#ifndef VLOG_H
#define VLOG_H 1
+#include <limits.h>
+#include <stdarg.h>
#include <stdbool.h>
+#include <time.h>
+#include "util.h"
/* Logging importance levels. */
enum vlog_level {
const char *vlog_get_module_name(enum vlog_module);
enum vlog_module vlog_get_module_val(const char *name);
+/* Rate-limiter for log messages. */
+struct vlog_rate_limit {
+ /* Configuration settings. */
+ unsigned int rate; /* Tokens per second. */
+ unsigned int burst; /* Max cumulative tokens credit. */
+
+ /* Current status. */
+ unsigned int tokens; /* Current number of tokens. */
+ time_t last_fill; /* Last time tokens added. */
+ time_t first_dropped; /* Time first message was dropped. */
+ unsigned int n_dropped; /* Number of messages dropped. */
+};
+
+/* Number of tokens to emit a message. We add 'rate' token per second, which
+ * is 60 times the unit used for 'rate', thus 60 tokens are required to emit
+ * one message. */
+#define VLOG_MSG_TOKENS 60
+
+/* Initializer for a struct vlog_rate_limit, to set up a maximum rate of RATE
+ * messages per minute and a maximum burst size of BURST messages. */
+#define VLOG_RATE_LIMIT_INIT(RATE, BURST) \
+ { \
+ RATE, /* rate */ \
+ (MIN(BURST, UINT_MAX / VLOG_MSG_TOKENS) \
+ * VLOG_MSG_TOKENS), /* burst */ \
+ 0, /* tokens */ \
+ 0, /* last_fill */ \
+ 0, /* n_dropped */ \
+ }
+
/* Configuring how each module logs messages. */
enum vlog_level vlog_get_level(enum vlog_module, enum vlog_facility);
void vlog_set_levels(enum vlog_module, enum vlog_facility, enum vlog_level);
void vlog_exit(void);
void vlog(enum vlog_module, enum vlog_level, const char *format, ...)
__attribute__((format(printf, 3, 4)));
+void vlog_valist(enum vlog_module, enum vlog_level, const char *, va_list)
+ __attribute__((format(printf, 3, 0)));
+void vlog_rate_limit(enum vlog_module, enum vlog_level,
+ struct vlog_rate_limit *, const char *, ...)
+ __attribute__((format(printf, 4, 5)));
/* Convenience macros. To use these, define THIS_MODULE as a macro that
* expands to the module used by the current source file, e.g.
#define VLOG_IS_WARN_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_WARN)
#define VLOG_IS_DBG_ENABLED() vlog_is_enabled(THIS_MODULE, VLL_DBG)
+/* Convenience macros. To use these, define THIS_MODULE as a macro that
+ * expands to the module used by the current source file, e.g.
+ * #include "vlog.h"
+ * #define THIS_MODULE VLM_netlink
+ * Guaranteed to preserve errno.
+ */
+#define VLOG_ERR_RL(RL, ...) \
+ vlog_rate_limit(THIS_MODULE, VLL_ERR, RL, __VA_ARGS__)
+#define VLOG_WARN_RL(RL, ...) \
+ vlog_rate_limit(THIS_MODULE, VLL_WARN, RL, __VA_ARGS__)
+#define VLOG_DBG_RL(RL, ...) \
+ vlog_rate_limit(THIS_MODULE, VLL_DBG, RL, __VA_ARGS__)
+
#endif /* vlog.h */
#include <syslog.h>
#include <time.h>
#include "dynamic-string.h"
+#include "sat-math.h"
#include "timeval.h"
#include "util.h"
*
* Guaranteed to preserve errno. */
void
-vlog(enum vlog_module module, enum vlog_level level, const char *message, ...)
+vlog_valist(enum vlog_module module, enum vlog_level level,
+ const char *message, va_list args)
{
bool log_console = levels[module][VLF_CONSOLE] >= level;
bool log_syslog = levels[module][VLF_SYSLOG] >= level;
errno = save_errno;
}
}
+
+void
+vlog(enum vlog_module module, enum vlog_level level, const char *message, ...)
+{
+ va_list args;
+
+ va_start(args, message);
+ vlog_valist(module, level, message, args);
+ va_end(args);
+}
+
+void
+vlog_rate_limit(enum vlog_module module, enum vlog_level level,
+ struct vlog_rate_limit *rl, const char *message, ...)
+{
+ va_list args;
+
+ if (!vlog_is_enabled(module, level)) {
+ return;
+ }
+
+ if (rl->tokens < VLOG_MSG_TOKENS) {
+ time_t now = time_now();
+ if (rl->last_fill > now) {
+ /* Last filled in the future? Time must have gone backward, or
+ * 'rl' has not been used before. */
+ rl->tokens = rl->burst;
+ } else if (rl->last_fill < now) {
+ unsigned int add = sat_mul(rl->rate, now - rl->last_fill);
+ unsigned int tokens = sat_add(rl->tokens, add);
+ rl->tokens = MIN(tokens, rl->burst);
+ rl->last_fill = now;
+ }
+ if (rl->tokens < VLOG_MSG_TOKENS) {
+ if (!rl->n_dropped) {
+ rl->first_dropped = now;
+ }
+ rl->n_dropped++;
+ return;
+ }
+ }
+ rl->tokens -= VLOG_MSG_TOKENS;
+
+ va_start(args, message);
+ vlog_valist(module, level, message, args);
+ va_end(args);
+
+ if (rl->n_dropped) {
+ vlog(module, level,
+ "Dropped %u messages in last %u seconds due to excessive rate",
+ rl->n_dropped, (unsigned int) (time_now() - rl->first_dropped));
+ rl->n_dropped = 0;
+ }
+}