From 3ef65533cf0624adf6b09b133ff50c88fdf1303f Mon Sep 17 00:00:00 2001
From: Mission Liao <mission.liao@dexon.org>
Date: Thu, 27 Dec 2018 11:00:13 +0800
Subject: Fix: consensusTimestamp panic when numChains increased at round
 1(#382)

---
 core/consensus-timestamp.go        |  9 +++++++++
 core/consensus-timestamp_test.go   | 12 ++++++++++++
 integration_test/consensus_test.go | 11 ++++++++---
 3 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/core/consensus-timestamp.go b/core/consensus-timestamp.go
index a1ace97..d7ce8e2 100644
--- a/core/consensus-timestamp.go
+++ b/core/consensus-timestamp.go
@@ -80,6 +80,15 @@ func (ct *consensusTimestamp) appendConfig(
 	if round != uint64(len(ct.numChainsOfRounds))+ct.numChainsBase {
 		return ErrRoundNotIncreasing
 	}
+	// This segment is to handle the corner case for config checking logic in
+	// processBlock method.
+	if len(ct.numChainsOfRounds) == 1 {
+		if ct.numChainsOfRounds[0] > config.NumChains {
+			ct.resizeTimetamps(ct.numChainsOfRounds[0])
+		} else {
+			ct.resizeTimetamps(config.NumChains)
+		}
+	}
 	ct.numChainsOfRounds = append(ct.numChainsOfRounds, config.NumChains)
 	return nil
 }
diff --git a/core/consensus-timestamp_test.go b/core/consensus-timestamp_test.go
index bbc58a2..9d199fe 100644
--- a/core/consensus-timestamp_test.go
+++ b/core/consensus-timestamp_test.go
@@ -189,6 +189,18 @@ func (s *ConsensusTimestampTest) TestTimestampRoundInterleave() {
 	s.Require().NoError(err)
 }
 
+func (s *ConsensusTimestampTest) TestNumChainsChangeAtSecondAppendedRound() {
+	now := time.Now().UTC()
+	ct := newConsensusTimestamp(now, 1, 4)
+	s.Require().NoError(ct.appendConfig(2, &types.Config{NumChains: 5}))
+	// We should be able to handle a block from the second appended round.
+	s.Require().NoError(ct.processBlocks([]*types.Block{
+		&types.Block{
+			Position:  types.Position{Round: 2},
+			Timestamp: now.Add(1 * time.Second),
+		}}))
+}
+
 func (s *ConsensusTimestampTest) TestTimestampSync() {
 	chainNum := 19
 	sigma := 100 * time.Millisecond
diff --git a/integration_test/consensus_test.go b/integration_test/consensus_test.go
index 23a4b3c..c68028f 100644
--- a/integration_test/consensus_test.go
+++ b/integration_test/consensus_test.go
@@ -258,19 +258,24 @@ func (s *ConsensusTestSuite) TestNumChainsChange() {
 			pubKeys, 100*time.Millisecond, &common.NullLogger{}, true),
 		core.ConfigRoundShift)
 	req.NoError(err)
-	// Setup configuration for round 0 and round 1.
 	req.NoError(seedGov.State().RequestChange(
 		test.StateChangeRoundInterval, 45*time.Second))
+	seedGov.CatchUpWithRound(0)
+	// Setup configuration for round 0 and round 1.
+	req.NoError(seedGov.State().RequestChange(
+		test.StateChangeNumChains, uint32(5)))
+	req.NoError(seedGov.State().RequestChange(
+		test.StateChangeRoundInterval, 55*time.Second))
 	seedGov.CatchUpWithRound(1)
 	// Setup configuration for round 2.
 	req.NoError(seedGov.State().RequestChange(
-		test.StateChangeNumChains, uint32(5)))
+		test.StateChangeNumChains, uint32(6)))
 	req.NoError(seedGov.State().RequestChange(
 		test.StateChangeRoundInterval, 55*time.Second))
 	seedGov.CatchUpWithRound(2)
 	// Setup configuration for round 3.
 	req.NoError(seedGov.State().RequestChange(
-		test.StateChangeNumChains, uint32(6)))
+		test.StateChangeNumChains, uint32(5)))
 	req.NoError(seedGov.State().RequestChange(
 		test.StateChangeRoundInterval, 75*time.Second))
 	seedGov.CatchUpWithRound(3)
-- 
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