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)
A list of times for each cache key in a TTL cache is kept in a Redis
sorted list, which can be queried efficiently to delete expired
cache items later in a scheduled task.
This change makes set and delete 2x slower (only for caches which use
TTL) but there is no impact on get performance.
Due to some changes in Redis 5 php extension Moodle fails to connect via TCP when
no port is set. It's fixed upstream in phpredis repo (version 5.0.0, 5.0.1 and
5.0.2 affected so far), but with this patch we'll send the right port anyway.
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.
sam marshall