1 files changed, 96 insertions, 0 deletions
diff --git a/src/nxt_log_moderation.c b/src/nxt_log_moderation.c
new file mode 100644
index 00000000..bba379de
--- /dev/null
+++ b/src/nxt_log_moderation.c
@@ -0,0 +1,96 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) NGINX, Inc.
+ */
+
+#include <nxt_main.h>
+
+
+static void nxt_log_moderate_timer_handler(nxt_thread_t *thr, void *obj,
+    void *data);
+
+
+nxt_bool_t
+nxt_log_moderate_allow(nxt_log_moderation_t *mod)
+{
+    nxt_uint_t    n;
+    nxt_time_t    now;
+    nxt_bool_t    allow, timer;
+    nxt_thread_t  *thr;
+
+    thr = nxt_thread();
+    now = nxt_thread_time(thr);
+
+    allow = 0;
+    timer = 0;
+
+    nxt_thread_spin_lock(&mod->lock);
+
+    n = mod->count++;
+
+    if (now != mod->last) {
+
+        if (n <= mod->limit) {
+            mod->last = now;
+            mod->count = 1;
+            allow = 1;
+        }
+
+        /* "n > mod->limit" means that timer has already been set. */
+
+    } else {
+
+        if (n < mod->limit) {
+            allow = 1;
+
+        } else if (n == mod->limit) {
+            /*
+             * There is a race condition on 32-bit many core system
+             * capable to fail an operation 2^32 times per second.
+             * This can be fixed by storing mod->count as uint64_t.
+             */
+            timer = 1;
+            mod->pid = nxt_pid;
+        }
+    }
+
+    nxt_thread_spin_unlock(&mod->lock);
+
+    if (timer) {
+        mod->timer.work_queue = &thr->work_queue.main;
+        mod->timer.handler = nxt_log_moderate_timer_handler;
+        mod->timer.log = &nxt_main_log;
+
+        nxt_event_timer_add(thr->engine, &mod->timer, 1000);
+    }
+
+    return allow;
+}
+
+
+static void
+nxt_log_moderate_timer_handler(nxt_thread_t *thr, void *obj, void *data)
+{
+    nxt_bool_t            msg;
+    nxt_atomic_uint_t     n;
+    nxt_event_timer_t     *ev;
+    nxt_log_moderation_t  *mod;
+
+    ev = obj;
+    mod = nxt_event_timer_data(ev, nxt_log_moderation_t, timer);
+
+    nxt_thread_spin_lock(&mod->lock);
+
+    mod->last = nxt_thread_time(thr);
+    n = mod->count;
+    mod->count = 0;
+    msg = (mod->pid == nxt_pid);
+
+    nxt_thread_spin_unlock(&mod->lock);
+
+    if (msg) {
+        nxt_log_error(mod->level, &nxt_main_log, "%s %uA times",
+                      mod->msg, n - mod->limit);
+    }
+}