[Plugin: W3 Total Cache] Trigger upload image to CDN?

Hi, great plugin!
I’m using the w3-total-cache plugin to upload and store images in CDN. I have a network setup where another plugin ThreeWP Broadcast distributes posts and attachment images from the master site to the children. The setup works nearly perfectly, but I need to do some kind of manual hack to go all the way..

The problem, I believe, is that the ThreeWP Broadcast plugin do a copy of attached images from master site to child but without triggering the w3-total-cache CDN upload. Thus images and attachments end up on the child site’s local server but not in CDN (ie. broken image links on front page ).

What I’m thinking is to add some code in ThreeWP Broadcast to force a trigger of the upload-to-CDN-hook…

ThreeBroadcast code snippet (copy of attachments):

private function copy_attachment( $attachment_data, $post_id) {
// Copy the file to the blog's upload directory
		$upload_dir = wp_upload_dir();

		if ( ! file_exists( $attachment_data->filename_path() ) )
			return false;
		copy( $attachment_data->filename_path(), $upload_dir['path'] . '/' . $attachment_data->filename_base() );

		// And now create the attachment stuff.
		// This is taken almost directly from http://codex.wordpress.org/Function_Reference/wp_insert_attachment
		$wp_filetype = wp_check_filetype( $attachment_data->filename_base(), null );
		$attachment = array(
			'post_mime_type' => $wp_filetype['type'],
			'post_title' => preg_replace( '/\.[^.]+$/', '', $attachment_data->filename_base() ),
			'post_content' => '',
			'post_status' => 'inherit'
		);
		$attach_id = wp_insert_attachment( $attachment, $upload_dir['path'] . '/' . $attachment_data->filename_base(), $post_id );

		// Now to handle the metadata.
		// 1. Create new metadata for this attachment.

		require_once(ABSPATH . "wp-admin" . '/includes/image.php' );
		$attach_data = wp_generate_attachment_metadata( $attach_id, $upload_dir['path'] . '/' . $attachment_data->filename_base() );

		// 2. Write the old metadata first.
		foreach( $attachment_data->post_custom as $key => $value )
		{
			$value = reset( $value );
			$value = maybe_unserialize( $value );
			switch( $key )
			{
				// Some values need to handle completely different upload paths (from different months, for example).
				case '_wp_attached_file':
					$value = $attach_data[ 'file' ];
					break;
			}
			update_post_meta( $attach_id, $key, $value );
		}

		// 3. Overwrite the metadata that needs to be overwritten with fresh data.
		wp_update_attachment_metadata( $attach_id,  $attach_data );

return $attach_id;
}

I have tried to add an extra update_attachement_file hoping it would trigger the hook…

update_attached_file($attach_id, $upload_dir['path'] . '/' . $attachment_data->filename_base());

.. but it fails.

Any hints on how to do this?

Best regards,
Mike

http://wordpress.org/extend/plugins/w3-total-cache/