stats: Add function to convert stats variable names to kebab-case.

go/stats/kebab_case_converter.go

@@ -0,0 +1,63 @@
+/*
+Copyright 2018 The Vitess Authors.
+
+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 stats
+
+import (
+	"regexp"
+	"strings"
+	"sync"
+)
+
+// toKebabCase produces a monitoring compliant name from the
+// original. It converts CamelCase to camel-case,
+// and CAMEL_CASE to camel-case. For numbers, it
+// converts 0.5 to v0_5.
+func toKebabCase(name string) (hyphenated string) {
+	memoizer.Lock()
+	defer memoizer.Unlock()
+	if hyphenated = memoizer.memo[name]; hyphenated != "" {
+		return hyphenated
+	}
+	hyphenated = name
+	for _, converter := range converters {
+		hyphenated = converter.re.ReplaceAllString(hyphenated, converter.repl)
+	}
+	hyphenated = strings.ToLower(hyphenated)
+	memoizer.memo[name] = hyphenated
+	return
+}
+
+var converters = []struct {
+	re   *regexp.Regexp
+	repl string
+}{
+	// example: LC -> L-C (e.g. CamelCase -> Camel-Case).
+	{regexp.MustCompile("([a-z])([A-Z])"), "$1-$2"},
+	// example: CCa -> C-Ca (e.g. CCamel -> C-Camel).
+	{regexp.MustCompile("([A-Z])([A-Z][a-z])"), "$1-$2"},
+	{regexp.MustCompile("_"), "-"},
+	{regexp.MustCompile("\\."), "_"},
+}
+
+var memoizer = memoizerType{
+	memo: make(map[string]string),
+}
+
+type memoizerType struct {
+	sync.Mutex
+	memo map[string]string
+}

go/stats/kebab_case_converter_test.go

@@ -0,0 +1,52 @@
+/*
+Copyright 2018 The Vitess Authors.
+
+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 stats
+
+import "testing"
+
+func TestToKebabCase(t *testing.T) {
+	var kebabCaseTest = []struct{ input, output string }{
+		{"Camel", "camel"},
+		{"Camel", "camel"},
+		{"CamelCase", "camel-case"},
+		{"CamelCaseAgain", "camel-case-again"},
+		{"CCamel", "c-camel"},
+		{"CCCamel", "cc-camel"},
+		{"CAMEL_CASE", "camel-case"},
+		{"camel-case", "camel-case"},
+		{"0", "0"},
+		{"0.0", "0_0"},
+		{"JSON", "json"},
+	}
+
+	for _, tt := range kebabCaseTest {
+		if got, want := toKebabCase(tt.input), tt.output; got != want {
+			t.Errorf("want '%s', got '%s'", want, got)
+		}
+	}
+}
+
+func TestMemoize(t *testing.T) {
+	key := "Test"
+	if memoizer.memo[key] != "" {
+		t.Errorf("want '', got '%s'", memoizer.memo[key])
+	}
+	toKebabCase(key)
+	if memoizer.memo[key] != "test" {
+		t.Errorf("want 'test', got '%s'", memoizer.memo[key])
+	}
+}