parlia: improve GetFinalizedHeader

Author: allformless

consensus/parlia/parlia.go

@@ -2296,29 +2296,31 @@ func (p *Parlia) GetFinalizedHeader(chain consensus.ChainHeaderReader, header *t
 		return chain.GetHeaderByNumber(0) // keep consistent with GetJustifiedNumberAndHash
 	}
 
-	currentJustifiedNumber := snap.Attestation.TargetNumber
-	currentJustifiedHash := snap.Attestation.TargetHash
+	finalizedHash := snap.Attestation.SourceHash
+	finalizedNumber := snap.Attestation.SourceNumber
 
+	currentJustifiedHash := snap.Attestation.TargetHash
+	currentJustifiedNumber := snap.Attestation.TargetNumber
 	// Try to check if currentJustifiedNumber can become finalized by checking VotePool.
 	// We only need to check currentJustifiedNumber + 1, since currentJustifiedNumber is already the latest justified.
 	if p.VotePool != nil && currentJustifiedNumber == header.Number.Uint64()-1 {
 		parentSnap, err := p.snapshot(chain, header.Number.Uint64()-1, header.ParentHash, nil)
-		if err != nil {
+		if err == nil {
+			// Check if the next block (direct child) has reached quorum in VotePool
+			votes := p.VotePool.FetchVotesByBlockHash(header.Hash(), currentJustifiedNumber)
+			quorum := cmath.CeilDiv(len(parentSnap.Validators)*2, 3)
+
+			if len(votes) >= quorum {
+				finalizedHash = currentJustifiedHash
+				finalizedNumber = currentJustifiedNumber
+			}
+		} else {
 			log.Error("Failed to get parent snapshot for finality check",
 				"error", err, "blockNumber", header.Number.Uint64()-1, "blockHash", header.ParentHash)
-			return chain.GetHeader(snap.Attestation.SourceHash, snap.Attestation.SourceNumber)
-		}
-		// Check if the next block (direct child) has reached quorum in VotePool
-		votes := p.VotePool.FetchVotesByBlockHash(header.Hash(), currentJustifiedNumber)
-		quorum := cmath.CeilDiv(len(parentSnap.Validators)*2, 3)
-
-		if len(votes) >= quorum {
-			return chain.GetHeader(currentJustifiedHash, currentJustifiedNumber)
 		}
 	}
 
-	// Fallback to the original logic: finalized is the source in attestation
-	return chain.GetHeader(snap.Attestation.SourceHash, snap.Attestation.SourceNumber)
+	return chain.GetHeader(finalizedHash, finalizedNumber)
 }
 
 // CheckFinalityAndNotify checks if votes for the target block have reached quorum,