Vendor dependencies for GCS

vendor/cloud.google.com/go/internal/testutil/unique.go

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+// 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.
+
+// This file supports generating unique IDs so that multiple test executions
+// don't interfere with each other, and cleaning up old entities that may
+// remain if tests exit early.
+
+package testutil
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"sync"
+	"time"
+)
+
+var startTime = time.Now().UTC()
+
+// A UIDSpace manages a set of unique IDs distinguished by a prefix.
+type UIDSpace struct {
+	Prefix string
+	re     *regexp.Regexp
+	mu     sync.Mutex
+	count  int
+}
+
+func NewUIDSpace(prefix string) *UIDSpace {
+	return &UIDSpace{
+		Prefix: prefix,
+		re:     regexp.MustCompile("^" + regexp.QuoteMeta(prefix) + `-(\d{4})(\d{2})(\d{2})-(\d+)-\d+$`),
+	}
+
+}
+
+// New generates a new unique ID . The ID consists of the UIDSpace's prefix, a
+// timestamp, and a counter value. All unique IDs generated in the same test
+// execution will have the same timestamp.
+//
+// Aside from the characters in the prefix, IDs contain only letters, numbers
+// and hyphens.
+func (s *UIDSpace) New() string { return s.newID(startTime) }
+
+func (s *UIDSpace) newID(t time.Time) string {
+	s.mu.Lock()
+	c := s.count
+	s.count++
+	s.mu.Unlock()
+	// Write the time as a date followed by nanoseconds from midnight of that date.
+	// That makes it easier to see the approximate time of the ID when it is displayed.
+	y, m, d := t.Date()
+	ns := t.Sub(time.Date(y, m, d, 0, 0, 0, 0, time.UTC))
+	// Zero-pad the counter for lexical sort order for IDs with the same timestamp.
+	return fmt.Sprintf("%s-%04d%02d%02d-%d-%04d", s.Prefix, y, m, d, ns, c)
+}
+
+// Timestamp extracts the timestamp of uid, which must have been generated by
+// s. The second return value is true on success, false if there was a problem.
+func (s *UIDSpace) Timestamp(uid string) (time.Time, bool) {
+	subs := s.re.FindStringSubmatch(uid)
+	if subs == nil {
+		return time.Time{}, false
+	}
+	y, err1 := strconv.Atoi(subs[1])
+	m, err2 := strconv.Atoi(subs[2])
+	d, err3 := strconv.Atoi(subs[3])
+	ns, err4 := strconv.Atoi(subs[4])
+	if err1 != nil || err2 != nil || err3 != nil || err4 != nil {
+		return time.Time{}, false
+	}
+	return time.Date(y, time.Month(m), d, 0, 0, 0, ns, time.UTC), true
+}
+
+// Older reports whether uid was created by m and has a timestamp older than
+// the current time by at least d.
+func (s *UIDSpace) Older(uid string, d time.Duration) bool {
+	ts, ok := s.Timestamp(uid)
+	if !ok {
+		return false
+	}
+	return time.Since(ts) > d
+}