Changeset 34704

Timestamp:

09/29/2015 09:59:44 PM (5 years ago)

Author:

boonebgorges

Message:

Improve lazyloading of term metadata in WP_Query loops.

[34529] introduced lazyloading for the metadata belonging to terms matching
posts in the main WP_Query. The current changeset improves this technique
in the following ways:

• Term meta lazyloading is now performed on the results of all WP_Query queries, not just the main query.
• Fewer global variable touches and greater encapsulation.
• The logic for looping through posts to identify terms is now only performed once per WP_Query.

Props dlh, boonebgorges.
See #34047.

Location:

trunk

Files:

• src/wp-includes/default-filters.php (modified) (1 diff)
• src/wp-includes/query.php (modified) (3 diffs)
• src/wp-includes/taxonomy-functions.php (modified) (1 diff)
• tests/phpunit/tests/term/meta.php (modified) (1 diff)

trunk/src/wp-includes/default-filters.php

@@ -202 +202 @@
 add_filter( 'title_save_pre',           'trim'                                );
 add_filter( 'get_comment_metadata',     'wp_lazyload_comment_meta',     10, 2 );
-add_filter( 'get_term_metadata',        'wp_lazyload_term_meta',        10, 2 );
 
 add_filter( 'http_request_host_is_external', 'allowed_http_request_hosts', 10, 2 );

trunk/src/wp-includes/query.php

@@ -1302 +1302 @@
      */
      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;
 
     /**
@@ -3542 +3551 @@
             $this->posts = array_map( 'get_post', $this->posts );
 
+
+        if ( $q['update_post_term_cache'] ) {
+            add_action( 'get_term_metadata', array( $this, 'lazyload_term_meta' ), 10, 2 );
+        }
+
         if ( ! $q['suppress_filters'] ) {
             /**
@@ -4723 +4737 @@
         }
     }
+
+    /**
+     * Lazy-loads termmeta for located posts.
+     *
+     * As a rule, term queries (`get_terms()` and `wp_get_object_terms()`) prime the metadata cache for matched
+     * terms by default. However, this can cause a slight performance penalty, especially when that metadata is
+     * not actually used. In the context of a `WP_Query` instance, we're able to avoid this potential penalty.
+     * `update_object_term_cache()`, called from `update_post_caches()`, does not 'update_term_meta_cache'.
+     * Instead, the first time `get_term_meta()` is called from within a `WP_Query` loop, the current method
+     * detects the fact, and then primes the metadata cache for all terms attached to all posts in the loop,
+     * with a single database query.
+     *
+     * This method is public so that it can be used as a filter callback. As a rule, there is no need to invoke it
+     * directly, from either inside or outside the `WP_Query` object.
+     *
+     * @since 4.4.0
+     * @access public
+     *
+     * @param null $check   The `$check` param passed from the 'pre_term_metadata' hook.
+     * @param int  $term_id ID of the term whose metadata is being cached.
+     * @return mixed In order not to short-circuit `get_metadata()`. Generally, this is `null`, but it could be
+     *               another value if filtered by a plugin.
+     */
+    public function lazyload_term_meta( $check, $term_id ) {
+        /*
+         * We only do this once per `WP_Query` instance.
+         * Can't use `remove_action()` 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();
+        foreach ( $this->posts as $post ) {
+            if ( $post instanceof WP_Post ) {
+                $posts[] = $post;
+            }
+        }
+        $_p = array();
+        foreach ( $posts as $post ) {
+            $_p[] = $post->ID;
+        }
+
+        if ( ! empty( $posts ) ) {
+            // Fetch cached term_ids for each post. Keyed by term_id for faster lookup.
+            $term_ids = array();
+            foreach ( $posts as $post ) {
+                $taxonomies = get_object_taxonomies( $post->post_type );
+                foreach ( $taxonomies 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 ] = 1;
+                            }
+                        }
+                    }
+                }
+            }
+
+            /*
+             * Only update the metadata cache for terms belonging to these posts if the term_id passed
+             * to `get_term_meta()` matches one of those terms. This prevents a single call to
+             * `get_term_meta()` from priming metadata for all `WP_Query` objects.
+             */
+            if ( isset( $term_ids[ $term_id ] ) ) {
+                update_termmeta_cache( array_keys( $term_ids ) );
+                $this->updated_term_meta_cache = true;
+            }
+        }
+
+        // If no terms were found, there's no need to run this again.
+        if ( empty( $term_ids ) ) {
+            $this->updated_term_meta_cache = true;
+        }
+
+        return $check;
+    }
 }
 

