* Makes it possible to safely call acquire_lock so that it throws an
exception instead of returning false if it can't get a lock (which
most existing uses assumed it already does).
* Fix some omissions from the requirelockingbeforewrite option (it
now checks on delete).
* Modinfo uses a versioned cache, so it is not necessary to delete
items, only increase the version. (Provided we keep track of
cacherev carefully...)
* all constans usable in ABORT_AFTER_CONFIG should be always defined
* MDL_PERFDB and $PERF->logwrites not used after legacy log removal
* MDL_PERF_TEST should be documented in codebase
* deprecated warnings in shutdowb manager
If a statically accelerated cache returns an empty array then the value
was still fetched from the non-static cache store.
The check of the `$result` should be strictly checked against `false`,
which is the value used if no value was found.
In PHP 8.2 and later, setting a value to an undeclared class property is
deprecated and emits a deprecation notice.
So we need to add missing class properties that still need to be declared.
Cache locking fails if the cache store supports multiple identifiers
(in core, the only two which do are cachestore_static and
cachestore_mongodb, so this is unlikely to cause severe problems).
In certain cases where it doesn't already redirect to run the upgrade,
users could see an exception 'Unexpectedly found non-versioned cache
entry'. This change ensures the upgrade happens instead.
Adds new set_versioned and get_versioned APIs to cache, which means you can
request a specific version from cache and it will not return an outdated
version.
This is important when using multi-layer-caches where a local cache might have
an outdated version of the cache, but the shared cache has a current version.
With this feature, the content of the cache does not have to be rebuilt, as
it will automatically retrieve it from the shared cache if necessary.
I checked using a diff tool and the difference between 'get' in cache
and cache_session is only:
a) cache_session: call to check_tracked_user at the start
b) cache: Includes code to use static acceleration (but this would
not run anyway in cache_session because use_static_acceleration
returns false)
c) cache: $setaftervalidation logic is used so that it sets it slightly
later (I can't see how this would make any difference)
d) cache_session: uses functions eg get_store() instead of variables
$store; those functions aren't overridden.
This seems like a ridiculous duplication of very complicated code, so
I'm going to remove the duplication before I change it.
For cache types which mean this information can be obtained without a
significant performance cost (i.e. just by calling strlen and not
having to serialize something that wasn't serialized already),
this change calculates the size of data read from or written to cache
in each request and includes it in the perfdebug table at bottom of
output (when that is turned on).
This supports the following cache types:
* File store
* Redis (only if caching is enabled)
\cache::make() may return a cache_disabled subclass but callers, specifically
user/lib.php:user_create_user(), invoke \cache::purge_current_user() which was
only implemented by the cache_session subclass. Added empty
\cache::purge_current_user() which subclasses can implement, i.e.
cache_session, or not, i.e. cache_disabled.
The current logic in the cache_session::check_tracked_user() is not
right. We must always set the current session id. A typical use case is
when the cache instance is instantiated for a not logged in user. We
can't let the sessionid property null in that case as it forms an
important part of the parsed key.
Similarly, even if we have the same user currently loaded, we must still
set the sessionid to make sure the data will be associated with the
current PHP session. Same user (including visitors or guest users) can
access the site from different browsers and each must end up with its
own key prefix.
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.
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.
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.
- We only now serialize when required, eg when the store doesn't do it.
- static acceleration now serializes on set to reduce overhead on load.
- null now works in static acceleration as we use an array for storage metadata
- static acceleration delete uses isset rather than an array_search.
- We only now serialize when required, eg when the store doesn't do it.
- static acceleration now serializes on set to reduce overhead on load.
- null now works in static acceleration as we use an array for storage metadata
- static acceleration delete uses isset rather than an array_search.
The cache store mode is now included in the performance stats
printed at the bottom of the page.
It is represented as either [a] [s] or [r] and a title is used
to actually state the mode.
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.
This issue makes several fixes for the session loader and the session store.
* maxsize argument now works for session caches.
* fixed performance hole when interation occurs frequently.
* fixed cache purge bug occuring when multiple caches are defined before being used.
* improved lastaccess handling.
Big thanks to Marina who contributed the following commits:
* Always make sure the elements in cache are sorted so we need to remove only elements in the beginning of array
* Remove expired elements from session store to free memory
* Minor bug fixes
This issue makes several fixes for the session loader and the session store.
* maxsize argument now works for session caches.
* fixed performance hole when interation occurs frequently.
* fixed cache purge bug occuring when multiple caches are defined before being used.
* improved lastaccess handling.
sam marshall