core: reduce blockrandomness message (#477)

* core: reduce blockchain randomness msg

* add test

3 files changed, 44 insertions, 14 deletions

diff --git a/core/blockchain.go b/core/blockchain.go
index aacb65d..b6c8b1d 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -311,21 +311,23 @@ func (bc *blockChain) addBlock(b *types.Block) error {
 	return nil
 }
 
+func (bc *blockChain) shouldAddRandomness(r *types.BlockRandomnessResult) bool {
+	bc.lock.RLock()
+	defer bc.lock.RUnlock()
+	if bc.lastDelivered != nil &&
+		bc.lastDelivered.Position.Newer(r.Position) {
+		return false
+	}
+	_, exists := bc.pendingRandomnesses[r.Position]
+	if exists {
+		return false
+	}
+	b := bc.findPendingBlock(r.Position)
+	return b == nil || len(b.Finalization.Randomness) == 0
+}
+
 func (bc *blockChain) addRandomness(r *types.BlockRandomnessResult) error {
-	if func() bool {
-		bc.lock.RLock()
-		defer bc.lock.RUnlock()
-		if bc.lastDelivered != nil &&
-			bc.lastDelivered.Position.Newer(r.Position) {
-			return true
-		}
-		_, exists := bc.pendingRandomnesses[r.Position]
-		if exists {
-			return true
-		}
-		b := bc.findPendingBlock(r.Position)
-		return b != nil && len(b.Finalization.Randomness) > 0
-	}() {
+	if !bc.shouldAddRandomness(r) {
 		return nil
 	}
 	ok, err := bc.verifyRandomness(r.BlockHash, r.Position.Round, r.Randomness)
diff --git a/core/blockchain_test.go b/core/blockchain_test.go
index 991dc94..46e7630 100644
--- a/core/blockchain_test.go
+++ b/core/blockchain_test.go
@@ -495,6 +495,31 @@ func (s *BlockChainTestSuite) TestAddEmptyBlockDirectly() {
 	s.Require().NotNil(rec.block)
 }
 
+func (s *BlockChainTestSuite) TestShouldAddRandomness() {
+	initBlock := s.newRoundOneInitBlock()
+	bc := s.newBlockChain(initBlock, 10)
+	blocks := s.newBlocks(2, initBlock)
+	b0, b1 := blocks[0], blocks[1]
+	r0 := s.newRandomnessFromBlock(b0)
+	r1 := s.newRandomnessFromBlock(b1)
+
+	// If a block is extracted, the randomness should not be added.
+	s.Require().NoError(bc.addBlock(b0))
+	s.True(bc.shouldAddRandomness(r0))
+	s.Require().NoError(bc.addRandomness(r0))
+	s.False(bc.shouldAddRandomness(r0))
+	s.Require().Len(bc.extractBlocks(), 1)
+	s.Require().Equal(b0.Hash, bc.lastDelivered.Hash)
+
+	// If a block has already have randomness, it should not be added.
+	s.True(bc.shouldAddRandomness(r1))
+	s.Require().NoError(bc.addRandomness(r1))
+	s.Require().Len(bc.pendingRandomnesses, 1)
+	s.False(bc.shouldAddRandomness(r1))
+	s.Require().NoError(bc.addBlock(b1))
+	s.False(bc.shouldAddRandomness(r1))
+}
+
 func TestBlockChain(t *testing.T) {
 	suite.Run(t, new(BlockChainTestSuite))
 }
diff --git a/core/consensus.go b/core/consensus.go
index 050bfe7..5945406 100644
--- a/core/consensus.go
+++ b/core/consensus.go
@@ -1070,6 +1070,9 @@ func (con *Consensus) ProcessBlockRandomnessResult(
 	if rand.Position.Round == 0 {
 		return nil
 	}
+	if !con.bcModule.shouldAddRandomness(rand) {
+		return nil
+	}
 	if err := con.bcModule.addRandomness(rand); err != nil {
 		return err
 	}