added method for finding cache key age

cache2go/cache.go

@@ -11,6 +11,7 @@ import (
 type expiringCacheEntry interface {
 	XCache(key string, expire time.Duration, value expiringCacheEntry)
 	timer() *time.Timer
+	age() time.Duration
 	KeepAlive()
 }
 
@@ -70,6 +71,11 @@ func (xe *XEntry) timer() *time.Timer {
 	return xe.t
 }
 
+func (xe *XEntry) age() time.Duration {
+	return time.Since(xe.timestamp)
+
+}
+
 // Mark entry to be kept another expirationDuration period
 func (xe *XEntry) KeepAlive() {
 	xe.Lock()
@@ -105,6 +111,24 @@ func GetCached(key string) (v interface{}, err error) {
 	return nil, errors.New("not found")
 }
 
+func GetKeyAge(key string) (time.Duration, error) {
+	mux.RLock()
+	defer mux.RUnlock()
+	if r, ok := cache[key]; ok {
+		return time.Since(r.timestamp), nil
+	}
+	return 0, errors.New("not found")
+}
+
+func GetXKeyAge(key string) (time.Duration, error) {
+	xMux.RLock()
+	defer xMux.RUnlock()
+	if r, ok := xcache[key]; ok {
+		return r.age(), nil
+	}
+	return 0, errors.New("not found")
+}
+
 func RemKey(key string) {
 	mux.Lock()
 	defer mux.Unlock()

cache2go/cache_test.go

@@ -96,3 +96,20 @@ func TestXRemKey(t *testing.T) {
 		t.Error("Error removing xcached key: ", err, t1)
 	}
 }
+
+func TestGetKeyAge(t *testing.T) {
+	Cache("t1", "test")
+	d, err := GetKeyAge("t1")
+	if err != nil || d > time.Millisecond || d < time.Nanosecond {
+		t.Error("Error getting cache key age: ", d)
+	}
+}
+
+func TestXGetKeyAge(t *testing.T) {
+	a := &myStruct{data: "mama are mere"}
+	a.XCache("t1", 10*time.Second, a)
+	d, err := GetXKeyAge("t1")
+	if err != nil || d > time.Millisecond || d < time.Nanosecond {
+		t.Error("Error getting cache key age: ", d)
+	}
+}