> On Jan 19, 2022, at 6:40 AM, Pavel Labath <[email protected]> wrote:
>
> Hi all,
>
> In case you haven't noticed, I'd like to draw your attention to the in-flight
> patches (https://reviews.llvm.org/D117382, https://reviews.llvm.org/D117490)
> whose goal clean up/improve/streamline the logging infrastructure.
>
> I'm don't want go into technical details here (they're on the patch), but the
> general idea is to replace statements like
> GetLogIf(Any/All)CategoriesSet(LIBLLDB_LOG_CAT1 | LIBLLDB_LOG_CAT2)
> with
> GetLogIf(Any/All)(LLDBLog::Cat1 | LLDBLog::Cat2)
> i.e., drop macros and make use of templates to make the function calls
> shorter and safer.
>
> The reason I'm writing this email is to ask about the "All" versions of these
> logging functions. Do you find them useful in practice?
>
> I'm asking that because I've never used this functionality. While I can't
> find anything wrong with the concept in theory, practically I think it's just
> confusing to have some log message appear only for some combination of
> enabled channels. It might have made some sense when we had a "verbose"
> logging channel, but that one is long gone (we still have a verbose logging
> *flag*).
>
> In fact, out of all our GetLogIf calls (1203), less than 1% (11*) uses the
> GetLogIfAll form with more than one category. Of those, three are in tests,
> one is definitely a bug (it combines the category with
> LLDB_LOG_OPTION_VERBOSE), and the others (7) are of questionable usefulness
> (to me anyway).
>
> If we got rid of this, we could simplify the logging calls even further and
> have something like:
> Log *log = GetLog(LLDBLog::Process);
Can a template function deduce the log type from an argument? Wouldn't this
have to be:
Log *log = GetLog<LLDBLog>(LLDBLog::Process);
That is why I was hinting if we want to just use the enum class itself:
Log *log = LLDBLog::GetLog(LLDBLog::Process);
The template class in your second patch seems cool, but I don't understand how
it worked without going and reading up on templates in C++ and spending 20
minutes trying to wrap my brain around it.
Or do we just switch to a dedicated log class with unique methods:
class LLDBLog: public Log {
Log *Process() { return GetLog(1u << 0); }
Log *Thread() { return GetLog(1u << 1); }
};
and avoid all the enums? Then we can't ever feed a bad enum or #define into the
wrong log class.
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