Changeset 36524

Timestamp:

02/13/2016 03:04:05 AM (9 years ago)

Author:

boonebgorges

Message:

Improve WP_Query lazyloading logic, for better performance.

Lazyloading for comment meta and term meta, introduced into WP_Query in
4.4, used flags - updated_term_meta_cache and updated_comment_meta_cache -
in an attempt to prevent cache priming from happening more than once per query
object. This technique was mostly effective, but not entirely efficient, since
the flag didn't prevent the lazyload_*_meta callbacks from running. The
obvious solution - removing the filter callback after it'd be run once - was
dismissed for 4.4 because of concerns that remove_filter() could disable
lazyloading too generally in the context of nested queries, due to the way
_wp_filter_build_unique_id() doesn't always build sufficiently unique IDs for
similar objects. However, further testing shows that this concern is only valid
in a very small subset of cases, while the cost of keeping the query objects in
memory, via the $wp_filter global, is quite significant. As such, this
changeset removes the flags in favor of the remove_filter() technique.

See #35454, #35816.

File:

• trunk/src/wp-includes/query.php (modified) (6 diffs)

trunk/src/wp-includes/query.php

@@ -1303 +1303 @@
      */
      public $thumbnails_cached = false;
-
-    /**
-     * Whether the term meta cache for matched posts has been primed.
-     *
-     * @since 4.4.0
-     * @access protected
-     * @var bool
-     */
-    public $updated_term_meta_cache = false;
-
-    /**
-     * Whether the comment meta cache for matched posts has been primed.
-     *
-     * @since 4.4.0
-     * @access protected
-     * @var bool
-     */
-    public $updated_comment_meta_cache = false;
 
     /**
@@ -4875 +4857 @@
      */
     public function lazyload_term_meta( $check, $term_id ) {
-        /*
-         * We only do this once per `WP_Query` instance.
-         * Can't use `remove_filter()` because of non-unique object hashes.
-         */
-        if ( $this->updated_term_meta_cache ) {
-            return $check;
-        }
-
         // We can only lazyload if the entire post object is present.
         $posts = array();
@@ -4916 +4890 @@
             if ( isset( $term_ids[ $term_id ] ) ) {
                 update_termmeta_cache( array_keys( $term_ids ) );
-                $this->updated_term_meta_cache = true;
+                remove_filter( 'get_term_metadata', array( $this, 'lazyload_term_meta' ), 10, 2 );
             }
         }
@@ -4922 +4896 @@
         // If no terms were found, there's no need to run this again.
         if ( empty( $term_ids ) ) {
-            $this->updated_term_meta_cache = true;
+            remove_filter( 'get_term_metadata', array( $this, 'lazyload_term_meta' ), 10, 2 );
         }
 
@@ -4941 +4915 @@
      */
     public function lazyload_comment_meta( $check, $comment_id ) {
-        /*
-         * We only do this once per `WP_Query` instance.
-         * Can't use `remove_filter()` because of non-unique object hashes.
-         */
-        if ( $this->updated_comment_meta_cache ) {
-            return $check;
-        }
-
         // Don't use `wp_list_pluck()` to avoid by-reference manipulation.
         $comment_ids = array();
@@ -4964 +4930 @@
         if ( in_array( $comment_id, $comment_ids ) ) {
             update_meta_cache( 'comment', $comment_ids );
-            $this->updated_comment_meta_cache = true;
+            remove_filter( 'get_comment_metadata', array( $this, 'lazyload_comment_meta' ), 10, 2 );
         } elseif ( empty( $comment_ids ) ) {
-            $this->updated_comment_meta_cache = true;
+            remove_filter( 'get_comment_metadata', array( $this, 'lazyload_comment_meta' ), 10, 2 );
         }