[Libreoffice] Assertions and Logging

[Jonathan Aquilina]

On 22/11/2011 06:35, Norbert Thiebaud wrote:
> On Fri, Nov 18, 2011 at 8:25 AM, Stephan Bergmann<sbergman at redhat.com>  wrote:
>>>     Second, at runtime the environment variable SAL_LOG further limits
>>> which
>>>     macro calls actually generate log output.  The environment varialbe
>>> SAL_LOG
>>>     must either be unset or must match the regular expression
> The run tine flexibility is a great feature, but the proposed
> implementation is scary perf-wise
>
> you don't want to re-parse the log-config at every log message.
>
> You need to parse it once and for all... and not use string but enum
> to identify the module/category you want to trace.
>
> as a one-time steup cost you parse you env variable and initialize a
> static array, which for each module/category contain the max
> acceptable level of log
> (0 = no log, 1=error, 2=warn, 3=info (4=debug?)

Wouldnt a linked list be better as we dont know how many of these error 
messages might end up occuring for each during build time?

>
> the test of log-ability should  be a simple if( array[module]>=
> level) and the macro writtin so that the no-trace path is as cheap as
> possible.
>
> To illustrate (this is for pure C where each 'module' actually have a
> init_module function to dynamically register themselves to the tracing
> system... that may not work nicely in c++ (ironically), but the
> general gist is the same:
>
> (excerpt)
>
> header:
>
> #define _msgs_out(rc) { msgs_trace_intern("%s<-- 0x%x", __func__, rc);};
> #define _msgs_cond(lvl) if((lvl<= MSGS_BUILD_TRACE_LEVEL)&&  (lvl<=
> MSGS_CONTEXT->level))
>
> #define msgs_major     _msgs_cond(LVL_MAJOR)     msgs_trace_intern
> #define msgs_normal    _msgs_cond(LVL_NORMAL)    msgs_trace_intern
> #define msgs_minor     _msgs_cond(LVL_MINOR)     msgs_trace_intern
> #define msgs_detail    _msgs_cond(LVL_DETAIL)    msgs_trace_intern
> #define msgs_verbose   _msgs_cond(LVL_VERBOSE)   msgs_trace_intern
> #define msgs_debug     _msgs_cond(LVL_DEBUG)     msgs_trace_intern
> #define msgs_logorrhea _msgs_cond(LVL_LOGORRHEA) msgs_trace_intern
> #define msgs_uncond    msgs_trace_intern
>
>
> static inline void msgs_trace_intern(const char format[], ...)
> {
> va_list list;
>
>      va_start(list, format);
>      msgs_do_trace(MSGS_CONTEXT, format, list);
>      va_end(list);
> }
>
> here MSGS_CONTEXT could be&g_aModules_Context[module_id] , modifying
> the api above, adding a module_id parm (in my case the module_id is
> implicit based on the location of the trace)
>
> Note: the lvl<= MSGS_BUILD_TRACE_LEVEL in _msgs_cond means that the
> whole things is optimized out at compile if the test is false (both
> part of the test are actually build time constant. the second part f
> the test means thta the test cost just a couple of integer compare to
> fail.
>
> Note that I have an intermediary static inlinee msgs_trace_intern due
> to the fact that I use a static variable MSGS_CONTEXT, static to each
> 'module'... in you case you do not need that, if you do a full
> centralized pre-registration.
>
> Note that you can use:
>
> log(writer,....)
>
>   and in the define of the log macro use module ## _LOG_ID to refer to
> the enum value, and #module to have a pretty sting to print, so that
> your log still show a human readable module name
>
> for example, I use something like :
>
> /* We need two macro here, to have a proper expansion of the 'module'
> parameter */
> #define CORE_DECLARE_MODULE(module) CORE_DECLARE_MODULE2(module)
>
> #define CORE_DECLARE_MODULE2(module) \
> static struct msgs_module_context g_context = { module ##  _MODULE_ID
> , -1, 0, 0, NULL,  #module}
>
> to define my module_level context
>
> Norbert
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