github.com/inflatablewoman/deis@v1.0.1-0.20141111034523-a4511c46a6ce/deisctl/Godeps/_workspace/src/code.google.com/p/go-uuid/uuid/version4.go (about)

     1  // Copyright 2011 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  // Random returns a Random (Version 4) UUID or panics.
     8  //
     9  // The strength of the UUIDs is based on the strength of the crypto/rand
    10  // package.
    11  //
    12  // A note about uniqueness derived from from the UUID Wikipedia entry:
    13  //
    14  //  Randomly generated UUIDs have 122 random bits.  One's annual risk of being
    15  //  hit by a meteorite is estimated to be one chance in 17 billion, that
    16  //  means the probability is about 0.00000000006 (6 × 10−11),
    17  //  equivalent to the odds of creating a few tens of trillions of UUIDs in a
    18  //  year and having one duplicate.
    19  func NewRandom() UUID {
    20  	uuid := make([]byte, 16)
    21  	randomBits([]byte(uuid))
    22  	uuid[6] = (uuid[6] & 0x0f) | 0x40 // Version 4
    23  	uuid[8] = (uuid[8] & 0x3f) | 0x80 // Variant is 10
    24  	return uuid
    25  }