Logging Plugin API

Servers and clients define a logger in their configuration. The logger is a plugin. A default plugin that logs to stdout is provided as an example. The logger plugin is stateful and can point to custom data. So it is possible to keep open file handlers in the logger context.

Every log message consists of a log level, a log category and a string message content. The timestamp of the log message is created within the logger.

typedef enum {
    UA_LOGLEVEL_TRACE   = 100,
    UA_LOGLEVEL_DEBUG   = 200,
    UA_LOGLEVEL_INFO    = 300,
    UA_LOGLEVEL_WARNING = 400,
    UA_LOGLEVEL_ERROR   = 500,
    UA_LOGLEVEL_FATAL   = 600
} UA_LogLevel;

#define UA_LOGCATEGORIES 10

typedef enum {
    UA_LOGCATEGORY_NETWORK = 0,
    UA_LOGCATEGORY_SECURECHANNEL,
    UA_LOGCATEGORY_SESSION,
    UA_LOGCATEGORY_SERVER,
    UA_LOGCATEGORY_CLIENT,
    UA_LOGCATEGORY_USERLAND,
    UA_LOGCATEGORY_SECURITYPOLICY,
    UA_LOGCATEGORY_EVENTLOOP,
    UA_LOGCATEGORY_PUBSUB,
    UA_LOGCATEGORY_DISCOVERY
} UA_LogCategory;

typedef struct UA_Logger {
    /* Log a message. The message string and following varargs are formatted
     * according to the rules of the printf command. Use the convenience macros
     * below that take the minimum log level defined in ua_config.h into
     * account. */
    void (*log)(void *logContext, UA_LogLevel level, UA_LogCategory category,
                const char *msg, va_list args);

    void *context; /* Logger state */

    void (*clear)(struct UA_Logger *logger); /* Clean up the logger plugin */
} UA_Logger;

static UA_INLINE UA_FORMAT(3,4) void
UA_LOG_TRACE(const UA_Logger *logger, UA_LogCategory category, const char *msg, ...) {
#if UA_LOGLEVEL <= 100
    if(!logger || !logger->log)
        return;
    va_list args; va_start(args, msg);
    logger->log(logger->context, UA_LOGLEVEL_TRACE, category, msg, args);
    va_end(args);
#else
    (void) logger;
    (void) category;
    (void) msg;
#endif
}

static UA_INLINE UA_FORMAT(3,4) void
UA_LOG_DEBUG(const UA_Logger *logger, UA_LogCategory category, const char *msg, ...) {
#if UA_LOGLEVEL <= 200
    if(!logger || !logger->log)
        return;
    va_list args; va_start(args, msg);
    logger->log(logger->context, UA_LOGLEVEL_DEBUG, category, msg, args);
    va_end(args);
#else
    (void) logger;
    (void) category;
    (void) msg;
#endif
}

static UA_INLINE UA_FORMAT(3,4) void
UA_LOG_INFO(const UA_Logger *logger, UA_LogCategory category, const char *msg, ...) {
#if UA_LOGLEVEL <= 300
    if(!logger || !logger->log)
        return;
    va_list args; va_start(args, msg);
    logger->log(logger->context, UA_LOGLEVEL_INFO, category, msg, args);
    va_end(args);
#else
    (void) logger;
    (void) category;
    (void) msg;
#endif
}

static UA_INLINE UA_FORMAT(3,4) void
UA_LOG_WARNING(const UA_Logger *logger, UA_LogCategory category, const char *msg, ...) {
#if UA_LOGLEVEL <= 400
    if(!logger || !logger->log)
        return;
    va_list args; va_start(args, msg);
    logger->log(logger->context, UA_LOGLEVEL_WARNING, category, msg, args);
    va_end(args);
#else
    (void) logger;
    (void) category;
    (void) msg;
#endif
}

static UA_INLINE UA_FORMAT(3,4) void
UA_LOG_ERROR(const UA_Logger *logger, UA_LogCategory category, const char *msg, ...) {
#if UA_LOGLEVEL <= 500
    if(!logger || !logger->log)
        return;
    va_list args; va_start(args, msg);
    logger->log(logger->context, UA_LOGLEVEL_ERROR, category, msg, args);
    va_end(args);
#else
    (void) logger;
    (void) category;
    (void) msg;
#endif
}

static UA_INLINE UA_FORMAT(3,4) void
UA_LOG_FATAL(const UA_Logger *logger, UA_LogCategory category, const char *msg, ...) {
#if UA_LOGLEVEL <= 600
    if(!logger || !logger->log)
        return;
    va_list args; va_start(args, msg);
    logger->log(logger->context, UA_LOGLEVEL_FATAL, category, msg, args);
    va_end(args);
#else
    (void) logger;
    (void) category;
    (void) msg;
#endif
}