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 5package uuid 6 7import "io" 8 9// New creates a new random UUID or panics. New is equivalent to 10// the expression 11// 12// uuid.Must(uuid.NewRandom()) 13func 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. 29func 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} 39