msgpack · pkg.go.dev

README

MessagePack encoding for Golang

Supports:

Primitives, arrays, maps, structs, time.Time and interface{}.
Appengine *datastore.Key and datastore.Cursor.
CustomEncoder/CustomDecoder interfaces for custom encoding.
Extensions to encode type information.
Renaming fields via msgpack:"my_field_name".
Omitting individual empty fields via msgpack:",omitempty" tag or all empty fields in a struct.
Map keys sorting.
Encoding/decoding all structs as arrays or individual structs.
Encoder.UseJSONTag with Decoder.UseJSONTag can turn msgpack into drop-in replacement for JSON.
Simple but very fast and efficient queries.

API docs: https://godoc.org/github.com/vmihailenco/msgpack. Examples: https://godoc.org/github.com/vmihailenco/msgpack#pkg-examples.

Installation

Install:

go get -u github.com/vmihailenco/msgpack

Quickstart

func ExampleMarshal() {
	type Item struct {
		Foo string
	}

	b, err := msgpack.Marshal(&Item{Foo: "bar"})
	if err != nil {
		panic(err)
	}

	var item Item
	err = msgpack.Unmarshal(b, &item)
	if err != nil {
		panic(err)
	}
	fmt.Println(item.Foo)
	// Output: bar
}

Benchmark

BenchmarkStructVmihailencoMsgpack-4   	  200000	     12814 ns/op	    2128 B/op	      26 allocs/op
BenchmarkStructUgorjiGoMsgpack-4      	  100000	     17678 ns/op	    3616 B/op	      70 allocs/op
BenchmarkStructUgorjiGoCodec-4        	  100000	     19053 ns/op	    7346 B/op	      23 allocs/op
BenchmarkStructJSON-4                 	   20000	     69438 ns/op	    7864 B/op	      26 allocs/op
BenchmarkStructGOB-4                  	   10000	    104331 ns/op	   14664 B/op	     278 allocs/op

Howto

Please go through examples to get an idea how to use this package.

Documentation

Index ¶

func Marshal(v interface{}) ([]byte, error)
func Register(value interface{}, enc encoderFunc, dec decoderFunc)
func RegisterExt(id int8, value interface{})
func Unmarshal(data []byte, v interface{}) error
type CustomDecoder
type CustomEncoder
type Decoder
- func NewDecoder(r io.Reader) *Decoder
type Encoder
- func NewEncoder(w io.Writer) *Encoder
type Marshaler
type Unmarshaler

Constants ¶

This section is empty.

Variables ¶

This section is empty.

Functions ¶

func Marshal ¶

func Marshal(v interface{}) ([]byte, error)

Marshal returns the MessagePack encoding of v.

Example ¶

package main

import (
	"fmt"

	"github.com/vmihailenco/msgpack"
)

func main() {
	type Item struct {
		Foo string
	}

	b, err := msgpack.Marshal(&Item{Foo: "bar"})
	if err != nil {
		panic(err)
	}

	var item Item
	err = msgpack.Unmarshal(b, &item)
	if err != nil {
		panic(err)
	}
	fmt.Println(item.Foo)
}

Output:

bar

Example (AsArray) ¶

package main

import (
	"bytes"
	"fmt"

	"github.com/vmihailenco/msgpack"
)

func main() {
	type Item struct {
		_msgpack struct{} `msgpack:",asArray"`
		Foo      string
		Bar      string
	}

	var buf bytes.Buffer
	enc := msgpack.NewEncoder(&buf)
	err := enc.Encode(&Item{Foo: "foo", Bar: "bar"})
	if err != nil {
		panic(err)
	}

	dec := msgpack.NewDecoder(&buf)
	v, err := dec.DecodeInterface()
	if err != nil {
		panic(err)
	}
	fmt.Println(v)
}

Output:

[foo bar]

Example (MapStringInterface) ¶

package main

import (
	"fmt"

	"github.com/vmihailenco/msgpack"
)

func main() {
	in := map[string]interface{}{"foo": 1, "hello": "world"}
	b, err := msgpack.Marshal(in)
	if err != nil {
		panic(err)
	}

	var out map[string]interface{}
	err = msgpack.Unmarshal(b, &out)
	if err != nil {
		panic(err)
	}

	fmt.Println("foo =", out["foo"])
	fmt.Println("hello =", out["hello"])

