When enabling the account validity feature, Synapse will look at startup for registered account without an expiration date, and will set one equals to 'now + validity_period' for them. On large servers, it can mean that a large number of users will have the same expiration date, which means that they will all be sent a renewal email at the same time, which isn't ideal.
In order to mitigate this, this PR allows server admins to define a 'max_delta' so that the expiration date is a random value in the [now + validity_period ; now + validity_period + max_delta] range. This allows renewal emails to be progressively sent over a configured period instead of being sent all in one big batch.
The list of server names was redundant, since it was equivalent to the keys on
the server_to_deferred map. This reduces the number of large lists being passed
around, and has the benefit of deduplicating the entries in `wait_on`.
Replaces DEFAULT_ROOM_VERSION constant with a method that first checks the config, then returns a hardcoded value if the option is not present.
That hardcoded value is now located in the server.py config file.
Rather than have three methods which have to have the same interface,
factor out a separate interface which is provided by three implementations.
I find it easier to grok the code this way.
This is a first step to checking that the key is valid at the required moment.
The idea here is that, rather than passing VerifyKey objects in and out of the
storage layer, we instead pass FetchKeyResult objects, which simply wrap the
VerifyKey and add a valid_until_ts field.
* Pass time_added_ms into process_v2_response
* Simplify process_v2_response
We can merge old_verify_keys into verify_keys, and reduce the number of dicts
flying around.
Storing server keys hammered the database a bit. This replaces the
implementation which stored a single key, with one which can do many updates at
once.
I was staring at this function trying to figure out wtf it was actually
doing. This is (hopefully) a non-functional refactor which makes it a bit
clearer.
