hgext3rd/__init__.py

httppeer: implement command executor for version 2 peer

Now that we have a new API for issuing commands which is compatible
with wire protocol version 2, we can start using it with wire protocol
version 2.

This commit replaces our hacky implementation of _call() with something
a bit more robust based on the new command executor interface.

We now have proper support for issuing multiple commands per HTTP
request. Each HTTP request maintains its own client reactor.

The implementation is similar to the one in the legacy wire protocol.
We use a ThreadPoolExecutor for spinning up a thread to read the HTTP
response in the background. This allows responses to resolve in any
order. While not implemented on the server yet, a client could use
concurrent.futures.as_completed() with a collection of futures and
handle responses as they arrive from the server.

The return value from issued commands is still a simple list of raw
or decoded CBOR data. This is still super hacky. We will want a rich
data type for representing command responses. But at least this
commit gets us one step closer to a proper peer implementation.

Differential Revision: https://phab.mercurial-scm.org/D3297

# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)