network time service, non-blocking?

[Petr Slansky]

Hello Gawk,

this is not real bug report, it is something like a feedback. I use gawk
4.1.4.

I tried to use gawk for some network service, to report progress of data
processed from pipeline to websocket but I think I cannot do that because
gawk doesn't support non-blocking sockets. To illustrate that, I use
example with simple time service, similar to
https://www.gnu.org/software/gawk/manual/gawkinet/html_node/Setting-Up.html#Setting-Up

$ cat timesrv.awk
# Time server
BEGIN {
  service = "/inet/tcp/8888/0/0";
  while (1) {
     time = strftime();
     print time;
     print time |& service;
     close(service);
  }
}

# run it
$ gawk -f timeserv.awk

# other terminal
$ sleep 45; date; curl http://localhost:8888

The problem of this server is that it reports "old" time. It samples time
to a variable and it waits for an incoming connection from a client, then
it reports time and samples new time. When clients don't connect
frequently, they get wrong (old) time.

Is there a way, to check if client connected to listening socket? Open
server socket, do some other tasks and from time to time check if client is
connected; when client is connected, serve fresh data otherwise continue to
process data. It is possible that I cannot use gawk for my task and I have
to use Python, Go or other tool.

Petr