/
logging.go
108 lines (89 loc) · 2.15 KB
/
logging.go
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package main
import (
"encoding/json"
"io"
"reflect"
"time"
)
type LogLevel struct {
Level byte
Name string
}
// Log levels. Only `log` module allowed to be called is fatal (because it's
// more human). Therefor, I'm not including that log level here.
var logLevels = []LogLevel{
{0, "DEBUG"},
{1, "INFO"},
{2, "WARN"},
{3, "ERROR"},
{4, "UNKNOWN"}, // Always log UNKNOWN log levels.
}
// Various views of log levels
var logLevelByName = make(map[string]LogLevel)
func init() {
for _, logLevel := range logLevels {
logLevelByName[logLevel.Name] = logLevel
}
}
type LogRecord struct {
Level string
Time string
Type string
Payload interface{}
}
type Logger interface {
Log(level LogLevel, payload interface{})
}
// Helper to add syntactic sugar to logging.
type MethodLogger struct {
Delegate Logger
}
func (m *MethodLogger) Debug(payload interface{}) {
m.Delegate.Log(logLevelByName["DEBUG"], payload)
}
func (m *MethodLogger) Info(payload interface{}) {
m.Delegate.Log(logLevelByName["INFO"], payload)
}
func (m *MethodLogger) Warn(payload interface{}) {
m.Delegate.Log(logLevelByName["WARN"], payload)
}
func (m *MethodLogger) Error(payload interface{}) {
m.Delegate.Log(logLevelByName["ERROR"], payload)
}
type LogWriter interface {
Write(LogRecord)
}
// Filters logging based log level.
type LogLevelFilter struct {
Level LogLevel
Delegate Logger
}
func (l *LogLevelFilter) Log(level LogLevel, payload interface{}) {
if level.Level >= l.Level.Level {
l.Delegate.Log(level, payload)
}
}
// Wraps payload in a LogRecord and delegates logging to a LogWriter.
type LogRecordLogger struct {
Writer LogWriter
}
func (l *LogRecordLogger) Log(level LogLevel, payload interface{}) {
l.Writer.Write(LogRecord{
Level: level.Name,
Time: time.Now().Format(time.RFC3339),
Type: reflect.TypeOf(payload).Name(),
Payload: payload,
})
}
// Outputs log records in JSON format.
type JSONOutputter struct {
Writer io.Writer
}
func (j *JSONOutputter) Write(record LogRecord) {
if data, err := json.Marshal(record); err == nil {
data = append(data, '\n')
j.Writer.Write(data)
} else {
logger.Warn(UnableToLog{err.Error()})
}
}