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protocol.go
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protocol.go
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package avro
import (
"crypto/md5"
"encoding/hex"
"errors"
"fmt"
"os"
jsoniter "github.com/json-iterator/go"
"github.com/mitchellh/mapstructure"
)
var (
protocolReserved = []string{"doc", "types", "messages", "protocol", "namespace"}
messageReserved = []string{"doc", "response", "request", "errors", "one-way"}
)
type protocolConfig struct {
doc string
props map[string]interface{}
}
// ProtocolOption is a function that sets a protocol option.
type ProtocolOption func(*protocolConfig)
// WithProtoDoc sets the doc on a protocol.
func WithProtoDoc(doc string) ProtocolOption {
return func(opts *protocolConfig) {
opts.doc = doc
}
}
// WithProtoProps sets the properties on a protocol.
func WithProtoProps(props map[string]interface{}) ProtocolOption {
return func(opts *protocolConfig) {
opts.props = props
}
}
// Protocol is an Avro protocol.
type Protocol struct {
name
properties
types []NamedSchema
messages map[string]*Message
doc string
hash string
}
// NewProtocol creates a protocol instance.
func NewProtocol(
name, namepsace string,
types []NamedSchema,
messages map[string]*Message,
opts ...ProtocolOption,
) (*Protocol, error) {
var cfg protocolConfig
for _, opt := range opts {
opt(&cfg)
}
n, err := newName(name, namepsace, nil)
if err != nil {
return nil, err
}
p := &Protocol{
name: n,
properties: newProperties(cfg.props, protocolReserved),
types: types,
messages: messages,
doc: cfg.doc,
}
b := md5.Sum([]byte(p.String()))
p.hash = hex.EncodeToString(b[:])
return p, nil
}
// Message returns a message with the given name or nil.
func (p *Protocol) Message(name string) *Message {
return p.messages[name]
}
// Doc returns the protocol doc.
func (p *Protocol) Doc() string {
return p.doc
}
// Hash returns the MD5 hash of the protocol.
func (p *Protocol) Hash() string {
return p.hash
}
// String returns the canonical form of the protocol.
func (p *Protocol) String() string {
types := ""
for _, f := range p.types {
types += f.String() + ","
}
if len(types) > 0 {
types = types[:len(types)-1]
}
messages := ""
for k, m := range p.messages {
messages += `"` + k + `":` + m.String() + ","
}
if len(messages) > 0 {
messages = messages[:len(messages)-1]
}
return `{"protocol":"` + p.Name() +
`","namespace":"` + p.Namespace() +
`","types":[` + types + `],"messages":{` + messages + `}}`
}
// Message is an Avro protocol message.
type Message struct {
properties
req *RecordSchema
resp Schema
errs *UnionSchema
oneWay bool
doc string
}
// NewMessage creates a protocol message instance.
func NewMessage(req *RecordSchema, resp Schema, errors *UnionSchema, oneWay bool, opts ...ProtocolOption) *Message {
var cfg protocolConfig
for _, opt := range opts {
opt(&cfg)
}
return &Message{
properties: newProperties(cfg.props, messageReserved),
req: req,
resp: resp,
errs: errors,
oneWay: oneWay,
doc: cfg.doc,
}
}
// Request returns the message request schema.
func (m *Message) Request() *RecordSchema {
return m.req
}
// Response returns the message response schema.
func (m *Message) Response() Schema {
return m.resp
}
// Errors returns the message errors union schema.
func (m *Message) Errors() *UnionSchema {
return m.errs
}
// OneWay determines of the message is a one way message.
func (m *Message) OneWay() bool {
return m.oneWay
}
// Doc returns the message doc.
func (m *Message) Doc() string {
return m.doc
}
// String returns the canonical form of the message.
func (m *Message) String() string {
fields := ""
for _, f := range m.req.fields {
fields += f.String() + ","
}
if len(fields) > 0 {
fields = fields[:len(fields)-1]
}
str := `{"request":[` + fields + `]`
if m.resp != nil {
str += `,"response":` + m.resp.String()
}
if m.errs != nil && len(m.errs.Types()) > 1 {
errs, _ := NewUnionSchema(m.errs.Types()[1:])
str += `,"errors":` + errs.String()
}
str += "}"
return str
}
// ParseProtocolFile parses an Avro protocol from a file.
func ParseProtocolFile(path string) (*Protocol, error) {
s, err := os.ReadFile(path)
if err != nil {
return nil, err
}
return ParseProtocol(string(s))
}
// MustParseProtocol parses an Avro protocol, panicing if there is an error.