trunk/src/wp-includes/taxonomy-functions.php

@@ -1590 +1590 @@
 
 /**
- * Lazy-loads termmeta when inside of a `WP_Query` loop.
- *
- * As a rule, term queries (`get_terms()` and `wp_get_object_terms()`) prime the metadata cache for matched terms by
- * default. However, this can cause a slight performance penalty, especially when that metadata is not actually used.
- * In the context of a `WP_Query` loop, we're able to avoid this potential penalty. `update_object_term_cache()`,
- * called from `update_post_caches()`, does not 'update_term_meta_cache'. Instead, the first time `get_term_meta()` is
- * called from within a `WP_Query` loop, the current function detects the fact, and then primes the metadata cache for
- * all terms attached to all posts in the loop, with a single database query.
- *
- * @since 4.4.0
- *
- * @param null $check   The `$check` param passed from the 'pre_term_metadata' hook.
- * @param int  $term_id ID of the term whose metadata is being cached.
- * @return null In order not to short-circuit `get_metadata()`.
- */
-function wp_lazyload_term_meta( $check, $term_id ) {
-    global $wp_query;
-
-    if ( $wp_query instanceof WP_Query && ! empty( $wp_query->posts ) && $wp_query->get( 'update_post_term_cache' ) ) {
-        // We can only lazyload if the entire post object is present.
-        $posts = array();
-        foreach ( $wp_query->posts as $post ) {
-            if ( $post instanceof WP_Post ) {
-                $posts[] = $post;
-            }
-        }
-
-        if ( empty( $posts ) ) {
-            return;
-        }
-
-        // Fetch cached term_ids for each post. Keyed by term_id for faster lookup.
-        $term_ids = array();
-        foreach ( $posts as $post ) {
-            $taxonomies = get_object_taxonomies( $post->post_type );
-            foreach ( $taxonomies as $taxonomy ) {
-                // No extra queries. 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 ] = 1;
-                        }
-                    }
-                }
-            }
-        }
-
-        if ( $term_ids ) {
-            update_termmeta_cache( array_keys( $term_ids ) );
-        }
-    }
-
-    return $check;
-}
-
-/**
  * Check if Term exists.
  *

trunk/tests/phpunit/tests/term/meta.php

@@ -146 +146 @@
     }
 
+    /**
+     * @ticket 34073
+     */
+    public function test_term_meta_should_be_lazy_loaded_only_for_the_queries_in_which_the_term_has_posts() {
+        global $wpdb;
+
+        $posts = $this->factory->post->create_many( 3, array( 'post_status' => 'publish' ) );
+        register_taxonomy( 'wptests_tax', 'post' );
+        $terms = $this->factory->term->create_many( 6, array( 'taxonomy' => 'wptests_tax' ) );
+
+        wp_set_object_terms( $posts[0], array( $terms[0], $terms[1] ), 'wptests_tax' );
+        wp_set_object_terms( $posts[1], array( $terms[2], $terms[3] ), 'wptests_tax' );
+        wp_set_object_terms( $posts[2], array( $terms[0], $terms[4], $terms[5] ), 'wptests_tax' );
+
+        foreach ( $terms as $t ) {
+            add_term_meta( $t, 'foo', 'bar' );
+        }
+
+        $q0 = new WP_Query( array( 'p' => $posts[0] ) );
+        $q1 = new WP_Query( array( 'p' => $posts[1] ) );
+        $q2 = new WP_Query( array( 'p' => $posts[2] ) );
+
+        /*
+         * $terms[0] belongs to both $posts[0] and $posts[2], so `get_term_meta( $terms[0] )` should prime
+         * the cache for term matched by $q0 and $q2.
+         */
+
+        // First request will hit the database.
+        $num_queries = $wpdb->num_queries;
+
+        // Prime caches.
+        $this->assertSame( 'bar', get_term_meta( $terms[0], 'foo', true ) );
+
+        // Two queries: one for $q0 and one for $q2.
+        $num_queries += 2;
+        $this->assertSame( $num_queries, $wpdb->num_queries );
+
+        // Next requests should be in cache.
+        $this->assertSame( 'bar', get_term_meta( $terms[1], 'foo', true ) );
+        $this->assertSame( 'bar', get_term_meta( $terms[4], 'foo', true ) );
+        $this->assertSame( 'bar', get_term_meta( $terms[5], 'foo', true ) );
+        $this->assertSame( $num_queries, $wpdb->num_queries );
+
+        // Querying for $terms[2] will prime $terms[3] as well.
+        $this->assertSame( 'bar', get_term_meta( $terms[2], 'foo', true ) );
+        $num_queries++;
+        $this->assertSame( $num_queries, $wpdb->num_queries );
+
+        $this->assertSame( 'bar', get_term_meta( $terms[3], 'foo', true ) );
+        $this->assertSame( $num_queries, $wpdb->num_queries );
+    }
+
     public function test_adding_term_meta_should_bust_get_terms_cache() {
         $terms = $this->factory->term->create_many( 2, array( 'taxonomy' => 'wptests_tax' ) );