We wanted to use the HEXPIRE command, but discovered that this command
is only available since the Redis 7.4 version (the latest), and this version
does not have an OSI compliant licence, so it is generally not installable
through common packages managers. The OSS fork is Valkey, but it still does
not have the HEXPIRE command.
So we decide to clean those keys manually, and in order no do this clean
task at each websocket connection, we only do it when we are the first user
to connect to a given map.
Co-authored-by: David Larlet <david@larlet.fr>