Add missing TTLCache

internal/ttlcache.go

@@ -0,0 +1,73 @@
+package internal
+
+import (
+	"sync"
+	"time"
+)
+
+type CachedItem struct {
+	Value  int
+	Expiry time.Time
+}
+
+func (item CachedItem) Expired() bool {
+	return time.Now().After(item.Expiry)
+}
+
+type CachedItems map[string]CachedItem
+
+type TTLCache struct {
+	sync.RWMutex
+
+	ttl   time.Duration
+	items map[string]CachedItem
+}
+
+func (cache *TTLCache) Dec(k string) int {
+	return cache.Set(k, cache.Get(k)-1)
+}
+
+func (cache *TTLCache) Inc(k string) int {
+	return cache.Set(k, cache.Get(k)+1)
+}
+
+func (cache *TTLCache) Get(k string) int {
+	cache.RLock()
+	defer cache.RUnlock()
+	v, ok := cache.items[k]
+	if !ok {
+		return 0
+	}
+	return v.Value
+}
+
+func (cache *TTLCache) Set(k string, v int) int {
+	cache.Lock()
+	defer cache.Unlock()
+
+	cache.items[k] = CachedItem{v, time.Now().Add(cache.ttl)}
+
+	return v
+}
+
+func (cache *TTLCache) Reset(k string) int {
+	return cache.Set(k, 0)
+}
+
+func NewTTLCache(ttl time.Duration) *TTLCache {
+	cache := &TTLCache{ttl: ttl, items: make(CachedItems)}
+
+	go func() {
+		for range time.Tick(ttl) {
+			cache.Lock()
+			for k, v := range cache.items {
+				if v.Expired() {
+					delete(cache.items, k)
+				}
+			}
+			cache.Unlock()
+		}
+	}()
+
+	return cache
+}