Improved perf by using const char* instead of std::string& when accepting format strings

include/spdlog/details/line_logger.h

@@ -71,7 +71,7 @@ public:
 
 
     template <typename... Args>
-    void write(const std::string& fmt, const Args&... args)
+    void write(const char* fmt, const Args&... args)
     {
         if (!_enabled)
             return;

include/spdlog/details/logger_impl.h

@@ -67,7 +67,7 @@ inline void spdlog::logger::set_pattern(const std::string& pattern)
 // cppformat API of the form logger.info("hello {} {}", "world", 1);
 //
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::_log(level::level_enum lvl, const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::_log(level::level_enum lvl, const char* fmt, const Args&... args)
 {
     bool msg_enabled = should_log(lvl);
     details::line_logger l(this, lvl, msg_enabled);
@@ -76,61 +76,61 @@ inline spdlog::details::line_logger spdlog::logger::_log(level::level_enum lvl,
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::log(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::log(const char* fmt, const Args&... args)
 {
     return _log(level::ALWAYS, fmt, args...);
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::trace(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::trace(const char* fmt, const Args&... args)
 {
     return _log(level::TRACE, fmt, args...);
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::debug(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::debug(const char* fmt, const Args&... args)
 {
     return _log(level::DEBUG, fmt, args...);
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::info(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::info(const char* fmt, const Args&... args)
 {
     return _log(level::INFO, fmt, args...);
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::notice(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::notice(const char* fmt, const Args&... args)
 {
     return _log(level::NOTICE, fmt, args...);
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::warn(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::warn(const char* fmt, const Args&... args)
 {
     return _log(level::WARN, fmt, args...);
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::error(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::error(const char* fmt, const Args&... args)
 {
     return _log(level::ERR, fmt, args...);
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::critical(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::critical(const char* fmt, const Args&... args)
 {
     return _log(level::CRITICAL, fmt, args...);
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::alert(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::alert(const char* fmt, const Args&... args)
 {
     return _log(level::ALERT, fmt, args...);
 }
 
 template <typename... Args>
-inline spdlog::details::line_logger spdlog::logger::emerg(const std::string& fmt, const Args&... args)
+inline spdlog::details::line_logger spdlog::logger::emerg(const char* fmt, const Args&... args)
 {
     return _log(level::EMERG, fmt, args...);
 }

include/spdlog/logger.h

@@ -65,16 +65,16 @@ public:
     //Stop logging
     void stop();
 
-    template <typename... Args> details::line_logger log(const std::string& fmt, const Args&... args);
-    template <typename... Args> details::line_logger trace(const std::string& fmt, const Args&... args);
-    template <typename... Args> details::line_logger debug(const std::string& fmt, const Args&... args);
-    template <typename... Args> details::line_logger info(const std::string& fmt, const Args&... args);
-    template <typename... Args> details::line_logger notice(const std::string& fmt, const Args&... args);
-    template <typename... Args> details::line_logger warn(const std::string& fmt, const Args&... args);
-    template <typename... Args> details::line_logger error(const std::string& fmt, const Args&... args);
-    template <typename... Args> details::line_logger critical(const std::string& fmt, const Args&... args);
-    template <typename... Args> details::line_logger alert(const std::string& fmt, const Args&... args);
-    template <typename... Args> details::line_logger emerg(const std::string& fmt, const Args&... args);
+    template <typename... Args> details::line_logger log(const char* fmt, const Args&... args);
+    template <typename... Args> details::line_logger trace(const char* fmt, const Args&... args);
+    template <typename... Args> details::line_logger debug(const char* fmt, const Args&... args);
+    template <typename... Args> details::line_logger info(const char* fmt, const Args&... args);
+    template <typename... Args> details::line_logger notice(const char* fmt, const Args&... args);
+    template <typename... Args> details::line_logger warn(const char* fmt, const Args&... args);
+    template <typename... Args> details::line_logger error(const char* fmt, const Args&... args);
+    template <typename... Args> details::line_logger critical(const char* fmt, const Args&... args);
+    template <typename... Args> details::line_logger alert(const char* fmt, const Args&... args);
+    template <typename... Args> details::line_logger emerg(const char* fmt, const Args&... args);
 
     //API to support logger.info() << ".." calls
 
@@ -100,7 +100,7 @@ protected:
     virtual void _set_formatter(formatter_ptr);
     virtual void _stop();
     details::line_logger _log(level::level_enum lvl);
-    template <typename... Args> details::line_logger _log(level::level_enum lvl, const std::string& fmt, const Args&... args);
+    template <typename... Args> details::line_logger _log(level::level_enum lvl, const char* fmt, const Args&... args);
 
 
     friend details::line_logger;