snapshot of https://github.com/nats-io/nats-server.git (main, 2026-09-15; blobs > 131072B omitted)

server/rate_counter.go

@@ -0,0 +1,65 @@
+// Copyright 2021-2025 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package server
+
+import (
+	"sync"
+	"time"
+)
+
+type rateCounter struct {
+	limit    int64
+	count    int64
+	blocked  uint64
+	end      time.Time
+	interval time.Duration
+	mu       sync.Mutex
+}
+
+func newRateCounter(limit int64) *rateCounter {
+	return &rateCounter{
+		limit:    limit,
+		interval: time.Second,
+	}
+}
+
+func (r *rateCounter) allow() bool {
+	now := time.Now()
+
+	r.mu.Lock()
+
+	if now.After(r.end) {
+		r.count = 0
+		r.end = now.Add(r.interval)
+	} else {
+		r.count++
+	}
+	allow := r.count < r.limit
+	if !allow {
+		r.blocked++
+	}
+
+	r.mu.Unlock()
+
+	return allow
+}
+
+func (r *rateCounter) countBlocked() uint64 {
+	r.mu.Lock()
+	blocked := r.blocked
+	r.blocked = 0
+	r.mu.Unlock()
+
+	return blocked
+}