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package cache
import "sync"
type Cacher interface {
Get(key interface{}) (value []byte, exists bool)
Set(key interface{}, value []byte)
Len() int
}
type FifoCache struct {
head, tail *fifoCacheEntry
data map[interface{}][]byte
capacity int
mutex sync.RWMutex
}
type fifoCacheEntry struct {
Key interface{}
Next *fifoCacheEntry
}
func NewFifoCache(capacity int) *FifoCache {
return &FifoCache{data: make(map[interface{}][]byte, capacity), capacity: capacity}
}
func (c *FifoCache) Get(key interface{}) (value []byte, exists bool) {
c.mutex.RLock()
defer c.mutex.RUnlock()
value, exists = c.data[key]
return
}
func (c *FifoCache) Set(key interface{}, value []byte) {
c.mutex.Lock()
defer c.mutex.Unlock()
if len(c.data) == c.capacity {
// Evict first entry
evicted := c.head
c.head = evicted.Next
delete(c.data, evicted.Key)
}
entry := &fifoCacheEntry{Key: key}
if c.head == nil {
c.head = entry
}
if c.tail == nil {
c.tail = entry
} else {
c.tail.Next = entry
c.tail = entry
}
c.data[key] = value
}
func (c *FifoCache) Len() int {
return len(c.data)
}
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