Depends on D18702. Ref T13008. This replaces the old hard-coded single rate limit with multiple flexible limits, and defines two types of limits:
- Rate: reject requests if a client has completed too many requests recently.
- Connection: reject requests if a client has too many more connections than disconnections recently.
The connection limit adds +1 to the score for each connection, then adds -1 for each disconnection. So the overall number is how many open connections they have, at least approximately.
Supporting multiple limits will let us do limiting by Hostname and by remote address (e.g., a specific IP can't exceed a low limit, and all requests to a hostname can't exceed a higher limit).
Configuring the new limits looks something like this:
PhabricatorStartup::addRateLimit(new PhabricatorClientRateLimit())
->setLimitKey('rate')
->setClientKey($_SERVER['REMOTE_ADDR'])
->setLimit(5);
PhabricatorStartup::addRateLimit(new PhabricatorClientConnectionLimit())
->setLimitKey('conn')
->setClientKey($_SERVER['REMOTE_ADDR'])
->setLimit(2);