94 lines
2.9 KiB
Go
94 lines
2.9 KiB
Go
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// Copyright 2017 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// This file supports generating unique IDs so that multiple test executions
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// don't interfere with each other, and cleaning up old entities that may
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// remain if tests exit early.
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package testutil
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import (
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"fmt"
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"regexp"
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"strconv"
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"sync"
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"time"
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)
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var startTime = time.Now().UTC()
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// A UIDSpace manages a set of unique IDs distinguished by a prefix.
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type UIDSpace struct {
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Prefix string
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re *regexp.Regexp
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mu sync.Mutex
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count int
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}
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func NewUIDSpace(prefix string) *UIDSpace {
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return &UIDSpace{
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Prefix: prefix,
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re: regexp.MustCompile("^" + regexp.QuoteMeta(prefix) + `-(\d{4})(\d{2})(\d{2})-(\d+)-\d+$`),
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}
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}
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// New generates a new unique ID . The ID consists of the UIDSpace's prefix, a
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// timestamp, and a counter value. All unique IDs generated in the same test
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// execution will have the same timestamp.
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//
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// Aside from the characters in the prefix, IDs contain only letters, numbers
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// and hyphens.
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func (s *UIDSpace) New() string { return s.newID(startTime) }
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func (s *UIDSpace) newID(t time.Time) string {
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s.mu.Lock()
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c := s.count
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s.count++
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s.mu.Unlock()
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// Write the time as a date followed by nanoseconds from midnight of that date.
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// That makes it easier to see the approximate time of the ID when it is displayed.
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y, m, d := t.Date()
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ns := t.Sub(time.Date(y, m, d, 0, 0, 0, 0, time.UTC))
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// Zero-pad the counter for lexical sort order for IDs with the same timestamp.
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return fmt.Sprintf("%s-%04d%02d%02d-%d-%04d", s.Prefix, y, m, d, ns, c)
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}
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// Timestamp extracts the timestamp of uid, which must have been generated by
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// s. The second return value is true on success, false if there was a problem.
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func (s *UIDSpace) Timestamp(uid string) (time.Time, bool) {
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subs := s.re.FindStringSubmatch(uid)
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if subs == nil {
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return time.Time{}, false
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}
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y, err1 := strconv.Atoi(subs[1])
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m, err2 := strconv.Atoi(subs[2])
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d, err3 := strconv.Atoi(subs[3])
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ns, err4 := strconv.Atoi(subs[4])
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if err1 != nil || err2 != nil || err3 != nil || err4 != nil {
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return time.Time{}, false
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}
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return time.Date(y, time.Month(m), d, 0, 0, 0, ns, time.UTC), true
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}
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// Older reports whether uid was created by m and has a timestamp older than
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// the current time by at least d.
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func (s *UIDSpace) Older(uid string, d time.Duration) bool {
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ts, ok := s.Timestamp(uid)
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if !ok {
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return false
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}
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return time.Since(ts) > d
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}
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