geektutu/7days-golang · warning

key is required

Error message

key is required

What it means

Same guard in day4 (consistent-hash peers): Group.Get rejects an empty key with 'key is required' before local lookup or consistent-hash peer selection. Empty keys would otherwise be hashed and possibly routed to a peer pointlessly.

Source

Thrown at gee-cache/day4-consistent-hash/geecache/geecache.go:62

		mainCache: cache{cacheBytes: cacheBytes},
	}
	groups[name] = g
	return g
}

// GetGroup returns the named group previously created with NewGroup, or
// nil if there's no such group.
func GetGroup(name string) *Group {
	mu.RLock()
	g := groups[name]
	mu.RUnlock()
	return g
}

// Get value for a key from cache
func (g *Group) Get(key string) (ByteView, error) {
	if key == "" {
		return ByteView{}, fmt.Errorf("key is required")
	}

	if v, ok := g.mainCache.get(key); ok {
		log.Println("[GeeCache] hit")
		return v, nil
	}

	return g.load(key)
}

func (g *Group) load(key string) (value ByteView, err error) {
	return g.getLocally(key)
}

func (g *Group) getLocally(key string) (ByteView, error) {
	bytes, err := g.getter.Get(key)
	if err != nil {
		return ByteView{}, err

View on GitHub (pinned to cf36443821)

Solutions

1. Ensure the key query parameter is present and non-empty on all cache requests
2. Validate the key before calling group.Get in application code
3. Return a 400 response for empty keys at the HTTP boundary
4. Check consistent-hash peer URL construction preserves the key parameter

Example fix

// before
key := r.URL.Query().Get("key")
v, err := group.Get(key)
// after
key := r.URL.Query().Get("key")
if key == "" { http.Error(w, "key is required", http.StatusBadRequest); return }
v, err := group.Get(key)

func getFromCache(g *geecache.Group, key string) (geecache.ByteView, error) {
    if strings.TrimSpace(key) == "" {
        return geecache.ByteView{}, errors.New("cache: key must be non-empty")
    }
    return g.Get(key)
}

v, err := group.Get(key)
if err != nil {
    if err.Error() == "key is required" {
        http.Error(w, "missing cache key", http.StatusBadRequest)
        return
    }
    http.Error(w, err.Error(), http.StatusInternalServerError)
}

When it happens

Trigger: Calling group.Get("") directly, or an HTTP cache request with a missing/empty key parameter, or an upstream caller forwarding an empty string from user input into the cache API.

Common situations: Missing query parameter in requests proxied through the consistent-hash peer pool; buggy URL builders; tests exercising the validation path.

Related errors

• key is required
• key is required
• key is required
• key is required
• key is required

AI-assisted analysis of geektutu/7days-golang@cf36443821 (2026-09-03). Data as JSON: /api/errors/e6ff9d822c0853be. Report an issue: GitHub.