feat(relayer): document indexer with comments, fix broken crawler log…

…ic, add new metrics (#16330)

Co-authored-by: Roger <50648015+RogerLamTd@users.noreply.github.com>

packages/relayer/indexer/config.go

@@ -12,6 +12,8 @@ import (
 	"gorm.io/gorm/logger"
 )
 
+// Config is a struct which should be created from the cli or environment variables, populated,
+// and used to create a new Indexer.
 type Config struct {
 	// address configs
 	SrcBridgeAddress        common.Address

packages/relayer/indexer/detect_and_handle_reorg.go

@@ -8,6 +8,8 @@ import (
 	"log/slog"
 )
 
+// detectAndHandleReorg will look up an event in the database to see if we have seen this event
+// before. If we have , we need to delete it before re-indexing.
 func (i *Indexer) detectAndHandleReorg(ctx context.Context, eventType string, msgHash string) error {
 	// dont check on crawling past blocks, it will be a secondary indexer.
 	// we expect to see duplicates in this mode.

packages/relayer/indexer/handle_chain_data_synced_event.go

@@ -74,5 +74,7 @@ func (i *Indexer) handleChainDataSyncedEvent(
 
 	slog.Info("chainDataSynced event saved")
 
+	relayer.ChainDataSyncedEventsIndexed.Inc()
+
 	return nil
 }

packages/relayer/indexer/handle_message_sent_event.go

@@ -121,6 +121,8 @@ func (i *Indexer) handleMessageSentEvent(
 		return errors.Wrap(err, "i.queue.Publish")
 	}
 
+	relayer.MessageSentEventsIndexed.Inc()
+
 	return nil
 }
 

packages/relayer/indexer/save_message_status_changed_events.go → packages/relayer/indexer/handle_message_status_changed_event.go

@@ -5,48 +5,13 @@ import (
 	"encoding/json"
 	"math/big"
 
-	"log/slog"
-
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/pkg/errors"
 	"github.com/taikoxyz/taiko-mono/packages/relayer"
 	"github.com/taikoxyz/taiko-mono/packages/relayer/bindings/bridge"
 )
 
-func (i *Indexer) saveMessageStatusChangedEvents(
-	ctx context.Context,
-	chainID *big.Int,
-	events *bridge.BridgeMessageStatusChangedIterator,
-) error {
-	if !events.Next() || events.Event == nil {
-		slog.Info("no messageStatusChanged events")
-		return nil
-	}
-
-	for {
-		event := events.Event
-
-		slog.Info("messageStatusChanged", "msgHash", common.Hash(event.MsgHash).Hex())
-
-		if err := i.detectAndHandleReorg(
-			ctx,
-			relayer.EventNameMessageStatusChanged,
-			common.Hash(event.MsgHash).Hex(),
-		); err != nil {
-			return errors.Wrap(err, "i.detectAndHandleReorg")
-		}
-
-		if err := i.saveMessageStatusChangedEvent(ctx, chainID, event); err != nil {
-			return errors.Wrap(err, "i.saveMessageStatusChangedEvent")
-		}
-
-		if !events.Next() {
-			return nil
-		}
-	}
-}
-
-func (i *Indexer) saveMessageStatusChangedEvent(
+func (i *Indexer) handleMessageStatusChangedEvent(
 	ctx context.Context,
 	chainID *big.Int,
 	event *bridge.BridgeMessageStatusChanged,
@@ -81,5 +46,7 @@ func (i *Indexer) saveMessageStatusChangedEvent(
 		return errors.Wrap(err, "i.eventRepo.Save")
 	}
 
+	relayer.MessageStatusChangedEventsIndexed.Inc()
+
 	return nil
 }

packages/relayer/indexer/handle_no_events_in_batch.go

@@ -10,8 +10,8 @@ import (
 	"github.com/taikoxyz/taiko-mono/packages/relayer"
 )
 
-// handleNoEventsInBatch is used when an entire batch call has no events in the entire response,
-// and we need to update the latest block processed
+// handleNoEventsInBatch is used when there are no events remaining in a batch, or
+// the batch itself contained no events.
 func (i *Indexer) handleNoEventsInBatch(
 	ctx context.Context,
 	chainID *big.Int,