Changeset 54352

Timestamp:

09/29/2022 10:07:34 AM (2 years ago)

Author:

spacedmonkey

Message:

Query: Save excessive cache add and sets in WP_Query.

In [53941] database query caching was added to WP_Query. However on sites with persistent object caching enabled, this resulted in a high number of unnecessary cache set and adds being run on every request. Caches are not set, if the query cache already exists and is cached. Replace usage of update_post_caches with _prime_post_caches to ensure that only posts that are not in cache are primed.

Props spacedmonkey, peterwilsoncc, mukesh27.
See #22176.

Location:

trunk

Files:

• src/wp-includes/class-wp-query.php (modified) (3 diffs)
• tests/phpunit/tests/query/cacheResults.php (modified) (1 diff)

trunk/src/wp-includes/class-wp-query.php

@@ -3100 +3100 @@
             }
 
-            $cache_key = "wp_query:$key:$last_changed";
-
+            $cache_key   = "wp_query:$key:$last_changed";
+            $cache_found = false;
             if ( null === $this->posts ) {
-                $cached_results = wp_cache_get( $cache_key, 'posts' );
+                $cached_results = wp_cache_get( $cache_key, 'posts', false, $cache_found );
 
                 if ( $cached_results ) {
@@ -3257 +3257 @@
         }
 
-        if ( $q['cache_results'] && $id_query_is_cacheable ) {
+        if ( $q['cache_results'] && $id_query_is_cacheable && ! $cache_found ) {
             $post_ids = wp_list_pluck( $this->posts, 'ID' );
 
@@ -3456 +3456 @@
 
             if ( $q['cache_results'] ) {
-                update_post_caches( $this->posts, $post_type, $q['update_post_term_cache'], $q['update_post_meta_cache'] );
+                $post_ids = wp_list_pluck( $this->posts, 'ID' );
+                _prime_post_caches( $post_ids, $q['update_post_term_cache'], $q['update_post_meta_cache'] );
             }
 

trunk/tests/phpunit/tests/query/cacheResults.php

@@ -985 +985 @@
         $this->assertNotSame( $num_queries, get_num_queries(), 'Removing term does not invalidate previous cache.' );
     }
+
+    /**
+     * @ticket 22176
+     * @dataProvider data_query_cache_with_empty_result_set
+     */
+    public function test_query_cache_with_empty_result_set( $fields_q1, $fields_q2 ) {
+        _delete_all_posts();
+
+        $args_q1 = array(
+            'fields' => $fields_q1,
+        );
+
+        $query_1  = new WP_Query();
+        $posts_q1 = $query_1->query( $args_q1 );
+        $this->assertEmpty( $posts_q1, 'First query does not return an empty result set.' );
+
+        $args_q2 = array(
+            'fields' => $fields_q2,
+        );
+
+        $num_queries = get_num_queries();
+        $query_2     = new WP_Query();
+        $posts_q2    = $query_2->query( $args_q2 );
+        $this->assertEmpty( $posts_q2, 'Second query does not return an empty result set.' );
+        $this->assertSame( $num_queries, get_num_queries(), 'Second query is not cached.' );
+    }
+
+    public function data_query_cache_with_empty_result_set() {
+        return array(
+            array( '', '' ),
+            array( '', 'ids' ),
+            array( '', 'id=>parent' ),
+
+            array( 'ids', '' ),
+            array( 'ids', 'ids' ),
+            array( 'ids', 'id=>parent' ),
+
+            array( 'id=>parent', '' ),
+            array( 'id=>parent', 'ids' ),
+            array( 'id=>parent', 'id=>parent' ),
+        );
+    }
 }