From 1eacbcbe3c890238da49fcfdddc151a5b7748265 Mon Sep 17 00:00:00 2001
From: Sonic <sonic@dexon.org>
Date: Wed, 20 Mar 2019 14:48:21 +0800
Subject: dex: ignore acceptableDist when force synchronise (#285)

---
 dex/blockproposer.go | 12 ++++++++++++
 dex/handler.go       |  2 +-
 dex/sync.go          | 14 ++++++++++----
 3 files changed, 23 insertions(+), 5 deletions(-)

(limited to 'dex')

diff --git a/dex/blockproposer.go b/dex/blockproposer.go
index 5af08f6c4..63aaa5b51 100644
--- a/dex/blockproposer.go
+++ b/dex/blockproposer.go
@@ -18,6 +18,10 @@ import (
 	"github.com/dexon-foundation/dexon/rlp"
 )
 
+var (
+	forceSyncTimeout = 20 * time.Second
+)
+
 type blockProposer struct {
 	mu        sync.Mutex
 	running   int32
@@ -223,6 +227,14 @@ ListenLoop:
 		case <-b.stopCh:
 			log.Debug("Early stop, before consensus core can run")
 			return nil, errors.New("early stop")
+		case <-time.After(forceSyncTimeout):
+			log.Debug("no new chain head for a while")
+			if p := b.dex.protocolManager.peers.BestPeer(); p != nil {
+				log.Debug("try force sync with peer", "id", p.id)
+				b.dex.protocolManager.synchronise(p, true)
+			} else {
+				log.Debug("no peer to sync")
+			}
 		case <-b.watchCat.Meow():
 			log.Info("WatchCat signaled to stop syncing")
 
diff --git a/dex/handler.go b/dex/handler.go
index 57315f90a..ea5c31b36 100644
--- a/dex/handler.go
+++ b/dex/handler.go
@@ -793,7 +793,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			// scenario should easily be covered by the fetcher.
 			currentBlock := pm.blockchain.CurrentBlock()
 			if trueNumber > currentBlock.NumberU64() {
-				go pm.synchronise(p)
+				go pm.synchronise(p, false)
 			}
 		}
 
diff --git a/dex/sync.go b/dex/sync.go
index 927c04bc3..93bed87c4 100644
--- a/dex/sync.go
+++ b/dex/sync.go
@@ -245,11 +245,11 @@ func (pm *ProtocolManager) syncer() {
 			if pm.peers.Len() < minDesiredPeerCount {
 				break
 			}
-			go pm.synchronise(pm.peers.BestPeer())
+			go pm.synchronise(pm.peers.BestPeer(), false)
 
 		case <-forceSync.C:
 			// Force a sync even if not enough peers are present
-			go pm.synchronise(pm.peers.BestPeer())
+			go pm.synchronise(pm.peers.BestPeer(), false)
 
 		case <-pm.noMorePeers:
 			return
@@ -258,7 +258,7 @@ func (pm *ProtocolManager) syncer() {
 }
 
 // synchronise tries to sync up our local block chain with a remote peer.
-func (pm *ProtocolManager) synchronise(peer *peer) {
+func (pm *ProtocolManager) synchronise(peer *peer, force bool) {
 	// Short circuit if no peers are available
 	if peer == nil {
 		return
@@ -271,9 +271,15 @@ func (pm *ProtocolManager) synchronise(peer *peer) {
 
 	// If we are behind the peer, but not more than acceptable distance, don't
 	// trigger a sync. Fetcher is able to cover this.
-	if pNumber <= number+acceptableDist {
+	var dist uint64
+	if !force {
+		dist = acceptableDist
+	}
+
+	if pNumber <= number+dist {
 		return
 	}
+
 	// Otherwise try to sync with the downloader
 	mode := downloader.FullSync
 	if atomic.LoadUint32(&pm.fastSync) == 1 {
-- 
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