wireproto: client reactor support for receiving frames We can now feed received frames into the client reactor and it will validate their sanity, dispatch them appropriately. The hacky HTTP peer has been updated to use the new code. No existing tests changed, somewhat proving the code works as expected. Rudimentary unit tests for the new functionality have been implemented. Differential Revision: https://phab.mercurial-scm.org/D3224

wireproto: introduce a reactor for client-side state We have a nice state machine of sorts for reacting to server-side events. Now it is time to implement the client equivalent. We introduce a "clientreactor." It allows callers to request that commands be issued. It has multiple modes of operation to reflect what the underlying transport supports. e.g. for SSH, we can perform wire sends immediately but for HTTP we need to buffer sends until all command requests are received. In addition, SSH allows sending multiple requests as long as the connection is open. But HTTP/1.1 only allows sending request data once. For SSH, we'll have one reactor per connection. For HTTP, we'll have one reactor per HTTP request. But because code that calls wire protocol commands should not be aware of how the underlying transport works, this will all be abstracted away by the peer interface. Our crude HTTP peer has been updated to use the reactor instead of formulating frames directly. No behavior should have changed here and tests seem to confirm that. Basic unit tests for the reactor behavior have been added. Differential Revision: https://phab.mercurial-scm.org/D3223

tests: extract wire protocol framing tests to own file I was lazy when I put these in test-wireproto-serverreactor.py. Let's do it properly. Differential Revision: https://phab.mercurial-scm.org/D3222

wireproto: disallow commands handlers for multiple transport versions I think it will be more trouble than it is worth to code version 1 and version 2 command handlers to the same interface. It will feel awkward to shoehorn functionality into e.g. the version 1 protocol handler interface. This would likely constrain the ability for version 2 to evolve. Previous commits introduced a clean separation between command handlers for version 1 and version 2 transports. This commit reinforces that separation by dropping support for having a single command handler service both version 1 and version 2 transports. Differential Revision: https://phab.mercurial-scm.org/D3208