From fd4cbda500816e78bda973102b1412ae78b568ad Mon Sep 17 00:00:00 2001
From: Minh Doan <minh@simple-rules.com>
Date: Wed, 21 Nov 2018 11:27:45 -0800
Subject: [PATCH] state_sync incremental improvement

---
 syncing/interface.go    | 13 +++++---
 syncing/syncing.go      | 73 +++++++++++++++++++++++++++--------------
 syncing/syncing_test.go |  1 +
 3 files changed, 59 insertions(+), 28 deletions(-)
 create mode 100644 syncing/syncing_test.go

diff --git a/syncing/interface.go b/syncing/interface.go
index 609f4413c..71e7f81ab 100644
--- a/syncing/interface.go
+++ b/syncing/interface.go
@@ -5,9 +5,14 @@ import (
 	"github.com/harmony-one/harmony/p2p"
 )
 
-// StateSync is the interface to do state-sync.
+// StateSyncInterface is the interface to do state-sync.
+// TODO(minhdoan): Nice to have, we should abstract the Blockchain type as generic type.
 type StateSyncInterface interface {
-	// Syncing Block in blockchain from other peers.
-	// The return channel is the signal of syncing finish.
-	ProcessStateSync(peers []p2p.Peer, bc *blockchain.Blockchain) (chan struct{}, error)
+	// Syncing blockchain from other peers.
+	// The returned channel is the signal of syncing finish.
+	ProcessStateSyncFromPeers(peers []p2p.Peer, bc *blockchain.Blockchain) (chan struct{}, error)
+
+	// Syncing blockchain from a single peer.
+	// The returned channel is the signal of syncing finish.
+	ProcessStateSyncFromSinglePeer(peer *p2p.Peer, bc *blockchain.Blockchain) (chan struct{}, error)
 }
diff --git a/syncing/syncing.go b/syncing/syncing.go
index 61a078114..dee3717c0 100644
--- a/syncing/syncing.go
+++ b/syncing/syncing.go
@@ -33,12 +33,21 @@ type SyncConfig struct {
 	peers []SyncPeerConfig
 }
 
-// StateSync is the main object used to do state sync.
+// GetStateSync returns the implementation of StateSyncInterface interface.
+func GetStateSync() *StateSync {
+	return &StateSync{}
+}
+
+// StateSync is the struct that implements StateSyncInterface.
 type StateSync struct {
+	peerNumber       int
+	activePeerNumber int
+	syncConfig       *SyncConfig
 }
 
-// ProcessStateSync used to do state sync.
-func (ss *StateSync) ProcessStateSync(peers []p2p.Peer, bc *blockchain.Blockchain) (chan struct{}, error) {
+// ProcessStateSyncFromPeers used to do state sync.
+func (ss *StateSync) ProcessStateSyncFromPeers(peers []p2p.Peer, bc *blockchain.Blockchain) (chan struct{}, error) {
+	// TODO: Validate peers.
 	done := make(chan struct{})
 	go func() {
 		ss.StartStateSync(peers, bc)
@@ -47,44 +56,59 @@ func (ss *StateSync) ProcessStateSync(peers []p2p.Peer, bc *blockchain.Blockchai
 	return done, nil
 }
 
-// StartStateSync starts state sync.
-func (ss *StateSync) StartStateSync(peers []p2p.Peer, bc *blockchain.Blockchain) {
-	peerNumber := len(peers)
-	syncConfig := SyncConfig{
-		peers: make([]SyncPeerConfig, peerNumber),
+// ProcessStateSyncFromSinglePeer used to do state sync from a single peer.
+func (ss *StateSync) ProcessStateSyncFromSinglePeer(peer *p2p.Peer, bc *blockchain.Blockchain) (chan struct{}, error) {
+	// Later.
+	return nil, nil
+}
+
+func (ss *StateSync) createSyncConfig(peers []p2p.Peer) {
+	ss.peerNumber = len(peers)
+	ss.syncConfig = &SyncConfig{
+		peers: make([]SyncPeerConfig, ss.peerNumber),
 	}
-	for id := range syncConfig.peers {
-		syncConfig.peers[id].peer = peers[id]
-		syncConfig.peers[id].trusted = false
+	for id := range ss.syncConfig.peers {
+		ss.syncConfig.peers[id].peer = peers[id]
+		ss.syncConfig.peers[id].trusted = false
 	}
+}
 
+func (ss *StateSync) makeConnectionToPeers() {
 	var wg sync.WaitGroup
-	wg.Add(peerNumber)
+	wg.Add(ss.peerNumber)
 
-	for id := range syncConfig.peers {
+	for _, synPeerConfig := range ss.syncConfig.peers {
 		go func(peerConfig *SyncPeerConfig) {
 			defer wg.Done()
 			peerConfig.conn, peerConfig.err = p2p.DialWithSocketClient(peerConfig.peer.Ip, peerConfig.peer.Port)
-		}(&syncConfig.peers[id])
+		}(&synPeerConfig)
 	}
 	wg.Wait()
-
-	activePeerNumber := 0
-	for _, configPeer := range syncConfig.peers {
+	ss.activePeerNumber = 0
+	for _, configPeer := range ss.syncConfig.peers {
 		if configPeer.err == nil {
-			activePeerNumber++
+			ss.activePeerNumber++
 			configPeer.w = bufio.NewWriter(configPeer.conn)
 			configPeer.trusted = true
 		}
 	}
+}
+
+// StartStateSync starts state sync.
+func (ss *StateSync) StartStateSync(peers []p2p.Peer, bc *blockchain.Blockchain) {
+	// Create sync config.
+	ss.createSyncConfig(peers)
+
+	// Make connections to peers.
+	ss.makeConnectionToPeers()
 
 	// Looping to get an array of block hashes from honest nodes.
 LOOP_HONEST_NODE:
 	for {
 		var wg sync.WaitGroup
-		wg.Add(activePeerNumber)
+		wg.Add(ss.activePeerNumber)
 
-		for _, configPeer := range syncConfig.peers {
+		for _, configPeer := range ss.syncConfig.peers {
 			if configPeer.err != nil {
 				continue
 			}
@@ -110,7 +134,7 @@ LOOP_HONEST_NODE:
 		}
 		wg.Wait()
 
-		if getConsensus(&syncConfig) {
+		if getConsensus(ss.syncConfig) {
 			break LOOP_HONEST_NODE
 		}
 	}
@@ -118,7 +142,7 @@ LOOP_HONEST_NODE:
 	taskSyncQueue := queue.New(0)
 	blockSize := 0
 TASK_LOOP:
-	for _, configPeer := range syncConfig.peers {
+	for _, configPeer := range ss.syncConfig.peers {
 		if configPeer.trusted {
 			for id, blockHash := range configPeer.blockHashes {
 				taskSyncQueue.Put(SyncBlockTask{index: id, blockHash: blockHash})
@@ -129,8 +153,9 @@ TASK_LOOP:
 	}
 	// Initialize blockchain
 	bc.Blocks = make([]*blockchain.Block, blockSize)
-	wg.Add(activePeerNumber)
-	for _, configPeer := range syncConfig.peers {
+	var wg sync.WaitGroup
+	wg.Add(ss.activePeerNumber)
+	for _, configPeer := range ss.syncConfig.peers {
 		if configPeer.err != nil {
 			continue
 		}
diff --git a/syncing/syncing_test.go b/syncing/syncing_test.go
new file mode 100644
index 000000000..3f8305535
--- /dev/null
+++ b/syncing/syncing_test.go
@@ -0,0 +1 @@
+package syncing