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Go中的HashMap缓存可以通过以下方法进行清理和维护:
time.AfterFunc
函数来实现这个功能。package main
import (
"fmt"
"time"
)
type CacheItem struct {
Value interface{}
ExpireTime time.Time
}
type HashMapCache struct {
items map[string]CacheItem
}
func NewHashMapCache() *HashMapCache {
return &HashMapCache{
items: make(map[string]CacheItem),
}
}
func (c *HashMapCache) Set(key string, value interface{}, duration time.Duration) {
expireTime := time.Now().Add(duration)
c.items[key] = CacheItem{
Value: value,
ExpireTime: expireTime,
}
}
func (c *HashMapCache) Get(key string) (interface{}, bool) {
item, ok := c.items[key]
if !ok || time.Now().After(item.ExpireTime) {
return nil, false
}
return item.Value, true
}
func (c *HashMapCache) Remove(key string) {
delete(c.items, key)
}
func (c *HashMapCache) Clear() {
c.items = make(map[string]CacheItem)
}
func main() {
cache := NewHashMapCache()
cache.Set("key1", "value1", 5*time.Second)
cache.Set("key2", "value2", 10*time.Second)
if value, ok := cache.Get("key1"); ok {
fmt.Println("key1:", value)
} else {
fmt.Println("key1 not found or expired")
}
time.Sleep(6 * time.Second)
if value, ok := cache.Get("key1"); ok {
fmt.Println("key1:", value)
} else {
fmt.Println("key1 not found or expired")
}
cache.Remove("key1")
if value, ok := cache.Get("key1"); ok {
fmt.Println("key1:", value)
} else {
fmt.Println("key1 not found or expired")
}
}
time.Ticker
来实现这个功能。package main
import (
"fmt"
"time"
)
type CacheItem struct {
Value interface{}
ExpireTime time.Time
}
type HashMapCache struct {
items map[string]CacheItem
}
func NewHashMapCache() *HashMapCache {
return &HashMapCache{
items: make(map[string]CacheItem),
}
}
func (c *HashMapCache) Set(key string, value interface{}, duration time.Duration) {
expireTime := time.Now().Add(duration)
c.items[key] = CacheItem{
Value: value,
ExpireTime: expireTime,
}
}
func (c *HashMapCache) Get(key string) (interface{}, bool) {
item, ok := c.items[key]
if !ok || time.Now().After(item.ExpireTime) {
return nil, false
}
return item.Value, true
}
func (c *HashMapCache) Remove(key string) {
delete(c.items, key)
}
func (c *HashMapCache) Clear() {
c.items = make(map[string]CacheItem)
}
func (c *HashMapCache) StartCleanupTimer(duration time.Duration) {
ticker := time.NewTicker(duration)
go func() {
for range ticker.C {
c.Cleanup()
}
}()
}
func (c *HashMapCache) Cleanup() {
now := time.Now()
for key, item := range c.items {
if now.After(item.ExpireTime) {
c.Remove(key)
}
}
}
func main() {
cache := NewHashMapCache()
cache.Set("key1", "value1", 5*time.Second)
cache.Set("key2", "value2", 10*time.Second)
cache.StartCleanupTimer(2 * time.Second)
time.Sleep(10 * time.Second)
cache.StopCleanupTimer()
}
sync.Pool
来实现这个功能。package main
import (
"container/list"
"fmt"
"time"
)
type CacheItem struct {
Value interface{}
ExpireTime time.Time
}
type HashMapCache struct {
items map[string]*list.Element
evict *list.List
}
func NewHashMapCache(maxSize int) *HashMapCache {
return &HashMapCache{
items: make(map[string]*list.Element),
evict: list.New(),
maxSize: maxSize,
}
}
func (c *HashMapCache) Set(key string, value interface{}, duration time.Duration) {
if elem, ok := c.items[key]; ok {
c.evict.MoveToFront(elem)
elem.Value.(*CacheItem).Value = value
elem.Value.(*CacheItem).ExpireTime = time.Now().Add(duration)
return
}
if c.evict.Len() >= c.maxSize {
lastElem := c.evict.Back()
c.removeItem(lastElem)
}
item := &CacheItem{
Value: value,
ExpireTime: time.Now().Add(duration),
}
elem := c.evict.PushFront(item)
c.items[key] = elem
}
func (c *HashMapCache) Get(key string) (interface{}, bool) {
if elem, ok := c.items[key]; ok {
if time.Now().After(elem.Value.(*CacheItem).ExpireTime) {
c.removeItem(elem)
return nil, false
}
c.evict.MoveToFront(elem)
return elem.Value.(*CacheItem).Value, true
}
return nil, false
}
func (c *HashMapCache) Remove(elem *list.Element) {
delete(c.items, elem.Value.(*CacheItem).Key)
c.evict.Remove(elem)
}
func (c *HashMapCache) Clear() {
c.items = make(map[string]*list.Element)
c.evict = list.New()
}
func main() {
cache := NewHashMapCache(2)
cache.Set("key1", "value1", 5*time.Second)
cache.Set("key2", "value2", 10*time.Second)
time.Sleep(6 * time.Second)
cache.Set("key3", "value3", 15*time.Second)
if value, ok := cache.Get("key1"); ok {
fmt.Println("key1:", value)
} else {
fmt.Println("key1 not found or expired")
}
if value, ok := cache.Get("key2"); ok {
fmt.Println("key2:", value)
} else {
fmt.Println("key2 not found or expired")
}
if value, ok := cache.Get("key3"); ok {
fmt.Println("key3:", value)
} else {
fmt.Println("key3 not found or expired")
}
}
这些方法可以根据实际需求进行组合使用,以实现更高效的缓存清理和维护。
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