fixes from review

cmd/tendermint/commands/run_node.go

@@ -47,7 +47,7 @@ func AddNodeFlags(cmd *cobra.Command) {
 	cmd.Flags().Bool("p2p.pex", config.P2P.PexReactor, "Enable Peer-Exchange (dev feature)")
 
 	// consensus flags
-	cmd.Flags().Bool("consensus.no_empty_blocks", config.Consensus.NoEmptyBlocks, "Prevent empty blocks from being proposed by correct processes")
+	cmd.Flags().Bool("consensus.no_empty_blocks", config.Consensus.NoEmptyBlocks, "Only produce blocks when there are txs and when the AppHash changes")
 }
 
 // Users wishing to:

consensus/state.go

@@ -790,9 +790,9 @@ func (cs *ConsensusState) enterNewRound(height int, round int) {
 func (cs *ConsensusState) waitForTxs(height, round int) {
 	// if we're the proposer, start a heartbeat routine
 	// to tell other peers we're just waiting for txs (for debugging)
-	done := make(chan struct{})
-	defer close(done)
 	if cs.isProposer() {
+		done := make(chan struct{})
+		defer close(done)
 		go cs.proposerHeartbeat(done)
 	}
 
@@ -816,7 +816,8 @@ func (cs *ConsensusState) proposerHeartbeat(done chan struct{}) {
 	}
 }
 
-// Enter: from enter NewRound(height,round), once txs are in the mempool
+// Enter (!NoEmptyBlocks): from enterNewRound(height,round)
+// Enter (NoEmptyBlocks) : after enterNewRound(height,round), once txs are in the mempool
 func (cs *ConsensusState) enterPropose(height int, round int) {
 	if cs.Height != height || round < cs.Round || (cs.Round == round && RoundStepPropose <= cs.Step) {
 		cs.Logger.Debug(cmn.Fmt("enterPropose(%v/%v): Invalid args. Current step: %v/%v/%v", height, round, cs.Height, cs.Round, cs.Step))

mempool/mempool.go

@@ -100,6 +100,7 @@ func NewMempool(config *cfg.MempoolConfig, proxyAppConn proxy.AppConnMempool) *M
 
 // FireOnTxsAvailable initializes the TxsAvailable channel,
 // ensuring it will trigger once every height when transactions are available.
+// NOTE: not thread safe - should only be called once, on startup
 func (mem *Mempool) FireOnTxsAvailable() {
 	mem.txsAvailable = make(chan struct{}, 1)
 }
@@ -225,7 +226,7 @@ func (mem *Mempool) resCbNormal(req *abci.Request, res *abci.Response) {
 				tx:      req.GetCheckTx().Tx,
 			}
 			mem.txs.PushBack(memTx)
-			mem.alertIfTxsAvailable()
+			mem.notifyIfTxsAvailable()
 		} else {
 			// ignore bad transaction
 			mem.logger.Info("Bad Transaction", "res", r)
@@ -268,20 +269,13 @@ func (mem *Mempool) resCbRecheck(req *abci.Request, res *abci.Response) {
 			atomic.StoreInt32(&mem.rechecking, 0)
 			mem.logger.Info("Done rechecking txs")
 
-			mem.alertIfTxsAvailable()
+			mem.notifyIfTxsAvailable()
 		}
 	default:
 		// ignore other messages
 	}
 }
 
-func (mem *Mempool) alertIfTxsAvailable() {
-	if !mem.notifiedTxsAvailable && mem.Size() > 0 {
-		mem.notifiedTxsAvailable = true
-		mem.txsAvailable <- struct{}{}
-	}
-}
-
 // 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.
@@ -292,7 +286,7 @@ func (mem *Mempool) TxsAvailable() chan struct{} {
 	return mem.txsAvailable
 }
 
-func (mem *Mempool) alertIfTxsAvailable() {
+func (mem *Mempool) notifyIfTxsAvailable() {
 	if mem.txsAvailable != nil &&
 		!mem.notifiedTxsAvailable && mem.Size() > 0 {
 
@@ -345,6 +339,8 @@ func (mem *Mempool) Update(height int, txs types.Txs) {
 	}
 
 	// Set height
+	// NOTE: the height is not set until Update is first called
+	// (so it will be wrong after a restart until the next block)
 	mem.height = height
 	mem.notifiedTxsAvailable = false