Options, Meta APIs: Prevent excessive `notoptions` key lookups.

When the `notoptions` key does not exist in a persistent object cache, it was requested hundreds of times until the first not-option is written.

This commit improves performance by setting the value to an empty array to prevent non-existent `notoptions` key from triggering multiple key lookups.

Follow-up to [4855], [14515].

Props tillkruess, dd32, spacedmonkey.
Fixes #56639.
Built from https://develop.svn.wordpress.org/trunk@54345


git-svn-id: http://core.svn.wordpress.org/trunk@53904 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/option.php

@@ -164,6 +164,12 @@ function get_option( $option, $default = false ) {
 		// Prevent non-existent options from triggering multiple queries.
 		$notoptions = wp_cache_get( 'notoptions', 'options' );
 
+		// Prevent non-existent `notoptions` key from triggering multiple key lookups.
+		if ( ! is_array( $notoptions ) ) {
+			$notoptions = array();
+			wp_cache_set( 'notoptions', $notoptions, 'options' );
+		}
+
 		if ( isset( $notoptions[ $option ] ) ) {
 			/**
 			 * Filters the default value for an option.

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-beta2-54344';
+$wp_version = '6.1-beta2-54345';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.