From c728a9694f2ab878368fc050686d0ec92215dc9b Mon Sep 17 00:00:00 2001
From: Jitendra Bhurat <jbhurat@gmail.com>
Date: Fri, 29 May 2020 15:14:25 -0400
Subject: [PATCH] Moving setting the consensus in the start instead of when
 getting a new backend

---
 consensus/istanbul/backend/backend.go | 8 ++------
 consensus/istanbul/backend/engine.go  | 8 ++++++++
 2 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/consensus/istanbul/backend/backend.go b/consensus/istanbul/backend/backend.go
index e5769fb48..11ecc5d48 100644
--- a/consensus/istanbul/backend/backend.go
+++ b/consensus/istanbul/backend/backend.go
@@ -62,11 +62,7 @@ func New(config *istanbul.Config, privateKey *ecdsa.PrivateKey, db ethdb.Databas
 		recentMessages:   recentMessages,
 		knownMessages:    knownMessages,
 	}
-	if backend.IsQIBFTConsensus() {
-		backend.core = qibftCore.New(backend, backend.config)
-	} else {
-		backend.core = istanbulCore.New(backend, backend.config)
-	}
+
 	return backend
 }
 
@@ -332,7 +328,7 @@ func (sb *backend) IsQIBFTConsensus() bool {
 		return false
 	}
 
-	if sb.qibftConsensusEnabled || sb.config.QibftBlock.Uint64() == 0{
+	if sb.qibftConsensusEnabled || sb.config.QibftBlock.Uint64() == 0 {
 		return true
 	}
 
diff --git a/consensus/istanbul/backend/engine.go b/consensus/istanbul/backend/engine.go
index f33c5139f..be9ae43b3 100644
--- a/consensus/istanbul/backend/engine.go
+++ b/consensus/istanbul/backend/engine.go
@@ -29,6 +29,7 @@ import (
 	"github.com/ethereum/go-ethereum/consensus/istanbul"
 	istanbulCore "github.com/ethereum/go-ethereum/consensus/istanbul/core"
 	"github.com/ethereum/go-ethereum/consensus/istanbul/validator"
+	qibftCore "github.com/ethereum/go-ethereum/consensus/qibft/core"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/log"
@@ -530,6 +531,13 @@ func (sb *backend) Start(chain consensus.ChainReader, currentBlock func() *types
 	sb.currentBlock = currentBlock
 	sb.hasBadBlock = hasBadBlock
 
+	// Check if qibft Consensus needs to be used after chain is set
+	if sb.IsQIBFTConsensus() {
+		sb.core = qibftCore.New(sb, sb.config)
+	} else {
+		sb.core = istanbulCore.New(sb, sb.config)
+	}
+
 	if err := sb.core.Start(); err != nil {
 		return err
 	}