Golang example of wrapping local cache and not have cache stampeding

lcache.go

package lcache

import (
	"context"
	"github.com/patrickmn/go-cache"
	"golang.org/x/sync/singleflight"
	"time"
)

type Cache struct {
	c  *cache.Cache
	sf singleflight.Group
}

func NewCache(defaultExpiration, cleanupInterval time.Duration) *Cache {
	return &Cache{
		c: cache.New(defaultExpiration, cleanupInterval),
	}
}

func (c *Cache) Get(ctx context.Context, key string, fn func(ctx context.Context) (interface{}, error)) (interface{}, error) {
	res, err, _ := c.sf.Do(key, func() (interface{}, error) {
		res, ok := c.c.Get(key)
		if ok {
			return res, nil
		}

		res, err := fn(ctx)
		if err != nil {
			return nil, err
		}
		c.c.Set(key, res, cache.DefaultExpiration)
		return res, nil
	})
	return res, err
}

func (c *Cache) Delete(key string) {
	c.c.Delete(key)
}