Initial commit: SRDB - High-performance LSM-Tree database
- Core engine with MemTable, SST, WAL - B+Tree indexing for SST files - Leveled compaction strategy - Multi-table database management - Schema validation and secondary indexes - Query builder with complex conditions - Web UI with HTMX for data visualization - Command-line tools for diagnostics
This commit is contained in:
265
schema.go
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265
schema.go
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package srdb
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import (
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"crypto/sha256"
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"encoding/hex"
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"fmt"
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"sort"
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"strings"
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"time"
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)
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// FieldType 字段类型
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type FieldType int
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const (
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FieldTypeInt64 FieldType = 1
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FieldTypeString FieldType = 2
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FieldTypeFloat FieldType = 3
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FieldTypeBool FieldType = 4
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)
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func (t FieldType) String() string {
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switch t {
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case FieldTypeInt64:
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return "int64"
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case FieldTypeString:
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return "string"
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case FieldTypeFloat:
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return "float64"
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case FieldTypeBool:
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return "bool"
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default:
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return "unknown"
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}
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}
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// Field 字段定义
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type Field struct {
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Name string // 字段名
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Type FieldType // 字段类型
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Indexed bool // 是否建立索引
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Comment string // 注释
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}
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// Schema 表结构定义
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type Schema struct {
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Name string // Schema 名称
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Fields []Field // 字段列表
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}
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// New 创建 Schema
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func NewSchema(name string, fields []Field) *Schema {
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return &Schema{
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Name: name,
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Fields: fields,
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}
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}
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// GetField 获取字段定义
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func (s *Schema) GetField(name string) (*Field, error) {
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for i := range s.Fields {
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if s.Fields[i].Name == name {
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return &s.Fields[i], nil
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}
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}
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return nil, fmt.Errorf("field %s not found", name)
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}
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// GetIndexedFields 获取所有需要索引的字段
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func (s *Schema) GetIndexedFields() []Field {
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var fields []Field
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for _, field := range s.Fields {
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if field.Indexed {
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fields = append(fields, field)
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}
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}
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return fields
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}
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// Validate 验证数据是否符合 Schema
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func (s *Schema) Validate(data map[string]any) error {
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for _, field := range s.Fields {
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value, exists := data[field.Name]
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if !exists {
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// 字段不存在，允许（可选字段）
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continue
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}
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// 验证类型
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if err := s.validateType(field.Type, value); err != nil {
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return fmt.Errorf("field %s: %v", field.Name, err)
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}
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}
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return nil
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}
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// ValidateType 验证值的类型（导出方法）
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func (s *Schema) ValidateType(typ FieldType, value any) error {
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return s.validateType(typ, value)
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}
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// validateType 验证值的类型
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func (s *Schema) validateType(typ FieldType, value any) error {
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switch typ {
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case FieldTypeInt64:
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switch value.(type) {
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case int, int64, int32, int16, int8:
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return nil
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case float64:
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// JSON 解析后数字都是 float64
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return nil
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default:
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return fmt.Errorf("expected int64, got %T", value)
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}
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case FieldTypeString:
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if _, ok := value.(string); !ok {
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return fmt.Errorf("expected string, got %T", value)
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}
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case FieldTypeFloat:
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switch value.(type) {
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case float64, float32:
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return nil
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default:
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return fmt.Errorf("expected float, got %T", value)
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}
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case FieldTypeBool:
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if _, ok := value.(bool); !ok {
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return fmt.Errorf("expected bool, got %T", value)
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}
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}
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return nil
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}
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// ExtractIndexValue 提取索引值
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func (s *Schema) ExtractIndexValue(field string, data map[string]any) (any, error) {
