From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Thu, 11 Apr 2024 21:11:18 +0000 (+0200)
Subject: Add WebSocket pings to try to work around Slack hangs.
X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;h=b7a75f2a797398aefb169a927fe9e4237c7ca1de;p=skvidarsync

Add WebSocket pings to try to work around Slack hangs.
---

diff --git a/bin/ws.pl b/bin/ws.pl
index dd6a0ae..8dbfd14 100644
--- a/bin/ws.pl
+++ b/bin/ws.pl
@@ -67,6 +67,36 @@ sub ws_cb {
 
 	print STDERR "Connected to the Slack WebSocket.\n";
 
+	bless $connection, 'PingableConnection';
+	$connection->{'_pending_ping'} = undef;
+	$connection->{'_ping_sent'} = undef;
+	$connection->{'_stuck_timer'} = AnyEvent->timer(
+		after => 5.0,
+		interval => 5.0,
+		cb => sub {
+			if (defined($connection->{'_pending_ping'})) {
+				print STDERR "Timed out while waiting for pong on '$connection->{'_pending_ping'}'; disconnecting.\n";
+				$connection->close;
+				return;
+			}
+			chomp ($connection->{'_pending_ping'} = ctime(time));
+			$connection->{'_ping_sent'} = [Time::HiRes::gettimeofday];
+			$connection->ping($connection->{'_pending_ping'});
+		});
+	$connection->on_pong(sub {
+		my ($conn, $msg) = @_;
+		if (defined($connection->{'_pending_ping'}) && $connection->{'_pending_ping'} eq $msg->{'body'}) {
+			my $t0 = Time::HiRes::tv_interval($connection->{'_ping_sent'});
+			print STDERR "Received expected pong: $msg->{'body'} ($t0 seconds RTT)\n";
+			undef $connection->{'_pending_ping'};
+			undef $connection->{'_ping_sent'};
+		} else {
+			print STDERR "Received unexpected pong '$msg->{'body'}' (expected '$connection->{'_pending_ping'}'); disconnecting.\n";
+			$connection->close;
+		}
+	});
+
+
 	$connection->on(each_message => sub {
 		my ($conn, $message) = @_;
 		my $now = [Time::HiRes::gettimeofday];
@@ -153,3 +183,30 @@ sub handle_event {
 		print STDERR "Type is $type (not a reaction added or removed); ignoring.\n";
 	}
 }
+
+# Override a little packet processing so that we get to see pong messages.
+
+package PingableConnection;
+use parent 'AnyEvent::WebSocket::Connection';
+
+sub on_pong {
+	my ($self, $cb) = @_;
+	push @{ $self->{'_pong_cb'} }, $cb;
+}
+
+sub ping {
+	my ($self, $message) = @_;
+
+	$self->send(AnyEvent::WebSocket::Message->new({
+		opcode => 9,  # ping
+		body => $message
+	}));
+}
+
+sub _process_message {
+	my ($self, $message) = @_;
+	if ($message->is_pong) {
+		$_->($self, $message) for @{$self->{'_pong_cb'}};
+	}
+	return $self->SUPER::_process_message($message);
+}