}

Output:

foo = 1
hello = world

Example (OmitEmpty) ¶

package main

import (
	"fmt"

	"github.com/vmihailenco/msgpack"
)

func main() {
	type Item struct {
		Foo string
		Bar string
	}

	item := &Item{
		Foo: "hello",
	}
	b, err := msgpack.Marshal(item)
	if err != nil {
		panic(err)
	}
	fmt.Printf("item: %q\n", b)

	type ItemOmitEmpty struct {
		_msgpack struct{} `msgpack:",omitempty"`
		Foo      string
		Bar      string
	}

	itemOmitEmpty := &ItemOmitEmpty{
		Foo: "hello",
	}
	b, err = msgpack.Marshal(itemOmitEmpty)
	if err != nil {
		panic(err)
	}
	fmt.Printf("item2: %q\n", b)

}

Output:

item: "\x82\xa3Foo\xa5hello\xa3Bar\xa0"
item2: "\x81\xa3Foo\xa5hello"

func Register ¶

func Register(value interface{}, enc encoderFunc, dec decoderFunc)

Register registers encoder and decoder functions for a value. This is low level API and in most cases you should prefer implementing Marshaler/CustomEncoder and Unmarshaler/CustomDecoder interfaces.

func RegisterExt ¶

func RegisterExt(id int8, value interface{})

RegisterExt records a type, identified by a value for that type, under the provided id. That id will identify the concrete type of a value sent or received as an interface variable. Only types that will be transferred as implementations of interface values need to be registered. Expecting to be used only during initialization, it panics if the mapping between types and ids is not a bijection.

Example ¶

package main

import (
	"encoding/binary"
	"fmt"
	"time"

	"github.com/vmihailenco/msgpack"
)

func init() {
	msgpack.RegisterExt(1, (*EventTime)(nil))
}

// https://github.com/fluent/fluentd/wiki/Forward-Protocol-Specification-v1#eventtime-ext-format
type EventTime struct {
	time.Time
}

var _ msgpack.Marshaler = (*EventTime)(nil)
var _ msgpack.Unmarshaler = (*EventTime)(nil)

func (tm *EventTime) MarshalMsgpack() ([]byte, error) {
	b := make([]byte, 8)
	binary.BigEndian.PutUint32(b, uint32(tm.Unix()))
	binary.BigEndian.PutUint32(b[4:], uint32(tm.Nanosecond()))
	return b, nil
}

func (tm *EventTime) UnmarshalMsgpack(b []byte) error {
	if len(b) != 8 {
		return fmt.Errorf("invalid data length: got %d, wanted 8", len(b))
	}
	sec := binary.BigEndian.Uint32(b)
	usec := binary.BigEndian.Uint32(b[4:])
	tm.Time = time.Unix(int64(sec), int64(usec))
	return nil
}

func main() {
	b, err := msgpack.Marshal(&EventTime{time.Unix(123456789, 123)})
	if err != nil {
		panic(err)
	}

	var v interface{}
	err = msgpack.Unmarshal(b, &v)
	if err != nil {
		panic(err)
	}
	fmt.Println(v.(*EventTime).UTC())

	tm := new(EventTime)
	err = msgpack.Unmarshal(b, tm)
	if err != nil {
		panic(err)
	}
	fmt.Println(tm.UTC())

}

Output:

1973-11-29 21:33:09.000000123 +0000 UTC
1973-11-29 21:33:09.000000123 +0000 UTC

func Unmarshal ¶

func Unmarshal(data []byte, v interface{}) error

Unmarshal decodes the MessagePack-encoded data and stores the result in the value pointed to by v.

