id,summary,reporter,owner,description,type,status,priority,milestone,component,version,severity,resolution,keywords,cc
14992,When Object Caching is enabled switch_to_blog causes issues with some functions,simonwheatley,,"When you use {{{switch_to_blog}}} with an Object caching plugin installed you get incorrect links from {{{home_url}}} and therefore also {{{get_permalink}}}.

To reproduce:

 1. Setup a WP Network using sub-directories with at least two sites
 2. Install an Object caching plugin
 3. Assuming that {{{get_option}}} has been called earlier, thereby loading the cache with {{{alloptions}}}, use {{{switch_to_blog}}} then {{{get_permalink}}}
 4. {{{get_permalink}}} returns a URL based on the site which was active '''before''' you used {{{switch_to_blog}}}

The problem seems to be that the Object cache caches {{{alloptions}}}, but these aren't refreshed or switched when {{{switch_to_blog}}} is used (at this point a new set of options should be made available).

I'm using this code to get around it (this is not a patch, obviously):

{{{
/**
 * Hooks the WP MS action switch_blog to switch some caches cache when a blog
 * is switched to.
 *
 * @param int $blog_id The ID of the blog which has been switched to 
 * @param int $prev_blog_id The ID of the blog we were in before switching 
 * @return void
 **/
function kcostb_switch_blog( $blog_id, $prev_blog_id ) {
	// Save the previous alloptions cache
	$prev_alloptions = wp_cache_get( 'alloptions', 'options' );
	// Do we have a previously cached alloptions for the new blog? If so,
	// replace the current alloptions cache otherwise delete it.
	if ( $alloptions = wp_cache_get( ""alloptions_$blog_id"", 'options' ) )
		wp_cache_replace( ""alloptions"", $alloptions, 'options' );
	else
		wp_cache_delete( 'alloptions', 'options' );
}
add_action( 'switch_blog', 'kcostb_switch_blog', null, 2 );
}}}

Questions:

 * Should this be solved by switching caches (as my mini plugin does)?
 * Should we simply delete the {{{alloptions}}} cache when {{{switch_to_blog}}} is used?
 * Are there any other areas affected similarly?

Happy to produce a patch if the first two questions could be advised upon.

Could be related to #12040",defect (bug),closed,high,,Multisite,,major,worksforme,,mpretty@… willmot tollmanz@…