first commit

internal/web/ratelimit.go

@@ -0,0 +1,40 @@
+package web
+
+import (
+	"sync"
+	"time"
+)
+
+type rateEntry struct {
+	since time.Time
+	n     int
+}
+type limiter struct {
+	mu      sync.Mutex
+	entries map[string]rateEntry
+}
+
+func newLimiter() *limiter { return &limiter{entries: make(map[string]rateEntry)} }
+func (l *limiter) allow(key string, max int, window time.Duration) bool {
+	now := time.Now()
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	e := l.entries[key]
+	if e.since.IsZero() || now.Sub(e.since) >= window {
+		l.entries[key] = rateEntry{since: now, n: 1}
+		return true
+	}
+	if e.n >= max {
+		return false
+	}
+	e.n++
+	l.entries[key] = e
+	if len(l.entries) > 10000 {
+		for k, v := range l.entries {
+			if now.Sub(v.since) > 2*window {
+				delete(l.entries, k)
+			}
+		}
+	}
+	return true
+}