Types ¶

type CustomDecoder ¶

type CustomDecoder interface {
	DecodeMsgpack(*Decoder) error
}

type CustomEncoder ¶

type CustomEncoder interface {
	EncodeMsgpack(*Encoder) error
}

Example ¶

package main

import (
	"fmt"

	"github.com/vmihailenco/msgpack"
)

type customStruct struct {
	S string
	N int
}

var _ msgpack.CustomEncoder = (*customStruct)(nil)
var _ msgpack.CustomDecoder = (*customStruct)(nil)

func (s *customStruct) EncodeMsgpack(enc *msgpack.Encoder) error {
	return enc.EncodeMulti(s.S, s.N)
}

func (s *customStruct) DecodeMsgpack(dec *msgpack.Decoder) error {
	return dec.DecodeMulti(&s.S, &s.N)
}

func main() {
	b, err := msgpack.Marshal(&customStruct{S: "hello", N: 42})
	if err != nil {
		panic(err)
	}

	var v customStruct
	err = msgpack.Unmarshal(b, &v)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%#v", v)
}

Output:

msgpack_test.customStruct{S:"hello", N:42}

type Decoder ¶

type Decoder struct {
	// contains filtered or unexported fields
}

func NewDecoder ¶

func NewDecoder(r io.Reader) *Decoder

NewDecoder returns a new decoder that reads from r.

The decoder introduces its own buffering and may read data from r beyond the MessagePack values requested. Buffering can be disabled by passing a reader that implements io.ByteScanner interface.

func (*Decoder) Decode ¶

func (d *Decoder) Decode(v interface{}) error

func (*Decoder) DecodeArrayLen ¶

func (d *Decoder) DecodeArrayLen() (int, error)

DecodeArrayLen decodes array length. Length is -1 when array is nil.

func (*Decoder) DecodeBool ¶

func (d *Decoder) DecodeBool() (bool, error)

func (*Decoder) DecodeBytes ¶

func (d *Decoder) DecodeBytes() ([]byte, error)

func (*Decoder) DecodeBytesLen ¶

func (d *Decoder) DecodeBytesLen() (int, error)

func (*Decoder) DecodeExtHeader ¶

func (d *Decoder) DecodeExtHeader() (typeId int8, length int, err error)

func (*Decoder) DecodeFloat32 ¶

func (d *Decoder) DecodeFloat32() (float32, error)

func (*Decoder) DecodeFloat64 ¶

func (d *Decoder) DecodeFloat64() (float64, error)

DecodeFloat64 decodes msgpack float32/64 into Go float64.

func (*Decoder) DecodeInt ¶

func (d *Decoder) DecodeInt() (int, error)

func (*Decoder) DecodeInt16 ¶

func (d *Decoder) DecodeInt16() (int16, error)

func (*Decoder) DecodeInt32 ¶

func (d *Decoder) DecodeInt32() (int32, error)

func (*Decoder) DecodeInt64 ¶

func (d *Decoder) DecodeInt64() (int64, error)

DecodeInt64 decodes msgpack int8/16/32/64 and uint8/16/32/64 into Go int64.

func (*Decoder) DecodeInt8 ¶

func (d *Decoder) DecodeInt8() (int8, error)

func (*Decoder) DecodeInterface ¶

func (d *Decoder) DecodeInterface() (interface{}, error)

DecodeInterface decodes value into interface. It returns following types:

- nil,
- bool,
- int8, int16, int32, int64,
- uint8, uint16, uint32, uint64,
- float32 and float64,
- string,
- []byte,
- slices of any of the above,
- maps of any of the above.

DecodeInterface should be used only when you don't know the type of value you are decoding. For example, if you are decoding number it is better to use DecodeInt64 for negative numbers and DecodeUint64 for positive numbers.

func (*Decoder) DecodeInterfaceLoose ¶

func (d *Decoder) DecodeInterfaceLoose() (interface{}, error)

DecodeInterfaceLoose is like DecodeInterface except that:

- int8, int16, and int32 are converted to int64,
- uint8, uint16, and uint32 are converted to uint64,
- float32 is converted to float64.

func (*Decoder) DecodeMap ¶

func (d *Decoder) DecodeMap() (interface{}, error)

func (*Decoder) DecodeMapLen ¶

func (d *Decoder) DecodeMapLen() (int, error)

DecodeMapLen decodes map length. Length is -1 when map is nil.

func (*Decoder) DecodeMulti ¶

func (d *Decoder) DecodeMulti(v ...interface{}) error

func (*Decoder) DecodeNil ¶

func (d *Decoder) DecodeNil() error

func (*Decoder) DecodeSlice ¶

func (d *Decoder) DecodeSlice() ([]interface{}, error)

func (*Decoder) DecodeString ¶

func (d *Decoder) DecodeString() (string, error)

func (*Decoder) DecodeTime ¶

func (d *Decoder) DecodeTime() (time.Time, error)

func (*Decoder) DecodeUint ¶

func (d *Decoder) DecodeUint() (uint, error)

func (*Decoder) DecodeUint16 ¶

func (d *Decoder) DecodeUint16() (uint16, error)

func (*Decoder) DecodeUint32 ¶

func (d *Decoder) DecodeUint32() (uint32, error)

func (*Decoder) DecodeUint64 ¶

func (d *Decoder) DecodeUint64() (uint64, error)

