Do we need an ArrowLogIsEnabled API?

[alinaliBQ]

Currently we have StartArrowLog which in theory should only be called once. Our team is working on an Arrow ODBC driver (#46099) which uses Arrow's logging framework, and the ODBC driver dll needs to support unloading, so any static variables stored at the ODBC dll will be reset after unloading; this prevents ODBC from saving the state of whether Arrow logs have started. Currently there is no check for an API like ArrowLogIsEnabled that returns whether StartArrowLog is already run. If we have such an API, it would be helpful to prevent StartArrowLog from being called twice.
What does everyone think?

[kou]

Can we use ShutDownArrowLog() to reset everything done by StartArrowLog()?

[alinaliBQ]

That is also one approach. I think that is not current behavior of ShutDownArrowLog. Below is what ODBC uses (we currently aren't using glog as it is getting replaced later #47465):

arrow/cpp/src/arrow/util/logging.cc

Lines 142 to 151 in eb9d519

	void ArrowLog::StartArrowLog(const std::string& app_name,
	ArrowLogLevel severity_threshold,
	const std::string& log_dir) {
	severity_threshold_ = severity_threshold;
	// In InitGoogleLogging, it simply keeps the pointer.
	// We need to make sure the app name passed to InitGoogleLogging exist.
	// We should avoid using static string is a dynamic lib.
	static std::unique_ptr<std::string> app_name_;
	app_name_.reset(new std::string(app_name));
	log_dir_.reset(new std::string(log_dir));

The variable static std::unique_ptr<std::string> app_name_;. isn't being reset at ShutDownArrowLog, as ShutDownArrowLog does a no-op if glog is not used.

[kou]

If it will work with the ODBC driver, let's improve ShutDownArrowLog().

[alinaliBQ]

Ok, I have created #47678 for this.