[cups-devel] IPP requests: Non-blocking or short timeout

[Till Kamppeter]

On 09/11/2016 03:22 PM, Michael Sweet wrote:
>
> The httpSetTimeout function can be used to manipulate the default read timeout for a given connection.

I have successfully applied this function now. I found out that it 
requires a callback which tell by its return value whether to stop. I 
have reduced all timeouts to 3 seconds now. This even works with 
cupsDoRequest, so I did not even need to separate cupsSendRequest and 
cupsGetResponse. cupsDoRequest also has quit after 3 seconds this way.

I also reduced the timeout of the creation of HTTP connections to 3 
seconds by calling httpConnect2() directly.

In addition I followed all g_main_loop_quit(gmainloop) calls with a 
g_main_context_wakeup(NULL) call, to make sure that the main loop gets 
quit as quick as possible.

This reduces the delay of cups-browsed shutdown when it has problems to 
access certain CUPS servers, but it does not reduce it to 3 seconds. In 
some cases it can even still hang for a minute or so.

Any hints for further improvement here?

A possible cause for the hangs was also that the implicitclass backend 
was bombing cups-browsed with requests as I exited it with 
CUPS_BACKEND_RETRY_CURRENT instead of CUPS_BACKEND_RETRY when it was not 
able to send the job off to the remote server. This way the job was 
tried again immediately and not after a delay.

Thank you very much for the help.

    Till