Sending multiple responses to a single request

[sorinluc]

Hello !

This question might be as related to HTTP as it is to Pistache itself but here we are :
Some operations performed by our server (built with Pistache ❤️) are long (several minutes before completion), so they trigger a client-side timeout.

I came across the 102 PROCESSING status code, that might be used to indicate "wait a bit more", but I am not sure it can be used with Pistache as following:

void onRequest(const Http::Request& request, Http::ResponseWriter response) {
    sleep(2);  // simulate long task
    response.send(Http::Code::Processing);
    sleep(2);  // a bit more of that long task
    response.send(Http::Code::Ok);
}

This produces the following TCP trace:

2 remarks:

• Both responses are sent together after 4 seconds (I would have expected one after 2 sec and another at 4 sec)
• The second response sort of "contains both the codes, concatenated", and is not interpreted correctly by the HTTP client I'm using

I, honestly, cannot point at the culprit :

• Is it expected behaviour, and the client just does not support that use case ?
• Is it a Pistache issue ?
• Is it just my poor understanding of HTTP ?

Thanks for the hard work on the library by the way !