_wp_admin_html_begin()
- Source
wp-admin/includes/template.php:2640
Compatibility
- WordPress
- core
- 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.
Performance profile
How much work a call to _wp_admin_html_begin() 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
- Scaling
- Constant
- Instructions
- 26–30
- Plugin surface
- 1 hook
- Called by
- 2
Reads stored settings via get_option(), cached per request but not free on a cold cache.
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 31.
Third-party callbacks on 'admin_xml_ns' run inside this call, and their cost is not bounded by anything here.
2 places in core call this, so the cost is paid more often than your own code shows.
What it touches
- hookthird-party callbacks
do_action()called directly - optionoption read or write
get_option()called directly - cacheobject cache
wp_cache_get()one call below _wp_admin_html_begin() - serializeserialisation
maybe_unserialize()one call below _wp_admin_html_begin()
Further down the call graph this can also reach query and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.
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_admin_html_begin() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 26–27 | is_admin_bar_showing(), do_action(), language_attributes(), bloginfo(), get_option() |
| always | 29–30 | is_admin_bar_showing(), header(), do_action(), language_attributes(), bloginfo(), get_option() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 31 instructions, 26–30 executed per call, 2 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.
Hooks and filters fired · 1
One hook fires while _wp_admin_html_begin() runs, in this order:
- do_action( admin_xml_ns )actionline 2658 (+18 into the body)
Fires inside the HTML tag in the admin header.
Uses · 5
- is_admin_bar_showing()Determines whether the admin bar should be showing.
- do_action()Calls the callback functions that have been added to an action hook.
- language_attributes()Displays the language attributes for the 'html' tag.
- bloginfo()Displays information about the current site.
- get_option()Retrieves an option value based on an option name.
Used by · 2
- iframe_header()Generic Iframe header for use with Thickbox.
- wp_iframe()Outputs the iframe to display the media upload page.
Source code
function _wp_admin_html_begin() { global $is_IE; $admin_html_class = ( is_admin_bar_showing() ) ? 'wp-toolbar' : ''; if ( $is_IE ) { header( 'X-UA-Compatible: IE=edge' ); } ?><!DOCTYPE html><html class="<?php echo $admin_html_class; ?>" <?php /** * Fires inside the HTML tag in the admin header. * * @since 2.2.0 */ do_action( 'admin_xml_ns' ); language_attributes(); ?>><head><meta http-equiv="Content-Type" content="<?php bloginfo( 'html_type' ); ?>; charset=<?php echo get_option( 'blog_charset' ); ?>" /> <?php}Changelog
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 6.7.7 tag, from
src/wp-admin/includes/template.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.