Logger interface and tmLogger impl based on go-kit

log/tmfmt_logger.go

@@ -0,0 +1,116 @@
+package log
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"sync"
+	"time"
+
+	kitlog "github.com/go-kit/kit/log"
+	"github.com/go-kit/kit/log/level"
+	"github.com/go-logfmt/logfmt"
+)
+
+type tmfmtEncoder struct {
+	*logfmt.Encoder
+	buf bytes.Buffer
+}
+
+func (l *tmfmtEncoder) Reset() {
+	l.Encoder.Reset()
+	l.buf.Reset()
+}
+
+var tmfmtEncoderPool = sync.Pool{
+	New: func() interface{} {
+		var enc tmfmtEncoder
+		enc.Encoder = logfmt.NewEncoder(&enc.buf)
+		return &enc
+	},
+}
+
+type tmfmtLogger struct {
+	w io.Writer
+}
+
+// NewTmFmtLogger returns a logger that encodes keyvals to the Writer in
+// Tendermint custom 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 NewTmfmtLogger(w io.Writer) kitlog.Logger {
+	return &tmfmtLogger{w}
+}
+
+func (l tmfmtLogger) Log(keyvals ...interface{}) error {
+	enc := tmfmtEncoderPool.Get().(*tmfmtEncoder)
+	enc.Reset()
+	defer tmfmtEncoderPool.Put(enc)
+
+	lvl := "none"
+	msg := "unknown"
+	lvlIndex := -1
+	msgIndex := -1
+
+	for i := 0; i < len(keyvals)-1; i += 2 {
+		// Extract level
+		if keyvals[i] == level.Key() {
+			lvlIndex = i
+			switch keyvals[i+1].(type) {
+			case string:
+				lvl = keyvals[i+1].(string)
+			case level.Value:
+				lvl = keyvals[i+1].(level.Value).String()
+			default:
+				panic(fmt.Sprintf("level value of unknown type %T", keyvals[i+1]))
+			}
+			continue
+		}
+
+		// and message
+		if keyvals[i] == msgKey {
+			msgIndex = i
+			msg = keyvals[i+1].(string)
+			continue
+		}
+
+		if lvlIndex > 0 && msgIndex > 0 { // found all we're looking for
+			break
+		}
+	}
+
+	// Form a custom Tendermint line
+	//
+	// Example:
+	//     D[05-02|11:06:44.322] Stopping AddrBook (ignoring: already stopped)
+	//
+	// Description:
+	//     D										- first character of the level, uppercase (ASCII only)
+	//     [05-02|11:06:44.322] - our time format (see https://golang.org/src/time/format.go)
+	//     Stopping ...					- message
+	enc.buf.WriteString(fmt.Sprintf("%c[%s] %-44s", lvl[0]-32, time.Now().UTC().Format("01-02|15:04:05.000"), msg))
+
+	for i := 0; i < len(keyvals)-1; i += 2 {
+		if i == lvlIndex || i == msgIndex {
+			continue
+		}
+		if err := enc.EncodeKeyval(keyvals[i], keyvals[i+1]); 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
+}