wp-includes/ms-functions.php:339Gets a blog's numeric ID from its URL.
$domainstring$pathstringoptional'/'intfunction get_blog_id_from_url( $domain, $path = '/' ) { $domain = strtolower( $domain ); $path = strtolower( $path ); $id = wp_cache_get( md5( $domain . $path ), 'blog-id-cache' ); if ( -1 == $id ) { // Blog does not exist. return 0; } elseif ( $id ) { return (int) $id; } $args = array( 'domain' => $domain, 'path' => $path, 'fields' => 'ids', 'number' => 1, 'update_site_meta_cache' => false, ); $result = get_sites( $args ); $id = array_shift( $result ); if ( ! $id ) { wp_cache_set( md5( $domain . $path ), -1, 'blog-id-cache' ); return 0; } wp_cache_set( md5( $domain . $path ), $id, 'blog-id-cache' ); return $id;}Introduced in MU (3.0.0). Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/ms-functions.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.