Log messages potentially not issued until program termination

[astoeckel]

Some log messages which are logged using the legacy Logger interface only get issued once the program terminates, such as

log(Logger::INFO) << "Connected to USB board.";

in Vmoduleusb.cpp. As far as I can see this is caused by the adventurous implementation of the Logger class, which puts a Message instance in a per-thread smart pointer, and the Message instance actually logging the message in its destructor.

I would propose the following patch to log4cxx/logger.h to fix this issue

diff --git a/log4cxx/logger.h b/log4cxx/logger.h
index 1cc1f84..def6cc3 100644
--- a/log4cxx/logger.h
+++ b/log4cxx/logger.h
@@ -56,8 +56,15 @@ struct Message

        ~Message()
        {
-               // do the actual logging
-               get_log4cxx().log(level(), get().str(), LOG4CXX_LOCATION);
+               log();
+       }
+
+       void log() {
+               if (_level != log4cxx::LevelPtr()) {
+                       // do the actual logging. once.
+                       get_log4cxx().log(level(), get().str(), LOG4CXX_LOCATION);
+                       _level = log4cxx::LevelPtr();
+               }
        }

 private:
@@ -179,7 +186,9 @@ public:

        static std::ostream& flush(std::ostream& stream)
        {
-               return std::flush(stream);
+               stream << std::flush;
+               Logger::instance()._buffer->log();
+               return stream;
        }

        template <typename T>

however, this requires flush to be actually called, which happens almost nowhere in the code base.