purge_all() and purge_by_definition() look in the configuration
for which caches are available and then creates them to purge them.
The configuration stores the values used by initialise(), not
initialise_unit_test_instance() and would therefore fail to purge
all caches if they were not purged by another means.
In the case of filestore, it's purged by unit tests, in the case
of memcache(d), it purges the whole store when a single definition
is requested.
Therefore all configuration was moved into the configuration file
during unit tests and does not have any special override codes in
the unit test infrastructure.
This code was originally taken from; https://github.com/durana/moodle-cachestore_redis
Special thanks to Mark Nielsen and Adam Durana for their work on this.
Since the original import;
- Mode session support has been added.
- Some cleanup of names has been made.
- Data guarantee and references support was added.
Static cache has a very flexible storage capability
and does not need all the checks performed on it.
Enabling dereferencing handling and multiple identifiers
removes a lot of unneeded overhead for request caches that
have many get calls.
The changes were modelled on the static acceleration changes
done in MDL-53208.