Asyncpong

[bubbleboy14]

This PR consists of a few things, with the general intention of improving asynchronous writes and reconnect behavior.

TL/DR: fixes #976 and #942 and #974

background

Running asynchronously (with rel dispatcher), I noticed a couple things.

Firstly, I was seeing an error (SSLEOFError) that occasionally occurred in the course of a write, in particular while sending a PONG (hence the name of this branch). I actually think I saw some ticket about this a while ago, but wasn't able to reproduce it at the time.

Secondly, I noticed that my on_reconnect callback wasn't being fired, and that reconnects weren't reliable - I had to handle some cases in an on_error handler.

reconnects

The reconnect-related fix is in WrappedDispatcher: the problem was that reconnect() (by way of timeout()) wasn't passing True (as reconnecting kwarg) to setSock(); I modified reconnect() and timeout() to address this - problem solved.

async writes

I figured this was happening due to my asynchronous usage of the socket - it was probably trying to write when there wasn't room in the write buffer or writes weren't available for some other reason. For reference, WebSocket.send_frame() (in the _core module, on line 340) is where an individual frame is sent.

The fix is to write asynchronously in custom dispatcher / async mode. I modified WebSocket._send() (line 562) to use the send() function on the dispatcher. DispatcherBase now has a send() function, which just calls _socket.send() (as WebSocket._send() did previously - so there is no change with the default sync dispatcher). WrappedDispatcher.send() uses dispatcher.buffwrite(), which is available in the latest version (0.4.9.17) of rel. The WebSocket constructor now takes a dispatcher kwarg, and saves it on self.

Back in the _app module, in WebSocketApp, create_dispatcher() takes a handleDisconnect kwarg, which is passed to WrappedDispatcher. Also in run_forever(): handleDisconnect(WebSocketConnectionClosedException, bool(reconnect)) lambda is passed (as handleDisconnect kwarg) to create_dispatcher() (which WrappedDispatcher.send() passes to buffwrite()); and setSock() passes the dispatcher to the WebSocket instance.

why the _dispatcher module?

I moved DispatcherBase, Dispatcher, SSLDispatcher, and WrappedDispatcher to the new _dispatcher module so that the _core module could non-circularly import DispatcherBase and WrappedDispatcher for the dispatcher kwarg type hint in the WebSocket constructor.

status

This is still something of a work in progress. I've been testing this branch, and for my use case it's performing better than the current master branch, but further testing would be a good idea.

Please test with your use case and LMK how it goes!