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

From: Martin Wilck <redacted>

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 <redacted>
---
  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 */