WP_Comment_Query::fill_descendants( WP_Comment[] $comments ): array
- Since
- 4.4.0
- Source
wp-includes/class-wp-comment-query.php:1046
Description
Instead of calling get_children() separately on each child comment, we do a single set of queries to fetch the descendant trees for all matched top-level comments.
Compatibility
- WordPress
- since 4.4.0
- PHP
- 7.4–8.6-dev
- 6.7.7
- 6.8.8
- 6.9.7
- 7.0.4
- 7.1.0
Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.
Parameters
$commentsWP_Comment[]- Array of top-level comments whose descendants should be filled in.
Return value
array
Performance profile
How much work a call to WP_Comment_Query::fill_descendants() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Heavy
- Scaling
- Scales with input
- Instructions
- 60–121
- Plugin surface
- None
- Called by
- 1
Reaches the database via get_comments().
The body loops, so the work grows with what you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 217.
Nothing here hands control to plugin code.
1 place in core call this, so the cost is paid more often than your own code shows.
What it touches
- cacheobject cache
wp_cache_get_last_changed()called directly - querycontent query
get_comments()called directly - serializeserialisation
serialize()called directly - hookthird-party callbacks
apply_filters()one call below WP_Comment_Query::fill_descendants()
What one call costs · 4 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost WP_Comment_Query::fill_descendants() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
!$i | 60–69 | wp_list_pluck(), array_keys(), wp_array_slice_assoc(), serialize(), md5(), wp_cache_get_last_changed(), _prime_comment_caches() |
!$i | 74–85 | wp_list_pluck(), array_keys(), wp_array_slice_assoc(), serialize(), md5(), wp_cache_get_last_changed(), array_values(), wp_cache_get_multiple_salted(), _prime_comment_caches() |
!$i | 93–105 | wp_list_pluck(), array_keys(), wp_array_slice_assoc(), serialize(), md5(), wp_cache_get_last_changed(), get_comments(), array_fill_keys(), wp_cache_set_multiple_salted(), _prime_comment_caches() |
!$i | 107–121 | wp_list_pluck(), array_keys(), wp_array_slice_assoc(), serialize(), md5(), wp_cache_get_last_changed(), array_values(), wp_cache_get_multiple_salted(), get_comments(), array_fill_keys(), wp_cache_set_multiple_salted(), _prime_comment_caches() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 217 instructions, 60–121 executed per call, 23 branches. The work does not change between versions.
An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.
Uses · 8
- wp_list_pluck()Plucks a certain field out of each object or array in an array.
- wp_array_slice_assoc()Extracts a slice of an array, given a list of keys.
- wp_cache_get_last_changed()Gets last changed date for the specified cache group.
- wp_cache_get_multiple_salted()Retrieves multiple items from the cache, only considering valid and unchanged items.
- get_comments()Retrieves a list of comments.
- wp_cache_set_multiple_salted()Stores multiple pieces of salted data in the cache.
- _prime_comment_caches()Adds any comments from the given IDs to the cache that do not already exist in cache.
- get_comment()Retrieves comment data given a comment ID or comment object.
Used by · 1
- WP_Comment_Query::get_comments()Get a list of comments matching the query vars.
Source code
protected function fill_descendants( $comments ) { $levels = array( 0 => wp_list_pluck( $comments, 'comment_ID' ), ); $key = md5( serialize( wp_array_slice_assoc( $this->query_vars, array_keys( $this->query_var_defaults ) ) ) ); $last_changed = wp_cache_get_last_changed( 'comment' ); // Fetch an entire level of the descendant tree at a time. $level = 0; $exclude_keys = array( 'parent', 'parent__in', 'parent__not_in' ); do { // Parent-child relationships may be cached. Only query for those that are not. $child_ids = array(); $uncached_parent_ids = array(); $_parent_ids = $levels[ $level ]; if ( $_parent_ids ) { $cache_keys = array(); foreach ( $_parent_ids as $parent_id ) { $cache_keys[ $parent_id ] = "get_comment_child_ids:$parent_id:$key"; } $cache_data = wp_cache_get_multiple_salted( array_values( $cache_keys ), 'comment-queries', $last_changed ); foreach ( $_parent_ids as $parent_id ) { $parent_child_ids = $cache_data[ $cache_keys[ $parent_id ] ]; if ( false !== $parent_child_ids ) { $child_ids = array_merge( $child_ids, $parent_child_ids ); } else { $uncached_parent_ids[] = $parent_id; } } } if ( $uncached_parent_ids ) { // Fetch this level of comments. $parent_query_args = $this->query_vars; foreach ( $exclude_keys as $exclude_key ) { $parent_query_args[ $exclude_key ] = ''; } $parent_query_args['parent__in'] = $uncached_parent_ids; $parent_query_args['no_found_rows'] = true; $parent_query_args['hierarchical'] = false; $parent_query_args['offset'] = 0; $parent_query_args['number'] = 0; $level_comments = get_comments( $parent_query_args ); // Cache parent-child relationships. $parent_map = array_fill_keys( $uncached_parent_ids, array() ); foreach ( $level_comments as $level_comment ) { $parent_map[ $level_comment->comment_parent ][] = $level_comment->comment_ID; $child_ids[] = $level_comment->comment_ID; } $data = array(); foreach ( $parent_map as $parent_id => $children ) { $cache_key = "get_comment_child_ids:$parent_id:$key"; $data[ $cache_key ] = $children; } wp_cache_set_multiple_salted( $data, 'comment-queries', $last_changed ); } ++$level; $levels[ $level ] = $child_ids; } while ( $child_ids ); // Prime comment caches for non-top-level comments. $descendant_ids = array(); for ( $i = 1, $c = count( $levels ); $i < $c; $i++ ) { $descendant_ids = array_merge( $descendant_ids, $levels[ $i ] ); } _prime_comment_caches( $descendant_ids, $this->query_vars['update_comment_meta_cache'] ); // Assemble a flat array of all comments + descendants. $all_comments = $comments; foreach ( $descendant_ids as $descendant_id ) { $all_comments[] = get_comment( $descendant_id ); } // If a threaded representation was requested, build the tree.Changelog
Introduced in 4.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
About this page
- Parsed data
- Generated from the wordpress-develop 7.1.0 tag, from
src/wp-includes/class-wp-comment-query.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it. - Corrections
- Something wrong on this page? Report it and it gets fixed in the next regeneration.