feat: cache add single-flight and timing-wheel.

pkg/common/localcache/lru.go

@@ -0,0 +1,89 @@
+package localcache
+
+import (
+	"github.com/hashicorp/golang-lru/v2/simplelru"
+	"sync"
+	"time"
+)
+
+type waitItem[V any] struct {
+	lock    sync.Mutex
+	expires int64
+	active  bool
+	err     error
+	value   V
+}
+
+func NewLRU[K comparable, V any](size int, successTTL, failedTTL time.Duration, target Target, onEvict EvictCallback[K, V]) *LRU[K, V] {
+	var cb simplelru.EvictCallback[K, *waitItem[V]]
+	if onEvict != nil {
+		cb = func(key K, value *waitItem[V]) {
+			onEvict(key, value.value)
+		}
+	}
+	core, err := simplelru.NewLRU[K, *waitItem[V]](size, cb)
+	if err != nil {
+		panic(err)
+	}
+	return &LRU[K, V]{
+		core:       core,
+		successTTL: successTTL,
+		failedTTL:  failedTTL,
+		target:     target,
+		s:          NewSingleFlight[K, V](),
+	}
+}
+
+type LRU[K comparable, V any] struct {
+	lock       sync.Mutex
+	core       *simplelru.LRU[K, *waitItem[V]]
+	successTTL time.Duration
+	failedTTL  time.Duration
+	target     Target
+	s          *SingleFlight[K, V]
+}
+
+func (x *LRU[K, V]) Get(key K, fetch func() (V, error)) (V, error) {
+	x.lock.Lock()
+	v, ok := x.core.Get(key)
+	if ok {
+		x.lock.Unlock()
+		v.lock.Lock()
+		expires, value, err := v.expires, v.value, v.err
+		if expires != 0 && expires > time.Now().UnixMilli() {
+			v.lock.Unlock()
+			x.target.IncrGetHit()
+			return value, err
+		}
+	} else {
+		v = &waitItem[V]{}
+		x.core.Add(key, v)
+		v.lock.Lock()
+		x.lock.Unlock()
+	}
+	defer v.lock.Unlock()
+	if v.expires > time.Now().UnixMilli() {
+		return v.value, v.err
+	}
+	v.value, v.err = fetch()
+	if v.err == nil {
+		v.expires = time.Now().Add(x.successTTL).UnixMilli()
+		x.target.IncrGetSuccess()
+	} else {
+		v.expires = time.Now().Add(x.failedTTL).UnixMilli()
+		x.target.IncrGetFailed()
+	}
+	return v.value, v.err
+}
+
+func (x *LRU[K, V]) Del(key K) bool {
+	x.lock.Lock()
+	ok := x.core.Remove(key)
+	x.lock.Unlock()
+	if ok {
+		x.target.IncrDelHit()
+	} else {
+		x.target.IncrDelNotFound()
+	}
+	return ok
+}