195 lines
3.1 KiB
Go
Vendored
195 lines
3.1 KiB
Go
Vendored
// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
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// All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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package cache
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import (
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"sync"
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"unsafe"
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)
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type lruNode struct {
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n *Node
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h *Handle
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ban bool
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next, prev *lruNode
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}
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func (n *lruNode) insert(at *lruNode) {
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x := at.next
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at.next = n
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n.prev = at
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n.next = x
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x.prev = n
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}
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func (n *lruNode) remove() {
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if n.prev != nil {
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n.prev.next = n.next
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n.next.prev = n.prev
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n.prev = nil
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n.next = nil
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} else {
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panic("BUG: removing removed node")
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}
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}
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type lru struct {
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mu sync.Mutex
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capacity int
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used int
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recent lruNode
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}
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func (r *lru) reset() {
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r.recent.next = &r.recent
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r.recent.prev = &r.recent
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r.used = 0
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}
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func (r *lru) Capacity() int {
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r.mu.Lock()
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defer r.mu.Unlock()
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return r.capacity
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}
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func (r *lru) SetCapacity(capacity int) {
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var evicted []*lruNode
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r.mu.Lock()
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r.capacity = capacity
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for r.used > r.capacity {
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rn := r.recent.prev
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if rn == nil {
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panic("BUG: invalid LRU used or capacity counter")
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}
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rn.remove()
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rn.n.CacheData = nil
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r.used -= rn.n.Size()
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evicted = append(evicted, rn)
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}
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r.mu.Unlock()
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for _, rn := range evicted {
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rn.h.Release()
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}
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}
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func (r *lru) Promote(n *Node) {
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var evicted []*lruNode
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r.mu.Lock()
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if n.CacheData == nil {
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if n.Size() <= r.capacity {
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rn := &lruNode{n: n, h: n.GetHandle()}
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rn.insert(&r.recent)
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n.CacheData = unsafe.Pointer(rn)
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r.used += n.Size()
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for r.used > r.capacity {
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rn := r.recent.prev
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if rn == nil {
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panic("BUG: invalid LRU used or capacity counter")
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}
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rn.remove()
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rn.n.CacheData = nil
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r.used -= rn.n.Size()
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evicted = append(evicted, rn)
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}
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}
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} else {
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rn := (*lruNode)(n.CacheData)
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if !rn.ban {
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rn.remove()
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rn.insert(&r.recent)
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}
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}
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r.mu.Unlock()
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for _, rn := range evicted {
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rn.h.Release()
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}
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}
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func (r *lru) Ban(n *Node) {
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r.mu.Lock()
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if n.CacheData == nil {
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n.CacheData = unsafe.Pointer(&lruNode{n: n, ban: true})
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} else {
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rn := (*lruNode)(n.CacheData)
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if !rn.ban {
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rn.remove()
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rn.ban = true
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r.used -= rn.n.Size()
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r.mu.Unlock()
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rn.h.Release()
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rn.h = nil
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return
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}
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}
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r.mu.Unlock()
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}
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func (r *lru) Evict(n *Node) {
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r.mu.Lock()
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rn := (*lruNode)(n.CacheData)
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if rn == nil || rn.ban {
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r.mu.Unlock()
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return
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}
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n.CacheData = nil
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r.mu.Unlock()
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rn.h.Release()
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}
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func (r *lru) EvictNS(ns uint64) {
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var evicted []*lruNode
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r.mu.Lock()
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for e := r.recent.prev; e != &r.recent; {
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rn := e
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e = e.prev
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if rn.n.NS() == ns {
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rn.remove()
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rn.n.CacheData = nil
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r.used -= rn.n.Size()
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evicted = append(evicted, rn)
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}
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}
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r.mu.Unlock()
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for _, rn := range evicted {
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rn.h.Release()
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}
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}
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func (r *lru) EvictAll() {
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r.mu.Lock()
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back := r.recent.prev
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for rn := back; rn != &r.recent; rn = rn.prev {
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rn.n.CacheData = nil
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}
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r.reset()
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r.mu.Unlock()
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for rn := back; rn != &r.recent; rn = rn.prev {
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rn.h.Release()
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}
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}
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func (r *lru) Close() error {
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return nil
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}
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// NewLRU create a new LRU-cache.
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func NewLRU(capacity int) Cacher {
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r := &lru{capacity: capacity}
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r.reset()
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return r
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}
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