DecodeUint64 decodes msgpack int8/16/32/64 and uint8/16/32/64 into Go uint64.

func (*Decoder) DecodeUint8 ¶

func (d *Decoder) DecodeUint8() (uint8, error)

func (*Decoder) DecodeValue ¶

func (d *Decoder) DecodeValue(v reflect.Value) error

func (*Decoder) PeekCode ¶

func (d *Decoder) PeekCode() (codes.Code, error)

PeekCode returns the next MessagePack code without advancing the reader. Subpackage msgpack/codes contains list of available codes.

func (*Decoder) Query ¶

func (d *Decoder) Query(query string) ([]interface{}, error)

Query extracts data specified by the query from the msgpack stream skipping any other data. Query consists of map keys and array indexes separated with dot, e.g. key1.0.key2.

Example ¶

package main

import (
	"bytes"
	"fmt"

	"github.com/vmihailenco/msgpack"
)

func main() {
	b, err := msgpack.Marshal([]map[string]interface{}{
		{"id": 1, "attrs": map[string]interface{}{"phone": 12345}},
		{"id": 2, "attrs": map[string]interface{}{"phone": 54321}},
	})
	if err != nil {
		panic(err)
	}

	dec := msgpack.NewDecoder(bytes.NewBuffer(b))
	values, err := dec.Query("*.attrs.phone")
	if err != nil {
		panic(err)
	}
	fmt.Println("phones are", values)

	dec.Reset(bytes.NewBuffer(b))
	values, err = dec.Query("1.attrs.phone")
	if err != nil {
		panic(err)
	}
	fmt.Println("2nd phone is", values[0])
}

Output:

phones are [12345 54321]
2nd phone is 54321

func (*Decoder) Reset ¶

func (d *Decoder) Reset(r io.Reader) error

func (*Decoder) SetDecodeMapFunc ¶

func (d *Decoder) SetDecodeMapFunc(fn func(*Decoder) (interface{}, error))

Example ¶

package main

import (
	"bytes"
	"fmt"

	"github.com/vmihailenco/msgpack"
)

func main() {
	buf := new(bytes.Buffer)

	enc := msgpack.NewEncoder(buf)
	in := map[string]string{"hello": "world"}
	err := enc.Encode(in)
	if err != nil {
		panic(err)
	}

	dec := msgpack.NewDecoder(buf)

	// Causes decoder to produce map[string]string instead of map[string]interface{}.
	dec.SetDecodeMapFunc(func(d *msgpack.Decoder) (interface{}, error) {
		n, err := d.DecodeMapLen()
		if err != nil {
			return nil, err
		}

		m := make(map[string]string, n)
		for i := 0; i < n; i++ {
			mk, err := d.DecodeString()
			if err != nil {
				return nil, err
			}

			mv, err := d.DecodeString()
			if err != nil {
				return nil, err
			}

			m[mk] = mv
		}
		return m, nil
	})

	out, err := dec.DecodeInterface()
	if err != nil {
		panic(err)
	}
	fmt.Printf("%#v", out)
}

Output:

map[string]string{"hello":"world"}

func (*Decoder) Skip ¶

func (d *Decoder) Skip() error

Skip skips next value.

func (*Decoder) UseDecodeInterfaceLoose ¶

func (d *Decoder) UseDecodeInterfaceLoose(flag bool) *Decoder

UseDecodeInterfaceLoose causes decoder to use DecodeInterfaceLoose to decode msgpack value into Go interface{}.

func (*Decoder) UseJSONTag ¶

func (d *Decoder) UseJSONTag(v bool) *Decoder

UseJSONTag causes the Decoder to use json struct tag as fallback option if there is no msgpack tag.

type Encoder ¶

type Encoder struct {
	// contains filtered or unexported fields
}

func NewEncoder ¶

func NewEncoder(w io.Writer) *Encoder

NewEncoder returns a new encoder that writes to w.

