package http import ( "hash/fnv" "net" "sync" ) type Cache struct { capacity int mu sync.RWMutex entries map[uint64]Response keys []uint64 } func NewCache(capacity int) *Cache { if capacity < 0 { capacity = 0 } return &Cache{ capacity: capacity, entries: make(map[uint64]Response), keys: make([]uint64, 0, capacity), } } func key(ip net.IP) uint64 { h := fnv.New64a() h.Write(ip) return h.Sum64() } func (c *Cache) Set(ip net.IP, resp Response) { if c.capacity == 0 { return } k := key(ip) c.mu.Lock() defer c.mu.Unlock() if len(c.entries) == c.capacity && c.capacity > 0 { delete(c.entries, c.keys[0]) c.keys = c.keys[1:] } c.entries[k] = resp c.keys = append(c.keys, k) } func (c *Cache) Get(ip net.IP) (Response, bool) { k := key(ip) c.mu.RLock() defer c.mu.RUnlock() r, ok := c.entries[k] return r, ok }