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Go monorepo.
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version6.go (2213B)

      1 // Copyright 2023 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 
      5 package uuid
      6 
      7 import "encoding/binary"
      8 
      9 // UUID version 6 is a field-compatible version of UUIDv1, reordered for improved DB locality.
     10 // It is expected that UUIDv6 will primarily be used in contexts where there are existing v1 UUIDs.
     11 // Systems that do not involve legacy UUIDv1 SHOULD consider using UUIDv7 instead.
     12 //
     13 // see https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format-03#uuidv6
     14 //
     15 // NewV6 returns a Version 6 UUID based on the current NodeID and clock
     16 // sequence, and the current time. If the NodeID has not been set by SetNodeID
     17 // or SetNodeInterface then it will be set automatically. If the NodeID cannot
     18 // be set NewV6 set NodeID is random bits automatically . If clock sequence has not been set by
     19 // SetClockSequence then it will be set automatically. If GetTime fails to
     20 // return the current NewV6 returns Nil and an error.
     21 func NewV6() (UUID, error) {
     22 	var uuid UUID
     23 	now, seq, err := GetTime()
     24 	if err != nil {
     25 		return uuid, err
     26 	}
     27 
     28 	/*
     29 	    0                   1                   2                   3
     30 	    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     31 	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     32 	   |                           time_high                           |
     33 	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     34 	   |           time_mid            |      time_low_and_version     |
     35 	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     36 	   |clk_seq_hi_res |  clk_seq_low  |         node (0-1)            |
     37 	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     38 	   |                         node (2-5)                            |
     39 	   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     40 	*/
     41 
     42 	binary.BigEndian.PutUint64(uuid[0:], uint64(now))
     43 	binary.BigEndian.PutUint16(uuid[8:], seq)
     44 
     45 	uuid[6] = 0x60 | (uuid[6] & 0x0F)
     46 	uuid[8] = 0x80 | (uuid[8] & 0x3F)
     47 
     48 	nodeMu.Lock()
     49 	if nodeID == zeroID {
     50 		setNodeInterface("")
     51 	}
     52 	copy(uuid[10:], nodeID[:])
     53 	nodeMu.Unlock()
     54 
     55 	return uuid, nil
     56 }