kyverno/pkg/utils/controller/handlers.go

package controller

import (
	"errors"
	"time"

	"github.com/go-logr/logr"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/util/workqueue"
)

type (
	addFunc     func(interface{})
	updateFunc  func(interface{}, interface{})
	deleteFunc  func(interface{})
	keyFunc     func(interface{}) (interface{}, error)
	EnqueueFunc func(interface{}) error
)

func AddEventHandlers(informer cache.SharedInformer, a addFunc, u updateFunc, d deleteFunc) {
	informer.AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc:    a,
		UpdateFunc: u,
		DeleteFunc: d,
	})
}

func AddKeyedEventHandlers(logger logr.Logger, informer cache.SharedInformer, queue workqueue.RateLimitingInterface, parseKey keyFunc) EnqueueFunc {
	enqueueFunc := LogError(logger, Parse(parseKey, Queue(queue)))
	AddEventHandlers(informer, AddFunc(logger, enqueueFunc), UpdateFunc(logger, enqueueFunc), DeleteFunc(logger, enqueueFunc))
	return enqueueFunc
}

func AddDelayedKeyedEventHandlers(logger logr.Logger, informer cache.SharedInformer, queue workqueue.RateLimitingInterface, delay time.Duration, parseKey keyFunc) EnqueueFunc {
	enqueueFunc := LogError(logger, Parse(parseKey, QueueAfter(queue, delay)))
	AddEventHandlers(informer, AddFunc(logger, enqueueFunc), UpdateFunc(logger, enqueueFunc), DeleteFunc(logger, enqueueFunc))
	return enqueueFunc
}

func AddDefaultEventHandlers(logger logr.Logger, informer cache.SharedInformer, queue workqueue.RateLimitingInterface) EnqueueFunc {
	return AddKeyedEventHandlers(logger, informer, queue, MetaNamespaceKey)
}

func AddDelayedDefaultEventHandlers(logger logr.Logger, informer cache.SharedInformer, queue workqueue.RateLimitingInterface, delay time.Duration) EnqueueFunc {
	return AddDelayedKeyedEventHandlers(logger, informer, queue, delay, MetaNamespaceKey)
}

func AddExplicitEventHandlers[K any](logger logr.Logger, informer cache.SharedInformer, queue workqueue.RateLimitingInterface, parseKey func(K) cache.ExplicitKey) EnqueueFunc {
	return AddKeyedEventHandlers(logger, informer, queue, ExplicitKey(parseKey))
}

func AddDelayedExplicitEventHandlers[K any](logger logr.Logger, informer cache.SharedInformer, queue workqueue.RateLimitingInterface, delay time.Duration, parseKey func(K) cache.ExplicitKey) EnqueueFunc {
	return AddDelayedKeyedEventHandlers(logger, informer, queue, delay, ExplicitKey(parseKey))
}

func LogError(logger logr.Logger, inner EnqueueFunc) EnqueueFunc {
	return func(obj interface{}) error {
		err := inner(obj)
		if err != nil {
			logger.Error(err, "failed to compute key name", "obj", obj)
		}
		return err
	}
}

func Parse(parseKey keyFunc, inner EnqueueFunc) EnqueueFunc {
	return func(obj interface{}) error {
		if key, err := parseKey(obj); err != nil {
			return err
		} else {
			return inner(key)
		}
	}
}

func Queue(queue workqueue.RateLimitingInterface) EnqueueFunc {
	return func(obj interface{}) error {
		queue.Add(obj)
		return nil
	}
}

func QueueAfter(queue workqueue.RateLimitingInterface, delay time.Duration) EnqueueFunc {
	return func(obj interface{}) error {
		queue.AddAfter(obj, delay)
		return nil
	}
}

func MetaNamespaceKey(obj interface{}) (interface{}, error) {
	return cache.MetaNamespaceKeyFunc(obj)
}

func ExplicitKey[K any](parseKey func(K) cache.ExplicitKey) keyFunc {
	return func(obj interface{}) (interface{}, error) {
		if obj == nil {
			return nil, errors.New("obj is nil")
		}
		if key, ok := obj.(K); !ok {
			return nil, errors.New("obj cannot be converted")
		} else {
			return parseKey(key), nil
		}
	}
}

func AddFunc(logger logr.Logger, enqueue EnqueueFunc) addFunc {
	return func(obj interface{}) {
		_ = enqueue(obj)
	}
}

func UpdateFunc(logger logr.Logger, enqueue EnqueueFunc) updateFunc {
	return func(_, obj interface{}) {
		_ = enqueue(obj)
	}
}

func DeleteFunc(logger logr.Logger, enqueue EnqueueFunc) deleteFunc {
	return func(obj interface{}) {
		_ = enqueue(obj)
	}
}