LogDog: Update protobufs, add support library.

common/logdog/protocol/protoutil/utils.go

Index: common/logdog/protocol/protoutil/utils.go
diff --git a/common/logdog/protocol/protoutil/utils.go b/common/logdog/protocol/protoutil/utils.go
new file mode 100644
index 0000000000000000000000000000000000000000..69ffae8d6e836102223045471ca502516d206454
--- /dev/null
+++ b/common/logdog/protocol/protoutil/utils.go
@@ -0,0 +1,39 @@
+// 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.
+

[tandrii(chromium), 2015/08/11 17:41:37]

// package protoutil is a library to operate on protobuf structures.

[dnj, 2015/08/11 18:20:37]

Done.

+package protoutil
+
+import (
+	"time"
+
+	"github.com/luci/luci-go/common/logdog/protocol"
+	"github.com/luci/luci-go/common/logdog/types"
+)
+
+// DescriptorPath returns the StreamPath for a descriptor.
+func DescriptorPath(d *protocol.LogStreamDescriptor) types.StreamPath {
+	if d == nil {
+		return types.StreamPath("")
+	}
+	return types.StreamName(d.GetPrefix()).Join(types.StreamName(d.GetName()))
+}
+
+// NewTimestamp creates a new Butler protocol Timestamp from a time.Time type.
+func NewTimestamp(t time.Time) *protocol.Timestamp {
+	value := uint64(t.UTC().UnixNano()) / uint64(time.Microsecond)
+	return &protocol.Timestamp{
+		UsFromEpoch: &value,
+	}
+}
+
+// TimeOffset returns the equivalent time offset in microseconds for a Duration.
+// This is suitable for use in offset-since-microseconds protobuf fields.
+func TimeOffset(d time.Duration) uint64 {
+	offset := d.Nanoseconds()

[tandrii(chromium), 2015/08/11 17:41:37]

bummer, i didn't expect time.Duration to miss .Microseconds() method.

[dnj, 2015/08/11 18:20:37]

Acknowledged.

+	if offset < 0 {
+		offset = 0
+	}
+	value := uint64(offset / int64(time.Microsecond))
+	return value
+}