Commit 90dd96e0 authored by Birte Kristina Friesel's avatar Birte Kristina Friesel
Browse files

Handle race condition when several workers are updating the same history entry

parent 7c7b5e9f

lib/Travelynx.pm

+25 −7
Original line number Diff line number Diff line
@@ -1485,6 +1485,7 @@ sub startup { 
			);

			my $stats = $self->compute_journey_stats(@journeys);



			eval {

				$self->pg->db->insert(

					'journey_stats',

					{
@@ -1494,6 +1495,23 @@ sub startup { 
						data    => JSON->new->encode($stats),

					}

				);

			};

			if ( my $err = $@ ) {

				if ( $err =~ m{duplicate key value violates unique constraint} )

				{

                 # When a user opens the same history page several times in

                 # short succession, there is a race condition where several

                 # Mojolicious workers execute this helper, notice that there is

                 # no up-to-date history, compute it, and insert it using the

                 # statement above. This will lead to a uniqueness violation

                 # in each successive insert. However, this is harmless, and

                 # thus ignored.

				}

				else {

					# Otherwise we probably have a problem.

					die($@);

				}

			}



			return $stats;

		}