Make WebSocketFrame reads fully async

[cswiedler]

Make WebSocketFrame reads fully async. Process close requests via the
message queue, so that anything received prior to the close frame is
handled

[cswiedler]

First time using GitHub so the request may be a little wonky.

We've found that at least in Unity (and maybe elsewhere), the way websocket-sharp does reads can cause deadlocks. The problem is that websocket-sharp does an async read to get the header for a frame, and then does synchronous reads to get the rest. If the synchronous reads block, then Bad Things can supposedly happen. Up until now we've put in a hack to use QueueUserWorkItem to do threaded blocking reads under Unity, but I'm concerned that even outside of Unity, the async/sync combination could be a problem, so this is my attempt to fix it.

So far this is only lightly tested.

[sta]

Hello there,

I plan to merge this manually by inches, adding some changes.

And when i merge your code, i will add a contributor info such as below.

/* * Contributors: * - cswiedler (or another name) <your e-mail address if you have> */ 

Is it okay?

Very thanks!

[cswiedler]

Sure, thanks. Unfortunately it turns out that it still doesn’t completely solve the hang we see in Unity. If I can’t figure it out, I’ll add an option to enable doing the receives on a thread (which is the workaround you suggested a while back). I’ll send another pull request when I have that in.

chris

From: sta [mailto:notifications@github.com]
Sent: Thursday, August 20, 2015 1:25 AM
To: sta/websocket-sharp
Cc: Chris Swiedler
Subject: Re: [websocket-sharp] Make WebSocketFrame reads fully async (#153)

Hello there,

I plan to merge this manually by inches, adding some changes.

And when i merge your code, i will add a contributor info such as below.

/*

• Contributors:

• • cswiedler (or another name)

  */

Is it okay?

Very thanks!

—
Reply to this email directly or view it on GitHubhttps://github.com//pull/153#issuecomment-132934360.

[253153]

@cswiedler Were you able to get to the bottom of where the problem in Unity was occurring? Or if possible, could you show me how you hacked the QueueUserWorkItem? I am experiencing lag (using websockets-sharp for client only) every couple of seconds, and I believe it is caused by this issue.

[cswiedler]

We ended up doing all network IO under Unity on a thread using blocking operations. It may be better in more recent versions. As far as I know, the changes I posted here would only be necessary/helpful if you were running out of threadpool threads, since in that case an async callback from one network operation would perform a (potentially) blocking read, preventing that threadpool thread from being released.

[253153]

@cswiedler I am using a lock in the update function for processing the data, but I'm not sure if it's working that well since I get lag when getting packets every couple seconds in my unity client that's not present in my javascript web app client, is that the same thing you are talking about?