-
Notifications
You must be signed in to change notification settings - Fork 569
/
checksum.go
242 lines (230 loc) · 5.11 KB
/
checksum.go
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
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
package server
import (
"crypto/md5"
"errors"
"fmt"
"io"
"os"
"time"
"github.com/tidwall/resp"
"github.com/tidwall/tile38/internal/log"
)
// checksum performs a simple md5 checksum on the aof file
func (s *Server) checksum(pos, size int64) (sum string, err error) {
if pos+size > int64(s.aofsz) {
return "", io.EOF
}
var f *os.File
f, err = os.Open(s.aof.Name())
if err != nil {
return
}
defer f.Close()
sumr := md5.New()
err = func() error {
if size == 0 {
n, err := f.Seek(int64(s.aofsz), 0)
if err != nil {
return err
}
if pos >= n {
return io.EOF
}
return nil
}
_, err = f.Seek(pos, 0)
if err != nil {
return err
}
_, err = io.CopyN(sumr, f, size)
if err != nil {
return err
}
return nil
}()
if err != nil {
if err == io.ErrUnexpectedEOF {
err = io.EOF
}
return "", err
}
return fmt.Sprintf("%x", sumr.Sum(nil)), nil
}
func connAOFMD5(conn *RESPConn, pos, size int64) (sum string, err error) {
v, err := conn.Do("aofmd5", pos, size)
if err != nil {
return "", err
}
if v.Error() != nil {
errmsg := v.Error().Error()
if errmsg == "ERR EOF" || errmsg == "EOF" {
return "", io.EOF
}
return "", v.Error()
}
sum = v.String()
if len(sum) != 32 {
return "", errors.New("checksum not ok")
}
return sum, nil
}
func (s *Server) matchChecksums(conn *RESPConn, pos, size int64) (match bool, err error) {
sum, err := s.checksum(pos, size)
if err != nil {
if err == io.EOF {
return false, nil
}
return false, err
}
csum, err := connAOFMD5(conn, pos, size)
if err != nil {
if err == io.EOF {
return false, nil
}
return false, err
}
return csum == sum, nil
}
// getEndOfLastValuePositionInFile is a very slow operation because it reads the file
// backwards on byte at a time. Eek. It seek+read, seek+read, etc.
func getEndOfLastValuePositionInFile(fname string, startPos int64) (int64, error) {
pos := startPos
f, err := os.Open(fname)
if err != nil {
return 0, err
}
defer f.Close()
readByte := func() (byte, error) {
if pos <= 0 {
return 0, io.EOF
}
pos--
if _, err := f.Seek(pos, 0); err != nil {
return 0, err
}
b := make([]byte, 1)
if n, err := f.Read(b); err != nil {
return 0, err
} else if n != 1 {
return 0, errors.New("invalid read")
}
return b[0], nil
}
for {
c, err := readByte()
if err != nil {
return 0, err
}
if c == '*' {
if _, err := f.Seek(pos, 0); err != nil {
return 0, err
}
rd := resp.NewReader(f)
_, telnet, n, err := rd.ReadMultiBulk()
if err != nil || telnet {
continue // keep reading backwards
}
return pos + int64(n), nil
}
}
}
// followCheckSome is not a full checksum. It just "checks some" data.
// We will do some various checksums on the leader until we find the correct position to start at.
func (s *Server) followCheckSome(addr string, followc int, auth string,
) (pos int64, err error) {
if s.opts.ShowDebugMessages {
log.Debug("follow:", addr, ":check some")
}
s.mu.Lock()
defer s.mu.Unlock()
if int(s.followc.Load()) != followc {
return 0, errNoLongerFollowing
}
if s.aofsz < checksumsz {
return 0, nil
}
conn, err := DialTimeout(addr, time.Second*2)
if err != nil {
return 0, err
}
defer conn.Close()
if auth != "" {
if err := s.followDoLeaderAuth(conn, auth); err != nil {
return 0, err
}
}
min := int64(0)
max := int64(s.aofsz) - checksumsz
limit := int64(s.aofsz)
match, err := s.matchChecksums(conn, min, checksumsz)
if err != nil {
return 0, err
}
if match {
min += checksumsz // bump up the min
for {
if max < min || max+checksumsz > limit {
pos = min
break
} else {
match, err = s.matchChecksums(conn, max, checksumsz)
if err != nil {
return 0, err
}
if match {
min = max + checksumsz
} else {
limit = max
}
max = (limit-min)/2 - checksumsz/2 + min // multiply
}
}
}
fullpos := pos
fname := s.aof.Name()
if pos == 0 {
s.aof.Close()
s.aof, err = os.Create(fname)
if err != nil {
log.Fatalf("could not recreate aof, possible data loss. %s", err.Error())
return 0, err
}
return 0, nil
}
// we want to truncate at a command location
// search for nearest command
pos, err = getEndOfLastValuePositionInFile(s.aof.Name(), fullpos)
if err != nil {
return 0, err
}
if pos == fullpos {
if s.opts.ShowDebugMessages {
log.Debug("follow: aof fully intact")
}
return pos, nil
}
log.Warnf("truncating aof to %d", pos)
// any errror below are fatal.
s.aof.Close()
if err := os.Truncate(fname, pos); err != nil {
log.Fatalf("could not truncate aof, possible data loss. %s", err.Error())
return 0, err
}
s.aof, err = os.OpenFile(fname, os.O_CREATE|os.O_RDWR, 0600)
if err != nil {
log.Fatalf("could not create aof, possible data loss. %s", err.Error())
return 0, err
}
// reset the entire system.
log.Infof("reloading aof commands")
s.reset()
if err := s.loadAOF(); err != nil {
log.Fatalf("could not reload aof, possible data loss. %s", err.Error())
return 0, err
}
if int64(s.aofsz) != pos {
log.Fatalf("aof size mismatch during reload, possible data loss.")
return 0, errors.New("?")
}
return pos, nil
}