feat: make the default cache expirable (#1203)

enforcer_cached.go

@@ -18,14 +18,15 @@ import (
 	"strings"
 	"sync"
 	"sync/atomic"
+	"time"
 
 	"github.com/casbin/casbin/v2/persist/cache"
 )
 
 // CachedEnforcer wraps Enforcer and provides decision cache
 type CachedEnforcer struct {
 	*Enforcer
-	expireTime  uint
+	expireTime  time.Duration
 	cache       cache.Cache
 	enableCache int32
 	locker      *sync.RWMutex
@@ -45,8 +46,7 @@ func NewCachedEnforcer(params ...interface{}) (*CachedEnforcer, error) {
 	}
 
 	e.enableCache = 1
-	cache := cache.DefaultCache(make(map[string]bool))
-	e.cache = &cache
+	e.cache, _ = cache.NewDefaultCache()
 	e.locker = new(sync.RWMutex)
 	return e, nil
 }
@@ -132,7 +132,7 @@ func (e *CachedEnforcer) getCachedResult(key string) (res bool, err error) {
 	return e.cache.Get(key)
 }
 
-func (e *CachedEnforcer) SetExpireTime(expireTime uint) {
+func (e *CachedEnforcer) SetExpireTime(expireTime time.Duration) {
 	e.expireTime = expireTime
 }
 

persist/cache/cache.go

@@ -20,7 +20,7 @@ var ErrNoSuchKey = errors.New("there's no such key existing in cache")
 
 type Cache interface {
 	// Set puts key and value into cache.
-	// First parameter for extra should be uint denoting expected survival time.
+	// First parameter for extra should be time.Time object denoting expected survival time.
 	// If survival time equals 0 or less, the key will always be survival.
 	Set(key string, value bool, extra ...interface{}) error
 

persist/cache/default-cache.go

@@ -14,18 +14,38 @@
 
 package cache
 
-type DefaultCache map[string]bool
+import "time"
+
+type cacheItem struct {
+	value     bool
+	expiresAt time.Time
+	ttl       time.Duration
+}
+
+type DefaultCache map[string]cacheItem
 
 func (c *DefaultCache) Set(key string, value bool, extra ...interface{}) error {
-	(*c)[key] = value
+	ttl := time.Duration(-1)
+	if len(extra) > 0 {
+		ttl = extra[0].(time.Duration)
+	}
+	(*c)[key] = cacheItem{
+		value:     value,
+		expiresAt: time.Now().Add(ttl),
+		ttl:       ttl,
+	}
 	return nil
 }
 
 func (c *DefaultCache) Get(key string) (bool, error) {
 	if res, ok := (*c)[key]; !ok {
 		return false, ErrNoSuchKey
 	} else {
-		return res, nil
+		if res.ttl > 0 && time.Now().After(res.expiresAt) {
+			delete(*c, key)
+			return false, ErrNoSuchKey
+		}
+		return res.value, nil
 	}
 }
 
@@ -42,3 +62,8 @@ func (c *DefaultCache) Clear() error {
 	*c = make(DefaultCache)
 	return nil
 }
+
+func NewDefaultCache() (Cache, error) {
+	cache := make(DefaultCache)
+	return &cache, nil
+}