Re: [libmicrohttpd] [EXTERNAL] Re: 0.9.71+ Connection Idle and Reuse Issue when Suspending and Resuming Connections

[Earp, Damon N. (GSFC-619.0)[SCIENCE SYSTEMS AND APPLICATIONS INC]]

Christian,

I've tested your version and indeed I see the expected behavior. I believe the 
disconnect is my lack of knowledge of the flow requirements of the access 
handler. I was under the impression that in a non-100 continue requests 
queueing a response on the 2nd callback was fine, but I see from your changes I 
need to wait till the 3rd callback. 

Access handler flow from your updated main.c:
Call 1. Increment the request access handler call count and return MHD_YES
Call 2. Create the thread, suspend the request and return MHD_YES
Call 3. queue the response return result

It appears that I've been combining the first 2 calls incorrectly. I updated my 
main.c to do nothing on the first call, suspend and create thread on second 
call, and queue response on third and now am seeing the correct behavior.

> The problem is that your logic queues a response during the *first*
> callback to 'access_handler'

Was that supposed to be *second* not *first*? I added extra logging and 
confirmed I am queuing on the second callback to the access_handler. As long as 
I moved the queuing of the response to the third call I saw proper reuse and 
idling of the connection. 

So to clarify: 

On all requests, regardless of method and existence of the Expect: 100 header, 
queuing a response on the first or second call to the access handler is "early" 
and leads to a forced closing of the connection. Therefore on all non-"Expect: 
100" requests, making the first call to the access handler a NOOP is a simple 
way to avoid queueing a response too early. 

Thanks again for your time and help.
Damon Earp