0.1.52 Gateway

server/internal/store/device_activity.go

@@ -0,0 +1,73 @@
+package store
+
+import (
+	"context"
+	"fmt"
+	"time"
+)
+
+// DeviceActivityRetention is how long the per-day marks are kept. They are not history
+// anybody reads — the notification they produced is the record, and that is itself pruned
+// at thirty days — so this only has to be long enough that a clock correction or a
+// database restored from a backup cannot make yesterday look like a day that never
+// happened.
+const DeviceActivityRetention = 90 * 24 * time.Hour
+
+// MarkDeviceDay records that a television was in use on a household-local day, and
+// reports whether this is the first time it has been seen today.
+//
+// The answer comes from the insert rather than from a read followed by a write, because
+// every set in the house can reach this at once and two of them racing on the same row
+// must not both be told they were first. `ON CONFLICT DO NOTHING` makes the primary key
+// the arbiter: exactly one insert affects a row.
+//
+// It is keyed on the viewer as well as the television because a household set that two
+// people sign into is two people opening Memby, and an operator reading the feed wants to
+// know which of them it was.
+func (s *Store) MarkDeviceDay(
+	ctx context.Context, deviceID, userID string, day time.Time,
+) (bool, error) {
+	if deviceID == "" {
+		return false, nil
+	}
+	tag, err := s.pool.Exec(ctx, `
+		INSERT INTO device_activity_days (device_id, emby_user_id, day)
+		VALUES ($1, $2, $3)
+		ON CONFLICT (device_id, emby_user_id, day) DO NOTHING`,
+		deviceID, userID, day.Format("2006-01-02"))
+	if err != nil {
+		return false, fmt.Errorf("store: mark device day: %w", err)
+	}
+	return tag.RowsAffected() > 0, nil
+}
+
+// PruneDeviceActivityDays drops marks older than the retention window.
+func (s *Store) PruneDeviceActivityDays(
+	ctx context.Context, retention time.Duration,
+) (int64, error) {
+	if retention <= 0 {
+		retention = DeviceActivityRetention
+	}
+	tag, err := s.pool.Exec(ctx,
+		`DELETE FROM device_activity_days WHERE first_seen_at < now() - $1::interval`,
+		fmt.Sprintf("%d seconds", int64(retention.Seconds())))
+	if err != nil {
+		return 0, fmt.Errorf("store: prune device activity days: %w", err)
+	}
+	return tag.RowsAffected(), nil
+}
+
+// DeleteDeviceActivityDays retires a television's marks along with the television, the
+// way its build history is retired: a set that is gone must not be able to announce a
+// first use it can no longer have.
+func (s *Store) DeleteDeviceActivityDays(ctx context.Context, deviceIDs ...string) error {
+	if len(deviceIDs) == 0 {
+		return nil
+	}
+	_, err := s.pool.Exec(ctx,
+		`DELETE FROM device_activity_days WHERE device_id = ANY($1::text[])`, deviceIDs)
+	if err != nil {
+		return fmt.Errorf("store: delete device activity days: %w", err)
+	}
+	return nil
+}