wp_start_object_cache() │ WP 3.0.0

Start the WordPress object cache.

If an object-cache.php file exists in the wp-content directory, it uses that drop-in as an external object cache.

Internal function — this function is designed to be used by the kernel itself. It is not recommended to use this function in your code.

Hooks from the function

enable_loading_object_cache_dropin

Return

null. Nothing (null).

Usage

wp_start_object_cache();

Examples

#1 Examples for this function do not make sense

There are no examples of how to use it, because this function doesn't need to be used anywhere! It is called in the file wp-settings.php by WordPress itself at an early stage of loading the kernel.

Notes

Global. Array. $wp_filter Stores all of the filters.

Changelog

Since 3.0.0

Introduced.

`wp_start_object_cache() wp start object cache` code ^{WP 6.5.2}

wp-includes/load.php

function wp_start_object_cache() {
	global $wp_filter;
	static $first_init = true;

	// Only perform the following checks once.

	/**
	 * Filters whether to enable loading of the object-cache.php drop-in.
	 *
	 * This filter runs before it can be used by plugins. It is designed for non-web
	 * runtimes. If false is returned, object-cache.php will never be loaded.
	 *
	 * @since 5.8.0
	 *
	 * @param bool $enable_object_cache Whether to enable loading object-cache.php (if present).
	 *                                  Default true.
	 */
	if ( $first_init && apply_filters( 'enable_loading_object_cache_dropin', true ) ) {
		if ( ! function_exists( 'wp_cache_init' ) ) {
			/*
			 * This is the normal situation. First-run of this function. No
			 * caching backend has been loaded.
			 *
			 * We try to load a custom caching backend, and then, if it
			 * results in a wp_cache_init() function existing, we note
			 * that an external object cache is being used.
			 */
			if ( file_exists( WP_CONTENT_DIR . '/object-cache.php' ) ) {
				require_once WP_CONTENT_DIR . '/object-cache.php';

				if ( function_exists( 'wp_cache_init' ) ) {
					wp_using_ext_object_cache( true );
				}

				// Re-initialize any hooks added manually by object-cache.php.
				if ( $wp_filter ) {
					$wp_filter = WP_Hook::build_preinitialized_hooks( $wp_filter );
				}
			}
		} elseif ( ! wp_using_ext_object_cache() && file_exists( WP_CONTENT_DIR . '/object-cache.php' ) ) {
			/*
			 * Sometimes advanced-cache.php can load object-cache.php before
			 * this function is run. This breaks the function_exists() check
			 * above and can result in wp_using_ext_object_cache() returning
			 * false when actually an external cache is in use.
			 */
			wp_using_ext_object_cache( true );
		}
	}

	if ( ! wp_using_ext_object_cache() ) {
		require_once ABSPATH . WPINC . '/cache.php';
	}

	require_once ABSPATH . WPINC . '/cache-compat.php';

	/*
	 * If cache supports reset, reset instead of init if already
	 * initialized. Reset signals to the cache that global IDs
	 * have changed and it may need to update keys and cleanup caches.
	 */
	if ( ! $first_init && function_exists( 'wp_cache_switch_to_blog' ) ) {
		wp_cache_switch_to_blog( get_current_blog_id() );
	} elseif ( function_exists( 'wp_cache_init' ) ) {
		wp_cache_init();
	}

	if ( function_exists( 'wp_cache_add_global_groups' ) ) {
		wp_cache_add_global_groups(
			array(
				'blog-details',
				'blog-id-cache',
				'blog-lookup',
				'blog_meta',
				'global-posts',
				'networks',
				'network-queries',
				'sites',
				'site-details',
				'site-options',
				'site-queries',
				'site-transient',
				'theme_files',
				'translation_files',
				'rss',
				'users',
				'user-queries',
				'user_meta',
				'useremail',
				'userlogins',
				'userslugs',
			)
		);

		wp_cache_add_non_persistent_groups( array( 'counts', 'plugins', 'theme_json' ) );
	}

	$first_init = false;
}