check_theme_switched()

Description

Performance profile

How much work a call to check_theme_switched() 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

Moderate

Reads stored settings via get_option(), cached per request but not free on a cold cache.

Scaling

Constant

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

Instructions

6–44

Executed per call on PHP 8.4, depending on the branch taken. The body compiles to 49.

Plugin surface

1 hook

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

Called by

0

Nothing in core calls this; the cost is only what you spend yourself.

What it touches

• optionoption read or writeget_option()called directly
• hookthird-party callbacksdo_action()called directly
• cacheobject cachewp_cache_get()one call below check_theme_switched()
• serializeserialisationmaybe_unserialize()one call below check_theme_switched()

Further down the call graph this can also reach transient and query — those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 5 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost check_theme_switched() can have, taken from its control-flow graph on PHP 8.4.

Across PHP versions

Oldest PHP that compiles this body: 7.4. An instruction is not a fixed amount of time, so a version with the same count is not necessarily the same speed; what the count rules out is a difference in the work itself.

Hooks and filters fired · 2

2 hooks fire while check_theme_switched() runs, in this order:

1. 1
   do_action( after_switch_theme )actionline 3503 (+28 into the body)

   Fires on the next WP load after the theme has been switched.

2. 2
   do_action( after_switch_theme )actionline 3506 (+31 into the body)

   Fires on the next WP load after the theme has been switched.

Uses · 6

• get_option()Retrieves an option value based on an option name.
• wp_get_theme()Gets a WP_Theme object for a theme.
• remove_action()Removes a callback function from an action hook.
• update_option()Updates the value of an option that was already added.
• do_action()Calls the callback functions that have been added to an action hook.
• flush_rewrite_rules()Removes rewrite rules and then recreate rewrite rules.

Source code

View on Trac ↗View on GitHub ↗

3475function check_theme_switched() {3476	$stylesheet = get_option( 'theme_switched' );3477 3478	if ( $stylesheet ) {3479		$old_theme = wp_get_theme( $stylesheet );3480 3481		// Prevent widget & menu mapping from running since Customizer already called it up front.3482		if ( get_option( 'theme_switched_via_customizer' ) ) {3483			remove_action( 'after_switch_theme', '_wp_menus_changed' );3484			remove_action( 'after_switch_theme', '_wp_sidebars_changed' );3485			update_option( 'theme_switched_via_customizer', false );3486		}3487 3488		if ( $old_theme->exists() ) {3489			/**3490			 * Fires on the next WP load after the theme has been switched.3491			 *3492			 * The parameters differ according to whether the old theme exists or not.3493			 * If the old theme is missing, the old name will instead be the slug3494			 * of the old theme.3495			 *3496			 * See {@see 'switch_theme'}.3497			 *3498			 * @since 3.3.03499			 *3500			 * @param string   $old_name  Old theme name.3501			 * @param WP_Theme $old_theme WP_Theme instance of the old theme.3502			 */3503			do_action( 'after_switch_theme', $old_theme->get( 'Name' ), $old_theme );3504		} else {3505			/** This action is documented in wp-includes/theme.php */3506			do_action( 'after_switch_theme', $stylesheet, $old_theme );3507		}3508 3509		flush_rewrite_rules();3510 3511		update_option( 'theme_switched', false );3512	}3513}

Changelog

Introduced in 3.3.0. 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/theme.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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