ducky/devices
2015-11-12
ducky/devices/vendor/code.google.com/p/go-uuid/uuid/time.go
Initial attempt. Create the basic types (Device, DeviceType, DeviceChange) that we'll be using in the service. Also, create our Storer interface, and the helper methods to store, retrieve, and update information in the datastore. Also, we're using Godep, so check in our Godeps folder and the vendor folder. Note that this only works on Go 1.5 and later, with the GO15VENDOREXPERIMENT environment variable set to 1.
| paddy@0 | 1 // Copyright 2014 Google Inc. All rights reserved. |
| paddy@0 | 2 // Use of this source code is governed by a BSD-style |
| paddy@0 | 3 // license that can be found in the LICENSE file. |
| paddy@0 | 4 |
| paddy@0 | 5 package uuid |
| paddy@0 | 6 |
| paddy@0 | 7 import ( |
| paddy@0 | 8 "encoding/binary" |
| paddy@0 | 9 "sync" |
| paddy@0 | 10 "time" |
| paddy@0 | 11 ) |
| paddy@0 | 12 |
| paddy@0 | 13 // A Time represents a time as the number of 100's of nanoseconds since 15 Oct |
| paddy@0 | 14 // 1582. |
| paddy@0 | 15 type Time int64 |
| paddy@0 | 16 |
| paddy@0 | 17 const ( |
| paddy@0 | 18 lillian = 2299160 // Julian day of 15 Oct 1582 |
| paddy@0 | 19 unix = 2440587 // Julian day of 1 Jan 1970 |
| paddy@0 | 20 epoch = unix - lillian // Days between epochs |
| paddy@0 | 21 g1582 = epoch * 86400 // seconds between epochs |
| paddy@0 | 22 g1582ns100 = g1582 * 10000000 // 100s of a nanoseconds between epochs |
| paddy@0 | 23 ) |
| paddy@0 | 24 |
| paddy@0 | 25 var ( |
| paddy@0 | 26 mu sync.Mutex |
| paddy@0 | 27 lasttime uint64 // last time we returned |
| paddy@0 | 28 clock_seq uint16 // clock sequence for this run |
| paddy@0 | 29 |
| paddy@0 | 30 timeNow = time.Now // for testing |
| paddy@0 | 31 ) |
| paddy@0 | 32 |
| paddy@0 | 33 // UnixTime converts t the number of seconds and nanoseconds using the Unix |
| paddy@0 | 34 // epoch of 1 Jan 1970. |
| paddy@0 | 35 func (t Time) UnixTime() (sec, nsec int64) { |
| paddy@0 | 36 sec = int64(t - g1582ns100) |
| paddy@0 | 37 nsec = (sec % 10000000) * 100 |
| paddy@0 | 38 sec /= 10000000 |
| paddy@0 | 39 return sec, nsec |
| paddy@0 | 40 } |
| paddy@0 | 41 |
| paddy@0 | 42 // GetTime returns the current Time (100s of nanoseconds since 15 Oct 1582) and |
| paddy@0 | 43 // clock sequence as well as adjusting the clock sequence as needed. An error |
| paddy@0 | 44 // is returned if the current time cannot be determined. |
| paddy@0 | 45 func GetTime() (Time, uint16, error) { |
| paddy@0 | 46 defer mu.Unlock() |
| paddy@0 | 47 mu.Lock() |
| paddy@0 | 48 return getTime() |
| paddy@0 | 49 } |
| paddy@0 | 50 |
| paddy@0 | 51 func getTime() (Time, uint16, error) { |
| paddy@0 | 52 t := timeNow() |
| paddy@0 | 53 |
| paddy@0 | 54 // If we don't have a clock sequence already, set one. |
| paddy@0 | 55 if clock_seq == 0 { |
| paddy@0 | 56 setClockSequence(-1) |
| paddy@0 | 57 } |
| paddy@0 | 58 now := uint64(t.UnixNano()/100) + g1582ns100 |
| paddy@0 | 59 |
| paddy@0 | 60 // If time has gone backwards with this clock sequence then we |
| paddy@0 | 61 // increment the clock sequence |
| paddy@0 | 62 if now <= lasttime { |
| paddy@0 | 63 clock_seq = ((clock_seq + 1) & 0x3fff) | 0x8000 |
