move statistics cache to a separate model class

1 files changed, 100 insertions, 0 deletions

diff --git a/lib/Travelynx/Model/JourneyStatsCache.pm b/lib/Travelynx/Model/JourneyStatsCache.pm
new file mode 100755
index 0000000..145208d
--- /dev/null
+++ b/lib/Travelynx/Model/JourneyStatsCache.pm
@@ -0,0 +1,100 @@
+package Travelynx::Model::JourneyStatsCache;
+# Copyright (C) 2020 Daniel Friesel
+#
+# SPDX-License-Identifier: MIT
+
+use strict;
+use warnings;
+use 5.020;
+use utf8;
+
+import JSON;
+
+sub new {
+	my ( $class, %opt ) = @_;
+
+	return bless( \%opt, $class );
+}
+
+sub add {
+	my ( $self, %opt ) = @_;
+
+	my $db  = $opt{db} // $self->{pg}->db;
+
+	eval {
+		$db->insert(
+			'journey_stats',
+			{
+				user_id => $opt{uid},
+				year    => $opt{year},
+				month   => $opt{month},
+				data    => JSON->new->encode($opt{stats}),
+			}
+		);
+	};
+	if ( my $err = $@ ) {
+		if ( $err =~ m{duplicate key value violates unique constraint} )
+		{
+				# If a user opens the same history page several times in
+				# short succession, there is a race condition where several
+				# Mojolicious workers execute this helper, notice that there is
+				# no up-to-date history, compute it, and insert it using the
+				# statement above. This will lead to a uniqueness violation
+				# in each successive insert. However, this is harmless, and
+				# thus ignored.
+		}
+		else {
+			# Otherwise we probably have a problem.
+			die($@);
+		}
+	}
+}
+
+sub get {
+	my ( $self, %opt ) = @_;
+
+	my $db  = $opt{db} // $self->{pg}->db;
+
+	my $stats = $db->select(
+		'journey_stats',
+		['data'],
+		{
+			user_id => $opt{uid},
+			year    => $opt{year},
+			month   => $opt{month}
+		}
+	)->expand->hash;
+
+	return $stats->{data};
+}
+
+# Statistics are partitioned by real_departure, which must be provided
+# when calling this function e.g. after journey deletion or editing.
+# If a joureny's real_departure has been edited, this function must be
+# called twice: once with the old and once with the new value.
+sub invalidate {
+	my ( $self, %opt ) = @_;
+
+	my $ts  = $opt{ts};
+	my $db  = $opt{db} // $self->{pg}->db;
+	my $uid = $opt{uid};
+
+	$db->delete(
+		'journey_stats',
+		{
+			user_id => $uid,
+			year    => $ts->year,
+			month   => $ts->month,
+		}
+	);
+	$db->delete(
+		'journey_stats',
+		{
+			user_id => $uid,
+			year    => $ts->year,
+			month   => 0,
+		}
+	);
+}
+
+1;