NAME
genericLogger - generic logging interface
SYNOPSIS
#include <genericLogger.h>
/* ---------------------------------- */
/* User-defined logger implementation */
/* ---------------------------------- */
typedef void (*genericLoggerCallback_t)(void *userDatavp,
genericLoggerLevel_t logLeveli,
const char *msgs);
/* ----------------------- */
/* Creation, Cloning, Free */
/* ----------------------- */
genericLogger_t *genericLogger_newp (genericLoggerCallback_t logCallbackp,
void *userDatavp,
genericLoggerLevel_t genericLoggerLeveli);
genericLogger_t *genericLogger_clonep(genericLogger_t *genericLoggerp);
void genericLogger_freev (genericLogger_t **genericLoggerpp);
/* ------- */
/* Logging */
/* ------- */
void genericLogger_logv (genericLogger_t *genericLoggerp,
genericLoggerLevel_t genericLoggerLeveli,
const char *fmts,
...);
void genericLogger_logapv(genericLogger_t *genericLoggerp,
genericLoggerLevel_t genericLoggerLeveli,
const char *fmts,
va_list ap);
/* ---------------- */
/* Level management */
/* ---------------- */
genericLoggerLevel_t genericLogger_logLevel_seti(genericLogger_t *genericLoggerp,
genericLoggerLevel_t logLeveli);
genericLoggerLevel_t genericLogger_logLevel_geti(genericLogger_t *genericLoggerp);DESCRIPTION
genericLogger is like a portable printf() with level filtering capability, designed to propagate already-formatted messages to user-defined log implementations.
METHODS
genericLogger_newp
typedef void (*genericLoggerCallback_t)(void *userDatavp,
genericLoggerLevel_t logLeveli,
const char *msgs);
genericLogger_t *genericLogger_newp(genericLoggerCallback_t logCallbackp,
void *userDatavp,
genericLoggerLevel_t genericLoggerLeveli);Creates and return a generic logger.
The argument logCallbackp may be NULL, or a function pointer to a logging implementation. Such callback will be called with the argument userDatavp, untouched (one call that the callback context), the level, and a pre-formatted message.
The argument genericLoggerLeveli may be one of
- GENERICLOGGER_LOGLEVEL_TRACE
- GENERICLOGGER_LOGLEVEL_DEBUG
- GENERICLOGGER_LOGLEVEL_INFO
- GENERICLOGGER_LOGLEVEL_NOTICE
- GENERICLOGGER_LOGLEVEL_WARNING
- GENERICLOGGER_LOGLEVEL_ERROR
- GENERICLOGGER_LOGLEVEL_CRITICAL
- GENERICLOGGER_LOGLEVEL_ALERT
- GENERICLOGGER_LOGLEVEL_EMERGENCY
it is guaranteed that logCallbackp will not be called whenever a message have a log level lower than genericLoggerLeveli.
If logCallbackp is NULL, then a default built-in implementation is used, with a hardcoded level set to GENERICLOGGER_LEVEL_TRACE (i.e. it will log everything), a hardcoded format string set to %d/%m/%Y %H:%M:%S %9s %s (i.e. date and time a-la-european style, a string giving the level, and the formatted message), and a hardcoded output to standard error.
Returns NULL on failure, system's errno will indicate the reason.
genericLogger_clonep
genericLogger_t *genericLogger_clonep(genericLogger_t *genericLoggerp);Clone the current generic logger and return a new one. The clone becomes independant, and must be freed using genericLogger_freev().
Returns NULL on failure, system's errno will indicate the reason.
genericLogger_freev
void genericLogger_freev(genericLogger_t **genericLoggerpp);Free the generic logger.
genericLogger_logv
void genericLogger_logv(genericLogger_t *genericLoggerp,
genericLoggerLevel_t genericLoggerLeveli,
const char *fmts,
...);Format the message using fmts format string and eventual remaining parameters, and send it to the log implementation.
genericLogger_logapv
void genericLogger_logapv(genericLogger_t *genericLoggerp,
genericLoggerLevel_t genericLoggerLeveli,
const char *fmts,
va_list ap);va_list version of genericLogger_logv().
genericLogger_logLevel_seti
genericLoggerLevel_t genericLogger_logLevel_seti(genericLogger_t *genericLoggerp,
genericLoggerLevel_t logLeveli);Set the log level to leveLeveli and return it.
genericLogger_logLevel_geti
genericLoggerLevel_t genericLogger_logLevel_geti(genericLogger_t *genericLoggerp);Return the current log level.
genericLogger_versions
const char *genericLogger_versions();Return the version number.
