parcoursmob/utils/storage/groupcache.go

package storage

import (
	"context"
	"fmt"
	"github.com/spf13/viper"
	"gopkg.in/square/go-jose.v2/json"
	"log"
	"net/http"
	"reflect"
	"time"

	"github.com/mailgun/groupcache/v2"
)

type GroupCacheHandler struct {
	KVHandler KVHandler
	Group     *groupcache.Group
	cacheTTL  int64
}

func NewGroupCacheHandler(cfg *viper.Viper) (*GroupCacheHandler, error) {
	var (
		endpoint     = cfg.GetString("storage.kv.groupcache.endpoint")
		ports        = cfg.GetStringSlice("storage.kv.groupcache.ports")
		cacheTTL     = cfg.GetInt64("storage.kv.groupcache.cacheTTL")
		cacheServers []*http.Server
	)

	var kvHandler KVHandler
	var getterFunc groupcache.GetterFunc
	kvType := cfg.GetString("storage.kv.groupcache.db")
	getterFunc = func(ctx context.Context, key string, dest groupcache.Sink) error {
		resp, err := kvHandler.Get(key)
		if err != nil {
			return err
		}
		if resp == nil {
			return fmt.Errorf("key not found in etcd: %s", key)
		}
		jsonResp, err := json.Marshal(resp.(map[string]interface{}))
		if err != nil {
			// Handle the error
		}
		dest.SetBytes(jsonResp, time.Now().Add(time.Duration(cacheTTL)*time.Minute))
		return nil

	}
	switch kvType {
	case "etcd":
		etcdHandler, err := NewEtcdHandler(cfg)
		if err != nil {
			return nil, err
		}
		kvHandler = etcdHandler
	case "badger":
		badgerHandler, err := NewBadgerHandler(cfg)
		if err != nil {
			return nil, err
		}
		kvHandler = badgerHandler
	default:
		return nil, fmt.Errorf("unsupported kvType: %s", kvType)
	}

	pool := groupcache.NewHTTPPoolOpts("", &groupcache.HTTPPoolOptions{})
	for _, port := range ports {
		pool.Set("http://" + endpoint + ":" + port)
		server := &http.Server{
			Addr:    endpoint + ":" + port,
			Handler: pool,
		}
		cacheServers = append(cacheServers, server)
		go func(srv *http.Server) {
			log.Printf("Serving cache server %s \n", srv.Addr)
			if err := srv.ListenAndServe(); err != nil {
				log.Fatal(err)
			}
		}(server)
	}

	group := groupcache.NewGroup("data", 3000000, getterFunc)
	handler := &GroupCacheHandler{
		KVHandler: kvHandler,
		Group:     group,
		cacheTTL:  cacheTTL,
	}

	return handler, nil
}

func (h *GroupCacheHandler) Put(k string, v any) error {
	// Update the value in the underlying key-value store
	err := h.KVHandler.Put(k, v)
	if err != nil {
		return err
	}

	// Check if the key exists in the cache
	var value []byte
	err = h.Group.Get(nil, k, groupcache.AllocatingByteSliceSink(&value))
	if err == nil {
		// Key exists in the cache, compare with the new value
		if !reflect.DeepEqual(value, v) {
			// Values are different, update the cache
			jsonValue, err := json.Marshal(v)
			if err != nil {
				return err
			}
			expireTime := time.Now().Add(time.Duration(h.cacheTTL) * time.Minute)
			err = h.Group.Set(context.Background(), k, jsonValue, expireTime, false)
			if err != nil {
				return err
			}
		}
	}

	return nil
}

func (h *GroupCacheHandler) PutWithTTL(k string, v any, duration time.Duration) error {

	err := h.KVHandler.PutWithTTL(k, v, duration)
	// Check if the key exists in the cache
	var value []byte
	err = h.Group.Get(nil, k, groupcache.AllocatingByteSliceSink(&value))
	if err == nil {
		// Key exists in the cache, compare with the new value
		if !reflect.DeepEqual(value, v) {
			// Values are different, update the cache
			jsonValue, err := json.Marshal(v)
			if err != nil {
				return err
			}
			expireTime := time.Now().Add(time.Duration(h.cacheTTL) * time.Minute)
			err = h.Group.Set(context.Background(), k, jsonValue, expireTime, false)
			if err != nil {
				return err
			}
		}
	}

	return nil

}

func (h *GroupCacheHandler) Get(k string) (any, error) {
	var value []byte
	err := h.Group.Get(nil, k, groupcache.AllocatingByteSliceSink(&value))
	if err != nil {
		fmt.Println("error", err)
		return nil, err
	}

	// If the value is empty, return an empty map
	if len(value) == 0 {
		return make(map[string]interface{}), nil
	}

	var result map[string]interface{}
	err = json.Unmarshal(value, &result)
	if err != nil {
		return nil, err
	}
	return result, nil

}

func (h *GroupCacheHandler) Delete(k string) error {
	err := h.KVHandler.Delete(k)
	if err != nil {
		return err
	}
	err = h.Group.Remove(context.Background(), k)
	if err != nil {
		return err
	}
	return nil
}