合理编写C++模块（.h、.cc）

模块划分

合理编写模块的 demo.h、demo.cc

下例为C++为后端服务编写的探活检测服务

• health_server.h

#ifndef  HEALTH_SERVER_H
#define  HEALTH_SERVER_H
#include <iostream>
//#include "utils/flags.h"
void health_server( const std::string &health_host , const std::string &health_port );
#endif

1. 必加#ifndef： 预处理功能（宏定义，文件包含和条件编译）中的条件编译，主要用来防止重复编译，“multiple define”错误
2. .h中的其它预处理功能include***，遵循最小使用原则，如上例 仅使用std::string，则对应 仅加入#include<iostream>
3. .cc文件也需要添加 对应#include "health_server.h" 文件
   
   health_server.cc

#include <dirent.h>
#include <fstream>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <atomic>
#include <memory>
#include <thread>
#include <iostream>
#include "health_server.h"
#include "./http_server.h"
mg_serve_http_opts oppo::HttpServer::s_server_option;
std::atomic<bool> server_stop(true);
std::unordered_map<std::string, oppo::ReqHandler> oppo::HttpServer::s_handler_map;
std::unordered_set<mg_connection *> oppo::HttpServer::s_websocket_session_set;
static bool HandleHealth(std::string url, std::string body,
  mg_connection *c, oppo::OnRspCallback rsp_callback)
{
  if (!server_stop)
	  rsp_callback(c, "OK");
  else
    rsp_callback(c, "STOP");
	return true;
}
static bool HandleStop(std::string url, std::string body,
  mg_connection *c, oppo::OnRspCallback rsp_callback)
{
  if (!server_stop) {
    server_stop = true;
    rsp_callback(c, "STOP OK");
  }
  else {
    rsp_callback(c, "IS STOP");
  }
	return true;
}
static bool HandleStart(std::string url, std::string body,
  mg_connection *c, oppo::OnRspCallback rsp_callback)
{
  if (server_stop) {
    server_stop = false;
    rsp_callback(c, "START OK");
  }
  else {
    rsp_callback(c, "IS START");
  }
	return true;
}
void health_server( const std::string &health_host , const std::string &health_port ){
      std::string health_address(health_host + ":" + health_port);
      auto health_server = std::unique_ptr<oppo::HttpServer>(new oppo::HttpServer);
      std::thread http_thread([&health_server, health_address]() {
        health_server->Init(health_address);
        health_server->AddHandler("/asr/health", HandleHealth);
        health_server->AddHandler("/asr/stop", HandleStop);
        health_server->AddHandler("/asr/start", HandleStart);
        health_server->Start();
      });
      http_thread.join();
}

依赖库部分：

• gflags使用DEFINE_int32(port, 10086, "grpc listening port")

#include <memory>
#include <gflags/gflags.h>
DEFINE_int32(port, 10086, "grpc listening port");

• atomic：原子变量，一般在多线程作为锁使用 依赖：#include <atomic>

ERROR

• 未定义的引用：
• 命令行编写：g++ speech-service-main.cc http_server.cc mongoose.cc -lpthread，严格按照依赖顺序写,-l链接动态库
• CMakeList.txt：

  add_library(health_server STATIC
    http/health_server.cc
    http/http_server.cc
    http/mongoose.cc
  )
  target_link_libraries(health_server PUBLIC pthread)
  add_executable(grpc_server_main bin/grpc_server_main.cc)
  target_link_libraries(grpc_server_main PUBLIC health_server)