[PATCH 06/35] monitor: Create a log() macro.

[Hannes Reinecke]

On 1/26/21 9:32 PM, mwilck at suse.com wrote:
> From: Martin Wilck <mwilck at suse.com>
> 
> As this is a long running program, we need to make the log output
> configurable. First step: replace fprintf() by log(). The log level
> and printing of time stamps can be configured at run time using
> global variables. These will live in fabrics.c.
> 
> Allow toggling function name printing at build time.
> Printing the function name is useful for development, but perhaps
> not desired for production.
> Put '#define LOG_FUNCNAME' before '#include "log.h"' to switch it on.
> 
> Signed-off-by: Martin Wilck <mwilck at suse.com>
> ---
>   log.h | 44 ++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 44 insertions(+)
>   create mode 100644 log.h
> 
> diff --git a/log.h b/log.h
> new file mode 100644
> index 0000000..2017731
> --- /dev/null
> +++ b/log.h
> @@ -0,0 +1,44 @@
> +#ifndef _LOG_H
> +#define _LOG_H
> +
> +#ifndef MAX_LOGLEVEL
> +#  define MAX_LOGLEVEL LOG_DEBUG
> +#endif
> +#ifndef DEFAULT_LOGLEVEL
> +#  define DEFAULT_LOGLEVEL LOG_NOTICE
> +#endif
> +
> +#ifdef LOG_FUNCNAME
> +#define _func_fmt "%s: "
> +#define _func_arg __func__
> +#else
> +#define _func_fmt "%s"
> +#define _func_arg ""
> +#endif
> +
> +extern int log_level;
> +extern bool log_timestamp;
> +#define _TIME_FMT "[%ld.%06ld] "
> +#define log(lvl, format, ...) \
> +	do {								\
> +		int __lvl = (lvl);					\
> +									\
> +		if (__lvl <= MAX_LOGLEVEL && __lvl <= log_level) {	\
> +			if (log_timestamp) {				\
> +				struct timespec __ts;			\
> +									\
> +				clock_gettime(CLOCK_MONOTONIC, &__ts);	\
> +				fprintf(stderr,				\
> +					_TIME_FMT _func_fmt format,	\
> +					__ts.tv_sec, __ts.tv_nsec / 1000,\
> +					_func_arg,			\
> +					##__VA_ARGS__);			\
> +			} else {					\
> +				fprintf(stderr, _func_fmt format,	\
> +					_func_arg,			\
> +					##__VA_ARGS__);			\
> +			};						\
> +		}							\
> +	} while (0)
> +
> +#endif /* _LOG_H */
> 
Urgh. Long macros are always horrible.
Can't you convert it into a function?

It might also be an idea to move this as the first function, as it's
arguably an extension to existing functionality, and not directly 
related to the monitor.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare at suse.de                              +49 911 74053 688
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