| Takahiro Suzuki | 241c10e | 2020-12-17 20:17:57 +0900 | [diff] [blame] | 1 | // 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 | |
| 5 | package uuid |
| 6 | |
| 7 | import "io" |
| 8 | |
| 9 | // New creates a new random UUID or panics. New is equivalent to |
| 10 | // the expression |
| 11 | // |
| 12 | // uuid.Must(uuid.NewRandom()) |
| 13 | func New() UUID { |
| 14 | return Must(NewRandom()) |
| 15 | } |
| 16 | |
| 17 | // NewRandom returns a Random (Version 4) UUID. |
| 18 | // |
| 19 | // The strength of the UUIDs is based on the strength of the crypto/rand |
| 20 | // package. |
| 21 | // |
| 22 | // A note about uniqueness derived from the UUID Wikipedia entry: |
| 23 | // |
| 24 | // Randomly generated UUIDs have 122 random bits. One's annual risk of being |
| 25 | // hit by a meteorite is estimated to be one chance in 17 billion, that |
| 26 | // means the probability is about 0.00000000006 (6 × 10−11), |
| 27 | // equivalent to the odds of creating a few tens of trillions of UUIDs in a |
| 28 | // year and having one duplicate. |
| 29 | func NewRandom() (UUID, error) { |
| 30 | var uuid UUID |
| 31 | _, err := io.ReadFull(rander, uuid[:]) |
| 32 | if err != nil { |
| 33 | return Nil, err |
| 34 | } |
| 35 | uuid[6] = (uuid[6] & 0x0f) | 0x40 // Version 4 |
| 36 | uuid[8] = (uuid[8] & 0x3f) | 0x80 // Variant is 10 |
| 37 | return uuid, nil |
| 38 | } |