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Changeset 34704


Ignore:
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:
4 edited

Legend:

Unmodified
Added
Removed
  • trunk/src/wp-includes/default-filters.php

    r34685 r34704  
    202202add_filter( 'title_save_pre',           'trim'                                );
    203203add_filter( 'get_comment_metadata',     'wp_lazyload_comment_meta',     10, 2 );
    204 add_filter( 'get_term_metadata',        'wp_lazyload_term_meta',        10, 2 );
    205204
    206205add_filter( 'http_request_host_is_external', 'allowed_http_request_hosts', 10, 2 );
  • trunk/src/wp-includes/query.php

    r34697 r34704  
    13021302     */
    13031303     public $thumbnails_cached = false;
     1304
     1305    /**
     1306     * Whether the term meta cache for matched posts has been primed.
     1307     *
     1308     * @since 4.4.0
     1309     * @access protected
     1310     * @var bool
     1311     */
     1312    public $updated_term_meta_cache = false;
    13041313
    13051314    /**
     
    35423551            $this->posts = array_map( 'get_post', $this->posts );
    35433552
     3553
     3554        if ( $q['update_post_term_cache'] ) {
     3555            add_action( 'get_term_metadata', array( $this, 'lazyload_term_meta' ), 10, 2 );
     3556        }
     3557
    35443558        if ( ! $q['suppress_filters'] ) {
    35453559            /**
     
    47234737        }
    47244738    }
     4739
     4740    /**
     4741     * Lazy-loads termmeta for located posts.
     4742     *
     4743     * As a rule, term queries (`get_terms()` and `wp_get_object_terms()`) prime the metadata cache for matched
     4744     * terms by default. However, this can cause a slight performance penalty, especially when that metadata is
     4745     * not actually used. In the context of a `WP_Query` instance, we're able to avoid this potential penalty.
     4746     * `update_object_term_cache()`, called from `update_post_caches()`, does not 'update_term_meta_cache'.
     4747     * Instead, the first time `get_term_meta()` is called from within a `WP_Query` loop, the current method
     4748     * detects the fact, and then primes the metadata cache for all terms attached to all posts in the loop,
     4749     * with a single database query.
     4750     *
     4751     * This method is public so that it can be used as a filter callback. As a rule, there is no need to invoke it
     4752     * directly, from either inside or outside the `WP_Query` object.
     4753     *
     4754     * @since 4.4.0
     4755     * @access public
     4756     *
     4757     * @param null $check   The `$check` param passed from the 'pre_term_metadata' hook.
     4758     * @param int  $term_id ID of the term whose metadata is being cached.
     4759     * @return mixed In order not to short-circuit `get_metadata()`. Generally, this is `null`, but it could be
     4760     *               another value if filtered by a plugin.
     4761     */
     4762    public function lazyload_term_meta( $check, $term_id ) {
     4763        /*
     4764         * We only do this once per `WP_Query` instance.
     4765         * Can't use `remove_action()` because of non-unique object hashes.
     4766         */
     4767        if ( $this->updated_term_meta_cache ) {
     4768            return $check;
     4769        }
     4770
     4771        // We can only lazyload if the entire post object is present.
     4772        $posts = array();
     4773        foreach ( $this->posts as $post ) {
     4774            if ( $post instanceof WP_Post ) {
     4775                $posts[] = $post;
     4776            }
     4777        }
     4778        $_p = array();
     4779        foreach ( $posts as $post ) {
     4780            $_p[] = $post->ID;
     4781        }
     4782
     4783        if ( ! empty( $posts ) ) {
     4784            // Fetch cached term_ids for each post. Keyed by term_id for faster lookup.
     4785            $term_ids = array();
     4786            foreach ( $posts as $post ) {
     4787                $taxonomies = get_object_taxonomies( $post->post_type );
     4788                foreach ( $taxonomies as $taxonomy ) {
     4789                    // Term cache should already be primed by 'update_post_term_cache'.
     4790                    $terms = get_object_term_cache( $post->ID, $taxonomy );
     4791                    if ( false !== $terms ) {
     4792                        foreach ( $terms as $term ) {
     4793                            if ( ! isset( $term_ids[ $term->term_id ] ) ) {
     4794                                $term_ids[ $term->term_id ] = 1;
     4795                            }
     4796                        }
     4797                    }
     4798                }
     4799            }
     4800
     4801            /*
     4802             * Only update the metadata cache for terms belonging to these posts if the term_id passed
     4803             * to `get_term_meta()` matches one of those terms. This prevents a single call to
     4804             * `get_term_meta()` from priming metadata for all `WP_Query` objects.
     4805             */
     4806            if ( isset( $term_ids[ $term_id ] ) ) {
     4807                update_termmeta_cache( array_keys( $term_ids ) );
     4808                $this->updated_term_meta_cache = true;
     4809            }
     4810        }
     4811
     4812        // If no terms were found, there's no need to run this again.
     4813        if ( empty( $term_ids ) ) {
     4814            $this->updated_term_meta_cache = true;
     4815        }
     4816
     4817        return $check;
     4818    }
    47254819}
    47264820
  • trunk/src/wp-includes/taxonomy-functions.php

