do_robots()

Compatibility

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 do_robots() 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

36–37

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 38.

Plugin surface

2 hooks

Third-party callbacks on 'do_robotstxt', 'robots_txt' 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

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

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 · 1 distinct outcome

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

Hooks and filters fired · 2

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

1. 1
   do_action( do_robotstxt )actionline 1709 (+8 into the body)

   Fires when displaying the robots.txt file.

2. 2
   apply_filters( robots_txt )filterline 1727 (+26 into the body)

   Filters the robots.txt output.

Uses · 4

• do_action()Calls the callback functions that have been added to an action hook.
• get_option()Retrieves an option value based on an option name.
• site_url()Retrieves the URL for the current site where WordPress application files (e.g. wp-blog-header.php or the wp-admin/ folder) are accessible.
• apply_filters()Calls the callback functions that have been added to a filter hook.

Source code

View on Trac ↗View on GitHub ↗

1701function do_robots() {1702	header( 'Content-Type: text/plain; charset=utf-8' );1703 1704	/**1705	 * Fires when displaying the robots.txt file.1706	 *1707	 * @since 2.1.01708	 */1709	do_action( 'do_robotstxt' );1710 1711	$output = "User-agent: *\n";1712	$public = get_option( 'blog_public' );1713 1714	$site_url = parse_url( site_url() );1715	$path     = ( ! empty( $site_url['path'] ) ) ? $site_url['path'] : '';1716	$output  .= "Disallow: $path/wp-admin/\n";1717	$output  .= "Allow: $path/wp-admin/admin-ajax.php\n";1718 1719	/**1720	 * Filters the robots.txt output.1721	 *1722	 * @since 3.0.01723	 *1724	 * @param string $output The robots.txt output.1725	 * @param bool   $public Whether the site is considered "public".1726	 */1727	echo apply_filters( 'robots_txt', $output, $public );1728}

Changelog

Introduced in 2.1.0. 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 6.7.7 tag, from src/wp-includes/functions.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

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