etcd-runner: move string generation to pkg/stringutil

pkg/stringutil/stringutil.go

@@ -0,0 +1,54 @@
+// Copyright 2016 The etcd 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 stringutil
+
+import "math/rand"
+
+const (
+	chars = "abcdefghijklmnopqrstuvwxyz0123456789"
+)
+
+// UniqueStrings retruns a slice of randomly generated unique strings.
+func UniqueStrings(maxlen uint, n int) []string {
+	exist := make(map[string]bool)
+	ss := make([]string, 0)
+
+	for len(ss) < n {
+		s := randomString(maxlen)
+		if !exist[s] {
+			exist[s] = true
+			ss = append(ss, s)
+		}
+	}
+
+	return ss
+}
+
+// RandomStrings retruns a slice of randomly generated strings.
+func RandomStrings(maxlen uint, n int) []string {
+	ss := make([]string, 0)
+	for i := 0; i < n; i++ {
+		ss = append(ss, randomString(maxlen))
+	}
+	return ss
+}
+
+func randomString(l uint) string {
+	s := make([]byte, l)
+	for i := 0; i < int(l); i++ {
+		s[i] = chars[rand.Intn(len(chars))]
+	}
+	return string(s)
+}