From 3dc744a17e87b328969484ea4d93116004226355 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Mon, 6 Nov 2023 22:19:40 +0100
Subject: [PATCH] Communicate through NOTIFY/LISTEN instead of a file.

Less delay, obviously.
---
 bin/sync.pl | 52 ++++++++++++++++++++++++++++++++++++----------------
 bin/ws.pl   |  5 ++---
 2 files changed, 38 insertions(+), 19 deletions(-)

diff --git a/bin/sync.pl b/bin/sync.pl
index 7f101dc..ef07ee7 100644
--- a/bin/sync.pl
+++ b/bin/sync.pl
@@ -8,13 +8,13 @@ use LWP::UserAgent;
 use DBI;
 use POSIX;
 use Time::HiRes;
+use IO::Select;
 binmode STDOUT, ':utf8';
 binmode STDERR, ':utf8';
 use utf8;
 
 require '../include/config.pm';
 
-my $dbh;
 my @log = ();
 
 my %rgb = (
@@ -448,15 +448,24 @@ sub possibly_nag_user {
 	$dbh->do('INSERT INTO users_nagged (userid, last_nag) VALUES (?, CURRENT_TIMESTAMP)', undef, $userid);
 }
 
+sub db_connect {
+	my $dbh = DBI->connect("dbi:Pg:dbname=$config::dbname;host=127.0.0.1", $config::dbuser, $config::dbpass, {RaiseError => 1})
+		or warn "Could not connect to Postgres: " . DBI->errstr;
+	if (!defined($dbh)) {
+		return undef;
+	}
+	$dbh->do('LISTEN skvupdate') or return undef;
+	return $dbh;
+}
+
 sub run {
+	my $dbh = shift;
 	my $total_start = [Time::HiRes::gettimeofday];
 
 	@log = ();
 	skv_log("Siste sync startet: " . POSIX::ctime(time));
 
 	# Initialize the handles we need for communication.
-	$dbh = DBI->connect("dbi:Pg:dbname=$config::dbname;host=127.0.0.1", $config::dbuser, $config::dbpass, {RaiseError => 1})
-		or die "Could not connect to Postgres: " . DBI->errstr;
 	my $ua = LWP::UserAgent->new('SKVidarLang/1.0');
 	my $token = get_oauth_bearer_token($dbh, $ua);
 
@@ -755,27 +764,38 @@ sub run {
 	printf "Tok %.0f ms.\n", 1e3 * $elapsed;
 }
 
+my $dbh = db_connect() or die;
 if ($#ARGV >= 0 && $ARGV[0] eq '--daemon') {
 	# Start with a single, forced run.
-	unlink("/srv/skvidar-slack.sesse.net/marker");
-	run();
+	run($dbh);
 
 	while (1) {
-		if (!unlink("/srv/skvidar-slack.sesse.net/marker")) {
-			unless ($!{ENOENT}) {
-				warn "/srv/skvidar-slack.sesse.net/marker: $!";
-			}
+		while (!defined($dbh)) {
+			print STDERR "Database connection lost, reconnecting...\n";
 			sleep 1;
+			$dbh = db_connect();
+		}
+		my $s = IO::Select->new($dbh->{pg_socket});
+		my @ready = $s->can_read(10.0);
+		my @exceptions = $s->has_exception(0.0);
+
+		if (scalar @exceptions > 0) {
+			$dbh->disconnect;
+			$dbh = undef;
 			next;
 		}
-		eval {
-			run();
-		};
-		if ($@) {
-			warn "Died with: $@";
+		if (scalar @ready > 0) {  
+			eval {
+				$dbh->{AutoCommit} = 1;
+				run($dbh);
+				$dbh->commit;
+			};
+			if ($@) {
+				warn "Died with: $@";
+				$dbh = undef;
+			}
 		}
-		$dbh->disconnect;
 	}
 } else {
-	run();
+	run($dbh);
 }
diff --git a/bin/ws.pl b/bin/ws.pl
index 1e4da98..69c7b1d 100644
--- a/bin/ws.pl
+++ b/bin/ws.pl
@@ -97,8 +97,7 @@ sub ws_cb {
 
 sub mark {
 	print STDERR "Marking that a sync is needed.\n";
-	open my $fh, ">", "/srv/skvidar-slack.sesse.net/marker";
-	close $fh;
+	$dbh->do('NOTIFY skvupdate');
 }
 
 sub handle_event {
@@ -139,7 +138,7 @@ sub handle_event {
 	if ($type eq 'reaction_added' || $type eq 'reaction_removed') {
 		$dbh->do('INSERT INTO reaction_log (userid, channel, ts, reaction, event_type, event_ts) VALUES (?,?,?,?,?,?)', undef,
 			$user, $channel, $ts, $reaction, $type, $event_ts);
-		mark();
+		mark($dbh);
 	} else {
 		print STDERR "Type is $type (not a reaction added or removed); ignoring.\n";
 	}
-- 
2.39.5