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kube-arangodb/pkg/util/loader.go

91 lines
1.6 KiB
Go

//
// DISCLAIMER
//
// Copyright 2024 ArangoDB GmbH, Cologne, Germany
//
// 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.
//
// Copyright holder is ArangoDB GmbH, Cologne, Germany
//
package util
import (
"sync"
"k8s.io/apimachinery/pkg/util/yaml"
)
type Loader[T any] interface {
MustGet() T
Get() (T, error)
}
type LoaderGen[T any] func() (T, error)
type loader[T any] struct {
lock sync.Mutex
gen LoaderGen[T]
object T
generated bool
}
func (l *loader[T]) MustGet() T {
obj, err := l.Get()
if err != nil {
panic(err.Error())
}
return obj
}
func (l *loader[T]) Get() (T, error) {
l.lock.Lock()
defer l.lock.Unlock()
if l.generated {
return l.object, nil
}
obj, err := l.gen()
if err != nil {
return Default[T](), err
}
l.generated = true
l.object = obj
return l.object, nil
}
func NewLoader[T any](gen LoaderGen[T]) Loader[T] {
return &loader[T]{
gen: gen,
}
}
func NewYamlLoader[T any](data []byte) Loader[T] {
return NewLoader[T](func() (T, error) {
var obj T
if err := yaml.Unmarshal(data, &obj); err != nil {
return Default[T](), err
}
return obj, nil
})
}