Fix partial header receive by WatsonTCP. Fixes #75

[sancheolz]

No description provided.

[yallie]

Hmm...

WatsonTcp Version=6.0.6 passes all unit tests.
WatsonTcp Version=6.0.8 freezes.

Looks like it's due to these changes:

_DataReceiver task is stuck on WaitingForActivation status and never gets to IsCompleted = true:

Not sure how it can happen given that _DataReceiver is created like this:

UPD. OK, looks like it means that the DataReceiver task is awaiting on something
and the continuation part is not yet scheduled by the task scheduler.

[yallie]

By the way, WatsonTcp 6.0.8 freezes as well on before-async versions.
I've tried reverting to commit f1387ae and it hangs as well.
Apparently the freeze has nothing to do with the async rewrite of the transport channels.

Any ideas? :)

[yallie]

Looks like commit fedfd5d introduced a deadlock 🤔

WatsonTcpClient.Disconnect waits for the DataReceive task to stop running.
But DataReceive task is waiting for the OnMessage event handler to complete, so Disconnect freezes.

I'm going to try reverting that commit.

@sancheolz could you please remember what issue it should have fixed?
Could we have a unit test for this issue?

[sancheolz]

@yallie If remote object implements remote method for proxy service like this:

public void CloseSession()
{
    RemotingSession.Current.Close();
}

RPC for CloseSession() may be executed without exceptions, with Disconnect event after. Or sometimes this RPC will interrupted with exception. It happens when processing of "session_closed" occurs before "rpc_result". So we need to synchronized processing of messages in OnMessage for predictable behavior. Test should try to cause this unpredictability, but I don't know how to do it yet.

[sancheolz]

@yallie I've brought back changes from fedfd5d in last revision and deadlock didn't occured. How often deadlock occurs?

[yallie]

It happens when processing of "session_closed" occurs before "rpc_result". So we need to synchronized processing of messages in OnMessage for predictable behavior.

Ok, now I see! Will look into this case.

How often deadlock occurs?

It was failing pretty consistently on Github actions, so I couldn't make tests pass even once, see screenshot.
Then I reproduced it locally a couple of times, looked at parallel stacks and found the issue.

[yallie]

@yallie If remote object implements remote method for proxy service like this:

public void CloseSession()
{
    RemotingSession.Current.Close();
}

RPC for CloseSession() may be executed without exceptions, with Disconnect event after. Or sometimes this RPC will interrupted with exception. It happens when processing of "session_closed" occurs before "rpc_result". So we need to synchronized processing of messages in OnMessage for predictable behavior. Test should try to cause this unpredictability, but I don't know how to do it yet.

@sancheolz, please have a look at #113

CloseSession should work fine without changes from commit fedfd5d.

[sancheolz]

Looks good to me. Thanks.