wp_old_slug_redirect()

Description

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 wp_old_slug_redirect() 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

Heavy

Reaches the database via get_post().

Scaling

Constant

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

Instructions

4–85

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 108.

Plugin surface

2 hooks

Third-party callbacks on 'old_slug_redirect_post_id', 'old_slug_redirect_url' 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 callbacksapply_filters()called directly
• cacheobject cachewp_cache_get_last_changed()one call below wp_old_slug_redirect()
• querycontent queryget_post()one call below wp_old_slug_redirect()
• optionoption read or writeget_option()one call below wp_old_slug_redirect()

Further down the call graph this can also reach serialize 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 · 64 distinct outcomes

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

Hooks and filters fired · 2

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

1. 1
   apply_filters( old_slug_redirect_post_id )filterline 1093 (+38 into the body)

   Filters the old slug redirect post ID.

2. 2
   apply_filters( old_slug_redirect_url )filterline 1114 (+59 into the body)

   Filters the old slug redirect URL.

Uses · 11

• is_404()Determines whether the query has resulted in a 404 (returns no results).
• get_query_var()Retrieves the value of a query variable in the WP_Query class.
• is_post_type_hierarchical()Determines whether the post type is hierarchical.
• _find_post_by_old_slug()Find the post ID for redirecting an old slug.
• _find_post_by_old_date()Find the post ID for redirecting an old date.
• apply_filters()Calls the callback functions that have been added to a filter hook.
• get_permalink()Retrieves the full permalink for the current post or post ID.
• user_trailingslashit()Retrieves a trailing-slashed string if the site is set for adding trailing slashes.
• trailingslashit()Appends a trailing slash.
• is_embed()Is the query for an embedded post?
• wp_redirect()Redirects to another page.

Source code

View on Trac ↗View on GitHub ↗

1055function wp_old_slug_redirect() {1056	if ( is_404() && '' !== get_query_var( 'name' ) ) {1057		// Guess the current post type based on the query vars.1058		if ( get_query_var( 'post_type' ) ) {1059			$post_type = get_query_var( 'post_type' );1060		} elseif ( get_query_var( 'attachment' ) ) {1061			$post_type = 'attachment';1062		} elseif ( get_query_var( 'pagename' ) ) {1063			$post_type = 'page';1064		} else {1065			$post_type = 'post';1066		}1067 1068		if ( is_array( $post_type ) ) {1069			if ( count( $post_type ) > 1 ) {1070				return;1071			}1072			$post_type = reset( $post_type );1073		}1074 1075		// Do not attempt redirect for hierarchical post types.1076		if ( is_post_type_hierarchical( $post_type ) ) {1077			return;1078		}1079 1080		$id = _find_post_by_old_slug( $post_type );1081 1082		if ( ! $id ) {1083			$id = _find_post_by_old_date( $post_type );1084		}1085 1086		/**1087		 * Filters the old slug redirect post ID.1088		 *1089		 * @since 4.9.31090		 *1091		 * @param int $id The redirect post ID.1092		 */1093		$id = apply_filters( 'old_slug_redirect_post_id', $id );1094 1095		if ( ! $id ) {1096			return;1097		}1098 1099		$link = get_permalink( $id );1100 1101		if ( get_query_var( 'paged' ) > 1 ) {1102			$link = user_trailingslashit( trailingslashit( $link ) . 'page/' . get_query_var( 'paged' ) );1103		} elseif ( is_embed() ) {1104			$link = user_trailingslashit( trailingslashit( $link ) . 'embed' );1105		}1106 1107		/**1108		 * Filters the old slug redirect URL.1109		 *1110		 * @since 4.4.01111		 *1112		 * @param string $link The redirect URL.1113		 */1114		$link = apply_filters( 'old_slug_redirect_url', $link );1115 1116		if ( ! $link ) {1117			return;1118		}1119 1120		wp_redirect( $link, 301 ); // Permanent redirect.1121		exit;1122	}1123}

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 7.0.4 tag, from src/wp-includes/query.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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