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