使用 xmake 编译 重构后的tiny webserver 失败

[yeangPan]

我重写了tinywebserver这个项目，主要的调整是组织结构调整了下，头文件和源文件分开：

写完后使用xmake发现编译失败，报错信息如下：

xmake -b
[  8%]: cache compiling.debug src/main.cpp
[ 83%]: linking.debug webserver
error: /usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/main.cpp.o: in function `main':
/home/yangp/projects/cpp/webserver/src/main.cpp:54: undefined reference to `Config::~Config()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/main.cpp:54: undefined reference to `Config::~Config()'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/connpool.cpp.o: in function `ConnectionPool::init(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, int, int, int)':
/home/yangp/projects/cpp/webserver/src/server/connpool.cpp:41: undefined reference to `mysql_init'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/connpool.cpp:44: undefined reference to `Log::get_instance()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/connpool.cpp:44: undefined reference to `Log::get_instance()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/connpool.cpp:48: undefined reference to `mysql_real_connect'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/connpool.cpp:52: undefined reference to `Log::get_instance()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/connpool.cpp:52: undefined reference to `Log::get_instance()'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/connpool.cpp.o: in function `ConnectionPool::DestroyPool()':
/home/yangp/projects/cpp/webserver/src/server/connpool.cpp:104: undefined reference to `mysql_close'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/log.cpp.o: in function `Log::init(char const*, int, int, int, int)':
/home/yangp/projects/cpp/webserver/src/server/log.cpp:37: undefined reference to `Log::flush_log_thread(void*)'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/httpconn.cpp.o: in function `HttpConn::initmysql_result(ConnectionPool*)':
/home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:45: undefined reference to `mysql_query'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:46: undefined reference to `Log::get_instance()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:46: undefined reference to `mysql_error'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:46: undefined reference to `Log::get_instance()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:50: undefined reference to `mysql_store_result'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:53: undefined reference to `mysql_num_fields'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:56: undefined reference to `mysql_fetch_fields'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:59: undefined reference to `mysql_fetch_row'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/httpconn.cpp.o: in function `HttpConn::parse_headers(char*)':
/home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:289: undefined reference to `Log::get_instance()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:289: undefined reference to `Log::get_instance()'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/httpconn.cpp.o: in function `HttpConn::process_read()':
/home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:313: undefined reference to `Log::get_instance()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:313: undefined reference to `Log::get_instance()'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/httpconn.cpp.o: in function `HttpConn::do_request()':
/home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:391: undefined reference to `mysql_query'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/httpconn.cpp.o: in function `HttpConn::add_response(char const*, ...)':
/home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:526: undefined reference to `Log::get_instance()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/httpconn.cpp:526: undefined reference to `Log::get_instance()'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/webserver.cpp.o: in function `WebServer::log_write()':
/home/yangp/projects/cpp/webserver/src/server/webserver.cpp:95: undefined reference to `Log::get_instance()'
/usr/bin/ld: /home/yangp/projects/cpp/webserver/src/server/webserver.cpp:97: undefined reference to `Log::get_instance()'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/webserver.cpp.o: in function `WebServer::adjust_time(Timer*)':
/home/yangp/projects/cpp/webserver/src/server/webserver.cpp:191: undefined reference to `Log::get_instance()'
/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/webserver.cpp.o:/home/yangp/projects/cpp/webserver/src/server/webserver.cpp:191: more undefined references to `Log::get_instance()' follow
collect2: error: ld returned 1 exit status

我的xmake配置如下：

add_rules("mode.debug", "mode.release")
set_languages("c99", "c++20")
set_defaultmode("debug")
set_targetdir("$(projectdir)/build")

target("webserver")
    set_kind("binary")
    add_files("src/*.cpp")
    add_files("src/server/*.cpp")

基于头文件和源文件分开的想法进行的调整，调整时发现 宏定义及模板类 的实现也需要放在头文件中，所以以上的模板类及宏定义无法被正常编译，主要是请教下，通常这种情况下的best practice是什么？ 即一个大型项目中，

1. 头文件即源文件，更进一步的整个项目的组织结构有没有一个best practice， 我自己整理了一个出来，这个是否可以，[email protected]:yeangPan/cppdev.git？
2. 如果严格按照头文件和源文件分离的思想，模板类实现及宏定义是放在头文件中的(从chatgpt3.5及4及网络搜索的结果)，这部分根据我上面这个报错看，应该也是需要编译的，这部分如何编译？

感谢

[star-hengxing]

1. 这方面其实没什么 best practice，只有个人习惯（项目约定）
2. cpp20 有模块后，声明与实现分离没那么重要了

[yeangPan]

我想把我重写的这个tinyserver 跑通，

/usr/bin/ld: build/.objs/webserver/linux/x86_64/debug/src/server/webserver.cpp.o: in function `WebServer::log_write()':
/home/yangp/projects/cpp/webserver/src/server/webserver.cpp:95: undefined reference to `Log::get_instance()'

类似这里的引用报错，这里原来的项目就是写在头文件里的，我应该怎么写才能顺利编译？

[star-hengxing]

Log::get_instance() 怎么实现的，用了 static 没导出符号？有导出符号，并把 log.cpp.obj 喂给 ld 就能正常链接

[yeangPan]

这是log.h文件，宏定义是直接写在头文件里面的

#define LOG_DEBUG(format, ...)                                                 \
  if (0 == m_close_log) {                                                      \
    Log::get_instance()->write_log(0, format, ##__VA_ARGS__);                  \
    Log::get_instance()->flush();                                              \
  }
#define LOG_INFO(format, ...)                                                  \
  if (0 == m_close_log) {                                                      \
    Log::get_instance()->write_log(1, format, ##__VA_ARGS__);                  \
    Log::get_instance()->flush();                                              \
  }
#define LOG_WARN(format, ...)                                                  \
  if (0 == m_close_log) {                                                      \
    Log::get_instance()->write_log(2, format, ##__VA_ARGS__);                  \
    Log::get_instance()->flush();                                              \
  }
#define LOG_ERROR(format, ...)                                                 \
  if (0 == m_close_log) {                                                      \
    Log::get_instance()->write_log(3, format, ##__VA_ARGS__);                  \
    Log::get_instance()->flush();                                              \
  }

[waruqi]

刚那只是调用处，Log::get_instance()这个实现在哪？

[yeangPan]

刚检查出来了，应该是实现那里对应的cpp里面没有实现导致的