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memory_cache.go
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/
memory_cache.go
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package main
import (
"time"
)
/*
过期 key 处理策略:
1、绑定定时器,过期了直接调用 delete 函数删除
2、get 时再删除
3、定时任务随机扫描部分 key 删除(洗牌算法)
*/
const (
TimeToDelete = 1 << 0 // 定时删除
LazyToDelete = 1 << 1 // 惰性删除
RegularlyScan = 1 << 2 // 定期扫描
)
const (
LRU = 1
LFU = 2
)
const (
RegularlyScanTime = 100 // 定期扫描间隔,单位为 ms
DeleteKeyPercent = 0.25 // 每次扫描过期 key 的占比, 1/4
)
type MemoryCache struct {
keyMgr KeyMgr
}
func MemoryCacheConstructor(cap int) *MemoryCache {
c := &MemoryCache{
keyMgr: LFUConstructor(cap),
}
// 开启线程定期扫描清除过期 key
go func() {
tick := time.Tick(RegularlyScanTime * time.Millisecond)
for {
select {
case <-tick:
c.keyMgr.ScanAndDelete(DeleteKeyPercent)
}
}
}()
return c
}
func (c *MemoryCache) Get(key string) interface{} {
return c.keyMgr.Get(key)
}
func (c *MemoryCache) Set(key string, val interface{}, expire int64) bool {
return c.keyMgr.Set(key, val, expire)
}
func (c *MemoryCache) Delete(key string) bool {
return c.keyMgr.Delete(key)
}