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lru.go
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lru.go
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package LRUCache
import (
"errors"
"time"
)
type Cache struct {
capacity int
items map[string]*CacheItem
}
type CacheItem struct {
value string
lastUsed int64
}
func New(c int) *Cache {
return &Cache{
capacity: c,
items: make(map[string]*CacheItem),
}
}
func (c *Cache) Set(key string, val string) {
// Add value, If key does not exist already
if _, ok := c.items[key]; !ok {
lastUsed := int64(time.Now().Nanosecond())
if len(c.items) == c.capacity {
var timestamp int64
var keyToDelete string
for key, item := range c.items {
if timestamp == 0 {
timestamp = item.lastUsed
keyToDelete = key
} else if timestamp > item.lastUsed {
timestamp = item.lastUsed
keyToDelete = key
}
}
delete(c.items, keyToDelete)
}
c.items[key] = &CacheItem{
value: val,
lastUsed: lastUsed,
}
}
}
func (c *Cache) Get(key string) (string, error) {
//Search the key in map
if item, ok := c.items[key]; ok {
item.lastUsed = time.Now().UnixNano()
return item.value, nil
}
return "", errors.New("key was not found")
}