Add config change signal and concurrent getters

config/database.go

@@ -133,12 +133,12 @@ func registerAsDatabase() error {
 		PrimaryAPI:  "",
 	})
   if err != nil {
-    return nil
+    return err
   }
 
   controller, err := database.InjectDatabase("config", &ConfigStorageInterface{})
   if err != nil {
-    return nil
+    return err
   }
 
   dbController = controller

config/get-safe.go

@@ -0,0 +1,74 @@
+package config
+
+import "sync"
+
+type safe struct{}
+
+var (
+	// Concurrent makes concurrency safe get methods available.
+	Concurrent = &safe{}
+)
+
+// GetAsString returns a function that returns the wanted string with high performance.
+func (cs *safe) GetAsString(name string, fallback string) StringOption {
+	valid := getValidityFlag()
+	value := findStringValue(name, fallback)
+	var lock sync.Mutex
+	return func() string {
+		lock.Lock()
+		defer lock.Unlock()
+		if !valid.IsSet() {
+			valid = getValidityFlag()
+			value = findStringValue(name, fallback)
+		}
+		return value
+	}
+}
+
+// GetAsStringArray returns a function that returns the wanted string with high performance.
+func (cs *safe) GetAsStringArray(name string, fallback []string) StringArrayOption {
+	valid := getValidityFlag()
+	value := findStringArrayValue(name, fallback)
+	var lock sync.Mutex
+	return func() []string {
+		lock.Lock()
+		defer lock.Unlock()
+		if !valid.IsSet() {
+			valid = getValidityFlag()
+			value = findStringArrayValue(name, fallback)
+		}
+		return value
+	}
+}
+
+// GetAsInt returns a function that returns the wanted int with high performance.
+func (cs *safe) GetAsInt(name string, fallback int64) IntOption {
+	valid := getValidityFlag()
+	value := findIntValue(name, fallback)
+	var lock sync.Mutex
+	return func() int64 {
+		lock.Lock()
+		defer lock.Unlock()
+		if !valid.IsSet() {
+			valid = getValidityFlag()
+			value = findIntValue(name, fallback)
+		}
+		return value
+	}
+}
+
+// GetAsBool returns a function that returns the wanted int with high performance.
+func (cs *safe) GetAsBool(name string, fallback bool) BoolOption {
+	valid := getValidityFlag()
+	value := findBoolValue(name, fallback)
+	var lock sync.Mutex
+	return func() bool {
+		lock.Lock()
+		defer lock.Unlock()
+		if !valid.IsSet() {
+			valid = getValidityFlag()
+			value = findBoolValue(name, fallback)
+		}
+		return value
+	}
+}

config/layers.go

@@ -19,8 +19,24 @@ var (
 
 	// ErrInvalidOptionType is returned by SetConfigOption and SetDefaultConfigOption if given an unsupported option type.
 	ErrInvalidOptionType = errors.New("invalid option value type")
+
+	changedSignal = make(chan struct{}, 0)
 )
 
+// Changed signals if any config option was changed.
+func Changed() <-chan struct{} {
+	configLock.RLock()
+	defer configLock.RUnlock()
+	return changedSignal
+}
+
+// triggerChange signals listeners that a config option was changed.
+func triggerChange() {
+	// must be locked!
+	close(changedSignal)
+	changedSignal = make(chan struct{}, 0)
+}
+
 // setConfig sets the (prioritized) user defined config.
 func setConfig(m map[string]interface{}) error {
 	configLock.Lock()
@@ -29,6 +45,7 @@ func setConfig(m map[string]interface{}) error {
 	resetValidityFlag()
 
 	go pushFullUpdate()
+	triggerChange()
 
 	return nil
 }
@@ -41,6 +58,7 @@ func SetDefaultConfig(m map[string]interface{}) error {
 	resetValidityFlag()
 
 	go pushFullUpdate()
+	triggerChange()
 
 	return nil
 }
@@ -124,6 +142,7 @@ func setConfigOption(name string, value interface{}, push bool) error {
 	if err == nil {
 		resetValidityFlag()
 		go saveConfig()
+		triggerChange()
 	}
 
 	return err
@@ -155,6 +174,7 @@ func setDefaultConfigOption(name string, value interface{}, push bool) error {
 
 	if err == nil {
 		resetValidityFlag()
+		triggerChange()
 	}
 
 	return err