mirror of
https://github.com/EchoVault/SugarDB.git
synced 2025-10-05 16:06:57 +08:00
104 lines
2.5 KiB
Go
104 lines
2.5 KiB
Go
// Copyright 2024 Kelvin Clement Mwinuka
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package eviction
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import (
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"container/heap"
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"slices"
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"time"
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)
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type EntryLRU struct {
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key string // The key, matching the key in the store
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unixTime int64 // Unix time in milliseconds when this key was accessed
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index int // The index of the entry in the heap
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}
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type CacheLRU struct {
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keys map[string]bool
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entries []*EntryLRU
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}
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func NewCacheLRU() CacheLRU {
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cache := CacheLRU{
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keys: make(map[string]bool),
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entries: make([]*EntryLRU, 0),
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}
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heap.Init(&cache)
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return cache
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}
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func (cache *CacheLRU) Len() int {
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return len(cache.entries)
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}
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func (cache *CacheLRU) Less(i, j int) bool {
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return cache.entries[i].unixTime > cache.entries[j].unixTime
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}
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func (cache *CacheLRU) Swap(i, j int) {
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cache.entries[i], cache.entries[j] = cache.entries[j], cache.entries[i]
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cache.entries[i].index = i
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cache.entries[j].index = j
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}
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func (cache *CacheLRU) Push(key any) {
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n := len(cache.entries)
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cache.entries = append(cache.entries, &EntryLRU{
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key: key.(string),
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unixTime: time.Now().UnixMilli(),
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index: n,
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})
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}
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func (cache *CacheLRU) Pop() any {
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old := cache.entries
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n := len(old)
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entry := old[n-1]
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old[n-1] = nil
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entry.index = -1
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cache.entries = old[0 : n-1]
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delete(cache.keys, entry.key)
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return entry.key
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}
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func (cache *CacheLRU) Update(key string) {
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// If the key does not already exist in the cache, then push it
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if !cache.contains(key) {
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heap.Push(cache, key)
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}
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// Get the item with key
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entryIdx := slices.IndexFunc(cache.entries, func(e *EntryLRU) bool {
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return e.key == key
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})
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entry := cache.entries[entryIdx]
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entry.unixTime = time.Now().UnixMilli()
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heap.Fix(cache, entryIdx)
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}
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func (cache *CacheLRU) Delete(key string) {
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entryIdx := slices.IndexFunc(cache.entries, func(entry *EntryLRU) bool {
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return entry.key == key
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})
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if entryIdx > -1 {
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heap.Remove(cache, cache.entries[entryIdx].index)
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}
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}
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func (cache *CacheLRU) contains(key string) bool {
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_, ok := cache.keys[key]
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return ok
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}
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