It is now safe to cache a reference to a cache and expect consistent results.
Changing identifiers altered cache results where a reference was
held to the cache. Identifiers have been set to be cached with
identifiers included so the caches are separate.
As a consequence of this it was identified that invalidation events
and identifiers don't easily work together as an event can't determine
which identifiers should be used for cache invalidation. So invalidation
events have been made incompatible with identifiers being set. No core
code used this combination as it's not possible to understand any expected
behaviour.
Event invalidation for application and session caches was centralised to the same
location. The only difference was the name of the lastinvalidation variable. This
improves support and consistency of invalidation code.
When a cachable object is store in the static cache from
the backing store, it was incorrect serialised rather than
using the wake function. This has been resolved and tests added.
During the investigation into cacheable_object, it was discovered
that set_identifiers never removes identifiers when you call it,
so set_identifiers(array('a')) and set_identifiers(array('b')) really
resulted in array('a','b') as the identifiers rather than 'b'.
The fix for this issue depends on the set_identifiers fix and
they have been coupled together as a result.
Cache data source aggregate functionality was found to be broken
and unused, because of this the decision was made to remove it
rather than fix it.
As it was broken we did not follow typical deprecation methods and
instead the code was removed outright with only structure
remaining and left deprecated.
Issues:
1. Fix setType calls
2. Changing from default to all and editing again, default is still selected.
3. Uncheck all options causes error.
4. Doesn't seem to be restricting based upon option.
5. Picked all and got coding error with the database thing.
6. Bad title: https://github.com/samhemelryk/moodle/commit/wip-MDL-37500-m25#L1R157
7. Amend comments - should only be removed once 2.5 is the minimum version for an upgrade.
8. Document the defaultsharing option.
Outcomes:
1. Fixed - copy paste error.
2. Fixed - mforms was applying the default value despite a value being provided. A quirk of elements with array names.
3. Fixed - validation now requires at least one option to be selected.
4. Fixed - issue rose from definitions not being re-parsed. cache/admin.php now reparses the first time a user visits the page.
5. Fixed - better purging of definitions when working with them anonymously. Unit test added.
6. Fixed - new string added and used.
7. Fixed - comments amended.
New issue to address parsing of definitions during upgrade.
New issue to add debugging notice if definition sets only one possible sharing option and that option is user input.
This change is a large change to the way sessions are handled
within MUC after it was discovered that session did not function
as expected when any store other than the default session store
was being used.
As part of this change the session loader has been largely
customised in order to consolidate session data for the loader.
The unit tests have also being greatly increased to provide
better coverage for sessions.