CONVENIENCE MACROS
GENERICLOGGER_NEW
maps to genericLogger_newp.
GENERICLOGGER_CUSTOM
maps to genericLogger_newp with a custom log implementation.
GENERICLOGGER_CLONE
maps to genericLogger_clonep.
GENERICLOGGER_XXX
GENERICLOGGER_XXXF
GENERICLOGGER_XXXAP
maps to all log levels, where XXX is one of
- TRACE
- DEBUG
- INFO
- NOTICE
- WARN
- ERROR
- CRITICAL
- ALERT
- EMERGENCY
For portability reasons, there are two different versions, depending if there are arguments or not: XXX or XXXF, respectively. The XXXAP is when the argument is a va_list.
The XXX and XXXF macros maps to genericLogger_logv(), while XXXAP maps to genericLogger_logapv(), and they all hardcode the level, so that the programmer do not have to write the later.
GENERICLOGGER_LEVEL_SET
maps to genericLogger_logLevel_seti.
GENERICLOGGER_LEVEL_GET
maps to genericLogger_logLevel_geti.
EXAMPLE
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <stdarg.h>
#include <genericLogger.h>
typedef struct localStruct { char *where; } localStruct_t;
static void localLogger(void *userDatavp, genericLoggerLevel_t logLeveli, const char *msgs);
static void forceTrace(genericLogger_t *loggerp, localStruct_t *localStructp, const char *fmts, ...);
int main() {
genericLogger_t *loggerp;
localStruct_t localStruct;
loggerp = GENERICLOGGER_CUSTOM(localLogger, &localStruct, GENERICLOGGER_LOGLEVEL_WARNING);
if (loggerp == NULL) { perror("GENERICLOGGER_CUSTOM"); exit(1); }
localStruct.where = "main";
GENERICLOGGER_TRACE(loggerp, "Nothing is logged");
{
genericLogger_t *clonep = GENERICLOGGER_CLONE(loggerp);
if (clonep == NULL) { perror("GENERICLOGGER_CLONE"); exit(1); }
GENERICLOGGER_LEVEL_SET(clonep, GENERICLOGGER_LOGLEVEL_WARNING)
GENERICLOGGER_WARNF(loggerp, "Clone is warning, current level is %d", GENERICLOGGER_LEVEL_GET(loggerp));
forceTrace(clonep, &localStruct, "Clone is forced to trace");
GENERICLOGGER_FREE(clonep);
}
GENERICLOGGER_TRACE(loggerp, "Parent is still not logging");
GENERICLOGGER_LEVEL_SET(loggerp, GENERICLOGGER_LOGLEVEL_DEBUG)
GENERICLOGGER_DEBUGF(loggerp, "Parent is logging, current level is %d", GENERICLOGGER_LEVEL_GET(loggerp));
forceTrace(loggerp, &localStruct, "Parent is forced to trace");
GENERICLOGGER_FREE(loggerp);
return 0;
}
static void forceTrace(genericLogger_t *loggerp, localStruct_t *localStructp, const char *fmts, ...) {
va_list ap;
char *previousWhere = localStructp->where;
int previousLevel = GENERICLOGGER_LEVEL_GET(loggerp);
localStructp->where = "mainap";
va_start(ap, fmts);
GENERICLOGGER_LEVEL_SET(loggerp, GENERICLOGGER_LOGLEVEL_TRACE)
GENERICLOGGER_TRACEAP (loggerp, fmts, ap);
GENERICLOGGER_LEVEL_SET(loggerp, previousLevel);
va_end(ap);
localStructp->where = previousWhere;
}
static void localLogger(void *userDatavp, genericLoggerLevel_t logLeveli, const char *msgs) {
localStruct_t *localStructp = (localStruct_t *) userDatavp;
fprintf(stderr, "[%-6s] msgs = %s\n", localStructp->where, msgs);
}
/*
[main ] msgs = Clone is warning, current level is 4
[mainap] msgs = Clone is forced to trace
[main ] msgs = Parent is logging, current level is 1
[mainap] msgs = Parent is forced to trace
*/