wp_cache_get_last_changed( string $group ): string
- Since
- 4.7.0
- Source
wp-includes/functions.php:8041
Compatibility
- WordPress
- since 4.7.0
- 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
$groupstring- Where the cache contents are grouped.
Return value
string- UNIX timestamp with microseconds representing when the group was last changed.
Performance profile
How much work a call to wp_cache_get_last_changed() 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
- Light
- Scaling
- Constant
- Instructions
- 8–11
- Plugin surface
- None
- Called by
- 15
Only touches the object cache, via wp_cache_get_last_changed().
No loop in the body: the same number of instructions runs whatever you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 12.
Nothing here hands control to plugin code.
15 places 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()this function does it - hookthird-party callbacks
do_action()one call below wp_cache_get_last_changed()
What one call costs · 2 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost wp_cache_get_last_changed() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 8 | wp_cache_get() |
| always | 11 | wp_cache_get(), wp_cache_set_last_changed() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 12 instructions, 8–11 executed per call, 1 branch. 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 · 2
- wp_cache_get()Retrieves the cache contents from the cache by key and group.
- wp_cache_set_last_changed()Sets last changed date for the specified cache group to now.
Used by · 15
- WP_Comment_Query::fill_descendants()Fetch descendants for located comments.
- WP_Comment_Query::get_comments()Get a list of comments matching the query vars.
- WP_Network_Query::get_networks()Gets a list of networks matching the query vars.
- WP_Query::generate_cache_key()Generates cache key.
- WP_Query::get_posts()Retrieves an array of posts based on query variables.
- WP_Site_Query::get_sites()Retrieves a list of sites matching the query vars.
- WP_Term_Query::generate_cache_key()Generate cache key.
- WP_User_Query::generate_cache_key()Generate cache key.
- _find_post_by_old_date()Find the post ID for redirecting an old date.
- _find_post_by_old_slug()Find the post ID for redirecting an old slug.
- count_user_posts()Gets the number of posts a user has written.
- get_adjacent_post()Retrieves the adjacent post.
Show all 15
- get_objects_in_term()Retrieves object IDs of valid taxonomy and term.
- get_page_by_path()Retrieves a page given its path.
- wp_get_archives()Displays archive links based on type and format.
Source code
function wp_cache_get_last_changed( $group ) { $last_changed = wp_cache_get( 'last_changed', $group ); if ( $last_changed ) { return $last_changed; } return wp_cache_set_last_changed( $group );}Changelog
Introduced in 4.7.0. 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 6.8.8 tag, from
src/wp-includes/functions.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.