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.
Built from https://develop.svn.wordpress.org/trunk@34704


git-svn-id: http://core.svn.wordpress.org/trunk@34668 1a063a9b-81f0-0310-95a4-ce76da25c4cd
This commit is contained in:
Boone Gorges 2015-09-29 22:00:24 +00:00
parent ae5f825093
commit db880777f4
4 changed files with 95 additions and 59 deletions

View File

@ -201,7 +201,6 @@ add_filter( 'pingback_ping_source_uri', 'pingback_ping_source_uri' );
add_filter( 'xmlrpc_pingback_error', 'xmlrpc_pingback_error' );
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 );

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@ -1302,6 +1302,15 @@ class WP_Query {
*/
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;
/**
* Cached list of search stopwords.
*
@ -3541,6 +3550,11 @@ class WP_Query {
if ( $this->posts )
$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'] ) {
/**
* Filter the raw post results array, prior to status checks.
@ -4722,6 +4736,86 @@ class WP_Query {
$this->setup_postdata( $this->post );
}
}
/**
* 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;
}
}
/**

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@ -1588,63 +1588,6 @@ function update_termmeta_cache( $term_ids ) {
return update_meta_cache( 'term', $term_ids );
}
/**
* 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.
*

View File

@ -4,7 +4,7 @@
*
* @global string $wp_version
*/
$wp_version = '4.4-alpha-34703';
$wp_version = '4.4-alpha-34704';
/**
* Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.