初步实验使用KV数据库（pebble）存储缓存索引

internal/caches/list_file_kv_objects.go

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+// Copyright 2024 GoEdge CDN goedge.cdn@gmail.com. All rights reserved. Official site: https://goedge.cn .
+
+package caches
+
+import (
+	"encoding/binary"
+	"encoding/json"
+	"strings"
+)
+
+// ItemKVEncoder item encoder
+type ItemKVEncoder[T interface{ *Item }] struct {
+}
+
+func NewItemKVEncoder[T interface{ *Item }]() *ItemKVEncoder[T] {
+	return &ItemKVEncoder[T]{}
+}
+
+func (this *ItemKVEncoder[T]) Encode(value T) ([]byte, error) {
+	return json.Marshal(value)
+}
+
+func (this *ItemKVEncoder[T]) EncodeField(value T, fieldName string) ([]byte, error) {
+	switch fieldName {
+	case "createdAt":
+		var b = make([]byte, 4)
+		var createdAt = any(value).(*Item).CreatedAt
+		binary.BigEndian.PutUint32(b, uint32(createdAt))
+		return b, nil
+	case "staleAt":
+		var b = make([]byte, 4)
+		var staleAt = any(value).(*Item).StaleAt
+		if staleAt < 0 {
+			staleAt = 0
+		}
+		binary.BigEndian.PutUint32(b, uint32(staleAt))
+		return b, nil
+	case "serverId":
+		var b = make([]byte, 4)
+		var serverId = any(value).(*Item).ServerId
+		if serverId < 0 {
+			serverId = 0
+		}
+		binary.BigEndian.PutUint32(b, uint32(serverId))
+		return b, nil
+	case "key":
+		return []byte(any(value).(*Item).Key), nil
+	case "wildKey":
+		var key = any(value).(*Item).Key
+		var dotIndex = strings.Index(key, ".")
+		if dotIndex > 0 {
+			var slashIndex = strings.LastIndex(key[:dotIndex], "/")
+			if slashIndex > 0 {
+				key = key[:dotIndex][:slashIndex+1] + "*" + key[dotIndex:]
+			}
+		}
+
+		return []byte(key), nil
+	}
+	return nil, nil
+}
+
+func (this *ItemKVEncoder[T]) Decode(valueBytes []byte) (value T, err error) {
+	err = json.Unmarshal(valueBytes, &value)
+	return
+}