feat(backend): 限流/登录失败锁状态外置 Redis（todo #2）

新包 internal/ratelimit：内存/redis(GCRA+Lua) 双实现 + 出错逐调用降级内存（fail-open 到内存不 fail-closed）。REDIS_ADDR 空=内存模式，行为与既往一致；配置后跨重启保状态、支持多实例。miniredis 全覆盖测试，零真实外部依赖。 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-05 10:42:23 +08:00
parent e850a1987c
commit 3c687e5e0b
15 changed files with 894 additions and 169 deletions
@@ -0,0 +1,212 @@
+package ratelimit
+
+import (
+	"sync"
+	"time"
+
+	"golang.org/x/time/rate"
+)
+
+// 内存实现：自 middleware.keyedLimiter 与 service.loginLimiter 迁入（2026-07，
+// 状态外置改造），行为与迁入前一致。单实例进程内状态，重启即清零。
+// 所有 map 均带 janitor 定期淘汰，保证不随攻击者构造的随机 key 无限增长。
+
+const (
+	memSweepEvery     = 5 * time.Minute
+	memLimiterIdleTTL = 10 * time.Minute
+	memLockerIdleTTL  = 30 * time.Minute
+	// 内存版给固定退避提示（redis 版有精确值）。
+	memRetryAfter = 60 * time.Second
+)
+
+type memoryStore struct {
+	counter *memCounter
+	locker  *memFailLocker
+}
+
+func newMemoryStore() *memoryStore {
+	return &memoryStore{
+		counter: newMemCounter(),
+		locker:  newMemFailLocker(),
+	}
+}
+
+func (s *memoryStore) NewLimiter(r rate.Limit, burst int) Limiter {
+	return newMemLimiter(r, burst)
+}
+func (s *memoryStore) Counter() Counter       { return s.counter }
+func (s *memoryStore) FailLocker() FailLocker { return s.locker }
+
+// ── Limiter：按 key 的令牌桶（原 keyedLimiter）──────────────────────────────
+
+type memLimiter struct {
+	mu      sync.Mutex
+	entries map[string]*memBucket
+	r       rate.Limit
+	burst   int
+}
+
+type memBucket struct {
+	lim      *rate.Limiter
+	lastSeen time.Time
+}
+
+func newMemLimiter(r rate.Limit, burst int) *memLimiter {
+	l := &memLimiter{entries: map[string]*memBucket{}, r: r, burst: burst}
+	go l.janitor()
+	return l
+}
+
+func (l *memLimiter) Allow(key string) Result {
+	l.mu.Lock()
+	b := l.entries[key]
+	if b == nil {
+		b = &memBucket{lim: rate.NewLimiter(l.r, l.burst)}
+		l.entries[key] = b
+	}
+	b.lastSeen = time.Now()
+	l.mu.Unlock()
+	return Result{Allowed: b.lim.Allow(), RetryAfter: memRetryAfter}
+}
+
+func (l *memLimiter) janitor() {
+	t := time.NewTicker(memSweepEvery)
+	defer t.Stop()
+	for range t.C {
+		l.sweep(memLimiterIdleTTL)
+	}
+}
+
+// sweep 淘汰超过 ttl 未活动的 key。拆出便于测试。
+func (l *memLimiter) sweep(ttl time.Duration) {
+	now := time.Now()
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	for k, b := range l.entries {
+		if now.Sub(b.lastSeen) > ttl {
+			delete(l.entries, k)
+		}
+	}
+}
+
+// ── Counter：带 TTL 的累加计数（日配额用）────────────────────────────────────
+
+type memCounter struct {
+	mu          sync.Mutex
+	entries     map[string]*memCount
+	janitorOnce sync.Once
+}
+
+type memCount struct {
+	val      int64
+	expireAt time.Time
+}
+
+func newMemCounter() *memCounter {
+	return &memCounter{entries: map[string]*memCount{}}
+}
+
+func (c *memCounter) Incr(key string, ttl time.Duration) (int64, error) {
+	c.startJanitor()
+	now := time.Now()
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	e := c.entries[key]
+	if e == nil || now.After(e.expireAt) {
+		e = &memCount{expireAt: now.Add(ttl)}
+		c.entries[key] = e
+	}
+	e.val++
+	return e.val, nil
+}
+
+func (c *memCounter) startJanitor() {
+	c.janitorOnce.Do(func() {
+		go func() {
+			t := time.NewTicker(memSweepEvery)
+			defer t.Stop()
+			for range t.C {
+				now := time.Now()
+				c.mu.Lock()
+				for k, e := range c.entries {
+					if now.After(e.expireAt) {
+						delete(c.entries, k)
+					}
+				}
+				c.mu.Unlock()
+			}
+		}()
+	})
+}
+
+// ── FailLocker：登录失败计数与锁（原 service.loginLimiter）───────────────────
+
+type memFailLocker struct {
+	mu          sync.Mutex
+	entries     map[string]*memFailEntry
+	janitorOnce sync.Once
+}
+
+type memFailEntry struct {
+	failures   int
+	lockedTill time.Time
+	lastSeen   time.Time
+}
+
+func newMemFailLocker() *memFailLocker {
+	return &memFailLocker{entries: map[string]*memFailEntry{}}
+}
+
+func (l *memFailLocker) Locked(key string) bool {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	e := l.entries[key]
+	if e == nil {
+		return false
+	}
+	e.lastSeen = time.Now()
+	return time.Now().Before(e.lockedTill)
+}
+
+func (l *memFailLocker) RecordFailure(key string, max int, lockFor time.Duration) {
+	l.startJanitor()
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	e := l.entries[key]
+	if e == nil {
+		e = &memFailEntry{}
+		l.entries[key] = e
+	}
+	e.lastSeen = time.Now()
+	e.failures++
+	if max > 0 && e.failures >= max {
+		e.lockedTill = time.Now().Add(lockFor)
+		e.failures = 0
+	}
+}
+
+func (l *memFailLocker) Reset(key string) {
+	l.mu.Lock()
+	defer l.mu.Unlock()
+	delete(l.entries, key)
+}
+
+// startJanitor 惰性启动后台清理：淘汰「未锁定且空闲超 TTL」的 entry。
+func (l *memFailLocker) startJanitor() {
+	l.janitorOnce.Do(func() {
+		go func() {
+			t := time.NewTicker(memSweepEvery)
+			defer t.Stop()
+			for range t.C {
+				now := time.Now()
+				l.mu.Lock()
+				for k, e := range l.entries {
+					if now.After(e.lockedTill) && now.Sub(e.lastSeen) > memLockerIdleTTL {
+						delete(l.entries, k)
+					}
+				}
+				l.mu.Unlock()
+			}
+		}()
+	})
+}