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fieldDef, err := s.GetField(field)
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if err != nil {
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return nil, err
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}
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value, exists := data[field]
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if !exists {
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return nil, fmt.Errorf("field %s not found in data", field)
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}
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// 类型转换
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switch fieldDef.Type {
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case FieldTypeInt64:
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switch v := value.(type) {
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case int:
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return int64(v), nil
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case int64:
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return v, nil
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case float64:
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return int64(v), nil
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default:
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return nil, fmt.Errorf("cannot convert %T to int64", value)
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}
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case FieldTypeString:
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if v, ok := value.(string); ok {
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return v, nil
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}
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return nil, fmt.Errorf("cannot convert %T to string", value)
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case FieldTypeFloat:
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if v, ok := value.(float64); ok {
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return v, nil
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}
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return nil, fmt.Errorf("cannot convert %T to float64", value)
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case FieldTypeBool:
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if v, ok := value.(bool); ok {
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return v, nil
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}
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return nil, fmt.Errorf("cannot convert %T to bool", value)
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}
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return nil, fmt.Errorf("unsupported type: %v", fieldDef.Type)
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}
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// ComputeChecksum 计算 Schema 的 SHA256 校验和
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// 使用确定性的字符串拼接算法，不依赖 json.Marshal
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// 这样即使 Schema struct 添加新字段，只要核心内容（Name、Fields）不变，checksum 就不会变
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// 重要：字段顺序不影响 checksum，会先按字段名排序
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// 格式: "name:<name>;fields:<field1_name>:<field1_type>:<field1_indexed>:<field1_comment>,<field2>..."
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func (s *Schema) ComputeChecksum() (string, error) {
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var builder strings.Builder
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// 1. Schema 名称
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builder.WriteString("name:")
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builder.WriteString(s.Name)
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builder.WriteString(";")
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// 2. 复制字段列表并按字段名排序（保证顺序无关性）
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sortedFields := make([]Field, len(s.Fields))
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copy(sortedFields, s.Fields)
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sort.Slice(sortedFields, func(i, j int) bool {
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return sortedFields[i].Name < sortedFields[j].Name
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})
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// 3. 拼接排序后的字段列表
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builder.WriteString("fields:")
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for i, field := range sortedFields {
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if i > 0 {
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builder.WriteString(",")
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}
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// 字段格式: name:type:indexed:comment
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builder.WriteString(field.Name)
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builder.WriteString(":")
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builder.WriteString(field.Type.String())
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builder.WriteString(":")
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if field.Indexed {
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builder.WriteString("1")
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} else {
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builder.WriteString("0")
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}
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builder.WriteString(":")
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builder.WriteString(field.Comment)
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}
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// 计算 SHA256
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hash := sha256.Sum256([]byte(builder.String()))
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return hex.EncodeToString(hash[:]), nil
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}
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// SchemaFile Schema 文件格式（带校验）
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type SchemaFile struct {
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Version int `json:"version"` // 文件格式版本
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Timestamp int64 `json:"timestamp"` // 保存时间戳
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Checksum string `json:"checksum"` // Schema 内容的 SHA256 校验和
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Schema *Schema `json:"schema"` // Schema 内容
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}
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// NewSchemaFile 创建带校验和的 Schema 文件
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func NewSchemaFile(schema *Schema) (*SchemaFile, error) {
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checksum, err := schema.ComputeChecksum()
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if err != nil {
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return nil, fmt.Errorf("compute checksum: %w", err)
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}
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return &SchemaFile{
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Version: 1, // 当前文件格式版本
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Timestamp: time.Now().Unix(),
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Checksum: checksum,
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Schema: schema,
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}, nil
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}
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// Verify 验证 Schema 文件的完整性
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func (sf *SchemaFile) Verify() error {
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if sf.Schema == nil {
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return fmt.Errorf("schema is nil")
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}
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// 重新计算 checksum
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actualChecksum, err := sf.Schema.ComputeChecksum()
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if err != nil {
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return fmt.Errorf("compute checksum: %w", err)
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}
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// 对比 checksum
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if actualChecksum != sf.Checksum {
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return fmt.Errorf("schema checksum mismatch: expected %s, got %s (schema may have been tampered with)", sf.Checksum, actualChecksum)
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}
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return nil
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}
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