Question

Alert: This function’s access is marked private. This means it is not intended for use by plugin or theme developers, only in other core functions. It is listed here for completeness.

wp_start_object_cache()

Start the WordPress object cache.

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description

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

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源代码

File: wp-includes/load.php

function wp_start_object_cache() {
	global $wp_filter;

	$first_init = false;
 	if ( ! function_exists( 'wp_cache_init' ) ) {
		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 );
			}
		}

		$first_init = true;
	} elseif ( ! wp_using_ext_object_cache() && file_exists( WP_CONTENT_DIR . '/object-cache.php' ) ) {
		/*
		 * Sometimes advanced-cache.php can load object-cache.php before
		 * it is loaded here. This breaks the function_exists check above
		 * and can result in `$_wp_using_ext_object_cache` being set
		 * incorrectly. Double check if an external cache exists.
		 */
		wp_using_ext_object_cache( true );
	}

	if ( ! wp_using_ext_object_cache() ) {
		require_once ( ABSPATH . WPINC . '/cache.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( 'users', 'userlogins', 'usermeta', 'user_meta', 'useremail', 'userslugs', 'site-transient', 'site-options', 'blog-lookup', 'blog-details', 'site-details', 'rss', 'global-posts', 'blog-id-cache', 'networks', 'sites' ) );
		wp_cache_add_non_persistent_groups( array( 'counts', 'plugins' ) );
	}
}

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更新日志

Version	description
3.0.0	Introduced.

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相关函数

Uses

• wp-includes/class-wp-hook.php: WP_Hook::build_preinitialized_hooks()
• wp-includes/cache.php: wp_cache_switch_to_blog()
• wp-includes/cache.php: wp_cache_init()
• wp-includes/cache.php: wp_cache_add_global_groups()
• wp-includes/cache.php: wp_cache_add_non_persistent_groups()
• wp-includes/load.php: get_current_blog_id()
• wp-includes/load.php: wp_using_ext_object_cache()
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User Contributed Notes