/
picolog.go
201 lines (181 loc) · 6.14 KB
/
picolog.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
/*
picolog is a tiny levelled logging package for go. It supports syslog
log levels, subloggers, and not much else. Written because all the
existing solutions either didn't do what I needed or were too weighty.
*/
package picolog
import (
"bufio"
"fmt"
"log"
"log/syslog"
"os"
"strings"
)
// Logger is a leveled logger type. It can be a sublogger of another
// logger, and have an arbitrary number of subloggers itself.
type Logger struct {
logLevel LogLevel
logger *log.Logger
writer *bufio.Writer
destStream *os.File
prefix string
subloggers []*Logger
initialized bool
}
// LogLevel is a type representing the usual syslog log levels from
// LOG_DEBUG to LOG_EMERG. It does not reflect the go syslog package's
// concept of 'Priority'.
type LogLevel syslog.Priority
const (
LogDebug LogLevel = LogLevel(syslog.LOG_DEBUG)
LogInfo = LogLevel(syslog.LOG_INFO)
LogNotice = LogLevel(syslog.LOG_NOTICE)
LogWarning = LogLevel(syslog.LOG_WARNING)
LogErr = LogLevel(syslog.LOG_ERR)
LogCrit = LogLevel(syslog.LOG_CRIT)
LogAlert = LogLevel(syslog.LOG_ALERT)
LogEmerg = LogLevel(syslog.LOG_EMERG)
)
// ParseLogLevel takes a string and returns a LogLevel according
// to the standard syslog string representation. Not case-sensitive.
func ParseLogLevel(level string) (LogLevel, error) {
level = strings.ToLower(level)
switch {
case level == "emerg":
return LogLevel(syslog.LOG_EMERG), nil
case level == "alert":
return LogLevel(syslog.LOG_ALERT), nil
case level == "crit":
return LogLevel(syslog.LOG_CRIT), nil
case level == "err":
return LogLevel(syslog.LOG_ERR), nil
case level == "warning":
return LogLevel(syslog.LOG_WARNING), nil
case level == "notice":
return LogLevel(syslog.LOG_NOTICE), nil
case level == "info":
return LogLevel(syslog.LOG_INFO), nil
case level == "debug":
return LogLevel(syslog.LOG_DEBUG), nil
}
return LogLevel(syslog.Priority(0)), fmt.Errorf("Invalid log level: %s", level)
}
// String returns the default (lowercase) string representation of a
// LogLevel.
func (l LogLevel) String() string {
switch l {
case LogLevel(syslog.LOG_EMERG):
return "emerg"
case LogLevel(syslog.LOG_ALERT):
return "alert"
case LogLevel(syslog.LOG_CRIT):
return "crit"
case LogLevel(syslog.LOG_ERR):
return "err"
case LogLevel(syslog.LOG_WARNING):
return "warning"
case LogLevel(syslog.LOG_NOTICE):
return "notice"
case LogLevel(syslog.LOG_INFO):
return "info"
case LogLevel(syslog.LOG_DEBUG):
return "debug"
}
return "invalid log level"
}
// Return a new Logger. logLevel is a syslog log level,
// subpackage is used to construct the log prefix, and dest is where to
// write the log to.
func NewLogger(logLevel LogLevel, subpackage string, dest *os.File) *Logger {
logger := new(Logger)
logger.logLevel = logLevel
flags := log.Ldate | log.Ltime
// If logging at DEBUG, include file paths and line numbers
if logLevel == LogLevel(syslog.LOG_DEBUG) {
flags |= log.Lshortfile
}
logger.prefix = subpackage
renderedPrefix := fmt.Sprintf("[%s] ", logger.prefix)
logger.destStream = dest
logger.writer = bufio.NewWriter(logger.destStream)
logger.logger = log.New(logger.writer, renderedPrefix, flags)
logger.initialized = true
return logger
}
// NewDefaultLogger returns a picolog.Logger initialized with workable
// defaults (outputs to stderr, prefix "default", priority DEBUG).
// Useful as a fallback when a logger hasn't been initialized.
func NewDefaultLogger() *Logger {
return NewLogger(LogDebug, "default", os.Stderr)
}
// initializeDefaultLogger takes a (possibly nil) *Logger and allocates
// and assigns a default logger as returned by NewDefaultLogger.
func (l *Logger) initializeDefaultLogger() {
defaultLogger := NewDefaultLogger()
l = defaultLogger
}
// ensureInitialized checks if the initialized flag has been set for l,
// and if not initializes a default logger.
func (l *Logger) ensureInitialized() {
if !l.initialized {
l.initializeDefaultLogger()
}
}
// NewSubLogger returns a Logger writing to the same stream, with a
// prefix constructed from the provided prefix and the parent Logger's
// prefix. Subloggers can be nested.
func (l *Logger) NewSubLogger(prefix string) *Logger {
subPrefix := fmt.Sprintf("%s][%s", l.prefix, prefix)
sub := NewLogger(l.logLevel, subPrefix, l.destStream)
l.subloggers = append(l.subloggers, sub)
return sub
}
// Printf is the lowest-level output function of our Logger. Will use a
// default logger if l is not initialized.
func (l *Logger) Printf(format string, level LogLevel, v ...interface{}) {
l.ensureInitialized()
if level <= l.logLevel {
msg := fmt.Sprintf(format, v...)
// We use logger.Output rather than logger.Printf
// so we can pass a custom calldepth for file
// {path,line}-resolution purposes (the default of 2
// is only useful when using the Logger type directly).
l.logger.Output(3, msg)
l.writer.Flush()
}
}
// Debugf logs one printf-formatted message at LOG_DEBUG.
func (l *Logger) Debugf(format string, v ...interface{}) {
l.Printf(format, LogDebug, v...)
}
// Errorf logs one printf-formatted message at LOG_ERR.
func (l *Logger) Errorf(format string, v ...interface{}) {
l.Printf(format, LogErr, v...)
}
// Warningf logs one printf-formatted message at LOG_WARNING.
func (l *Logger) Warningf(format string, v ...interface{}) {
l.Printf(format, LogWarning, v...)
}
// Fatalf logs one printf-formatted message at LOG_CRIT, and then exits
// with an error code.
func (l *Logger) Fatalf(format string, v ...interface{}) {
l.Printf(format, LogErr, v...)
os.Exit(1)
}
// Infof logs one printf-formatted message at LOG_INFO.
func (l *Logger) Infof(format string, v ...interface{}) {
l.Printf(format, LogInfo, v...)
}
// Emergf logs one printf-formatted message at LOG_EMERG.
func (l *Logger) Emergf(format string, v ...interface{}) {
l.Printf(format, LogEmerg, v...)
}
// Alertf logs one printf-formatted message at LOG_ALERT.
func (l *Logger) Alertf(format string, v ...interface{}) {
l.Printf(format, LogAlert, v...)
}
// Noticef logs one printf-formatted message at LOG_NOTICE.
func (l *Logger) Noticef(format string, v ...interface{}) {
l.Printf(format, LogNotice, v...)
}