[wp-trac] [WordPress Trac] #59239: wp_generate_uuid4 collisions

[WordPress Trac]

#59239: wp_generate_uuid4 collisions
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 Reporter:  joppuyo                         |       Owner:  jorbin
     Type:  defect (bug)                    |      Status:  assigned
 Priority:  normal                          |   Milestone:  7.0
Component:  General                         |     Version:
 Severity:  normal                          |  Resolution:
 Keywords:  has-patch needs-testing commit  |     Focuses:
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Comment (by peterwilsoncc):

 @siliconforks I don't think it's worth the additional logic.

 The risk of collision with `mt_rand()` is present but very low. The
 updated function will only ever fire if a third party developers calls it
 somewhere between the mu-plugins includes and before the `plugins_loaded`
 hook. Which itself is rare.

 Running the following using the existing (collision prone) code about
 tenish didn't result in any collisions.


 {{{#!php
 <?php
 function gguid_collision_test() {
         $gguids = array();
         $count = 0;

         $tries = 1000000;

         for ( $i = 0; $i < $tries; $i++ ) {
                 $gguid = wp_generate_uuid4();
                 if ( isset( $gguids[ $gguid ] ) ) {
                         echo "Collision detected after $count tries.\n";
                         return;
                 }
                 $gguids[ $gguid ] = true;
                 $count++;
         }

         echo "No collisions detected after $count tries.\n";
 }

 echo '<pre>';
 gguid_collision_test();
 exit;

 }}}


 As this isn't using `mt_rand` for cryptographic purposes, I think it's
 fine to use the KISS approach for a `low^2` probability.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/59239#comment:16>
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