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lru.go
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lru.go
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package lru
import "sync"
type node struct {
key int
block []byte
older *node
newer *node
}
type LRU struct {
size int
blocks map[int]*node
newest *node
oldest *node
sync.Mutex
}
func NewLRU(size int) *LRU {
return &LRU{size, make(map[int]*node), nil, nil, sync.Mutex{}}
}
func (l *LRU) Get(i int) ([]byte, bool) {
l.Lock()
defer l.Unlock()
if b, ok := l.blocks[i]; ok {
l.moveToFront(b)
return b.block, true
}
return nil, false
}
func (l *LRU) Add(i int, v []byte) {
l.Lock()
defer l.Unlock()
for len(l.blocks) >= l.size {
delete(l.blocks, l.oldest.key)
l.oldest = l.oldest.newer
if l.oldest != nil {
l.oldest.older = nil
}
}
n := &node{i, v, nil, nil}
l.moveToFront(n)
l.blocks[i] = n
}
func (l *LRU) moveToFront(n *node) {
if n == l.newest {
return
}
if n == l.oldest {
l.oldest = n.newer
}
if n.older != nil {
n.older.newer = n.newer
}
if n.newer != nil {
n.newer.older = n.older
}
n.newer = nil
n.older = l.newest
l.newest = n
if l.oldest == nil {
l.oldest = n
}
}