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c++代码实现同一台主机两个程序实现实时通信
对于进程间通信方式有很多种，对于本机两个程序中可以实时通信那么应该选择哪个呢？很多人最快想到的就是socket通信。
套接字适用于跨网络的进程间通信，具有网络透明性、灵活性和安全性高的优点，但性能开销较大，延迟较高！
共享内存适用于同一台机器上的进程间通信，具有高性能、低延迟和高吞吐量的优点，但需要手动管理同步机制，安全性较低。所以我们优先使用共享内存来实现，在智能驾驶等工业场景中使用非常多。
共享内存实现
进程A：
#include <cstring>
#include <iostream>
#include <sys/shm.h>
#include <thread>
#include <unistd.h>#define SHM_KEY_A 12345
#define SHM_KEY_B 67890
#define SHM_SIZE 1024void send_messages(char* send_data)
{std::string message;while (std::getline(std::cin, message)) {if (message == "exit") {break;}strncpy(send_data, message.c_str(), SHM_SIZE - 1);send_data[SHM_SIZE - 1] = '\0';while (std::strlen(send_data) > 0) {usleep(100000); // 等待 100 毫秒}}
}void receive_messages(char* recv_data)
{while (true) {while (std::strlen(recv_data) == 0) {usleep(100000); // 等待 100 毫秒}std::cout << "Received message: " << recv_data << std::endl;std::memset(recv_data, 0, SHM_SIZE);}
}int main()
{// 创建共享内存A（用于接收消息）int shmid_a = shmget(SHM_KEY_A, SHM_SIZE, 0666);if (shmid_a == -1) {std::cerr << "Failed to get shared memory A" << std::endl;return 1;}// 创建共享内存B（用于发送消息）int shmid_b = shmget(SHM_KEY_B, SHM_SIZE, 0666);if (shmid_b == -1) {std::cerr << "Failed to get shared memory B" << std::endl;return 1;}// 将共享内存连接到当前进程char* recv_data = (char*)shmat(shmid_a, nullptr, 0);char* send_data = (char*)shmat(shmid_b, nullptr, 0);if (recv_data == (char*)-1 || send_data == (char*)-1) {std::cerr << "Failed to attach shared memory" << std::endl;return 1;}std::thread sender(send_messages, send_data);std::thread receiver(receive_messages, recv_data);sender.join();receiver.join();// 清理共享内存shmdt(recv_data);shmdt(send_data);shmctl(shmid_a, IPC_RMID, nullptr);shmctl(shmid_b, IPC_RMID, nullptr);return 0;
}
进程B：
#include <cstring>
#include <iostream>
#include <sys/shm.h>
#include <thread>
#include <unistd.h>#define SHM_KEY_A 12345
#define SHM_KEY_B 67890
#define SHM_SIZE 1024void send_messages(char* send_data)
{std::string message;while (std::getline(std::cin, message)) {if (message == "exit") {break;}strncpy(send_data, message.c_str(), SHM_SIZE - 1);send_data[SHM_SIZE - 1] = '\0';while (std::strlen(send_data) > 0) {usleep(100000); // 等待 100 毫秒}}
}void receive_messages(char* recv_data)
{while (true) {while (std::strlen(recv_data) == 0) {usleep(100000); // 等待 100 毫秒}std::cout << "Received message: " << recv_data << std::endl;std::memset(recv_data, 0, SHM_SIZE);}
}int main()
{// 获取共享内存A（用于发送消息）int shmid_a = shmget(SHM_KEY_A, SHM_SIZE, IPC_CREAT | 0666);if (shmid_a == -1) {std::cerr << "Failed to create shared memory A" << std::endl;return 1;}// 获取共享内存B（用于接收消息）int shmid_b = shmget(SHM_KEY_B, SHM_SIZE, IPC_CREAT | 0666);if (shmid_b == -1) {std::cerr << "Failed to create shared memory B" << std::endl;return 1;}// 将共享内存连接到当前进程char* send_data = (char*)shmat(shmid_a, nullptr, 0);char* recv_data = (char*)shmat(shmid_b, nullptr, 0);if (send_data == (char*)-1 || recv_data == (char*)-1) {std::cerr << "Failed to attach shared memory" << std::endl;return 1;}std::thread sender(send_messages, send_data);std::thread receiver(receive_messages, recv_data);sender.join();receiver.join();// 清理共享内存shmdt(send_data);shmdt(recv_data);shmctl(shmid_a, IPC_RMID, nullptr);shmctl(shmid_b, IPC_RMID, nullptr);return 0;
