Broadcasted attachments W3TC CDN

Since I have neither w3tc nor a CDN, maybe you could test the code and then get back to me if it works?

I just tested this. It did not seem to change anything for me. I’m using ThreeWP and w3TC W3 Total Cache with Rackspace Cloud Hosting CDN.

Is $target a variable I should change? I’m not sure I understand the edit, but I would like to.

My manual workaround is to go to the media library and “purge the CDN” for the image listed.

@rtklwm That’s not the only problem. When an image-filled post is broadcasted to multiple sites, my code (if it worked) would cause each attachment to be sent to the CDN one at a time for every image for every site. This can easily trigger a load balancer timeout resulting in the post only being created on some sites or only being partially created on some sites.

Instead I think we need to use an event hook that is triggered after a post is broadcasted. Then bulk upload the way the W3TC – CDN – Upload Attachments</em. button works. I haven’t looked into how to do this yet.

Digging further. The function I mentioned above is export_library in /path/to/wp-content/plugins/w3-total-cache/lib/W3/Plugin/CdnAdmin.php. We need to replicate that functionality.

We can hook into broadcast’s threewp_broadcast_broadcasting_modify_post action and need to pass to w3_instance('W3_Plugin_CdnCommon')->upload() an array of files that look like:

[
    [
        'local_path' => '/path/to/wp-content/uploads/2012/07/Comfit2.jpg',
        'remote_path' => 'wp-content/uploads/2012/07/Comfit2.jpg',
        'original_url' => 'https://mysite.com/path/to/wp-content/uploads/2012/07/Comfit2.jpg',
    ],
    [
        'local_path' => '/path/to/wp-content/uploads/2012/07/Comfit2-190x100.jpg',
        'remote_path' => 'wp-content/uploads/2012/07/Comfit2-190x100.jpg',
        'original_url' => 'https://mysite.com/path/to/wp-content/uploads/2012/07/Comfit2-190x100.jpg',
    ],
    ...
]

This shouldn’t be too difficult to figure out. I’ll keep you posted.

There’s a better hook f?r that:

threewp_broadcast_broadcasting_before_restore_current_blog

It is called with the $action parameter, which contains the following interesting data:

$bcd = $action->broadcasting_data;
$bcd->copied_attachments <– array of old and new attachment data.

After a whole lot of debugging I believe I’ve solved the conflict between ThreeWP Broadcast and W3TC with CDN push enabled. Below is what you’ll need in your functions.php:

// Fixes https://core.trac.www.ads-software.com/ticket/25650
// This is required due to a conflict between ThreeWP Broadcast and W3TC when
// W3TC uses CDN push.
//
// When broadcast calls switch_to_blog() during a broadcast, W3TC calls
// wp_upload_dir() to deterine where to upload the new file. This path will
// contain the URL of the old blog due to WP_CONTENT_URL constant being
// wrong.
add_action('switch_blog', function($new_blog, $prev_blog_id) {
	update_option( 'upload_url_path',  get_option('siteurl') . '/wp-content/uploads');
}, 10, 2);

Make sure to change /wp-content/uploads to the location of your uploads directory if you’re using a custom directory.

I’ve whipped up a better version of my above script. This version deletes the option from each site after a broadcast has completed so that the_post_thumbnail() doesn’t break. It also lessens the risk of things breaking if a rogue plugin uses switch_to_blog() without a matching restore_current_blog().

/**
 * Fixes https://core.trac.www.ads-software.com/ticket/25650
 * This is required due to a conflict between ThreeWP Broadcast and W3TC when
 * W3TC uses CDN push.
 *
 * When broadcast calls switch_to_blog() during a broadcast, W3TC calls
 * wp_upload_dir() to deterine where to upload the new file. This path will
 * contain the URL of the old blog due to WP_CONTENT_URL constant being
 * wrong.
 *
 * @param  int  $new_blog  New blog iD
 * @param  int  $old_blog  Old blog ID
 */
add_action('switch_blog', function($new_blog, $prev_blog_id) {
	// We only want to set this option during a broadcast. We don't want the option to
	// exist at all let alone be used outside of broadcasts as it affects wp_upload_dir()
	// method.
	if ( \threewp_broadcast\ThreeWP_Broadcast::instance()->is_broadcasting() )
		update_option( 'upload_url_path',  get_option('siteurl') . '/wp-content/uploads');
}, 10, 2);

/**
 * Now that broadcasting has finished, we need to remove the upload_url_path option
 * from each site it was added to, or the_post_thumbnail() URLs will be broken because
 * they use /blog/files/2015/05/foo.jpg instead of /blog/wp-content/uploads/2015/05/foo.jpg
 *
 * Run at priority 1000 so it'll execute after a broadcast has completed. If we run this
 * before broadcast is completed, the above switch_blog action will execute because
 * is_broadcasting() will still be true.
 *
 * @param  threewp_broadcast\broadcasting_data  $bcd
 */
add_filter('threewp_broadcast_broadcast_post', function($bcd) {
	// For nested broadcasts. Just in case.
	switch_to_blog( $bcd->parent_blog_id );

	foreach( $bcd->blogs as $child_blog )
	{
		$child_blog->switch_to();
		delete_option('upload_url_path');
		$child_blog->switch_from();
	}

	delete_option('upload_url_path');
	restore_current_blog();
	delete_option('upload_url_path');
}, 1000);

We’ve spoken over e-mail and we came to the conclusion that this is best left as a plugin.

Or rather: I stated and you agreed. ??