    r34679 r34704  
    15901590
    15911591/**
    1592  * Lazy-loads termmeta when inside of a `WP_Query` loop.
    1593  *
    1594  * As a rule, term queries (`get_terms()` and `wp_get_object_terms()`) prime the metadata cache for matched terms by
    1595  * default. However, this can cause a slight performance penalty, especially when that metadata is not actually used.
    1596  * In the context of a `WP_Query` loop, we're able to avoid this potential penalty. `update_object_term_cache()`,
    1597  * called from `update_post_caches()`, does not 'update_term_meta_cache'. Instead, the first time `get_term_meta()` is
    1598  * called from within a `WP_Query` loop, the current function detects the fact, and then primes the metadata cache for
    1599  * all terms attached to all posts in the loop, with a single database query.
    1600  *
    1601  * @since 4.4.0
    1602  *
    1603  * @param null $check   The `$check` param passed from the 'pre_term_metadata' hook.
    1604  * @param int  $term_id ID of the term whose metadata is being cached.
    1605  * @return null In order not to short-circuit `get_metadata()`.
    1606  */
    1607 function wp_lazyload_term_meta( $check, $term_id ) {
    1608     global $wp_query;
    1609 
    1610     if ( $wp_query instanceof WP_Query && ! empty( $wp_query->posts ) && $wp_query->get( 'update_post_term_cache' ) ) {
    1611         // We can only lazyload if the entire post object is present.
    1612         $posts = array();
    1613         foreach ( $wp_query->posts as $post ) {
    1614             if ( $post instanceof WP_Post ) {
    1615                 $posts[] = $post;
    1616             }
    1617         }
    1618 
    1619         if ( empty( $posts ) ) {
    1620             return;
    1621         }
    1622 
    1623         // Fetch cached term_ids for each post. Keyed by term_id for faster lookup.
    1624         $term_ids = array();
    1625         foreach ( $posts as $post ) {
    1626             $taxonomies = get_object_taxonomies( $post->post_type );
    1627             foreach ( $taxonomies as $taxonomy ) {
    1628                 // No extra queries. Term cache should already be primed by 'update_post_term_cache'.
    1629                 $terms = get_object_term_cache( $post->ID, $taxonomy );
    1630                 if ( false !== $terms ) {
    1631                     foreach ( $terms as $term ) {
    1632                         if ( ! isset( $term_ids[ $term->term_id ] ) ) {
    1633                             $term_ids[ $term->term_id ] = 1;
    1634                         }
    1635                     }
    1636                 }
    1637             }
    1638         }
    1639 
    1640         if ( $term_ids ) {
    1641             update_termmeta_cache( array_keys( $term_ids ) );
    1642         }
    1643     }
    1644 
    1645     return $check;
    1646 }
    1647 
    1648 /**
    16491592 * Check if Term exists.
    16501593 *
  • trunk/tests/phpunit/tests/term/meta.php

    r34538 r34704  
    146146    }
    147147
     148    /**
     149     * @ticket 34073
     150     */
     151    public function test_term_meta_should_be_lazy_loaded_only_for_the_queries_in_which_the_term_has_posts() {
     152        global $wpdb;
     153
     154        $posts = $this->factory->post->create_many( 3, array( 'post_status' => 'publish' ) );
     155        register_taxonomy( 'wptests_tax', 'post' );
     156        $terms = $this->factory->term->create_many( 6, array( 'taxonomy' => 'wptests_tax' ) );
     157
     158        wp_set_object_terms( $posts[0], array( $terms[0], $terms[1] ), 'wptests_tax' );
     159        wp_set_object_terms( $posts[1], array( $terms[2], $terms[3] ), 'wptests_tax' );
     160        wp_set_object_terms( $posts[2], array( $terms[0], $terms[4], $terms[5] ), 'wptests_tax' );
     161
     162        foreach ( $terms as $t ) {
     163            add_term_meta( $t, 'foo', 'bar' );
     164        }
     165
     166        $q0 = new WP_Query( array( 'p' => $posts[0] ) );
     167        $q1 = new WP_Query( array( 'p' => $posts[1] ) );
     168        $q2 = new WP_Query( array( 'p' => $posts[2] ) );
     169
     170        /*
     171         * $terms[0] belongs to both $posts[0] and $posts[2], so `get_term_meta( $terms[0] )` should prime
     172         * the cache for term matched by $q0 and $q2.
     173         */
     174
     175        // First request will hit the database.
     176        $num_queries = $wpdb->num_queries;
     177
     178        // Prime caches.
     179        $this->assertSame( 'bar', get_term_meta( $terms[0], 'foo', true ) );
     180
     181        // Two queries: one for $q0 and one for $q2.
     182        $num_queries += 2;
     183        $this->assertSame( $num_queries, $wpdb->num_queries );
     184
     185        // Next requests should be in cache.
     186        $this->assertSame( 'bar', get_term_meta( $terms[1], 'foo', true ) );
     187        $this->assertSame( 'bar', get_term_meta( $terms[4], 'foo', true ) );
     188        $this->assertSame( 'bar', get_term_meta( $terms[5], 'foo', true ) );
     189        $this->assertSame( $num_queries, $wpdb->num_queries );
     190
     191        // Querying for $terms[2] will prime $terms[3] as well.
     192        $this->assertSame( 'bar', get_term_meta( $terms[2], 'foo', true ) );
     193        $num_queries++;
     194        $this->assertSame( $num_queries, $wpdb->num_queries );
     195
     196        $this->assertSame( 'bar', get_term_meta( $terms[3], 'foo', true ) );
     197        $this->assertSame( $num_queries, $wpdb->num_queries );
     198    }
     199
    148200    public function test_adding_term_meta_should_bust_get_terms_cache() {
    149201        $terms = $this->factory->term->create_many( 2, array( 'taxonomy' => 'wptests_tax' ) );
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