实现内存缓存

internal/caches/writer_memory.go

@@ -0,0 +1,83 @@
+package caches
+
+import (
+	"github.com/dchest/siphash"
+	"sync"
+)
+
+type MemoryWriter struct {
+	key            string
+	expiredAt      int64
+	m              map[uint64]*MemoryItem
+	locker         *sync.RWMutex
+	isFirstWriting bool
+	size           int64
+}
+
+func NewMemoryWriter(m map[uint64]*MemoryItem, key string, expiredAt int64, locker *sync.RWMutex) *MemoryWriter {
+	return &MemoryWriter{
+		m:              m,
+		key:            key,
+		expiredAt:      expiredAt,
+		locker:         locker,
+		isFirstWriting: true,
+	}
+}
+
+// 写入数据
+func (this *MemoryWriter) Write(data []byte) (n int, err error) {
+	this.size += int64(len(data))
+
+	hash := this.hash(this.key)
+	this.locker.Lock()
+	item, ok := this.m[hash]
+	if ok {
+		// 第一次写先清空
+		if this.isFirstWriting {
+			item.Value = nil
+			this.isFirstWriting = false
+		}
+		item.Value = append(item.Value, data...)
+	} else {
+		item := &MemoryItem{}
+		item.Value = append([]byte{}, data...)
+		item.ExpiredAt = this.expiredAt
+		this.m[hash] = item
+	}
+	this.locker.Unlock()
+	return len(data), nil
+}
+
+// 数据尺寸
+func (this *MemoryWriter) Size() int64 {
+	return this.size
+}
+
+// 关闭
+func (this *MemoryWriter) Close() error {
+	return nil
+}
+
+// 丢弃
+func (this *MemoryWriter) Discard() error {
+	hash := this.hash(this.key)
+	this.locker.Lock()
+	delete(this.m, hash)
+	this.locker.Unlock()
+	return nil
+}
+
+// Key
+func (this *MemoryWriter) Key() string {
+	return this.key
+}
+
+// 过期时间
+func (this *MemoryWriter) ExpiredAt() int64 {
+	return this.expiredAt
+}
+
+// 计算Key Hash
+func (this *MemoryWriter) hash(key string) uint64 {
+	return siphash.Hash(0, 0, []byte(key))
+}