From 959d9989af4ff24ce4967ba2a534d73e052a517e Mon Sep 17 00:00:00 2001
From: lizhefeng <lizhefeng1993@gmail.com>
Date: Tue, 5 Feb 2019 10:48:24 -0800
Subject: [PATCH 1/2] Make state recover from empty if the recovery height is
 lower than the current state height

---
 blockchain/blockchain.go      | 16 +++++++++++++++-
 blockchain/blockchain_test.go | 12 +++++++++---
 server/main.go                |  4 +++-
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/blockchain/blockchain.go b/blockchain/blockchain.go
index 12ab9f1d07..f064e6323d 100644
--- a/blockchain/blockchain.go
+++ b/blockchain/blockchain.go
@@ -9,6 +9,7 @@ package blockchain
 import (
 	"context"
 	"math/big"
+	"os"
 	"strconv"
 	"sync"
 	"sync/atomic"
@@ -961,13 +962,26 @@ func (bc *blockchain) startExistingBlockchain(recoveryHeight uint64) error {
 		}
 		startHeight = 1
 	}
-	if recoveryHeight > 0 && startHeight <= recoveryHeight {
+	if recoveryHeight > 0 {
 		for bc.tipHeight > recoveryHeight {
 			if err := bc.dao.deleteTipBlock(); err != nil {
 				return err
 			}
 			bc.tipHeight--
 		}
+		if startHeight > bc.tipHeight {
+			startHeight = 0
+			// Delete existing state DB and reinitialize it
+			if err := os.Remove(bc.config.Chain.TrieDBPath); err != nil {
+				return errors.Wrap(err, "failed to delete existing state DB")
+			}
+			if err := DefaultStateFactoryOption()(bc, bc.config); err != nil {
+				return errors.Wrap(err, "failed to reinitialize state DB")
+			}
+			if err := bc.sf.Start(context.Background()); err != nil {
+				return errors.Wrap(err, "failed to start state factory")
+			}
+		}
 	}
 	for i := startHeight; i <= bc.tipHeight; i++ {
 		blk, err := bc.getBlockByHeight(i)
diff --git a/blockchain/blockchain_test.go b/blockchain/blockchain_test.go
index 03c961778b..ff3f57bfb6 100644
--- a/blockchain/blockchain_test.go
+++ b/blockchain/blockchain_test.go
@@ -1098,7 +1098,7 @@ func TestStartExistingBlockchain(t *testing.T) {
 	}()
 
 	require.NoError(addTestingTsfBlocks(bc))
-	require.True(5 == bc.TipHeight())
+	require.True(bc.TipHeight() == 5)
 
 	// delete state db and recover to tip
 	testutil.CleanupPath(t, testTriePath)
@@ -1114,7 +1114,7 @@ func TestStartExistingBlockchain(t *testing.T) {
 	height, _ := chain.sf.Height()
 	require.Equal(bc.TipHeight(), height)
 
-	// recover to height 3
+	// recover to height 3 from empty state DB
 	testutil.CleanupPath(t, testTriePath)
 	sf, err = factory.NewFactory(cfg, factory.DefaultTrieOption())
 	require.NoError(err)
@@ -1125,7 +1125,13 @@ func TestStartExistingBlockchain(t *testing.T) {
 	require.NoError(chain.startExistingBlockchain(3))
 	height, _ = chain.sf.Height()
 	require.Equal(bc.TipHeight(), height)
-	require.True(3 == height)
+	require.True(height == 3)
+
+	// recover to height 2 from an existing state DB with Height 3
+	require.NoError(chain.startExistingBlockchain(2))
+	height, _ = chain.sf.Height()
+	require.Equal(bc.TipHeight(), height)
+	require.True(height == 2)
 }
 
 func addCreatorToFactory(sf factory.Factory) error {
diff --git a/server/main.go b/server/main.go
index 7965cd9d84..995f52c0da 100644
--- a/server/main.go
+++ b/server/main.go
@@ -25,6 +25,7 @@ import (
 	_ "go.uber.org/automaxprocs"
 	"go.uber.org/zap"
 
+	"github.com/iotexproject/iotex-core/blockchain"
 	"github.com/iotexproject/iotex-core/config"
 	"github.com/iotexproject/iotex-core/pkg/log"
 	"github.com/iotexproject/iotex-core/pkg/probe"
@@ -50,6 +51,7 @@ func main() {
 	signal.Notify(stop, os.Interrupt)
 	signal.Notify(stop, syscall.SIGTERM)
 	ctx, cancel := context.WithCancel(context.Background())
+	ctxWithValue := context.WithValue(ctx, blockchain.RecoveryHeightKey, uint64(recoveryHeight))
 	stopped := make(chan struct{})
 	livenessCtx, livenessCancel := context.WithCancel(context.Background())
 
@@ -93,7 +95,7 @@ func main() {
 		}
 	}
 
-	itx.StartServer(ctx, svr, probeSvr, cfg)
+	itx.StartServer(ctxWithValue, svr, probeSvr, cfg)
 	close(stopped)
 	<-livenessCtx.Done()
 }

From b8b0f914565dd28489ca7554adb2554e9b2aa67c Mon Sep 17 00:00:00 2001
From: lizhefeng <lizhefeng1993@gmail.com>
Date: Tue, 5 Feb 2019 16:55:38 -0800
Subject: [PATCH 2/2] address comment

---
 blockchain/blockchain_test.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/blockchain/blockchain_test.go b/blockchain/blockchain_test.go
index ff3f57bfb6..fccb7d5f9e 100644
--- a/blockchain/blockchain_test.go
+++ b/blockchain/blockchain_test.go
@@ -1098,7 +1098,7 @@ func TestStartExistingBlockchain(t *testing.T) {
 	}()
 
 	require.NoError(addTestingTsfBlocks(bc))
-	require.True(bc.TipHeight() == 5)
+	require.Equal(uint64(5), bc.TipHeight())
 
 	// delete state db and recover to tip
 	testutil.CleanupPath(t, testTriePath)
@@ -1125,13 +1125,13 @@ func TestStartExistingBlockchain(t *testing.T) {
 	require.NoError(chain.startExistingBlockchain(3))
 	height, _ = chain.sf.Height()
 	require.Equal(bc.TipHeight(), height)
-	require.True(height == 3)
+	require.Equal(uint64(3), height)
 
 	// recover to height 2 from an existing state DB with Height 3
 	require.NoError(chain.startExistingBlockchain(2))
 	height, _ = chain.sf.Height()
 	require.Equal(bc.TipHeight(), height)
-	require.True(height == 2)
+	require.Equal(uint64(2), height)
 }
 
 func addCreatorToFactory(sf factory.Factory) error {