fix: implement Shutdown() for processors (#22)

core/indexer/indexer.go

@@ -91,6 +91,10 @@ func (i *Indexer[T]) Run(ctx context.Context) (err error) {
 		select {
 		case <-i.quit:
 			logger.InfoContext(ctx, "Got quit signal, stopping indexer")
+			if err := i.Processor.Shutdown(ctx); err != nil {
+				logger.ErrorContext(ctx, "Failed to shutdown processor", slogx.Error(err))
+				return errors.Wrap(err, "processor shutdown failed")
+			}
 			return nil
 		case <-ctx.Done():
 			return nil

core/indexer/interface.go

@@ -29,6 +29,9 @@ type Processor[T Input] interface {
 	// VerifyStates verifies the states of the indexed data and the indexer
 	// to ensure the last shutdown was graceful and no missing data.
 	VerifyStates(ctx context.Context) error
+
+	// Shutdown gracefully stops the processor. Database connections, network calls, leftover states, etc. should be closed and cleaned up here.
+	Shutdown(ctx context.Context) error
 }
 
 type IndexerWorker interface {