/
reader.go
151 lines (126 loc) · 3.06 KB
/
reader.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
package main
import (
"bufio"
"fmt"
log "github.com/Sirupsen/logrus"
"os"
"time"
)
const (
BUFFER_SIZE = 50
READ_BUFFER_SIZE = 16
CHECK_TIME = 500 * time.Millisecond
)
type Reader struct {
filename string
lastModify time.Time
position int64
channel chan string
Buffer []string
}
func (self *Reader) read() {
file, err := os.Open(self.filename)
if err != nil {
log.WithFields(log.Fields{"file": self.filename, "error": err}).Fatal("Open file error")
}
if self.position > 0 {
file.Seek(self.position, 0)
}
defer file.Close()
reader := bufio.NewReaderSize(file, READ_BUFFER_SIZE)
for {
line, err := reader.ReadString('\n')
if line != "" && line[0] == '{' {
l := fmt.Sprintf(`{"position": %d, "data": %s}`, self.getPosition(file), line)
self.channel <- l
self.Buffer = append(self.Buffer, l)
if len(self.Buffer) > BUFFER_SIZE {
self.Buffer = self.Buffer[len(self.Buffer)-BUFFER_SIZE:]
}
}
if err != nil {
break
}
}
self.savePosition(file)
}
func (self *Reader) savePosition(file *os.File) {
var err error
self.position, err = file.Seek(0, os.SEEK_CUR)
if err != nil {
log.WithField("error", err).Error("Get position error")
}
}
func (self *Reader) getPosition(file *os.File) int64 {
position, err := file.Seek(0, os.SEEK_CUR)
if err != nil {
log.WithField("error", err).Error("Get position error")
}
return position
}
func (self *Reader) GetHistory(position int64) ([]string, int64, error) {
log.WithField("position", position).Info("Get history")
result := []string{}
file, err := os.Open(self.filename)
if err != nil {
log.WithFields(log.Fields{"file": self.filename, "error": err}).Fatal("Open file error")
return result, position, err
}
newPosition, _ := file.Seek(max(position-5000, 0), 0)
defer file.Close()
log.WithField("pos", newPosition).Debug("New position")
reader := bufio.NewReaderSize(file, READ_BUFFER_SIZE)
for {
line, err := reader.ReadString('\n')
if err != nil {
break
}
if line == "" || line[0] != '{' {
continue
}
result = append(result, line)
log.WithFields(log.Fields{"line": line, "postition": self.getPosition(file)}).Debug("History loaded")
if self.getPosition(file) >= position {
break
}
}
pos, _ := file.Seek(0, os.SEEK_CUR)
log.WithFields(log.Fields{"postition": pos}).Info("History loaded")
return result, newPosition, nil
}
func (self *Reader) Watch() {
ticker := time.NewTicker(CHECK_TIME)
for {
info, err := os.Stat(self.filename)
if err != nil {
log.Errorf("Open file error")
}
if info.ModTime().After(self.lastModify) {
self.lastModify = info.ModTime()
self.read()
}
<-ticker.C
}
}
func NewReader(filename string, channel chan string) *Reader {
reader := Reader{
filename: filename,
channel: channel,
Buffer: []string{},
}
reader.read()
info, err := os.Stat(filename)
if err != nil {
log.WithField("error", err).Error("Open file error")
}
reader.lastModify = info.ModTime()
log.Info("File loaded")
return &reader
}
func max(a, b int64) int64 {
if a > b {
return a
} else {
return b
}
}