func (*Encoder) Encode ¶

func (e *Encoder) Encode(v interface{}) error

func (*Encoder) EncodeArrayLen ¶

func (e *Encoder) EncodeArrayLen(l int) error

func (*Encoder) EncodeBool ¶

func (e *Encoder) EncodeBool(value bool) error

func (*Encoder) EncodeBytes ¶

func (e *Encoder) EncodeBytes(v []byte) error

func (*Encoder) EncodeBytesLen ¶

func (e *Encoder) EncodeBytesLen(l int) error

func (*Encoder) EncodeExtHeader ¶

func (e *Encoder) EncodeExtHeader(typeId int8, length int) error

func (*Encoder) EncodeFloat32 ¶

func (e *Encoder) EncodeFloat32(n float32) error

func (*Encoder) EncodeFloat64 ¶

func (e *Encoder) EncodeFloat64(n float64) error

func (*Encoder) EncodeInt ¶

func (e *Encoder) EncodeInt(n int64) error

EncodeNumber encodes an int64 in 1, 2, 3, 5, or 9 bytes. Type of number is lost during encoding.

func (*Encoder) EncodeInt16 ¶

func (e *Encoder) EncodeInt16(n int16) error

EncodeInt16 encodes an int16 in 3 bytes preserving type of the number.

func (*Encoder) EncodeInt32 ¶

func (e *Encoder) EncodeInt32(n int32) error

EncodeInt32 encodes an int32 in 5 bytes preserving type of the number.

func (*Encoder) EncodeInt64 ¶

func (e *Encoder) EncodeInt64(n int64) error

EncodeInt64 encodes an int64 in 9 bytes preserving type of the number.

func (*Encoder) EncodeInt8 ¶

func (e *Encoder) EncodeInt8(n int8) error

EncodeInt8 encodes an int8 in 2 bytes preserving type of the number.

func (*Encoder) EncodeMapLen ¶

func (e *Encoder) EncodeMapLen(l int) error

func (*Encoder) EncodeMulti ¶

func (e *Encoder) EncodeMulti(v ...interface{}) error

func (*Encoder) EncodeNil ¶

func (e *Encoder) EncodeNil() error

func (*Encoder) EncodeString ¶

func (e *Encoder) EncodeString(v string) error

func (*Encoder) EncodeTime ¶

func (e *Encoder) EncodeTime(tm time.Time) error

func (*Encoder) EncodeUint ¶

func (e *Encoder) EncodeUint(n uint64) error

EncodeUnsignedNumber encodes an uint64 in 1, 2, 3, 5, or 9 bytes. Type of the number is lost during encoding.

func (*Encoder) EncodeUint16 ¶

func (e *Encoder) EncodeUint16(n uint16) error

EncodeUint16 encodes an uint16 in 3 bytes preserving type of the number.

func (*Encoder) EncodeUint32 ¶

func (e *Encoder) EncodeUint32(n uint32) error

EncodeUint32 encodes an uint16 in 5 bytes preserving type of the number.

func (*Encoder) EncodeUint64 ¶

func (e *Encoder) EncodeUint64(n uint64) error

EncodeUint64 encodes an uint16 in 9 bytes preserving type of the number.

func (*Encoder) EncodeUint8 ¶

func (e *Encoder) EncodeUint8(n uint8) error

EncodeUint8 encodes an uint8 in 2 bytes preserving type of the number.

func (*Encoder) EncodeValue ¶

func (e *Encoder) EncodeValue(v reflect.Value) error

func (*Encoder) SortMapKeys ¶

func (e *Encoder) SortMapKeys(flag bool) *Encoder

SortMapKeys causes the Encoder to encode map keys in increasing order. Supported map types are:

- map[string]string
- map[string]interface{}

func (*Encoder) StructAsArray ¶

func (e *Encoder) StructAsArray(flag bool) *Encoder

StructAsArray causes the Encoder to encode Go structs as MessagePack arrays.

