Add support for terabyte and petabyte memory units. (google#138)

* Add support for terabyte and petabyte memory units.

This fixes google#137 (but not google#136, this will come separately once we decide
what we want to do if anything).

* Add a test.

* Update copyright year

internal/measurement/measurement.go

@@ -170,12 +170,16 @@ func memoryLabel(value int64, fromUnit, toUnit string) (v float64, u string, ok
 
 	switch fromUnit {
 	case "byte", "b":
-	case "kilobyte", "kb":
+	case "kb", "kbyte", "kilobyte":
 		value *= 1024
-	case "megabyte", "mb":
+	case "mb", "mbyte", "megabyte":
 		value *= 1024 * 1024
-	case "gigabyte", "gb":
+	case "gb", "gbyte", "gigabyte":
 		value *= 1024 * 1024 * 1024
+	case "tb", "tbyte", "terabyte":
+		value *= 1024 * 1024 * 1024 * 1024
+	case "pb", "pbyte", "petabyte":
+		value *= 1024 * 1024 * 1024 * 1024 * 1024
 	default:
 		return 0, "", false
 	}
@@ -188,8 +192,12 @@ func memoryLabel(value int64, fromUnit, toUnit string) (v float64, u string, ok
 			toUnit = "kb"
 		case value < 1024*1024*1024:
 			toUnit = "mb"
-		default:
+		case value < 1024*1024*1024*1024:
 			toUnit = "gb"
+		case value < 1024*1024*1024*1024*1024:
+			toUnit = "tb"
+		default:
+			toUnit = "pb"
 		}
 	}
 
@@ -203,6 +211,10 @@ func memoryLabel(value int64, fromUnit, toUnit string) (v float64, u string, ok
 		output, toUnit = float64(value)/(1024*1024), "MB"
 	case "gb", "gbyte", "gigabyte":
 		output, toUnit = float64(value)/(1024*1024*1024), "GB"
+	case "tb", "tbyte", "terabyte":
+		output, toUnit = float64(value)/(1024*1024*1024*1024), "TB"
+	case "pb", "pbyte", "petabyte":
+		output, toUnit = float64(value)/(1024*1024*1024*1024*1024), "PB"
 	}
 	return output, toUnit, true
 }

internal/measurement/measurement_test.go

@@ -0,0 +1,43 @@
+// Copyright 2017 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package measurement
+
+import (
+	"testing"
+)
+
+func TestScale(t *testing.T) {
+	for _, tc := range []struct {
+		value            int64
+		fromUnit, toUnit string
+		wantValue        float64
+		wantUnit         string
+	}{
+		{1, "s", "ms", 1000, "ms"},
+		{1, "kb", "b", 1024, "B"},
+		{1, "kbyte", "b", 1024, "B"},
+		{1, "kilobyte", "b", 1024, "B"},
+		{1, "mb", "kb", 1024, "kB"},
+		{1, "gb", "mb", 1024, "MB"},
+		{1024, "gb", "tb", 1, "TB"},
+		{1024, "tb", "pb", 1, "PB"},
+		{2048, "mb", "auto", 2, "GB"},
+	} {
+		if gotValue, gotUnit := Scale(tc.value, tc.fromUnit, tc.toUnit); gotValue != tc.wantValue || gotUnit != tc.wantUnit {
+			t.Errorf("Scale(%d, %q, %q) = (%f, %q), want (%f, %q)",
+				tc.value, tc.fromUnit, tc.toUnit, gotValue, gotUnit, tc.wantValue, tc.wantUnit)
+		}
+	}
+}