router data model test

common/config/value.go

@@ -0,0 +1,91 @@
+/*
+	Copyright NetFoundry Inc.
+
+	Licensed under the Apache License, Version 2.0 (the "License");
+	you may not use this file except in compliance with the License.
+	You may obtain a copy of the License at
+
+	https://www.apache.org/licenses/LICENSE-2.0
+
+	Unless required by applicable law or agreed to in writing, software
+	distributed under the License is distributed on an "AS IS" BASIS,
+	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+	See the License for the specific language governing permissions and
+	limitations under the License.
+*/
+
+package config
+
+import (
+	"github.com/openziti/foundation/v2/concurrenz"
+	"sync"
+)
+
+type Listener[T any] interface {
+	NotifyChanged(init bool, old T, new T)
+}
+
+type ListenerFunc[T any] func(init bool, old T, new T)
+
+func (f ListenerFunc[T]) NotifyChanged(init bool, old T, new T) {
+	f(init, old, new)
+}
+
+func NewConfigValue[T comparable]() *Value[T] {
+	return &Value[T]{
+		notifyInitialized: make(chan struct{}),
+	}
+}
+
+type Value[T comparable] struct {
+	lock              sync.Mutex
+	initialized       bool
+	notifyInitialized chan struct{}
+	value             concurrenz.AtomicValue[T]
+	listeners         concurrenz.CopyOnWriteSlice[Listener[T]]
+}
+
+func (self *Value[T]) Store(value T) {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
+	first := !self.initialized
+	old := self.value.Swap(value)
+
+	if first || old != value {
+		for _, l := range self.listeners.Value() {
+			l.NotifyChanged(first, old, value)
+		}
+	}
+
+	if first {
+		self.initialized = true
+		close(self.notifyInitialized)
+	}
+}
+
+func (self *Value[T]) Load() T {
+	return self.value.Load()
+}
+
+func (self *Value[T]) AddListener(listener Listener[T]) {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
+	self.listeners.Append(listener)
+
+	if self.initialized {
+		listener.NotifyChanged(true, self.Load(), self.Load())
+	}
+}
+
+func (self *Value[T]) RemoveListener(listener Listener[T]) {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+
+	self.listeners.Delete(listener)
+}
+
+func (self *Value[T]) GetInitNotifyChannel() <-chan struct{} {
+	return self.notifyInitialized
+}