/
buffered_write_syncer.go
187 lines (159 loc) · 5.37 KB
/
buffered_write_syncer.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
// Copyright (c) 2021 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package zapcore
import (
"bufio"
"sync"
"time"
"go.uber.org/multierr"
)
const (
// _defaultBufferSize specifies the default size used by Buffer.
_defaultBufferSize = 256 * 1024 // 256 kB
// _defaultFlushInterval specifies the default flush interval for
// Buffer.
_defaultFlushInterval = 30 * time.Second
)
// A BufferedWriteSyncer is a WriteSyncer that buffers writes in-memory before
// flushing them to a wrapped WriteSyncer after reaching some limit, or at some
// fixed interval--whichever comes first.
//
// BufferedWriteSyncer is safe for concurrent use. You don't need to use
// zapcore.Lock for WriteSyncers with BufferedWriteSyncer.
type BufferedWriteSyncer struct {
// WS is the WriteSyncer around which BufferedWriteSyncer will buffer
// writes. The provided WriteSyncer must not be used directly once
// wrapped in a BufferedWriteSyncer.
//
// This field is required.
WS WriteSyncer
// Size specifies the maximum amount of data the writer will buffered
// before flushing.
//
// Defaults to 256 kB if unspecified.
Size int
// FlushInterval specifies how often the writer should flush data if
// there have been no writes.
//
// Defaults to 30 seconds if unspecified.
FlushInterval time.Duration
// Clock, if specified, provides control of the source of time for the
// writer.
//
// Defaults to the system clock.
Clock Clock
// unexported fields for state
mu sync.Mutex
initialized bool // whether initialize() has run
writer *bufio.Writer
ticker *time.Ticker
stop chan struct{} // closed when flushLoop should stop
done chan struct{} // closed when flushLoop has stopped
}
func (s *BufferedWriteSyncer) initialize() {
size := s.Size
if size == 0 {
size = _defaultBufferSize
}
flushInterval := s.FlushInterval
if flushInterval == 0 {
flushInterval = _defaultFlushInterval
}
if s.Clock == nil {
s.Clock = DefaultClock
}
s.ticker = s.Clock.NewTicker(flushInterval)
// Unpack to the underlying WriteSyncer if we have a lockedWriteSyncer
// to avoid double-locking. Note that there's a risk here if the user
// tries to use the Lock-ed WriteSyncer directly in addition to using
// it with BufferedWriteSyncer, so we declare that the wrapped
// WriteSyncer is only ours to use once wrapped.
if w, ok := s.WS.(*lockedWriteSyncer); ok {
s.WS = w.ws
}
s.writer = bufio.NewWriterSize(s.WS, size)
s.stop = make(chan struct{})
s.done = make(chan struct{})
s.initialized = true
go s.flushLoop()
}
// Write writes log data into buffer syncer directly, multiple Write calls will be batched,
// and log data will be flushed to disk when the buffer is full or periodically.
func (s *BufferedWriteSyncer) Write(bs []byte) (int, error) {
s.mu.Lock()
defer s.mu.Unlock()
if !s.initialized {
s.initialize()
}
// To avoid partial writes from being flushed, we manually flush the existing buffer if:
// * The current write doesn't fit into the buffer fully, and
// * The buffer is not empty (since bufio will not split large writes when the buffer is empty)
if len(bs) > s.writer.Available() && s.writer.Buffered() > 0 {
if err := s.writer.Flush(); err != nil {
return 0, err
}
}
return s.writer.Write(bs)
}
// Sync flushes buffered log data into disk directly.
func (s *BufferedWriteSyncer) Sync() error {
s.mu.Lock()
defer s.mu.Unlock()
var err error
if w := s.writer; w != nil {
// w is nil if we haven't yet been initialized.
err = w.Flush()
}
return multierr.Append(err, s.WS.Sync())
}
// flushLoop flushes the buffer at the configured interval until Stop is
// called.
func (s *BufferedWriteSyncer) flushLoop() {
defer close(s.done)
for {
select {
case <-s.ticker.C:
// we just simply ignore error here
// because the underlying bufio writer stores any errors
// and we return any error from Sync() as part of the close
_ = s.Sync()
case <-s.stop:
return
}
}
}
// Stop closes the buffer, cleans up background goroutines, and flushes
// remaining unwritten data.
//
// This must be called exactly once per BufferedWriteSyncer.
func (s *BufferedWriteSyncer) Stop() error {
// Critical section.
func() {
s.mu.Lock()
defer s.mu.Unlock()
if !s.initialized {
return
}
s.ticker.Stop()
close(s.stop) // tell flushLoop to stop
<-s.done // and wait until it has
}()
return s.Sync()
}