pavel.go

func main() {
	m := NewLRUHashMap(3)
	m.Put("1", "a")
	m.Put("2", "b")
	m.Put("3", "c")
	m.Put("4", "d")
	fmt.Println(m.Get("1"))
	fmt.Println(m.Get("4"))
	fmt.Println(m.cache)
}

type LRUHashMap struct {
	cache map[string]interface{}
	queue chan string
	max   int
}

func NewLRUHashMap(max int) *LRUHashMap {
	return &LRUHashMap{
		max:   max,
		cache: map[string]interface{}{},
		queue: make(chan string, max),
	}
}

func (m *LRUHashMap) Put(k string, val interface{}) {
	if _, found := m.cache[k]; found {
		tmp := make(chan string, m.max)
		close(m.queue)
		for key := range m.queue {
			if key == k {
				continue
			}
			tmp <- key
		}
		m.queue = tmp
	} else {
		if len(m.queue) >= m.max {
			key := <-m.queue
			delete(m.cache, key)
		}
	}
	m.queue <- k
	m.cache[k] = val
}

func (m *LRUHashMap) Get(k string) interface{} {
	v, found := m.cache[k]
	if !found {
		return nil
	}
	tmp := make(chan string, m.max)
	close(m.queue)
	for key := range m.queue {
		if key == k {
			continue
		}
		tmp <- key
	}
	tmp <- k
	m.queue = tmp
	return v
}