wp_cache_set_last_changed( string $group ): string

Compatibility

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 when the group was last changed.

Performance profile

How much work a call to wp_cache_set_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

Only touches the object cache, via wp_cache_set_last_changed().

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

21

Executed per call on PHP 8.5. The body compiles to 21.

Plugin surface

1 hook

Third-party callbacks on 'wp_cache_set_last_changed' run inside this call, and their cost is not bounded by anything here.

Called by

7

7 places in core call this, so the cost is paid more often than your own code shows.

What it touches

• cacheobject cachewp_cache_set_last_changed()this function does it
• hookthird-party callbacksdo_action()called directly

What one call costs · 1 distinct outcome

One number would be a lie: the work depends on which branch runs. These are every distinct cost wp_cache_set_last_changed() can have, taken from its control-flow graph on PHP 8.5.

Hooks and filters fired · 1

One hook fires while wp_cache_set_last_changed() runs, in this order:

1. 1
   do_action( wp_cache_set_last_changed )actionline 8271 (+18 into the body)

   Fires after a cache group `last_changed` time is updated.

Uses · 3

• wp_cache_get()Retrieves the cache contents from the cache by key and group.
• wp_cache_set()Saves the data to the cache.
• do_action()Calls the callback functions that have been added to an action hook.

Used by · 7

• clean_network_cache()Removes a network from the object cache.
• wp_cache_get_last_changed()Gets last changed date for the specified cache group.
• wp_cache_set_comments_last_changed()Sets the last changed time for the 'comment' cache group.
• wp_cache_set_posts_last_changed()Sets the last changed time for the 'posts' cache group.
• wp_cache_set_sites_last_changed()Sets the last changed time for the 'sites' cache group.
• wp_cache_set_terms_last_changed()Sets the last changed time for the 'terms' cache group.
• wp_cache_set_users_last_changed()Sets the last changed time for the 'users' cache group.

Source code

View on Trac ↗View on GitHub ↗

8253function wp_cache_set_last_changed( $group ) {8254	$previous_time = wp_cache_get( 'last_changed', $group );8255 8256	$time = microtime();8257 8258	wp_cache_set( 'last_changed', $time, $group );8259 8260	/**8261	 * Fires after a cache group `last_changed` time is updated.8262	 * This may occur multiple times per page load and registered8263	 * actions must be performant.8264	 *8265	 * @since 6.3.08266	 *8267	 * @param string       $group         The cache group name.8268	 * @param string       $time          The new last changed time (msec sec).8269	 * @param string|false $previous_time The previous last changed time. False if not previously set.8270	 */8271	do_action( 'wp_cache_set_last_changed', $group, $time, $previous_time );8272 8273	return $time;8274}

Changelog

Introduced in 6.3.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 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/functions.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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