[wp-trac] [WordPress Trac] #55952: add_option() racy behaviour

[WordPress Trac]

#55952: add_option() racy behaviour
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 Reporter:  karl94              |      Owner:  (none)
     Type:  defect (bug)        |     Status:  new
 Priority:  normal              |  Milestone:  Awaiting Review
Component:  Options, Meta APIs  |    Version:
 Severity:  normal              |   Keywords:
  Focuses:                      |
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 If two or more processes try to add an option via `add_option()` at the
 same time with both the same value, the following calls to `get_option()`
 may return `false` as if the option wasn't set.

 This happens for example if two processes A and B: both reach past the
 check in https://github.com/WordPress/wordpress-develop/blob/6.0/src/wp-
 includes/option.php#L622-L624 before any of the two performs the `INSERT`.
 In this scenario, the first process which gets to execute the `INSERT`
 will return `true` and will have the correct value in its object cache.
 The other process's `add_option()` will return `false` and it's object
 cache will continue to believe the option doesn't exists.

 https://github.com/WordPress/wordpress-develop/blob/6.0/src/wp-
 includes/option.php#L640-L641
 https://github.com/WordPress/wordpress-develop/blob/6.0/src/wp-includes
 /wp-db.php#L2116-L2131
 https://dev.mysql.com/doc/refman/8.0/en/insert-on-
 duplicate.html#:~:text=0%20if%20an%20existing%20row%20is%20set%20to%20its%20current%20values

 You can find attached a plugin designed for testing this race condition.

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Ticket URL: <https://core.trac.wordpress.org/ticket/55952>
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