Add WebSocketHandler helper for websocket-based FrontendConnection extensions

[frankier]

Previously outlined here: #244

[frankier]

@SimonDanisch Could you please approve my workflows? :o)

[frankier]

I think the CI is timing out, but it does not appear to obviously be related to the content of the PR.

Looks like the documentation preview wasn't built because the PR is from a fork.

[SimonDanisch]

It does seem to be related?

Warning: error while cleaning up server
│   exception =
│    MethodError: no method matching isopen(::Nothing)
│    Closest candidates are:
│      isopen(!Matched::Union{Base.AsyncCondition, Timer}) at asyncevent.jl:138
│      isopen(!Matched::Base.AbstractPipe) at io.jl:385
│      isopen(!Matched::HTTP.Servers.Server) at /home/runner/.julia/packages/HTTP/sJD5V/src/Servers.jl:127
│      ...
│    Stacktrace:
│     [1] isopen(ws::WebSocketConnection)
│       @ Bonito ~/work/Bonito.jl/Bonito.jl/src/connection/websocket.jl:14
│     [2] isopen(session::Session{WebSocketConnection})
│       @ Bonito ~/work/Bonito.jl/Bonito.jl/src/session.jl:162
│     [3] (::Bonito.var"#100#101"{Server, Set{WebSocketConnection}})()
│       @ Bonito ~/work/Bonito.jl/Bonito.jl/src/connection/websocket.jl:87
│     [4] lock(f::Bonito.var"#100#101"{Server, Set{WebSocketConnection}}, l::ReentrantLock)
│       @ Base ./lock.jl:187
│     [5] cleanup_server
│       @ ~/work/Bonito.jl/Bonito.jl/src/connection/websocket.jl:75 [inlined]
│     [6] macro expansion
│       @ ~/work/Bonito.jl/Bonito.jl/src/connection/websocket.jl:112 [inlined]
│     [7] (::Bonito.var"#103#105"{Server})()
│       @ Bonito ./task.jl:417
└ @ Bonito ~/work/Bonito.jl/Bonito.jl/src/connection/websocket.jl:115

[frankier]

Ah. Looks like I pushed a slightly different version from the one I had manually tested. For some reason. I have trouble running the tests locally (they seem to pop up a few windows and then freeze indefinitely).

As for the CI, when I inspect the output it looks like it's timed out after 6 hours and all of the output after the first 50 lines (featuring package installs) is blank so I don't see the error you pasted.

[frankier]

I'll wait to see how #248 gets fixed and then rebase + try to fix this.

[frankier]

Figured out the problem -- it was rather simple and but not fully obvious due to exceptions not printing in sub threads -- it should work now. I was able to run the tests locally using xvfb-run.

Can still hold off until #251 if you like

[SimonDanisch]

it was rather simple and but not fully obvious due to exceptions not printing in sub threads

I did run into this as well... Not really clear why though -.- I suspect apply_handler to suck up exceptions in HTTP.jl, so maybe we need a try catch there to show them ourselves.

[SimonDanisch]

Should this be isopen(handler) ?

[frankier]

This line is copied from

Bonito.jl/src/connection/websocket.jl

Line 95 in 1964ec0

while !isclosed(websocket)

The reference for the method is here https://juliaweb.github.io/HTTP.jl/stable/reference/#HTTP.WebSockets.isclosed

Do you mean Base.isopen? Is it the opposite?

[SimonDanisch]

Yeah I just realized I have these comments in our isopen implementation:

Bonito.jl/src/connection/websocket-handler.jl

Lines 45 to 56 in 3175f80

	function Base.isopen(ws::WebSocketHandler)
	isnothing(ws.socket) && return false
	# isclosed(ws.socket) returns readclosed && writeclosed
	# but we consider it closed if either is closed?
	if ws.socket.readclosed || ws.socket.writeclosed
	return false
	end
	# So, it turns out, ws connection where the tab gets closed
	# stay open indefinitely, but aren't writable anymore
	# TODO, figure out how to check for that
	return true
	end

[frankier]

Okay done since it seems fine to change then. It should just mean we get rid of half-closed sockets quicker I suppose.

[SimonDanisch]

Yeah that's what I hope :) Although, the web does keep surprising me!

[SimonDanisch]

Thank you :)