These hooks are called right before an object is sent to the publishing queue. Using these, you can freely read & write data based on the operation: content type, author, publishing time, you choose. The system doesn't provide any means to store extra data. That means you must design your own system for that, but on the other hand, this gives full flexibility over your mechanisms.

Add MyPriorityHandler::queue() before the item is queued::

ezpContentPublishingQueue::signals()->connect( 'preQueue', 'MyPriorityHandler::queue' );

Hooks can also be attached using INI settings if you want the call to be made every time::

[PublishingSettings]
AsynchronousPublishingPreQueueHooks[]=MyPriorityHandler::queue

These hooks are given two parameters:
* the content object version (integer)
* the content object id (integer)

They're not supposed to return any value.