add log message if in da check at slot end (#13776)

* add log message if in da check at slot end

* don't bother logging late da check start

* break up defer with a var, too dense all together

* pass slot instead of block ref

---------

Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>

beacon-chain/blockchain/process_block.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
 	"go.opencensus.io/trace"
 
 	"github.com/prysmaticlabs/prysm/v5/beacon-chain/core/blocks"
@@ -558,6 +559,20 @@ func (s *Service) isDataAvailable(ctx context.Context, root [32]byte, signed int
 	// The gossip handler for blobs writes the index of each verified blob referencing the given
 	// root to the channel returned by blobNotifiers.forRoot.
 	nc := s.blobNotifiers.forRoot(root)
+
+	// Log for DA checks that cross over into the next slot; helpful for debugging.
+	nextSlot := slots.BeginsAt(signed.Block().Slot()+1, s.genesisTime)
+	// Avoid logging if DA check is called after next slot start.
+	if nextSlot.After(time.Now()) {
+		nst := time.AfterFunc(time.Until(nextSlot), func() {
+			if len(missing) == 0 {
+				return
+			}
+			log.WithFields(daCheckLogFields(root, signed.Block().Slot(), expected, len(missing))).
+				Error("Still waiting for DA check at slot end.")
+		})
+		defer nst.Stop()
+	}
 	for {
 		select {
 		case idx := <-nc:
@@ -576,6 +591,15 @@ func (s *Service) isDataAvailable(ctx context.Context, root [32]byte, signed int
 	}
 }
 
+func daCheckLogFields(root [32]byte, slot primitives.Slot, expected, missing int) logrus.Fields {
+	return logrus.Fields{
+		"slot":          slot,
+		"root":          root,
+		"blobsExpected": expected,
+		"blobsWaiting":  missing,
+	}
+}
+
 // lateBlockTasks  is called 4 seconds into the slot and performs tasks
 // related to late blocks. It emits a MissedSlot state feed event.
 // It calls FCU and sets the right attributes if we are proposing next slot