How to use spdlog in DLLs
- 最近想把spdlog放在common.dll里,给serverdll用,好像不行,
- 一直报错,查了下,应该是spdlog 都是头文件,模板类必须把实现和头文件放一起
1>------ 已启动生成: 项目: SfuServer, 配置: Debug Win32 ------
1>SfuServer.cpp
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\common\slog.h(105,44): warning C4251: “Logger::text_log_”: class“std::shared_ptr<spdlog::logger>”需要有 dll 接口由 class“Logger”的客户端使用
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\third_party\spdlog\include\spdlog\details\registry.h(33): message : 参见“std::shared_ptr<spdlog::logger>”的声明
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\common\slog.h(106,47): warning C4251: “Logger::console_log_”: class“std::shared_ptr<spdlog::logger>”需要有 dll 接口由 class“Logger”的客户端使用
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\third_party\spdlog\include\spdlog\details\registry.h(33): message : 参见“std::shared_ptr<spdlog::logger>”的声明
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\common\bolt_logger.h(38,53): warning C4251: “Bolt::Log::s_CoreLogger”: class“std::shared_ptr<spdlog::logger>”需要有 dll 接口由 class“Bolt::Log”的客户端使用
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\third_party\spdlog\include\spdlog\details\registry.h(33): message : 参见“std::shared_ptr<spdlog::logger>”的声明
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\common\bolt_logger.h(39,55): warning C4251: “Bolt::Log::s_ClientLogger”: class“std::shared_ptr<spdlog::logger>”需要有 dll 接口由 class“Bolt::Log”的客户端使用
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\third_party\spdlog\include\spdlog\details\registry.h(33): message : 参见“std::shared_ptr<spdlog::logger>”的声明
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\common\bolt_logger.h(40,52): warning C4251: “Bolt::Log::s_LuaLogger”: class“std::shared_ptr<spdlog::logger>”需要有 dll 接口由 class“Bolt::Log”的客户端使用
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\third_party\spdlog\include\spdlog\details\registry.h(33): message : 参见“std::shared_ptr<spdlog::logger>”的声明
1> 正在创建库 G:\RRRRRtc\licode-windows-commshare\onlyServer\SfuServer\..\OutDir\Debug\SfuServer.lib 和对象 G:\RRRRRtc\licode-windows-commshare\onlyServer\SfuServer\..\OutDir\Debug\SfuServer.exp
1>SfuServer.obj : error LNK2001: 无法解析的外部符号 "private: static class std::shared_ptr<class spdlog::logger> Bolt::Log::s_CoreLogger" (?s_CoreLogger@Log@Bolt@@0V?$shared_ptr@Vlogger@spdlog@@@std@@A)
1>SfuServer.obj : error LNK2001: 无法解析的外部符号 "private: static class std::shared_ptr<class spdlog::logger> Bolt::Log::s_ClientLogger" (?s_ClientLogger@Log@Bolt@@0V?$shared_ptr@Vlogger@spdlog@@@std@@A)
1>SfuServer.obj : error LNK2001: 无法解析的外部符号 "private: static class std::shared_ptr<class spdlog::logger> Bolt::Log::s_LuaLogger" (?s_LuaLogger@Log@Bolt@@0V?$shared_ptr@Vlogger@spdlog@@@std@@A)
1>G:\RRRRRtc\licode-windows-commshare\onlyServer\SfuServer\..\OutDir\Debug\SfuServer.exe : fatal error LNK1120: 3 个无法解析的外部命令
1>已完成生成项目“SfuServer.vcxproj”的操作 - 失败。
========== 生成: 成功 0 个,失败 1 个,最新 0 个,跳过 0 个 ==========
- zz 官方
Wambou edited this page on 30 Aug 2018 · 1 revision
Problem
- Because spdlog is header-only, building shared libraries and using it in a main program will not share the registry between them. This means that calls to functions like spdlog::set_level(spdlog::level::level_enum::info) will not change loggers in DLLs.
官方例子,封装函数解决 Workaround
-What can be done is to register the logger in both registries.
/*
* Disclaimer:
* This was not compiled but extracted from documentation and some code.
*/
// mylibrary.h
// In library, we skip the symbol exporting part 跳过了符号导出
#include <memory>
#include <vector>
#include <spdlog/logger.h>
#include <spdlog/sinks/stdout_color_sinks.h>
namespace library
{
static const std::string logger_name = "example";
std::shared_ptr<spdlog::logger> setup_logger(std::vector<spdlog::sink_ptr> sinks)
{
auto logger = spdlog::get(logger_name);
if(not logger)
{
if(sinks.size() > 0)
{
logger = std::make_shared<spdlog::logger>(logger_name,
std::begin(sinks),
std::end(sinks));
spdlog::register_logger(logger);
}
else
{
logger = spdlog::stdout_color_mt(logger_name);
}
}
return logger;
}
void test(std::string message)
{
auto logger = spdlog::get(logger_name);
if(logger)
{
logger->debug("{}::{}", __FUNCTION__, message);
}
}
}
// In the main program 主程序
#include <mylibrary.h>
#include <spdlog/logger.h>
#include <spdlog/sinks/daily_file_sink.h>
#include <spdlog/sinks/stdout_sinks.h>
int main()
{
// We assume that we load the library here 在这里加载库
...
// Let's use the library
std::vector<spdlog::sink_ptr> sinks;
sinks.push_back(std::make_shared<spdlog::sinks::stdout_sink_st>());
sinks.push_back(std::make_shared<spdlog::sinks::daily_file_sink_st>("logfile", 23, 59));
//设置
auto logger = library::setup_logger(sinks);
spdlog::set_level(spdlog::level::level_enum::debug); // No effect for the library.
//不打印
library::test("Hello World!"); // No logging
spdlog::register_logger(logger);
// Now this will also affect the library logger
spdlog::set_level(spdlog::level::level_enum::debug);
//打印
library::test("Hello World!"); // Hurray !
return 0;
}