Data commit

Task/Atomic-updates/Perl/atomic-updates.pl

@@ -0,0 +1,52 @@
+use strict;
+use 5.10.0;
+
+use threads 'yield';
+use threads::shared;
+
+my @a :shared = (100) x 10;
+my $stop :shared = 0;
+
+sub pick2 {
+	my $i = int(rand(10));
+	my $j;
+	$j = int(rand(10)) until $j != $i;
+	($i, $j)
+}
+
+sub even {
+	lock @a;
+	my ($i, $j) = pick2;
+	my $sum = $a[$i] + $a[$j];
+	$a[$i] = int($sum / 2);
+	$a[$j] = $sum - $a[$i];
+}
+
+sub rand_move {
+	lock @a;
+	my ($i, $j) = pick2;
+
+	my $x = int(rand $a[$i]);
+	$a[$i] -= $x;
+	$a[$j] += $x;
+}
+
+sub show {
+	lock @a;
+	my $sum = 0;
+	$sum += $_ for (@a);
+	printf "%4d", $_ for @a;
+	print " total $sum\n";
+}
+
+my $t1 = async { even		until $stop }
+my $t2 = async { rand_move	until $stop }
+my $t3 = async {
+	for (1 .. 10) {
+		show;
+		sleep(1);
+	}
+	$stop = 1;
+};
+
+$t1->join; $t2->join; $t3->join;