func MustParseProtocol(protocol string) *Protocol {
parsed, err := ParseProtocol(protocol)
if err != nil {
panic(err)
}
return parsed
}
// ParseProtocol parses an Avro protocol.
func ParseProtocol(protocol string) (*Protocol, error) {
cache := &SchemaCache{}
var m map[string]interface{}
if err := jsoniter.Unmarshal([]byte(protocol), &m); err != nil {
return nil, err
}
return parseProtocol(m, cache)
}
type protocol struct {
Protocol string `mapstructure:"protocol"`
Namespace string `mapstructure:"namespace"`
Doc string `mapstructure:"doc"`
Types []interface{} `mapstructure:"types"`
Messages map[string]map[string]interface{} `mapstructure:"messages"`
Props map[string]interface{} `mapstructure:",remain"`
}
func parseProtocol(m map[string]interface{}, cache *SchemaCache) (*Protocol, error) {
var (
p protocol
meta mapstructure.Metadata
)
if err := decodeMap(m, &p, &meta); err != nil {
return nil, fmt.Errorf("avro: error decoding protocol: %w", err)
}
if err := checkParsedName(p.Protocol, p.Namespace, hasKey(meta.Keys, "namespace")); err != nil {
return nil, err
}
var (
types []NamedSchema
err error
)
if len(p.Types) > 0 {
types, err = parseProtocolTypes(p.Namespace, p.Types, cache)
if err != nil {
return nil, err
}
}
messages := map[string]*Message{}
if len(p.Messages) > 0 {
for k, msg := range p.Messages {
message, err := parseMessage(p.Namespace, msg, cache)
if err != nil {
return nil, err
}
messages[k] = message
}
}
return NewProtocol(p.Protocol, p.Namespace, types, messages, WithProtoDoc(p.Doc), WithProtoProps(p.Props))
}
func parseProtocolTypes(namespace string, types []interface{}, cache *SchemaCache) ([]NamedSchema, error) {
ts := make([]NamedSchema, len(types))
for i, typ := range types {
schema, err := parseType(namespace, typ, cache)
if err != nil {
return nil, err
}
namedSchema, ok := schema.(NamedSchema)
if !ok {
return nil, errors.New("avro: protocol types must be named schemas")
}
ts[i] = namedSchema
}
return ts, nil
}
type message struct {
Doc string `mapstructure:"doc"`
Request []map[string]interface{} `mapstructure:"request"`
Response interface{} `mapstructure:"response"`
Errors []interface{} `mapstructure:"errors"`
OneWay bool `mapstructure:"one-way"`
Props map[string]interface{} `mapstructure:",remain"`
}
func parseMessage(namespace string, m map[string]interface{}, cache *SchemaCache) (*Message, error) {
var (
msg message
meta mapstructure.Metadata
)
if err := decodeMap(m, &msg, &meta); err != nil {
return nil, fmt.Errorf("avro: error decoding message: %w", err)
}
fields := make([]*Field, len(msg.Request))
for i, f := range msg.Request {
field, err := parseField(namespace, f, cache)
if err != nil {
return nil, err
}
fields[i] = field
}
request := &RecordSchema{
name: name{},
properties: properties{},
fields: fields,
}
var response Schema
if msg.Response != nil {
schema, err := parseType(namespace, msg.Response, cache)
if err != nil {
return nil, err
}
if schema.Type() != Null {
response = schema
}
}
types := []Schema{NewPrimitiveSchema(String, nil)}
if len(msg.Errors) > 0 {
for _, e := range msg.Errors {
schema, err := parseType(namespace, e, cache)
if err != nil {
return nil, err
}
if rec, ok := schema.(*RecordSchema); ok && !rec.IsError() {
return nil, errors.New("avro: errors record schema must be of type error")
}
types = append(types, schema)
}
}
errs, err := NewUnionSchema(types)
if err != nil {
return nil, err
}
oneWay := msg.OneWay
if hasKey(meta.Keys, "one-way") && oneWay && (len(errs.Types()) > 1 || response != nil) {
return nil, errors.New("avro: one-way messages cannot not have a response or errors")
}
if !oneWay && len(errs.Types()) <= 1 && response == nil {
oneWay = true
}
return NewMessage(request, response, errs, oneWay, WithProtoDoc(msg.Doc), WithProtoProps(msg.Props)), nil
}