108 lines
2.9 KiB
Go
108 lines
2.9 KiB
Go
// Package codec is an interface for encoding messages
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package codec // import "go.unistack.org/micro/v3/codec"
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import (
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"errors"
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"io"
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"go.unistack.org/micro/v3/metadata"
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)
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// Message types
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const (
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Error MessageType = iota
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Request
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Response
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Event
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)
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var (
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// ErrInvalidMessage returned when invalid messge passed to codec
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ErrInvalidMessage = errors.New("invalid message")
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// ErrUnknownContentType returned when content-type is unknown
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ErrUnknownContentType = errors.New("unknown content-type")
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)
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var (
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// DefaultMaxMsgSize specifies how much data codec can handle
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DefaultMaxMsgSize = 1024 * 1024 * 4 // 4Mb
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// DefaultCodec is the global default codec
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DefaultCodec = NewCodec()
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// DefaultTagName specifies struct tag name to control codec Marshal/Unmarshal
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DefaultTagName = "codec"
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)
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// MessageType specifies message type for codec
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type MessageType int
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// Codec encodes/decodes various types of messages used within micro.
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// ReadHeader and ReadBody are called in pairs to read requests/responses
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// from the connection. Close is called when finished with the
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// connection. ReadBody may be called with a nil argument to force the
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// body to be read and discarded.
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type Codec interface {
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ReadHeader(r io.Reader, m *Message, mt MessageType) error
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ReadBody(r io.Reader, v interface{}) error
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Write(w io.Writer, m *Message, v interface{}) error
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Marshal(v interface{}, opts ...Option) ([]byte, error)
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Unmarshal(b []byte, v interface{}, opts ...Option) error
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String() string
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}
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// Message represents detailed information about
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// the communication, likely followed by the body.
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// In the case of an error, body may be nil.
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type Message struct {
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Header metadata.Metadata
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Target string
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Method string
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Endpoint string
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Error string
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ID string
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Body []byte
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Type MessageType
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}
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// NewMessage creates new codec message
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func NewMessage(t MessageType) *Message {
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return &Message{Type: t, Header: metadata.New(0)}
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}
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// MarshalAppend calls codec.Marshal(v) and returns the data appended to buf.
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// If codec implements MarshalAppend, that is called instead.
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func MarshalAppend(buf []byte, c Codec, v interface{}, opts ...Option) ([]byte, error) {
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if nc, ok := c.(interface {
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MarshalAppend([]byte, interface{}, ...Option) ([]byte, error)
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}); ok {
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return nc.MarshalAppend(buf, v, opts...)
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}
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mbuf, err := c.Marshal(v, opts...)
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if err != nil {
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return nil, err
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}
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return append(buf, mbuf...), nil
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}
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// RawMessage is a raw encoded JSON value.
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// It implements Marshaler and Unmarshaler and can be used to delay decoding or precompute a encoding.
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type RawMessage []byte
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// MarshalJSON returns m as the JSON encoding of m.
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func (m *RawMessage) MarshalJSON() ([]byte, error) {
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if m == nil {
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return []byte("null"), nil
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}
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return *m, nil
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}
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// UnmarshalJSON sets *m to a copy of data.
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func (m *RawMessage) UnmarshalJSON(data []byte) error {
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if m == nil {
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return errors.New("RawMessage UnmarshalJSON on nil pointer")
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}
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*m = append((*m)[0:0], data...)
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return nil
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}
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