Before this change the query examined at every course_module record in
the context table.
With this change we use the course_modules table to more efficiently
find all the activities in the course, which means that many less
records in the context table need to be examined.
This chagne adds support for a new feature known as Context Locking.
This allows a context to be locked, thereby removing all write
capabilities for all users (including admin) for that context, and all
child contexts.
When searching for non-empty children first retrieve list of all non-empty
fileareas in modules and then check access for each of them. This will be
much faster than checking access for each module and then look for files
and areas inside this module.
Do the same with course file areas
- file_info class now has new methods get_non_empty_children and count_non_empty_children; added default implementation;
- all core classes extending file_info have their implementation of those methods;
- class repository_local_file used for caching get_children() results is removed;
- class repository_local rewritten to use new methods from file_info;
- added caching of retrieved modules in file_browser::get_file_info_context_module() - this query is slow and executed multiple times on big servers
- Removed 'Private files' from 'Server files' repository;
- Show only non-empty directories (taking into account filetype filter);
- If there is only one non-empty filearea within a module, do not show it and skip the extra subdirectory level;
- If the user is not admin (does not have 'moodle/course:update' capability in system context), do not show course categories, just list available courses;
- Also when retrieving the course files capability to managefiles is checked before retrieving the modules list for performance tuning on sites with a lot of courses
