LogDog: Add Butler Output package.

client/internal/logdog/butler/output/null/null.go

Index: client/internal/logdog/butler/output/null/null.go
diff --git a/client/internal/logdog/butler/output/null/null.go b/client/internal/logdog/butler/output/null/null.go
new file mode 100644
index 0000000000000000000000000000000000000000..568179a454db0495eb062563b7927b5ee21259ac
--- /dev/null
+++ b/client/internal/logdog/butler/output/null/null.go
@@ -0,0 +1,110 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package null
+
+import (
+	"encoding/hex"
+	"strconv"
+	"sync"
+
+	"github.com/golang/protobuf/proto"
+	"github.com/luci/luci-go/client/internal/logdog/butler/output"
+	"github.com/luci/luci-go/common/logdog/protocol"
+	"github.com/luci/luci-go/common/logdog/types"
+	log "github.com/luci/luci-go/common/logging"
+	"golang.org/x/net/context"
+)
+
+// nullOutput is an Output implementation that logs messages to its contexts'
+// Logger instance.
+type nullOutput struct {
+	ctx context.Context
+
+	// bundleSize is the maximum size of the Butler bundle to use.
+	bundleSize int
+
+	stats   output.StatsBase
+	statsMu sync.Mutex
+}
+
+// nullOutput implements output.Output.
+var _ output.Output = (*nullOutput)(nil)
+
+func (o *nullOutput) String() string {
+	return "Null"
+}
+
+// New instantes a new null output instance.
+func New(ctx context.Context, bundleSize int) output.Output {
+	o := nullOutput{
+		ctx:        ctx,
+		bundleSize: bundleSize,
+	}
+	o.ctx = log.SetFields(o.ctx, log.Fields{
+		"output": &o,
+	})
+	return &o
+}
+
+func (o *nullOutput) SendBundle(bundle *protocol.ButlerLogBundle) error {
+	st := output.StatsBase{}
+	defer o.mergeStats(&st)
+
+	for _, e := range bundle.Entries {
+		path := types.StreamName(e.Desc.Prefix).Join(types.StreamName(e.Desc.Name))
+		ctx := log.SetField(o.ctx, "streamPath", path)
+
+		log.Fields{
+			"count":      len(e.Logs),
+			"descriptor": e.Desc.String(),
+		}.Infof(ctx, "Received stream logs.")
+
+		for _, le := range e.Logs {
+			log.Fields{
+				"timeOffset":  le.TimeOffset.Duration(),
+				"prefixIndex": le.PrefixIndex,
+				"streamIndex": le.StreamIndex,
+				"sequence":    le.Sequence,
+			}.Infof(ctx, "Received message.")
+			if c := le.GetText(); c != nil {
+				for idx, l := range c.Lines {
+					log.Infof(ctx, "Line %d) %s (%s)", idx, l.Value, strconv.Quote(l.Delimiter))
+				}
+			}
+			if c := le.GetBinary(); c != nil {
+				log.Infof(ctx, "Binary) %s", hex.EncodeToString(c.Data))
+			}
+			if c := le.GetDatagram(); c != nil {
+				log.Infof(ctx, "Datagram %d: %s", c.Size, hex.EncodeToString(c.Data))
+			}
+
+			st.F.SentMessages++
+		}
+	}
+	st.F.SentBytes += proto.Size(bundle)
+
+	return nil
+}
+
+func (o *nullOutput) MaxSize() int {
+	return o.bundleSize
+}
+
+func (o *nullOutput) Stats() output.Stats {
+	o.statsMu.Lock()
+	defer o.statsMu.Unlock()
+
+	st := o.stats
+	return &st
+}
+
+func (o *nullOutput) Close() {}
+
+func (o *nullOutput) mergeStats(s output.Stats) {
+	o.statsMu.Lock()
+	defer o.statsMu.Unlock()
+
+	o.stats.Merge(s)
+}