blob: 199a1ac65403edc1438d27c9aa71c698e6efeda4 [file] [log] [blame]
divyadesai19009132020-03-04 12:58:08 +00001// Copyright 2016 Google Inc. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package uuid
6
7import (
8 "encoding/binary"
9)
10
11// NewUUID returns a Version 1 UUID based on the current NodeID and clock
12// sequence, and the current time. If the NodeID has not been set by SetNodeID
13// or SetNodeInterface then it will be set automatically. If the NodeID cannot
14// be set NewUUID returns nil. If clock sequence has not been set by
15// SetClockSequence then it will be set automatically. If GetTime fails to
16// return the current NewUUID returns nil and an error.
17//
18// In most cases, New should be used.
19func NewUUID() (UUID, error) {
20 nodeMu.Lock()
21 if nodeID == zeroID {
22 setNodeInterface("")
23 }
24 nodeMu.Unlock()
25
26 var uuid UUID
27 now, seq, err := GetTime()
28 if err != nil {
29 return uuid, err
30 }
31
32 timeLow := uint32(now & 0xffffffff)
33 timeMid := uint16((now >> 32) & 0xffff)
34 timeHi := uint16((now >> 48) & 0x0fff)
35 timeHi |= 0x1000 // Version 1
36
37 binary.BigEndian.PutUint32(uuid[0:], timeLow)
38 binary.BigEndian.PutUint16(uuid[4:], timeMid)
39 binary.BigEndian.PutUint16(uuid[6:], timeHi)
40 binary.BigEndian.PutUint16(uuid[8:], seq)
41 copy(uuid[10:], nodeID[:])
42
43 return uuid, nil
44}