mirror of https://github.com/poanetwork/gecko.git
144 lines
2.5 KiB
Go
144 lines
2.5 KiB
Go
// (c) 2019-2020, Ava Labs, Inc. All rights reserved.
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// See the file LICENSE for licensing terms.
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package cache
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import (
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"container/list"
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"sync"
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"github.com/ava-labs/gecko/ids"
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)
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const (
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minCacheSize = 32
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)
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type entry struct {
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Key ids.ID
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Value interface{}
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}
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// LRU is a key value store with bounded size. If the size is attempted to be
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// exceeded, then an element is removed from the cache before the insertion is
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// done, based on evicting the least recently used value.
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type LRU struct {
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lock sync.Mutex
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entryMap map[[32]byte]*list.Element
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entryList *list.List
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Size int
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}
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// Put implements the cache interface
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func (c *LRU) Put(key ids.ID, value interface{}) {
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c.lock.Lock()
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defer c.lock.Unlock()
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c.put(key, value)
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}
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// Get implements the cache interface
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func (c *LRU) Get(key ids.ID) (interface{}, bool) {
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c.lock.Lock()
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defer c.lock.Unlock()
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return c.get(key)
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}
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// Evict implements the cache interface
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func (c *LRU) Evict(key ids.ID) {
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c.lock.Lock()
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defer c.lock.Unlock()
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c.evict(key)
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}
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// Flush implements the cache interface
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func (c *LRU) Flush() {
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c.lock.Lock()
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defer c.lock.Unlock()
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c.flush()
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}
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func (c *LRU) init() {
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if c.entryMap == nil {
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c.entryMap = make(map[[32]byte]*list.Element, minCacheSize)
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}
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if c.entryList == nil {
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c.entryList = list.New()
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}
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if c.Size <= 0 {
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c.Size = 1
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}
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}
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func (c *LRU) resize() {
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for c.entryList.Len() > c.Size {
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e := c.entryList.Front()
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c.entryList.Remove(e)
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val := e.Value.(*entry)
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delete(c.entryMap, val.Key.Key())
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}
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}
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func (c *LRU) put(key ids.ID, value interface{}) {
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c.init()
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c.resize()
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if e, ok := c.entryMap[key.Key()]; !ok {
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if c.entryList.Len() >= c.Size {
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e = c.entryList.Front()
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c.entryList.MoveToBack(e)
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val := e.Value.(*entry)
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delete(c.entryMap, val.Key.Key())
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val.Key = key
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val.Value = value
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} else {
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e = c.entryList.PushBack(&entry{
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Key: key,
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Value: value,
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})
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}
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c.entryMap[key.Key()] = e
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} else {
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c.entryList.MoveToBack(e)
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val := e.Value.(*entry)
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val.Value = value
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}
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}
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func (c *LRU) get(key ids.ID) (interface{}, bool) {
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c.init()
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c.resize()
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if e, ok := c.entryMap[key.Key()]; ok {
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c.entryList.MoveToBack(e)
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val := e.Value.(*entry)
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return val.Value, true
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}
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return struct{}{}, false
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}
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func (c *LRU) evict(key ids.ID) {
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c.init()
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c.resize()
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keyBytes := key.Key()
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if e, ok := c.entryMap[keyBytes]; ok {
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c.entryList.Remove(e)
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delete(c.entryMap, keyBytes)
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}
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}
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func (c *LRU) flush() {
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c.init()
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c.entryMap = make(map[[32]byte]*list.Element, minCacheSize)
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c.entryList = list.New()
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}
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