针对 WordPress 大型网络的后台加速方案

WordPress 多站点是一个很棒的工具，但它有其局限性和警告，特别是当你处理非常大的网络时。在薇晓朵网站，我们使用此代码段来阻止 「我的网站」 菜单查询用户所属的网络上的每个网站。

这对于小型网络或只是少数博客/网站的用户来说并不是那么糟糕，但如果你有超级管理员，他们是大多数 （如果不是全部） 网站的成员，那么你肯定会想要这个片段。

/**
 * Loading all sites menu for large multisite
 * is inefficient and bad news
 */
function large_network_remove_wp_admin_bar_my_sites_menu() {
    remove_action( 'admin_bar_menu', 'wp_admin_bar_my_sites_menu', 20 );
}
add_action( 'add_admin_bar_menus', 'large_network_remove_wp_admin_bar_my_sites_menu' );
 
/**
 * Let's replace that menu with one that has
 * links to the network dashboard instead.
 */
function large_network_replacement_my_sites_menu( $wp_admin_bar ) {
    if ( ! current_user_can( 'manage_network' ) ) {
        // bail.. no network menu for you!
        return;
    }
    
    $wp_admin_bar->add_menu( array(
        'id'    => 'prefix-my-sites',
        'title' => __( 'My Sites' ),
        'href'  => admin_url( 'my-sites.php' ),
    ));
 
    $wp_admin_bar->add_menu( array(
        'id'    => 'prefix-network-admin',
        'parent' => 'prefix-my-sites',
        'title' => __( 'Network Dashboard' ),
        'href'  => network_admin_url(),
    ));
 
    $wp_admin_bar->add_menu( array(
        'id'    => 'prefix-network-sites',
        'parent' => 'prefix-my-sites',
        'title' => __( 'Network Sites' ),
        'href'  => network_admin_url( 'sites.php' ),
    ));
 
    $wp_admin_bar->add_menu( array(
        'id'    => 'prefix-network-users',
        'parent' => 'prefix-my-sites',
        'title' => __( 'Network Users' ),
        'href'  => network_admin_url( 'users.php' ),
    ));
}
add_action( 'admin_bar_menu', 'large_network_replacement_my_sites_menu', 20 );

更新：当 WordPress 用户登录并且是许多站点的成员 （例如数千个） 时，仍然存在一些性能问题。我在 WordPress trac 上创建了一张新票，希望它有一些动力，但在那之前我提供了一个有用的片段，它有助于解决超级管理员成为数千个网站 「成员」 的问题。

/**
 * Remove all site capability keys when retrieving user meta
 * This prevents `get_blog_details` lookups for all the sites
 * a super admin is a member or admin
 *
 * @link  https://core.trac.wordpress.org/ticket/31746#comment:1 get_blogs_of_user() can be very slow when a user is a member of thousands of sites
 */
function large_network_skip_get_blogs_of_user_with_many_sites( $null, $object_id, $meta_key ) {
    global $wpdb;
 
    // Don't proceed if fetching a specific meta key, or the current user is not a super admin
    if ( $meta_key || ! is_super_admin() ) {
        return $null;
    }
 
    // Ok, then fetch all the user meta (remove this filter to do so)
    remove_filter( 'get_user_metadata', __FUNCTION__, 10, 4 );
    $keys = get_user_meta( $object_id );
    add_filter( 'get_user_metadata', __FUNCTION__, 10, 4 );
 
    // And loop through them
    foreach ( $keys as $key => $value ) {
        // Ignore non-capability meta keys
        if ( 'capabilities' !== substr( $key, -12 ) ) {
            continue;
        }
 
        // Ignore meta keys w/o the base_prefix
        if ( $wpdb->base_prefix && 0 !== strpos( $key, $wpdb->base_prefix ) ) {
            continue;
        }
 
        // Attempt to get the blog id from the string
        $blog_id = str_replace( array( $wpdb->base_prefix, '_capabilities' ), '', $key );
 
        // If it's not numeric, ignore this too
        if ( ! is_numeric( $blog_id ) ) {
            continue;
        }
 
        // Ok, let's black-list this capability meta from being sent back
        unset( $keys[ $key ] );
    }
 
    return $keys;
}
add_filter( 'get_user_metadata', 'large_network_skip_get_blogs_of_user_with_many_sites', 10, 3 );