prometheus/vendor/github.com/go-kit/kit/log/logfmt_logger.go

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2017-02-07 03:42:02 -08:00
package log
import (
"bytes"
"io"
"sync"
"github.com/go-logfmt/logfmt"
)
type logfmtEncoder struct {
*logfmt.Encoder
buf bytes.Buffer
}
func (l *logfmtEncoder) Reset() {
l.Encoder.Reset()
l.buf.Reset()
}
var logfmtEncoderPool = sync.Pool{
New: func() interface{} {
var enc logfmtEncoder
enc.Encoder = logfmt.NewEncoder(&enc.buf)
return &enc
},
}
type logfmtLogger struct {
w io.Writer
}
// NewLogfmtLogger returns a logger that encodes keyvals to the Writer in
// logfmt format. Each log event produces no more than one call to w.Write.
// The passed Writer must be safe for concurrent use by multiple goroutines if
// the returned Logger will be used concurrently.
func NewLogfmtLogger(w io.Writer) Logger {
return &logfmtLogger{w}
}
func (l logfmtLogger) Log(keyvals ...interface{}) error {
enc := logfmtEncoderPool.Get().(*logfmtEncoder)
enc.Reset()
defer logfmtEncoderPool.Put(enc)
if err := enc.EncodeKeyvals(keyvals...); err != nil {
return err
}
// Add newline to the end of the buffer
if err := enc.EndRecord(); err != nil {
return err
}
// The Logger interface requires implementations to be safe for concurrent
// use by multiple goroutines. For this implementation that means making
// only one call to l.w.Write() for each call to Log.
if _, err := l.w.Write(enc.buf.Bytes()); err != nil {
return err
}
return nil
}