check if the connection to websocket still open with Net::Async::WebSocket

Question

I am Perl beginner and I am fighting with websockets at the moments. After a lot of reading, trying and copy-pasting I got this code to work:

use strict;
use warnings;
use utf8;
use Data::Dumper;
use IO::Async::Loop;
use IO::Async::Timer::Periodic;
use Net::Async::WebSocket::Client;
use Protocol::WebSocket::URL;

my ($url, $msg, $last_update);
$url  = 'ws://127.0.0.1/stream';
$msg  = 'get_lists';

my $uri = Protocol::WebSocket::URL->new->parse($url);
my $loop = IO::Async::Loop->new;
my $client = Net::Async::WebSocket::Client->new(
        on_frame => sub {
                my ($self, $frame) = @_; 
                chomp($frame);
                $last_update = time(); # use this in timer below

                # do something else
        }   
);
$loop->add($client);

$client->connect(
        host    => $uri->host, 
        service => $uri->port, 
        url     => $url, 
        on_connected => sub {
                warn "Connection established";

                if ($msg) {
                        $client->send_frame("$msg\n");
                }   
        },  
        on_connect_error=> sub { die "CONNECT: ".Dumper \@_; },
        on_resolve_error=> sub { die "RESOLVE: ".Dumper \@_; },
        on_fail         => sub { die "FAIL: ".Dumper \@_; },
        on_read_eof     => sub {
                $loop->remove($client);

                # reconnect?
        }   
);

# is the connection to socket is still open?
# check every 30 seconds if $last_update was not updated
my $timer = IO::Async::Timer::Periodic->new(
        interval=> 30,
        on_tick => sub {
                if (!$last_update || time()-30 > $last_update) {
                        warn "Connection probably dead. No new data for 20 seconds.";

                        ## check connection

                        ## and reconnect if needed
                }
        },
);
$timer->start;
$loop->add($timer);

$loop->loop_forever;

I need one more thing here and I am not sure how to solve this:

I found some info like https://stackoverflow.com/a/12091867/1645170 but I do not understand how to put SO_KEEPALIVE in my code. I should probably make my own IO::Socket connection and somehow pass it to Async::Net::WebSocket but I was not able to do it. Actually I don't really have an idea how shoud I do this. Obviously beginner's problems.

I tried the second approach with a timer which should check every 30 seconds whether the connection is open (if no new data came through socket). Again, same problem but from the other side: not sure how to check with the above code whether the connection is open.

I could make a basic IO::Socket connection but I would like to do somehow with the above code because I like how Net::Async::WebSocket does it with events (on_read-eof, on_frame etc).

Answer 1

How to check if it is still works?

Create a "heartbeat". Send a "ping" at every x second from a client and wait until a "pong" gets back. Die if timeout reached.

On the server you could add your own socket (from one of the examples).

If hope it will help you.

my $serversock = IO::Socket::INET->new(
   LocalHost => "127.0.0.1",
   Listen => 1,
) or die "Cannot allocate listening socket - $@";

$serversock->setsockopt(SOL_SOCKET, SO_KEEPALIVE, 1);

my @serverframes;

my $acceptedclient;
my $server = Net::Async::WebSocket::Server->new(
   handle => $serversock,