Example ¶

package main

import (
	"bytes"
	"fmt"

	"github.com/vmihailenco/msgpack"
)

func main() {
	type Item struct {
		Foo string
		Bar string
	}

	var buf bytes.Buffer
	enc := msgpack.NewEncoder(&buf).StructAsArray(true)
	err := enc.Encode(&Item{Foo: "foo", Bar: "bar"})
	if err != nil {
		panic(err)
	}

	dec := msgpack.NewDecoder(&buf)
	v, err := dec.DecodeInterface()
	if err != nil {
		panic(err)
	}
	fmt.Println(v)
}

Output:

[foo bar]

func (*Encoder) UseCompactEncoding ¶

func (e *Encoder) UseCompactEncoding(flag bool) *Encoder

UseCompactEncoding causes the Encoder to chose the most compact encoding. For example, it allows to encode Go int64 as msgpack int8 saving 7 bytes.

func (*Encoder) UseJSONTag ¶

func (e *Encoder) UseJSONTag(flag bool) *Encoder

UseJSONTag causes the Encoder to use json struct tag as fallback option if there is no msgpack tag.

type Marshaler ¶

type Marshaler interface {
	MarshalMsgpack() ([]byte, error)
}

type Unmarshaler ¶

type Unmarshaler interface {
	UnmarshalMsgpack([]byte) error
}

Source Files

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README

MessagePack encoding for Golang

Installation

Quickstart

Benchmark

Howto

See also

Documentation

Index ¶

Examples ¶

Constants ¶

Variables ¶

Functions ¶

func Marshal ¶

func Register ¶

func RegisterExt ¶

func Unmarshal ¶

Types ¶

type CustomDecoder ¶

type CustomEncoder ¶

type Decoder ¶

func NewDecoder ¶

func (*Decoder) Decode ¶

func (*Decoder) DecodeArrayLen ¶

func (*Decoder) DecodeBool ¶

func (*Decoder) DecodeBytes ¶

func (*Decoder) DecodeBytesLen ¶

func (*Decoder) DecodeExtHeader ¶

func (*Decoder) DecodeFloat32 ¶

func (*Decoder) DecodeFloat64 ¶

func (*Decoder) DecodeInt ¶

func (*Decoder) DecodeInt16 ¶

func (*Decoder) DecodeInt32 ¶

func (*Decoder) DecodeInt64 ¶

func (*Decoder) DecodeInt8 ¶

func (*Decoder) DecodeInterface ¶

func (*Decoder) DecodeInterfaceLoose ¶

func (*Decoder) DecodeMap ¶

func (*Decoder) DecodeMapLen ¶

func (*Decoder) DecodeMulti ¶

func (*Decoder) DecodeNil ¶

func (*Decoder) DecodeSlice ¶

func (*Decoder) DecodeString ¶

func (*Decoder) DecodeTime ¶

func (*Decoder) DecodeUint ¶

func (*Decoder) DecodeUint16 ¶

func (*Decoder) DecodeUint32 ¶

func (*Decoder) DecodeUint64 ¶

func (*Decoder) DecodeUint8 ¶

func (*Decoder) DecodeValue ¶

func (*Decoder) PeekCode ¶

func (*Decoder) Query ¶

func (*Decoder) Reset ¶

func (*Decoder) SetDecodeMapFunc ¶

func (*Decoder) Skip ¶

func (*Decoder) UseDecodeInterfaceLoose ¶

func (*Decoder) UseJSONTag ¶

type Encoder ¶

func NewEncoder ¶

func (*Encoder) Encode ¶

func (*Encoder) EncodeArrayLen ¶

func (*Encoder) EncodeBool ¶

func (*Encoder) EncodeBytes ¶

func (*Encoder) EncodeBytesLen ¶

func (*Encoder) EncodeExtHeader ¶

func (*Encoder) EncodeFloat32 ¶

func (*Encoder) EncodeFloat64 ¶

func (*Encoder) EncodeInt ¶

func (*Encoder) EncodeInt16 ¶

func (*Encoder) EncodeInt32 ¶

func (*Encoder) EncodeInt64 ¶

func (*Encoder) EncodeInt8 ¶

func (*Encoder) EncodeMapLen ¶

func (*Encoder) EncodeMulti ¶

func (*Encoder) EncodeNil ¶

func (*Encoder) EncodeString ¶

func (*Encoder) EncodeTime ¶

func (*Encoder) EncodeUint ¶

func (*Encoder) EncodeUint16 ¶

func (*Encoder) EncodeUint32 ¶