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
|
package fs
import (
"bufio"
"compress/gzip"
"context"
"fmt"
"io"
"os"
"strings"
"time"
"github.com/mimecast/dtail/internal/io/line"
"github.com/mimecast/dtail/internal/io/logger"
"github.com/mimecast/dtail/internal/lcontext"
"github.com/mimecast/dtail/internal/regex"
"github.com/DataDog/zstd"
)
// Used to tail and filter a local log file.
type readFile struct {
// Various statistics (e.g. regex hit percentage, transfer percentage).
stats
// Path of log file to tail.
filePath string
// The glob identifier of the file.
globID string
// Channel to send a server message to the dtail client
serverMessages chan<- string
// Periodically retry reading file.
retry bool
// Can I skip messages when there are too many?
canSkipLines bool
// Seek to the EOF before processing file?
seekEOF bool
limiter chan struct{}
}
func (f readFile) makeReader(fd *os.File) (reader *bufio.Reader, err error) {
switch {
case strings.HasSuffix(f.FilePath(), ".gz"):
fallthrough
case strings.HasSuffix(f.FilePath(), ".gzip"):
logger.Info(f.FilePath(), "Detected gzip compression format")
var gzipReader *gzip.Reader
gzipReader, err = gzip.NewReader(fd)
if err != nil {
return
}
reader = bufio.NewReader(gzipReader)
case strings.HasSuffix(f.FilePath(), ".zst"):
logger.Info(f.FilePath(), "Detected zstd compression format")
reader = bufio.NewReader(zstd.NewReader(fd))
default:
reader = bufio.NewReader(fd)
}
return
}
// String returns the string representation of the readFile
func (f readFile) String() string {
return fmt.Sprintf("readFile(filePath:%s,globID:%s,retry:%v,canSkipLines:%v,seekEOF:%v)",
f.filePath,
f.globID,
f.retry,
f.canSkipLines,
f.seekEOF)
}
// FilePath returns the full file path.
func (f readFile) FilePath() string {
return f.filePath
}
// Retry reading the file on error?
func (f readFile) Retry() bool {
return f.retry
}
// Start tailing a log file.
func (f readFile) Start(ctx context.Context, lContext lcontext.LContext, lines chan<- line.Line, re regex.Regex) error {
logger.Debug("readFile", f)
defer func() {
select {
case <-f.limiter:
default:
}
}()
select {
case f.limiter <- struct{}{}:
default:
select {
case f.serverMessages <- logger.Warn(f.filePath, f.globID, "Server limit reached. Queuing file..."):
case <-ctx.Done():
return nil
}
f.limiter <- struct{}{}
}
fd, err := os.Open(f.filePath)
if err != nil {
return err
}
defer fd.Close()
if f.seekEOF {
fd.Seek(0, io.SeekEnd)
}
rawLines := make(chan []byte, 100)
readCtx, readCancel := context.WithCancel(ctx)
filterDone := make(chan struct{})
go func() {
f.filter(ctx, rawLines, lines, re, lContext)
close(filterDone)
// If the filter stopped, make the reader stop too, no need to read
// more data if there is nothing more the filter wants to filter for!
// E.g. it could be that we only want to filter N matches but not more.
readCancel()
}()
err = f.read(readCtx, fd, rawLines)
close(rawLines)
// Filter may flushes some data still. So wait until it is done here.
<-filterDone
return err
}
func (f readFile) read(ctx context.Context, fd *os.File, rawLines chan []byte) error {
var offset uint64
reader, err := f.makeReader(fd)
if err != nil {
return err
}
rawLine := make([]byte, 0, 512)
lineLengthThreshold := 1024 * 1024 // 1mb
longLineWarning := false
checkTruncate := f.truncateTimer(ctx)
for {
select {
case <-ctx.Done():
return nil
default:
}
select {
case <-checkTruncate:
if isTruncated, err := f.truncated(fd); isTruncated {
return err
}
logger.Info(f.filePath, "Current offset", offset)
default:
}
// Read some bytes (max 4k at once as of go 1.12). isPrefix will
// be set if line does not fit into 4k buffer.
bytes, isPrefix, err := reader.ReadLine()
if err != nil {
// If EOF, sleep a couple of ms and return with nil error.
// If other error, return with non-nil error.
if err != io.EOF {
return err
}
if !f.seekEOF {
logger.Debug(f.FilePath(), "End of file reached")
return nil
}
time.Sleep(time.Millisecond * 100)
continue
}
rawLine = append(rawLine, bytes...)
offset += uint64(len(bytes))
if !isPrefix {
// last LineRead call returned contend until end of line.
rawLine = append(rawLine, '\n')
select {
case rawLines <- rawLine:
case <-ctx.Done():
return nil
}
rawLine = make([]byte, 0, 512)
if longLineWarning {
longLineWarning = false
}
continue
}
// Last LineRead call could not read content until end of line, buffer
// was too small. Determine whether we exceed the max line length we
// want dtail to send to the client at once. Possibly split up log line
// into multiple log lines.
if len(rawLine) >= lineLengthThreshold {
if !longLineWarning {
f.serverMessages <- logger.Warn(f.filePath, "Long log line, splitting into multiple lines")
// Only print out one warning per long log line.
longLineWarning = true
}
rawLine = append(rawLine, '\n')
select {
case rawLines <- rawLine:
case <-ctx.Done():
return nil
}
rawLine = make([]byte, 0, 512)
}
}
}
|
