Bound shutdown hooks by their stop context (closes #102)

internal/database/export_test.go

@@ -46,8 +46,19 @@ func (r *RetentionReaper) ExportStart() {
 }
 
 // ExportStop stops the reaper's background loop for tests.
-func (r *RetentionReaper) ExportStop() {
-	r.stop()
+func (r *RetentionReaper) ExportStop(ctx context.Context) error {
+	return r.stop(ctx)
+}
+
+// ExportWedgeLoop adds a goroutine to the reaper's WaitGroup that
+// never observes cancellation and returns only when release is
+// closed. It stands in for a sweep stuck on a locked database.
+func (r *RetentionReaper) ExportWedgeLoop(
+	release <-chan struct{},
+) {
+	r.wg.Go(func() {
+		<-release
+	})
 }
 
 // ExportSetInterval overrides the sweep interval for tests.