Query: Move cache key generation to its own method.

Introduce `WP_Query::generate_cache_key()` for generating the cache key used by the main database query.

This removes the need for a filter to test that cache keys do not include the WPDB placeholder causing unreachable cache keys. The tests now call `WP_Query::generate_cache_key()` directly.

The filter `wp_query_cache_key` is removed as a hard deprecation. The filter was not included in a stable release.

Follow up to [54685].

Props spacedmonkey, jorbin, azaozz, hellofromtonya, mukesh27, peterwilsoncc, desrosj, audrasjb, adamsilverstein, flixos90, davidbaumwald, joedolson, sergeybiryukov.
Reviewed by mikeschroder.
Merges [54685] to the 6.1 branch.
Fixes #56802.
Built from https://develop.svn.wordpress.org/branches/6.1@54692


git-svn-id: http://core.svn.wordpress.org/branches/6.1@54244 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-query.php

@@ -3106,41 +3106,8 @@ public function get_posts() {
 		 */
 		$id_query_is_cacheable = ! str_contains( strtoupper( $orderby ), ' RAND(' );
 		if ( $q['cache_results'] && $id_query_is_cacheable ) {
-			$cache_args = $q;
-
-			unset(
-				$cache_args['suppress_filters'],
-				$cache_args['cache_results'],
-				$cache_args['fields'],
-				$cache_args['update_post_meta_cache'],
-				$cache_args['update_post_term_cache'],
-				$cache_args['lazy_load_term_meta'],
-				$cache_args['update_menu_item_cache'],
-				$cache_args['search_orderby_title']
-			);
-
 			$new_request = str_replace( $fields, "{$wpdb->posts}.*", $this->request );
-			$new_request = $wpdb->remove_placeholder_escape( $new_request );
-			$key         = md5( serialize( $cache_args ) . $new_request );
-
-			$last_changed = wp_cache_get_last_changed( 'posts' );
-			if ( ! empty( $this->tax_query->queries ) ) {
-				$last_changed .= wp_cache_get_last_changed( 'terms' );
-			}
-
-			$cache_key = "wp_query:$key:$last_changed";
-
-			/**
-			 * Filters query cache key.
-			 *
-			 * @since 6.1.0
-			 *
-			 * @param string   $cache_key   Cache key.
-			 * @param array    $cache_args  Query args used to generate the cache key.
-			 * @param string   $new_request SQL Query.
-			 * @param WP_Query $query       The WP_Query instance.
-			 */
-			$cache_key = apply_filters( 'wp_query_cache_key', $cache_key, $cache_args, $new_request, $this );
+			$cache_key   = $this->generate_cache_key( $q, $new_request );
 
 			$cache_found = false;
 			if ( null === $this->posts ) {
@@ -4755,6 +4722,62 @@ public function generate_postdata( $post ) {
 
 		return $elements;
 	}
+
+	/**
+	 * Generate cache key.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @global wpdb $wpdb WordPress database abstraction object.
+	 *
+	 * @param array  $args Query arguments.
+	 * @param string $sql  SQL statement.
+	 *
+	 * @return string Cache key.
+	 */
+	protected function generate_cache_key( array $args, $sql ) {
+		global $wpdb;
+
+		unset(
+			$args['cache_results'],
+			$args['fields'],
+			$args['lazy_load_term_meta'],
+			$args['update_post_meta_cache'],
+			$args['update_post_term_cache'],
+			$args['update_menu_item_cache'],
+			$args['suppress_filters']
+		);
+
+		$placeholder = $wpdb->placeholder_escape();
+		array_walk_recursive(
+			$args,
+			/*
+			 * Replace wpdb placeholders with the string used in the database
+			 * query to avoid unreachable cache keys. This is necessary because
+			 * the placeholder is randomly generated in each request.
+			 *
+			 * $value is passed by reference to allow it to be modified.
+			 * array_walk_recursive() does not return an array.
+			 */
+			function ( &$value ) use ( $wpdb, $placeholder ) {
+				if ( is_string( $value ) && str_contains( $value, $placeholder ) ) {
+					$value = $wpdb->remove_placeholder_escape( $value );
+				}
+			}
+		);
+
+		// Replace wpdb placeholder in the SQL statement used by the cache key.
+		$sql = $wpdb->remove_placeholder_escape( $sql );
+		$key = md5( serialize( $args ) . $sql );
+
+		$last_changed = wp_cache_get_last_changed( 'posts' );
+		if ( ! empty( $this->tax_query->queries ) ) {
+			$last_changed .= wp_cache_get_last_changed( 'terms' );
+		}
+
+		return "wp_query:$key:$last_changed";
+	}
+
 	/**
 	 * After looping through a nested query, this function
 	 * restores the $post global to the current post in this query.

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-RC2-54691';
+$wp_version = '6.1-RC2-54692';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.