From 56ff16f61f5c66a2089ca4967d940cf71a9b466e Mon Sep 17 00:00:00 2001
From: krish-z <122767080+krish-nr@users.noreply.github.com>
Date: Tue, 27 Aug 2024 17:42:30 +0800
Subject: [PATCH] (op-geth) Add extra error info when meet an unexpected el
 sync (#132)

---
 eth/catalyst/api.go        |  3 +++
 eth/catalyst/api_test.go   | 12 +++++++-----
 eth/downloader/skeleton.go |  6 +++++-
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/eth/catalyst/api.go b/eth/catalyst/api.go
index 31da11533b..e8703f7532 100644
--- a/eth/catalyst/api.go
+++ b/eth/catalyst/api.go
@@ -722,6 +722,9 @@ func (api *ConsensusAPI) delayPayloadImport(block *types.Block) (engine.PayloadS
 		// that the parent state is missing and the syncer rejected extending the
 		// current cycle with the new payload.
 		log.Warn("Ignoring payload with missing parent", "number", block.NumberU64(), "hash", block.Hash(), "parent", block.ParentHash(), "reason", err)
+		if errors.Is(err, downloader.ErrForcedNeeded) {
+			return engine.PayloadStatusV1{Status: engine.SYNCING}, err
+		}
 	} else {
 		// In non-full sync mode (i.e. snap sync) all payloads are rejected until
 		// snap sync terminates as snap sync relies on direct database injections
diff --git a/eth/catalyst/api_test.go b/eth/catalyst/api_test.go
index 8b6a4f7169..64907080af 100644
--- a/eth/catalyst/api_test.go
+++ b/eth/catalyst/api_test.go
@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"context"
 	crand "crypto/rand"
+	"errors"
 	"fmt"
 	"math/big"
 	"math/rand"
@@ -30,6 +31,8 @@ import (
 
 	"github.com/stretchr/testify/require"
 
+	"github.com/mattn/go-colorable"
+
 	"github.com/ethereum/go-ethereum/beacon/engine"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
@@ -50,7 +53,6 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
 	"github.com/ethereum/go-ethereum/trie"
-	"github.com/mattn/go-colorable"
 )
 
 var (
@@ -715,7 +717,7 @@ func TestEmptyBlocks(t *testing.T) {
 	payload := getNewPayload(t, api, commonAncestor, nil)
 
 	status, err := api.NewPayloadV1(*payload)
-	if err != nil {
+	if err != nil && !errors.Is(err, downloader.ErrForcedNeeded) {
 		t.Fatal(err)
 	}
 	if status.Status != engine.VALID {
@@ -731,7 +733,7 @@ func TestEmptyBlocks(t *testing.T) {
 	payload = setBlockhash(payload)
 	// Now latestValidHash should be the common ancestor
 	status, err = api.NewPayloadV1(*payload)
-	if err != nil {
+	if err != nil && !errors.Is(err, downloader.ErrForcedNeeded) {
 		t.Fatal(err)
 	}
 	if status.Status != engine.INVALID {
@@ -749,7 +751,7 @@ func TestEmptyBlocks(t *testing.T) {
 	payload = setBlockhash(payload)
 	// Now latestValidHash should be the common ancestor
 	status, err = api.NewPayloadV1(*payload)
-	if err != nil {
+	if err != nil && !errors.Is(err, downloader.ErrForcedNeeded) {
 		t.Fatal(err)
 	}
 	if status.Status != engine.SYNCING {
@@ -861,7 +863,7 @@ func TestTrickRemoteBlockCache(t *testing.T) {
 	// feed the payloads to node B
 	for _, payload := range invalidChain {
 		status, err := apiB.NewPayloadV1(*payload)
-		if err != nil {
+		if err != nil && !errors.Is(err, downloader.ErrForcedNeeded) {
 			panic(err)
 		}
 		if status.Status == engine.VALID {
diff --git a/eth/downloader/skeleton.go b/eth/downloader/skeleton.go
index 59d03c954f..129ffb7f61 100644
--- a/eth/downloader/skeleton.go
+++ b/eth/downloader/skeleton.go
@@ -82,6 +82,10 @@ var errChainGapped = errors.New("chain gapped")
 // of the current sync cycle is forked with the one advertised by consensus client.
 var errChainForked = errors.New("chain forked")
 
+// ErrForcedNeeded is a public error to signal that the header chain
+// of the current sync cycle needs a forced flag at startup.
+var ErrForcedNeeded = errors.New("forced head needed for startup")
+
 // maxBlockNumGapTolerance is the max gap tolerance by peer
 var maxBlockNumGapTolerance = uint64(30)
 
@@ -269,7 +273,7 @@ func (s *skeleton) startup() {
 			// New head announced, start syncing to it, looping every time a current
 			// cycle is terminated due to a chain event (head reorg, old chain merge).
 			if !event.force {
-				event.errc <- errors.New("forced head needed for startup")
+				event.errc <- ErrForcedNeeded
 				continue
 			}
 			event.errc <- nil // forced head accepted for startup