internal/config/change_handler.go

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

// Package config contains the operator's runtime configuration.
package config

import (
	"sync"

	"github.com/go-logr/logr"
	logf "sigs.k8s.io/controller-runtime/pkg/log"
)

// changeHandler is implemented by any structure that is able to register callbacks
// and call them using one single method.
type changeHandler interface {
	// Do will call every registered callback.
	Do() error
	// Register this function as a callback that will be executed when Do() is called.
	Register(f func() error)
}

// newOnChange returns a thread-safe ChangeHandler.
func newOnChange() changeHandler {
	return &onChange{
		logger: logf.Log.WithName("change-handler"),
	}
}

type onChange struct {
	logger logr.Logger

	callbacks   []func() error
	muCallbacks sync.Mutex
}

func (o *onChange) Do() error {
	o.muCallbacks.Lock()
	defer o.muCallbacks.Unlock()
	for _, fn := range o.callbacks {
		if err := fn(); err != nil {
			o.logger.Error(err, "change callback failed")
		}
	}
	return nil
}

func (o *onChange) Register(f func() error) {
	o.muCallbacks.Lock()
	defer o.muCallbacks.Unlock()
	o.callbacks = append(o.callbacks, f)
}