout << *strTest << endl;
		mq.send(&i, sizeof(i), 0);
		std::this_thread::sleep_for(std::chrono::milliseconds(1000));
	}
	cout << "发送over" << endl;
	getchar();
	return 0;
}


//接收端
int main()
{
	//1 读取共享内存
	shared_memory_object shm(open_only, "MySharedMemory_Name", read_only);

	//2 映射共享内存
	mapped_region region(shm, read_only);
	try {
		//Open a message queue.
		message_queue mq
		(open_only        //only create
			, "message_queue"  //name
		);

		unsigned int priority;
		message_queue::size_type recvd_size;

		//Receive 100 numbers
		for (int i = 0; i < 100; ++i) {
			int number;
			mq.receive(&number, sizeof(number), recvd_size, priority);
			if (recvd_size != sizeof(number))
				return 1;
			cout<<"recv " << number << endl;

			//3 获取数据
			char *mem = static_cast<char*>(region.get_address());
			string str(mem, region.get_size());


			cout << str<< endl;
		}
	}
	catch (interprocess_exception &ex) {
		message_queue::remove("message_queue");
		std::cout << ex.what() << std::endl;
		return 1;
	}
	message_queue::remove("message_queue");
	return 0;
}