Added unit annotation supports onto tsmon in go.

common/tsmon/types/metricdataunits.go

Index: common/tsmon/types/metricdataunits.go
diff --git a/common/tsmon/types/metricdataunits.go b/common/tsmon/types/metricdataunits.go
new file mode 100644
index 0000000000000000000000000000000000000000..e3e02100aed991bc5a004b83c3d905ab71343c6a
--- /dev/null
+++ b/common/tsmon/types/metricdataunits.go
@@ -0,0 +1,89 @@
+// Copyright 2016 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package types
+
+import (
+	"fmt"
+
+	pb "github.com/luci/luci-go/common/tsmon/ts_mon_proto"
+)
+
+// MetricDataUnits are enums for the units of metrics data.
+type MetricDataUnits int32
+
+// Units of metrics data.
+const (
+	// NotSpecified is a magic value to skip Units property
+	// in a MetricsData proto message.
+	// Note that this should be defined with 0 so that all the existing
+	// codes without units specified would be given NotSpecified
+	// for the Units property automatically.
+	NotSpecified MetricDataUnits = iota
+	Unknown
+	Seconds
+	Milliseconds
+	Microseconds
+	Nanoseconds
+	Bits
+	Bytes
+
+	Kilobytes // 1000 bytes (not 1024).
+	Megabytes // 1e6 (1,000,000) bytes.
+	Gigabytes // 1e9 (1,000,000,000) bytes.
+	Kibibytes // 1024 bytes.
+	Mebibytes // 1024^2 (1,048,576) bytes.
+	Gibibytes // 1024^3 (1,073,741,824) bytes.
+
+	// * Extended Units
+	AmpUnit
+	MilliampUnit
+	DegreeCelsiusUnit
+)
+
+// IsSpecified returns true if a unit annotation has been specified
+// for a given metric.
+func (units MetricDataUnits) IsSpecified() bool {
+	return units != NotSpecified
+}
+
+// AsProto returns the protobuf representation of a given MetricDataUnits
+// object.
+func (units MetricDataUnits) AsProto() *pb.MetricsData_Units {
+	switch units {
+	case Unknown:
+		return pb.MetricsData_UNKNOWN_UNITS.Enum()
+	case Seconds:
+		return pb.MetricsData_SECONDS.Enum()
+	case Milliseconds:
+		return pb.MetricsData_MILLISECONDS.Enum()
+	case Microseconds:
+		return pb.MetricsData_MICROSECONDS.Enum()
+	case Nanoseconds:
+		return pb.MetricsData_NANOSECONDS.Enum()
+	case Bits:
+		return pb.MetricsData_BITS.Enum()
+	case Bytes:
+		return pb.MetricsData_BYTES.Enum()
+	case Kilobytes:
+		return pb.MetricsData_KILOBYTES.Enum()
+	case Megabytes:
+		return pb.MetricsData_MEGABYTES.Enum()
+	case Gigabytes:
+		return pb.MetricsData_GIGABYTES.Enum()
+	case Kibibytes:
+		return pb.MetricsData_KIBIBYTES.Enum()
+	case Mebibytes:
+		return pb.MetricsData_MEBIBYTES.Enum()
+	case Gibibytes:
+		return pb.MetricsData_GIBIBYTES.Enum()
+	case AmpUnit:
+		return pb.MetricsData_AMPS.Enum()
+	case MilliampUnit:
+		return pb.MetricsData_MILLIAMPS.Enum()
+	case DegreeCelsiusUnit:
+		return pb.MetricsData_DEGREES_CELSIUS.Enum()
+	}
+	panic(fmt.Sprintf("unknown MetricDataUnits %d", units))
+}