1 files changed, 78 insertions, 0 deletions
diff --git a/src/lib/log-throttle.c b/src/lib/log-throttle.c
new file mode 100644
index 0000000..d4b13c4
--- /dev/null
+++ b/src/lib/log-throttle.c
@@ -0,0 +1,78 @@
+/* Copyright (c) 2016-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "ioloop.h"
+#include "time-util.h"
+#include "log-throttle.h"
+
+struct log_throttle {
+	struct log_throttle_settings set;
+	log_throttle_callback_t *callback;
+	void *context;
+
+	struct timeval last_time;
+	unsigned int last_count;
+
+	struct timeout *to_throttled;
+};
+
+#undef log_throttle_init
+struct log_throttle *
+log_throttle_init(const struct log_throttle_settings *set,
+		  log_throttle_callback_t *callback, void *context)
+{
+	struct log_throttle *throttle;
+
+	i_assert(set->throttle_at_max_per_interval > 0);
+	i_assert(set->unthrottle_at_max_per_interval > 0);
+
+	throttle = i_new(struct log_throttle, 1);
+	throttle->set = *set;
+	if (throttle->set.interval_msecs == 0)
+		throttle->set.interval_msecs = 1000;
+	throttle->callback = callback;
+	throttle->context = context;
+	throttle->last_time = ioloop_timeval;
+	return throttle;
+}
+
+void log_throttle_deinit(struct log_throttle **_throttle)
+{
+	struct log_throttle *throttle = *_throttle;
+
+	*_throttle = NULL;
+	timeout_remove(&throttle->to_throttled);
+	i_free(throttle);
+}
+
+static void log_throttle_callback(struct log_throttle *throttle)
+{
+	if (throttle->last_count > 0)
+		throttle->callback(throttle->last_count, throttle->context);
+	if (throttle->last_count < throttle->set.unthrottle_at_max_per_interval)
+		timeout_remove(&throttle->to_throttled);
+	throttle->last_count = 0;
+}
+
+bool log_throttle_accept(struct log_throttle *throttle)
+{
+	if (throttle->to_throttled != NULL) {
+		/* unthrottling and last_count resets are done only by
+		   the callback */
+		throttle->last_count++;
+		return FALSE;
+	} else if (timeval_diff_msecs(&ioloop_timeval, &throttle->last_time) >=
+				(int)throttle->set.interval_msecs) {
+		throttle->last_time = ioloop_timeval;
+		throttle->last_count = 1;
+		return TRUE;
+	} else if (++throttle->last_count <= throttle->set.throttle_at_max_per_interval) {
+		return TRUE;
+	} else {
+		throttle->last_count = 1;
+		throttle->to_throttled =
+			timeout_add(throttle->set.interval_msecs,
+				    log_throttle_callback, throttle);
+		return FALSE;
+	}
+}