| // Copyright 2023 Google Inc. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package uuid |
| |
| import "encoding/binary" |
| |
| // UUID version 6 is a field-compatible version of UUIDv1, reordered for improved DB locality. |
| // It is expected that UUIDv6 will primarily be used in contexts where there are existing v1 UUIDs. |
| // Systems that do not involve legacy UUIDv1 SHOULD consider using UUIDv7 instead. |
| // |
| // see https://datatracker.ietf.org/doc/html/draft-peabody-dispatch-new-uuid-format-03#uuidv6 |
| // |
| // NewV6 returns a Version 6 UUID based on the current NodeID and clock |
| // sequence, and the current time. If the NodeID has not been set by SetNodeID |
| // or SetNodeInterface then it will be set automatically. If the NodeID cannot |
| // be set NewV6 set NodeID is random bits automatically . If clock sequence has not been set by |
| // SetClockSequence then it will be set automatically. If GetTime fails to |
| // return the current NewV6 returns Nil and an error. |
| func NewV6() (UUID, error) { |
| var uuid UUID |
| now, seq, err := GetTime() |
| if err != nil { |
| return uuid, err |
| } |
| |
| /* |
| 0 1 2 3 |
| 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 |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | time_high | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | time_mid | time_low_and_version | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| |clk_seq_hi_res | clk_seq_low | node (0-1) | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | node (2-5) | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| */ |
| |
| binary.BigEndian.PutUint64(uuid[0:], uint64(now)) |
| binary.BigEndian.PutUint16(uuid[8:], seq) |
| |
| uuid[6] = 0x60 | (uuid[6] & 0x0F) |
| uuid[8] = 0x80 | (uuid[8] & 0x3F) |
| |
| nodeMu.Lock() |
| if nodeID == zeroID { |
| setNodeInterface("") |
| } |
| copy(uuid[10:], nodeID[:]) |
| nodeMu.Unlock() |
| |
| return uuid, nil |
| } |