}
代码简洁比较容易。有些捞仔可能会问了，除了共享内存还有没有其它方式呢？有！当然有，只不过性能不如共享内存啦。
命名管道实现
进程A：
#include <fstream>
#include <iostream>
#include <sys/stat.h>
#include <thread>
#include <unistd.h>#define PIPE_NAME_A "pipe_a"
#define PIPE_NAME_B "pipe_b"void send_messages(const std::string& pipe_name)
{std::ofstream pipe(pipe_name);if (!pipe) {std::cerr << "Failed to open named pipe for writing" << std::endl;return;}std::cout << "Enter messages to send (type 'exit' to quit):" << std::endl;while (true) {std::string message;std::getline(std::cin, message);if (message == "exit") {break;}pipe << message << std::endl;pipe.flush();}
}void receive_messages(const std::string& pipe_name)
{std::ifstream pipe(pipe_name);if (!pipe) {std::cerr << "Failed to open named pipe for reading" << std::endl;return;}std::cout << "Waiting for messages..." << std::endl;while (true) {std::string message;std::getline(pipe, message);// 处理程序在没有数据时不会频繁地检查管道，从而节省CPU资源，同时保持对新数据的响应if (pipe.eof()) {sleep(1);pipe.clear();pipe.seekg(0, std::ios::end);} else {std::cout << "Received message: " << message << std::endl;}}
}int main()
{// 创建命名管道if (mkfifo(PIPE_NAME_A, 0666) == -1) {std::cerr << "Failed to create named pipe A" << std::endl;return 1;}if (mkfifo(PIPE_NAME_B, 0666) == -1) {std::cerr << "Failed to create named pipe B" << std::endl;return 1;}std::thread sender(send_messages, PIPE_NAME_A);std::thread receiver(receive_messages, PIPE_NAME_B);sender.join();receiver.join();return 0;
}
进程B：
#include <fstream>
#include <iostream>
#include <sys/stat.h>
#include <thread>
#include <unistd.h>#define PIPE_NAME_A "pipe_a"
#define PIPE_NAME_B "pipe_b"void send_messages(const std::string& pipe_name)
{std::ofstream pipe(pipe_name);if (!pipe) {std::cerr << "Failed to open named pipe for writing" << std::endl;return;}std::cout << "Enter messages to send (type 'exit' to quit):" << std::endl;while (true) {std::string message;std::getline(std::cin, message);if (message == "exit") {break;}pipe << message << std::endl;pipe.flush();}
}void receive_messages(const std::string& pipe_name)
{std::ifstream pipe(pipe_name);if (!pipe) {std::cerr << "Failed to open named pipe for reading" << std::endl;return;}std::cout << "Waiting for messages..." << std::endl;while (true) {std::string message;std::getline(pipe, message);if (pipe.eof()) {sleep(1);pipe.clear();pipe.seekg(0, std::ios::end);} else {std::cout << "Received message: " << message << std::endl;}}
}int main()
{std::thread sender(send_messages, PIPE_NAME_B);std::thread receiver(receive_messages, PIPE_NAME_A);sender.join();receiver.join();return 0;
}
相对于共享内存的优缺点：
优点：
- 简单易用：命名管道的实现相对简单，适合用于简单的进程间通信。
缺点：
- 性能开销：命名管道的性能略低于共享内存，因为数据需要通过内核缓冲区传输。共享内存是所有进程间通信（IPC）机制中最快的，因为它不需要在进程之间复制数据。
- 单向通信：命名管道通常是单向的，需要两个管道实现双向通信。
还可以使用消息队列实现（本人使用的是wsl2，微软不支持，故没有代码）