/
singleton.go
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/
singleton.go
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/*
Copyright 2022 The KubeVela Authors.
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
http://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 singleton
import (
"sync"
"k8s.io/apimachinery/pkg/util/runtime"
)
// Singleton global unique data struct
type Singleton[T any] struct {
mu sync.Mutex
loaded bool
loader func() T
data T
}
// Get retrieve underlying data, if not initialized, will trigger initialization
func (in *Singleton[T]) Get() T {
in.mu.Lock()
if !in.loaded && in.loader != nil {
in.mu.Unlock()
in.Set(in.loader())
in.mu.Lock()
}
defer in.mu.Unlock()
return in.data
}
// Set write the underlying data
func (in *Singleton[T]) Set(data T) {
in.mu.Lock()
defer in.mu.Unlock()
in.loaded = true
in.data = data
}
// Reload trigger loader
func (in *Singleton[T]) Reload() {
if in.loader != nil {
in.Set(in.loader())
}
}
// NewSingleton create a new singleton with loader
func NewSingleton[T any](loader func() T) *Singleton[T] {
return &Singleton[T]{
loader: loader,
}
}
// NewSingletonE create a new singleton with error-returned loader
func NewSingletonE[T any](loaderE func() (T, error)) *Singleton[T] {
loader := func() T {
t, err := loaderE()
runtime.Must(err)
return t
}
return NewSingleton(loader)
}