实现内存缓存

internal/caches/storage_memory.go

@@ -0,0 +1,167 @@
+package caches
+
+import (
+	"fmt"
+	"github.com/TeaOSLab/EdgeCommon/pkg/serverconfigs"
+	"github.com/TeaOSLab/EdgeNode/internal/errors"
+	"github.com/TeaOSLab/EdgeNode/internal/utils"
+	"github.com/dchest/siphash"
+	"strconv"
+	"sync"
+	"time"
+)
+
+type MemoryItem struct {
+	ExpiredAt int64
+	Value     []byte
+}
+
+type MemoryStorage struct {
+	policy        *serverconfigs.HTTPCachePolicy
+	list          *List
+	totalSize     int64 // 需要实现
+	locker        *sync.RWMutex
+	valuesMap     map[uint64]*MemoryItem
+	ticker        *utils.Ticker
+	purgeDuration time.Duration
+}
+
+func NewMemoryStorage(policy *serverconfigs.HTTPCachePolicy) *MemoryStorage {
+	return &MemoryStorage{
+		policy:    policy,
+		list:      NewList(),
+		locker:    &sync.RWMutex{},
+		valuesMap: map[uint64]*MemoryItem{},
+	}
+}
+
+// 初始化
+func (this *MemoryStorage) Init() error {
+	if this.purgeDuration <= 0 {
+		this.purgeDuration = 30 * time.Second
+	}
+
+	// 启动定时清理任务
+	this.ticker = utils.NewTicker(this.purgeDuration)
+	go func() {
+		for this.ticker.Next() {
+			this.purgeLoop()
+		}
+	}()
+
+	return nil
+}
+
+// 读取缓存
+func (this *MemoryStorage) Read(key string, readerBuf []byte, callback func(data []byte, size int64, expiredAt int64, isEOF bool)) error {
+	hash := this.hash(key)
+
+	this.locker.RLock()
+	item := this.valuesMap[hash]
+	if item == nil {
+		this.locker.RUnlock()
+		return ErrNotFound
+	}
+
+	if item.ExpiredAt > utils.UnixTime() {
+		callback(item.Value, int64(len(item.Value)), item.ExpiredAt, true)
+		this.locker.RUnlock()
+		return nil
+	}
+	this.locker.RUnlock()
+
+	_ = this.Delete(key)
+
+	return ErrNotFound
+}
+
+// 打开缓存写入器等待写入
+func (this *MemoryStorage) Open(key string, expiredAt int64) (Writer, error) {
+	// 检查是否超出最大值
+	if this.policy.MaxKeys > 0 && this.list.Count() > this.policy.MaxKeys {
+		return nil, errors.New("too many keys in cache storage")
+	}
+
+	return NewMemoryWriter(this.valuesMap, key, expiredAt, this.locker), nil
+}
+
+// 删除某个键值对应的缓存
+func (this *MemoryStorage) Delete(key string) error {
+	hash := this.hash(key)
+	this.locker.Lock()
+	delete(this.valuesMap, hash)
+	this.list.Remove(fmt.Sprintf("%d", hash))
+	this.locker.Unlock()
+	return nil
+}
+
+// 统计缓存
+func (this *MemoryStorage) Stat() (*Stat, error) {
+	this.locker.RLock()
+	defer this.locker.RUnlock()
+
+	return this.list.Stat(func(hash string) bool {
+		return true
+	}), nil
+}
+
+// 清除所有缓存
+func (this *MemoryStorage) CleanAll() error {
+	this.locker.Lock()
+	this.valuesMap = map[uint64]*MemoryItem{}
+	this.list.Reset()
+	this.locker.Unlock()
+	return nil
+}
+
+// 批量删除缓存
+func (this *MemoryStorage) Purge(keys []string) error {
+	for _, key := range keys {
+		err := this.Delete(key)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// 停止缓存策略
+func (this *MemoryStorage) Stop() {
+	this.locker.Lock()
+	defer this.locker.Unlock()
+
+	this.valuesMap = map[uint64]*MemoryItem{}
+	this.list.Reset()
+	if this.ticker != nil {
+		this.ticker.Stop()
+	}
+}
+
+// 获取当前存储的Policy
+func (this *MemoryStorage) Policy() *serverconfigs.HTTPCachePolicy {
+	return this.policy
+}
+
+// 将缓存添加到列表
+func (this *MemoryStorage) AddToList(item *Item) {
+	item.Size = item.ValueSize + int64(len(item.Key))
+	hash := fmt.Sprintf("%d", this.hash(item.Key))
+	this.list.Add(hash, item)
+}
+
+// 计算Key Hash
+func (this *MemoryStorage) hash(key string) uint64 {
+	return siphash.Hash(0, 0, []byte(key))
+}
+
+// 清理任务
+func (this *MemoryStorage) purgeLoop() {
+	this.list.Purge(1000, func(hash string) {
+		uintHash, err := strconv.ParseUint(hash, 10, 64)
+		if err == nil {
+			this.locker.Lock()
+			delete(this.valuesMap, uintHash)
+			this.locker.Unlock()
+		}
+	})
+}