I've been put to work on a very complex Drupal 7 based system with multiple custom written modules for which the developers have gone or been re-assigned. Documentation for the system is very sparse. I think it would help me to get a a better overall picture of the system, as well as to figure out what is happening in particular parts of the system that I have been asked to fix or change, if I could see a listing of all of the hooks that are implemented.
I presume that Drupal scans all of the code in the system and builds itself some sort of structure or associative array in its cache memory so that it can quickly find any hooks that need to be invoked. Is the result stored somewhere that I can read, for example in a database table or a global variable? If I need to figure it out myself, is there a particular function, for example in the system module or bootstrap code that all hooks must pass through once? If so, perhaps I could (temporarily) hack it to get the information I want.
If someone knows how to do this, I'd love to hear how. If you don't know how to do it but have ideas about especially fruitful places to look in the code, database, drush functions, or wherever, that could be useful too.
Thank you very much.