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fix incorrect timestamp in uuid v6 #161

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merged 1 commit into from
Jun 3, 2024
Merged

fix incorrect timestamp in uuid v6 #161

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4 changes: 3 additions & 1 deletion time.go
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Original file line number Diff line number Diff line change
Expand Up @@ -113,7 +113,9 @@ func (uuid UUID) Time() Time {
var t Time
switch uuid.Version() {
case 6:
time := binary.BigEndian.Uint64(uuid[:8]) // Ignore uuid[6] version b0110
time := int64(binary.BigEndian.Uint32(uuid[0:4])) << 28
time |= int64(binary.BigEndian.Uint16(uuid[4:6])) << 12
time |= int64(binary.BigEndian.Uint16(uuid[6:8]) & 0xfff)
t = Time(time)
case 7:
time := binary.BigEndian.Uint64(uuid[:8])
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12 changes: 8 additions & 4 deletions version6.go
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Expand Up @@ -39,12 +39,16 @@ func NewV6() (UUID, error) {
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/

binary.BigEndian.PutUint64(uuid[0:], uint64(now))
timeHigh := uint32((now >> 28) & 0xffffffff)
timeMid := uint16((now >> 12) & 0xffff)
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The & 0xffffffff and & 0xffff are not needed as typecasting to uint32 and uint16 automatically do that but hopefully the compiler will figure that out and elide the extra operation

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That's right. bitmasking is borrowed from the existing uuid v1 code for consistent code style.
Would it be better to remove that part?

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@bormanp bormanp Jun 3, 2024 •
edited
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Hah! I wrote the V1 code back in 2011 when Go was pretty new then and I was being paranoid. Probably would do many things different if I were to rewrite it (which I do not plan on doing).

You can choose if you want to leave it in or take it out. I am okay with either.

timeLow := uint16(now & 0x0fff)
timeLow |= 0x6000 // Version 6

binary.BigEndian.PutUint32(uuid[0:], timeHigh)
binary.BigEndian.PutUint16(uuid[4:], timeMid)
binary.BigEndian.PutUint16(uuid[6:], timeLow)
binary.BigEndian.PutUint16(uuid[8:], seq)

uuid[6] = 0x60 | (uuid[6] & 0x0F)
uuid[8] = 0x80 | (uuid[8] & 0x3F)

nodeMu.Lock()
if nodeID == zeroID {
setNodeInterface("")
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