Summary: Refactor clients storage: array -> map. A lot of logic looks up clients by their id, which is currently done with an array.find operation, which is pretty inefficient. This diff changes it to a map, that is pretty important, as in the next diff the decoupled client message handing will need to find the client again for every message that arrives.
Reviewed By: timur-valiev
Differential Revision: D31303536
fbshipit-source-id: ca3f540a3de7665930d2354436d37cb0fbfd5546
026f8fc308