1 files changed, 60 insertions, 0 deletions
diff --git a/src/basic/ratelimit.c b/src/basic/ratelimit.c
new file mode 100644
index 0000000..41ca070
--- /dev/null
+++ b/src/basic/ratelimit.c
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <sys/time.h>
+
+#include "macro.h"
+#include "ratelimit.h"
+
+/* Modelled after Linux' lib/ratelimit.c by Dave Young
+ * <hidave.darkstar@gmail.com>, which is licensed GPLv2. */
+
+bool ratelimit_below(RateLimit *r) {
+        usec_t ts;
+
+        assert(r);
+
+        if (!ratelimit_configured(r))
+                return true;
+
+        ts = now(CLOCK_MONOTONIC);
+
+        if (r->begin <= 0 ||
+            usec_sub_unsigned(ts, r->begin) > r->interval) {
+                r->begin = ts;  /* Start a new time window */
+                r->num = 1;     /* Reset counter */
+                return true;
+        }
+
+        if (_unlikely_(r->num == UINT_MAX))
+                return false;
+
+        r->num++;
+        return r->num <= r->burst;
+}
+
+unsigned ratelimit_num_dropped(RateLimit *r) {
+        assert(r);
+
+        if (r->num == UINT_MAX) /* overflow, return as special case */
+                return UINT_MAX;
+
+        return LESS_BY(r->num, r->burst);
+}
+
+usec_t ratelimit_end(const RateLimit *rl) {
+        assert(rl);
+
+        if (rl->begin == 0)
+                return 0;
+
+        return usec_add(rl->begin, rl->interval);
+}
+
+usec_t ratelimit_left(const RateLimit *rl) {
+        assert(rl);
+
+        if (rl->begin == 0)
+                return 0;
+
+        return usec_sub_unsigned(ratelimit_end(rl), now(CLOCK_MONOTONIC));
+}