ing

context/attributes.go

@@ -1,20 +1,28 @@
 package context
 
+import "sync"
+
 type AttributeManager interface {
 	Init()
 	SetAttribute(key string, value interface{})
 	GetAttribute(key string) (value interface{})
-	GetAttributeNames() []string
 	RemoveAttribute(key string)
 	Contains(key string) (exist bool)
 	Destroy()
 }
 
 type AttributeManagers struct {
+	Parent     AttributeManager
 	attributes map[string]interface{}
+
+	mtx sync.RWMutex
 }
 
 func (am *AttributeManagers) Init() {
+	if nil != am.Parent {
+		am.Parent.Init()
+	}
+
 	if nil == am.attributes {
 		am.Destroy()
 	}
@@ -22,48 +30,76 @@ func (am *AttributeManagers) Init() {
 }
 
 func (am *AttributeManagers) SetAttribute(key string, value interface{}) {
-	if nil == am.attributes {
-		am.attributes = make(map[string]interface{})
-	}
+	am.checkInitialized()
+
+	am.mtx.Lock()
+	defer am.mtx.Unlock()
+
 	am.attributes[key] = value
 }
 
 func (am *AttributeManagers) GetAttribute(key string) (value interface{}) {
-	if nil == am.attributes {
-		return nil
-	}
+	am.checkInitialized()
+
+	am.mtx.RLock()
+	defer am.mtx.RUnlock()
+
+	if _, ok := am.attributes[key]; ok {
 		return am.attributes[key]
 	}
 
-func (am *AttributeManagers) GetAttributeNames() []string {
-	if nil == am.attributes {
+	if nil == am.Parent {
 		return nil
 	}
-	keys := []string{}
-	for k, _ := range am.attributes {
-		keys = append(keys, k)
-	}
-
-	return keys
+	return am.Parent.GetAttribute(key)
 }
 
 func (am *AttributeManagers) RemoveAttribute(key string) {
-	if nil == am.attributes {
+	am.checkInitialized()
+
+	am.mtx.Lock()
+	defer am.mtx.Unlock()
+
+	if _, ok := am.attributes[key]; ok {
+		delete(am.attributes, key)
 		return
 	}
-	delete(am.attributes, key)
+
+	if nil == am.Parent {
+		return
+	}
+
+	am.Parent.RemoveAttribute(key)
 }
 
 func (am *AttributeManagers) Contains(key string) (exist bool) {
-	if nil == am.attributes {
+	am.checkInitialized()
+
+	am.mtx.RLock()
+	defer am.mtx.RUnlock()
+
+	if _, ok := am.attributes[key]; ok {
+		return true
+	}
+
+	if nil == am.Parent {
 		return false
 	}
-	_, ok := am.attributes[key]
-	return ok
+	return am.Parent.Contains(key)
 }
 
 func (am *AttributeManagers) Destroy() {
 	if nil != am.attributes {
 		am.attributes = nil
 	}
+
+	if nil != am.Parent {
+		am.Parent.Destroy()
+	}
+}
+
+func (am *AttributeManagers) checkInitialized() {
+	if nil == am.attributes {
+		panic("Attribute Manager: must be initialized")
+	}
 }