mirror of https://github.com/ledisdb/ledisdb.git
96 lines
1.9 KiB
Go
96 lines
1.9 KiB
Go
package rpl
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import (
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"container/list"
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"encoding/binary"
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)
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type logLRUCache struct {
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itemsList *list.List
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itemsMap map[uint64]*list.Element
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size int
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capability int
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maxNum int
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}
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func newLogLRUCache(capability int, maxNum int) *logLRUCache {
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if capability <= 0 {
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capability = 1024 * 1024
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}
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if maxNum <= 0 {
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maxNum = 16
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}
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return &logLRUCache{
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itemsList: list.New(),
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itemsMap: make(map[uint64]*list.Element),
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size: 0,
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capability: capability,
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maxNum: maxNum,
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}
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}
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func (cache *logLRUCache) Set(id uint64, data []byte) {
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elem, ok := cache.itemsMap[id]
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if ok {
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//we may not enter here
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// item already exists, so move it to the front of the list and update the data
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cache.itemsList.MoveToFront(elem)
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ol := elem.Value.([]byte)
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elem.Value = data
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cache.size += (len(data) - len(ol))
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} else {
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cache.size += len(data)
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// item doesn't exist, so add it to front of list
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elem = cache.itemsList.PushFront(data)
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cache.itemsMap[id] = elem
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}
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// evict LRU entry if the cache is full
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for cache.size > cache.capability || cache.itemsList.Len() > cache.maxNum {
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removedElem := cache.itemsList.Back()
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l := removedElem.Value.([]byte)
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cache.itemsList.Remove(removedElem)
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delete(cache.itemsMap, binary.BigEndian.Uint64(l[0:8]))
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cache.size -= len(l)
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if cache.size <= 0 {
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cache.size = 0
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}
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}
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}
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func (cache *logLRUCache) Get(id uint64) []byte {
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elem, ok := cache.itemsMap[id]
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if !ok {
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return nil
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}
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// item exists, so move it to front of list and return it
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cache.itemsList.MoveToFront(elem)
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l := elem.Value.([]byte)
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return l
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}
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func (cache *logLRUCache) Delete(id uint64) {
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elem, ok := cache.itemsMap[id]
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if !ok {
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return
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}
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cache.itemsList.Remove(elem)
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delete(cache.itemsMap, id)
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}
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func (cache *logLRUCache) Len() int {
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return cache.itemsList.Len()
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}
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func (cache *logLRUCache) Reset() {
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cache.itemsList = list.New()
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cache.itemsMap = make(map[uint64]*list.Element)
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cache.size = 0
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}
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