1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
|
package objects
import (
"fmt"
"io"
"strconv"
"strings"
)
type ObjectType string
const (
OTBlob ObjectType = "blob"
OTFile ObjectType = "file"
OTTree ObjectType = "tree"
OTSnapshot ObjectType = "snapshot"
)
type RawObject struct {
Type ObjectType
Payload []byte
}
// Serialize writes the binary representation of an object to a io.Writer
func (o RawObject) Serialize(w io.Writer) error {
if _, err := fmt.Fprintf(w, "%s %d\n", o.Type, len(o.Payload)); err != nil {
return err
}
_, err := w.Write(o.Payload)
return err
}
func (o RawObject) SerializeAndId(w io.Writer, algo ObjectIdAlgo) (ObjectId, error) {
gen := algo.Generator()
if err := o.Serialize(io.MultiWriter(w, gen)); err != nil {
return ObjectId{}, err
}
return gen.GetId(), nil
}
type UnserializeError struct {
Reason error
}
func (err UnserializeError) Error() string {
if err.Reason == nil {
return "Invalid object"
} else {
return fmt.Sprintf("Invalid object: %s", err.Reason)
}
}
type bytewiseReader struct {
r io.Reader
buf []byte
}
func newBytewiseReader(r io.Reader) io.ByteReader {
return &bytewiseReader{
r: r,
buf: make([]byte, 1),
}
}
func (br *bytewiseReader) ReadByte() (b byte, err error) {
_, err = br.r.Read(br.buf)
b = br.buf[0]
return
}
// Unserialize attempts to read an object from a stream.
// It is advisable to pass a buffered reader, if feasible.
func Unserialize(r io.Reader) (RawObject, error) {
br := newBytewiseReader(r)
line := []byte{}
for {
b, err := br.ReadByte()
if err != nil {
return RawObject{}, UnserializeError{err}
}
if b == '\n' {
break
}
line = append(line, b)
}
parts := strings.SplitN(string(line), " ", 2)
if len(parts) != 2 {
return RawObject{}, UnserializeError{}
}
size, err := strconv.ParseUint(parts[1], 10, 64)
if err != nil {
return RawObject{}, UnserializeError{err}
}
o := RawObject{
Type: ObjectType(parts[0]),
Payload: make([]byte, size),
}
if _, err := io.ReadFull(r, o.Payload); err != nil {
return RawObject{}, UnserializeError{err}
}
return o, nil
}
type Object interface {
Type() ObjectType
Payload() []byte
FromPayload([]byte) error
}
|