| paddy@0 | 64 } |
| paddy@0 | 65 lasttime = now |
| paddy@0 | 66 return Time(now), clock_seq, nil |
| paddy@0 | 67 } |
| paddy@0 | 68 |
| paddy@0 | 69 // ClockSequence returns the current clock sequence, generating one if not |
| paddy@0 | 70 // already set. The clock sequence is only used for Version 1 UUIDs. |
| paddy@0 | 71 // |
| paddy@0 | 72 // The uuid package does not use global static storage for the clock sequence or |
| paddy@0 | 73 // the last time a UUID was generated. Unless SetClockSequence a new random |
| paddy@0 | 74 // clock sequence is generated the first time a clock sequence is requested by |
| paddy@0 | 75 // ClockSequence, GetTime, or NewUUID. (section 4.2.1.1) sequence is generated |
| paddy@0 | 76 // for |
| paddy@0 | 77 func ClockSequence() int { |
| paddy@0 | 78 defer mu.Unlock() |
| paddy@0 | 79 mu.Lock() |
| paddy@0 | 80 return clockSequence() |
| paddy@0 | 81 } |
| paddy@0 | 82 |
| paddy@0 | 83 func clockSequence() int { |
| paddy@0 | 84 if clock_seq == 0 { |
| paddy@0 | 85 setClockSequence(-1) |
| paddy@0 | 86 } |
| paddy@0 | 87 return int(clock_seq & 0x3fff) |
| paddy@0 | 88 } |
| paddy@0 | 89 |
| paddy@0 | 90 // SetClockSeq sets the clock sequence to the lower 14 bits of seq. Setting to |
| paddy@0 | 91 // -1 causes a new sequence to be generated. |
| paddy@0 | 92 func SetClockSequence(seq int) { |
| paddy@0 | 93 defer mu.Unlock() |
| paddy@0 | 94 mu.Lock() |
| paddy@0 | 95 setClockSequence(seq) |
| paddy@0 | 96 } |
| paddy@0 | 97 |
| paddy@0 | 98 func setClockSequence(seq int) { |
| paddy@0 | 99 if seq == -1 { |
| paddy@0 | 100 var b [2]byte |
| paddy@0 | 101 randomBits(b[:]) // clock sequence |
| paddy@0 | 102 seq = int(b[0])<<8 | int(b[1]) |
| paddy@0 | 103 } |
| paddy@0 | 104 old_seq := clock_seq |
| paddy@0 | 105 clock_seq = uint16(seq&0x3fff) | 0x8000 // Set our variant |
| paddy@0 | 106 if old_seq != clock_seq { |
| paddy@0 | 107 lasttime = 0 |
| paddy@0 | 108 } |
| paddy@0 | 109 } |
| paddy@0 | 110 |
| paddy@0 | 111 // Time returns the time in 100s of nanoseconds since 15 Oct 1582 encoded in |
| paddy@0 | 112 // uuid. It returns false if uuid is not valid. The time is only well defined |
| paddy@0 | 113 // for version 1 and 2 UUIDs. |
| paddy@0 | 114 func (uuid UUID) Time() (Time, bool) { |
| paddy@0 | 115 if len(uuid) != 16 { |
| paddy@0 | 116 return 0, false |
| paddy@0 | 117 } |
| paddy@0 | 118 time := int64(binary.BigEndian.Uint32(uuid[0:4])) |
| paddy@0 | 119 time |= int64(binary.BigEndian.Uint16(uuid[4:6])) << 32 |
| paddy@0 | 120 time |= int64(binary.BigEndian.Uint16(uuid[6:8])&0xfff) << 48 |
| paddy@0 | 121 return Time(time), true |
| paddy@0 | 122 } |
| paddy@0 | 123 |
| paddy@0 | 124 // ClockSequence returns the clock sequence encoded in uuid. It returns false |
| paddy@0 | 125 // if uuid is not valid. The clock sequence is only well defined for version 1 |
| paddy@0 | 126 // and 2 UUIDs. |
| paddy@0 | 127 func (uuid UUID) ClockSequence() (int, bool) { |
| paddy@0 | 128 if len(uuid) != 16 { |
| paddy@0 | 129 return 0, false |
| paddy@0 | 130 } |
| paddy@0 | 131 return int(binary.BigEndian.Uint16(uuid[8:10])) & 0x3fff, true |
| paddy@0 | 132 } |