github.com/go-kit/log@v0.2.1/logfmt_logger.go (about)

     1  package log
     2  
     3  import (
     4  	"bytes"
     5  	"io"
     6  	"sync"
     7  
     8  	"github.com/go-logfmt/logfmt"
     9  )
    10  
    11  type logfmtEncoder struct {
    12  	*logfmt.Encoder
    13  	buf bytes.Buffer
    14  }
    15  
    16  func (l *logfmtEncoder) Reset() {
    17  	l.Encoder.Reset()
    18  	l.buf.Reset()
    19  }
    20  
    21  var logfmtEncoderPool = sync.Pool{
    22  	New: func() interface{} {
    23  		var enc logfmtEncoder
    24  		enc.Encoder = logfmt.NewEncoder(&enc.buf)
    25  		return &enc
    26  	},
    27  }
    28  
    29  type logfmtLogger struct {
    30  	w io.Writer
    31  }
    32  
    33  // NewLogfmtLogger returns a logger that encodes keyvals to the Writer in
    34  // logfmt format. Each log event produces no more than one call to w.Write.
    35  // The passed Writer must be safe for concurrent use by multiple goroutines if
    36  // the returned Logger will be used concurrently.
    37  func NewLogfmtLogger(w io.Writer) Logger {
    38  	return &logfmtLogger{w}
    39  }
    40  
    41  func (l logfmtLogger) Log(keyvals ...interface{}) error {
    42  	enc := logfmtEncoderPool.Get().(*logfmtEncoder)
    43  	enc.Reset()
    44  	defer logfmtEncoderPool.Put(enc)
    45  
    46  	if err := enc.EncodeKeyvals(keyvals...); err != nil {
    47  		return err
    48  	}
    49  
    50  	// Add newline to the end of the buffer
    51  	if err := enc.EndRecord(); err != nil {
    52  		return err
    53  	}
    54  
    55  	// The Logger interface requires implementations to be safe for concurrent
    56  	// use by multiple goroutines. For this implementation that means making
    57  	// only one call to l.w.Write() for each call to Log.
    58  	if _, err := l.w.Write(enc.buf.Bytes()); err != nil {
    59  		return err
    60  	}
    61  	return nil
    62  }