From 124032e3e93b614fa9fdfc61ed366a9c4bd28b75 Mon Sep 17 00:00:00 2001
From: Ethan Buchman <ethan@coinculture.info>
Date: Thu, 13 Jul 2017 13:19:44 -0400
Subject: [PATCH] NoEmptyBlocks config option

---
 config/config.go   |  9 ++++++---
 consensus/state.go |  6 +++++-
 mempool/mempool.go | 22 +++++++++++++++++++++-
 node/node.go       |  4 ++++
 4 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/config/config.go b/config/config.go
index e552b33b..a633b7fb 100644
--- a/config/config.go
+++ b/config/config.go
@@ -301,8 +301,9 @@ type ConsensusConfig struct {
 	SkipTimeoutCommit bool `mapstructure:"skip_timeout_commit"`
 
 	// BlockSize
-	MaxBlockSizeTxs   int `mapstructure:"max_block_size_txs"`
-	MaxBlockSizeBytes int `mapstructure:"max_block_size_bytes"`
+	MaxBlockSizeTxs   int  `mapstructure:"max_block_size_txs"`
+	MaxBlockSizeBytes int  `mapstructure:"max_block_size_bytes"`
+	NoEmptyBlocks     bool `mapstructure:"no_empty_blocks"`
 
 	// TODO: This probably shouldn't be exposed but it makes it
 	// easy to write tests for the wal/replay
@@ -357,7 +358,8 @@ func DefaultConsensusConfig() *ConsensusConfig {
 		TimeoutCommit:               1000,
 		SkipTimeoutCommit:           false,
 		MaxBlockSizeTxs:             10000,
-		MaxBlockSizeBytes:           1,                          // TODO
+		MaxBlockSizeBytes:           1, // TODO
+		NoEmptyBlocks:               true,
 		BlockPartSize:               types.DefaultBlockPartSize, // TODO: we shouldnt be importing types
 		PeerGossipSleepDuration:     100,
 		PeerQueryMaj23SleepDuration: 2000,
@@ -375,6 +377,7 @@ func TestConsensusConfig() *ConsensusConfig {
 	config.TimeoutPrecommitDelta = 1
 	config.TimeoutCommit = 10
 	config.SkipTimeoutCommit = true
+	config.NoEmptyBlocks = false
 	return config
 }
 
diff --git a/consensus/state.go b/consensus/state.go
index 6378297a..ff5b42c7 100644
--- a/consensus/state.go
+++ b/consensus/state.go
@@ -780,7 +780,11 @@ func (cs *ConsensusState) enterNewRound(height int, round int) {
 
 	// Wait for txs to be available in the mempool
 	// before we enterPropose
-	go cs.waitForTxs(height, round)
+	if cs.config.NoEmptyBlocks {
+		go cs.waitForTxs(height, round)
+	} else {
+		cs.enterPropose(height, round)
+	}
 }
 
 func (cs *ConsensusState) waitForTxs(height, round int) {
diff --git a/mempool/mempool.go b/mempool/mempool.go
index e3c9e216..160ab7d0 100644
--- a/mempool/mempool.go
+++ b/mempool/mempool.go
@@ -92,13 +92,18 @@ func NewMempool(config *cfg.MempoolConfig, proxyAppConn proxy.AppConnMempool) *M
 		recheckEnd:    nil,
 		logger:        log.NewNopLogger(),
 		cache:         newTxCache(cacheSize),
-		txsAvailable:  make(chan struct{}, 1),
 	}
 	mempool.initWAL()
 	proxyAppConn.SetResponseCallback(mempool.resCb)
 	return mempool
 }
 
+// FireOnTxsAvailable initializes the TxsAvailable channel,
+// ensuring it will trigger once every height when transactions are available.
+func (mem *Mempool) FireOnTxsAvailable() {
+	mem.txsAvailable = make(chan struct{}, 1)
+}
+
 // SetLogger sets the Logger.
 func (mem *Mempool) SetLogger(l log.Logger) {
 	mem.logger = l
@@ -277,10 +282,25 @@ func (mem *Mempool) alertIfTxsAvailable() {
 	}
 }
 
+// TxsAvailable returns a channel which fires once for every height,
+// and only when transactions are available in the mempool.
+// XXX: Will panic if mem.FireOnTxsAvailable() has not been called.
 func (mem *Mempool) TxsAvailable() chan struct{} {
+	if mem.txsAvailable == nil {
+		panic("mem.txsAvailable is nil")
+	}
 	return mem.txsAvailable
 }
 
+func (mem *Mempool) alertIfTxsAvailable() {
+	if mem.txsAvailable != nil &&
+		!mem.notifiedTxsAvailable && mem.Size() > 0 {
+
+		mem.notifiedTxsAvailable = true
+		mem.txsAvailable <- struct{}{}
+	}
+}
+
 // Reap returns a list of transactions currently in the mempool.
 // If maxTxs is -1, there is no cap on the number of returned transactions.
 func (mem *Mempool) Reap(maxTxs int) types.Txs {
diff --git a/node/node.go b/node/node.go
index 51390200..c76ae5fa 100644
--- a/node/node.go
+++ b/node/node.go
@@ -143,6 +143,10 @@ func NewNode(config *cfg.Config, privValidator *types.PrivValidator, clientCreat
 	mempoolReactor := mempl.NewMempoolReactor(config.Mempool, mempool)
 	mempoolReactor.SetLogger(mempoolLogger)
 
+	if config.Consensus.NoEmptyBlocks {
+		mempool.FireOnTxsAvailable()
+	}
+
 	// Make ConsensusReactor
 	consensusState := consensus.NewConsensusState(config.Consensus, state.Copy(), proxyApp.Consensus(), blockStore, mempool)
 	consensusState.SetLogger(consensusLogger)