/
encoding.go
119 lines (107 loc) · 3.1 KB
/
encoding.go
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package encoding
import (
"encoding"
"errors"
"reflect"
"strings"
)
var (
// ErrNotAPointer .
ErrNotAPointer = errors.New("v argument must be a pointer")
)
// Codec defines the interface gRPC uses to encode and decode messages. Note
// that implementations of this interface must be thread safe; a Codec's
// methods can be called from concurrent goroutines.
type Codec interface {
// Marshal returns the wire format of v.
Marshal(v interface{}) ([]byte, error)
// Unmarshal parses the wire format into v.
Unmarshal(data []byte, v interface{}) error
// Name returns the name of the Codec implementation. The returned string
// will be used as part of content type in transmission. The result must be
// static; the result cannot change between calls.
Name() string
}
var registeredCodecs = make(map[string]Codec)
// RegisterCodec registers the provided Codec for use with all transport clients and
// servers.
//
// The Codec will be stored and looked up by result of its Name() method, which
// should match the content-subtype of the encoding handled by the Codec. This
// is case-insensitive, and is stored and looked up as lowercase. If the
// result of calling Name() is an empty string, RegisterCodec will panic. See
// Content-Type on
// https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md#requests for
// more details.
//
// NOTE: this function must only be called during initialization time (i.e. in
// an init() function), and is not thread-safe. If multiple Compressors are
// registered with the same name, the one registered last will take effect.
func RegisterCodec(codec Codec) {
if codec == nil {
panic("cannot register a nil Codec")
}
if codec.Name() == "" {
panic("cannot register Codec with empty string result for Name()")
}
contentSubtype := strings.ToLower(codec.Name())
registeredCodecs[contentSubtype] = codec
}
// GetCodec gets a registered Codec by content-subtype, or nil if no Codec is
// registered for the content-subtype.
//
// The content-subtype is expected to be lowercase.
func GetCodec(contentSubtype string) Codec {
return registeredCodecs[contentSubtype]
}
// Encoding 编码接口定义
type Encoding interface {
Marshal(v interface{}) ([]byte, error)
Unmarshal(data []byte, v interface{}) error
}
// Marshal encode data
func Marshal(e Encoding, v interface{}) (data []byte, err error) {
if !isPointer(v) {
return data, ErrNotAPointer
}
bm, ok := v.(encoding.BinaryMarshaler)
if ok && e == nil {
data, err = bm.MarshalBinary()
return
}
data, err = e.Marshal(v)
if err == nil {
return
}
if ok {
data, err = bm.MarshalBinary()
}
return
}
// Unmarshal decode data
func Unmarshal(e Encoding, data []byte, v interface{}) (err error) {
if !isPointer(v) {
return ErrNotAPointer
}
bm, ok := v.(encoding.BinaryUnmarshaler)
if ok && e == nil {
err = bm.UnmarshalBinary(data)
return err
}
err = e.Unmarshal(data, v)
if err == nil {
return
}
if ok {
return bm.UnmarshalBinary(data)
}
return
}
func isPointer(data interface{}) bool {
switch reflect.ValueOf(data).Kind() {
case reflect.Ptr, reflect.Interface:
return true
default:
return false
}
}