Changeset 36566 for trunk/src/wp-includes/post.php

Timestamp:

02/17/2016 10:57:33 PM (9 years ago)

Author:

boonebgorges

Message:

More performance improvements to metadata lazyloading.

Comment and term meta lazyloading for WP_Query loops, introduced in 4.4,
depended on filter callback methods belonging to WP_Query objects. This meant
storing WP_Query objects in the $wp_filter global (via add_filter()),
requiring that PHP retain the objects in memory, even when the local variables
would typically be expunged during normal garbage collection. In cases where a
large number of WP_Query objects were instantiated on a single pageload,
and/or where the contents of the WP_Query objects were quite large, serious
performance issues could result.

We skirt this problem by moving metadata lazyloading out of WP_Query. The
new WP_Metadata_Lazyloader class acts as a lazyload queue. Query instances
register items whose metadata should be lazyloaded - such as post terms, or
comments - and a WP_Metadata_Lazyloader method will intercept comment and
term meta requests to perform the cache priming. Since WP_Metadata_Lazyloader
instances are far smaller than WP_Query (containing only object IDs), and
clean up after themselves far better than the previous WP_Query methods (bp
only running their callbacks a single time for a given set of queued objects),
the resource use is decreased dramatically.

See [36525] for an earlier step in this direction.

Props lpawlik, stevegrunwell, boonebgorges.
Fixes #35816.

File:

• trunk/src/wp-includes/post.php (modified) (1 diff)

trunk/src/wp-includes/post.php

@@ -5949 +5949 @@
 
 /**
+ * Queue posts for lazyloading of term meta.
+ *
+ * @since 4.5.0
+ *
+ * @param array $posts Array of WP_Post objects.
+ */
+function wp_queue_posts_for_term_meta_lazyload( $posts ) {
+    $post_type_taxonomies = $term_ids = array();
+    foreach ( $posts as $post ) {
+        if ( ! ( $post instanceof WP_Post ) ) {
+            continue;
+        }
+
+        if ( ! isset( $post_type_taxonomies[ $post->post_type ] ) ) {
+            $post_type_taxonomies[ $post->post_type ] = get_object_taxonomies( $post->post_type );
+        }
+
+        foreach ( $post_type_taxonomies[ $post->post_type ] as $taxonomy ) {
+            // Term cache should already be primed by `update_post_term_cache()`.
+            $terms = get_object_term_cache( $post->ID, $taxonomy );
+            if ( false !== $terms ) {
+                foreach ( $terms as $term ) {
+                    if ( ! isset( $term_ids[ $term->term_id ] ) ) {
+                        $term_ids[] = $term->term_id;
+                    }
+                }
+            }
+        }
+    }
+
+    if ( $term_ids ) {
+        $lazyloader = wp_metadata_lazyloader();
+        $lazyloader->queue_objects( 'term', $term_ids );
+    }
+}
+
+/**
  * Update the custom taxonomies' term counts when a post's status is changed.
  *