Merge pull request #2922 from tendermint/release/v0.26.4

Release/v0.26.4
2026-01-07 13:55:17 +00:00 · 2018-11-27 08:51:45 -05:00
parent 22dcc92232 1abf34aa91
commit b771798d48
58 changed files with 1265 additions and 406 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,48 @@
 # Changelog

+## v0.26.4
+
+*November 27th, 2018*
+
+Special thanks to external contributors on this release:
+ackratos, goolAdapter, james-ray, joe-bowman, kostko,
+nagarajmanjunath, tomtau
+
+
+Friendly reminder, we have a [bug bounty
+program](https://hackerone.com/tendermint).
+
+### FEATURES:
+
+- [rpc] [\#2747](https://github.com/tendermint/tendermint/issues/2747) Enable subscription to tags emitted from `BeginBlock`/`EndBlock` (@kostko)
+- [types] [\#2747](https://github.com/tendermint/tendermint/issues/2747) Add `ResultBeginBlock` and `ResultEndBlock` fields to `EventDataNewBlock`
+    and `EventDataNewBlockHeader` to support subscriptions (@kostko)
+- [types] [\#2918](https://github.com/tendermint/tendermint/issues/2918) Add Marshal, MarshalTo, Unmarshal methods to various structs
+  to support Protobuf compatibility (@nagarajmanjunath)
+
+### IMPROVEMENTS:
+
+- [config] [\#2877](https://github.com/tendermint/tendermint/issues/2877) Add `blocktime_iota` to the config.toml (@ackratos)
+    - NOTE: this should be a ConsensusParam, not part of the config, and will be
+      removed from the config at a later date
+      ([\#2920](https://github.com/tendermint/tendermint/issues/2920).
+- [mempool] [\#2882](https://github.com/tendermint/tendermint/issues/2882) Add txs from Update to cache
+- [mempool] [\#2891](https://github.com/tendermint/tendermint/issues/2891) Remove local int64 counter from being stored in every tx
+- [node] [\#2866](https://github.com/tendermint/tendermint/issues/2866) Add ability to instantiate IPCVal (@joe-bowman)
+
+### BUG FIXES:
+
+- [blockchain] [\#2731](https://github.com/tendermint/tendermint/issues/2731) Retry both blocks if either is bad to avoid getting stuck during fast sync (@goolAdapter)
+- [consensus] [\#2893](https://github.com/tendermint/tendermint/issues/2893) Use genDoc.Validators instead of state.NextValidators on replay when appHeight==0 (@james-ray)
+- [log] [\#2868](https://github.com/tendermint/tendermint/issues/2868) Fix `module=main` setting overriding all others
+    - NOTE: this changes the default logging behaviour to be much less verbose.
+      Set `log_level="info"` to restore the previous behaviour.
+- [rpc] [\#2808](https://github.com/tendermint/tendermint/issues/2808) Fix `accum` field in `/validators` by calling `IncrementAccum` if necessary
+- [rpc] [\#2811](https://github.com/tendermint/tendermint/issues/2811) Allow integer IDs in JSON-RPC requests (@tomtau)
+- [txindex/kv] [\#2759](https://github.com/tendermint/tendermint/issues/2759) Fix tx.height range queries
+- [txindex/kv] [\#2775](https://github.com/tendermint/tendermint/issues/2775) Order tx results by index if height is the same
+- [txindex/kv] [\#2908](https://github.com/tendermint/tendermint/issues/2908) Don't return false positives when searching for a prefix of a tag value
+
 ## v0.26.3

 *November 17th, 2018*
--- a/CHANGELOG_PENDING.md
+++ b/CHANGELOG_PENDING.md
@@ -1,6 +1,6 @@
 # Pending

-## v0.26.4
+## v0.27.0

 *TBD*

--- a/blockchain/pool.go
+++ b/blockchain/pool.go
@@ -168,9 +168,12 @@ func (pool *BlockPool) IsCaughtUp() bool {
 		return false
 	}

-	// some conditions to determine if we're caught up
-	receivedBlockOrTimedOut := (pool.height > 0 || time.Since(pool.startTime) > 5*time.Second)
-	ourChainIsLongestAmongPeers := pool.maxPeerHeight == 0 || pool.height >= pool.maxPeerHeight
+	// Some conditions to determine if we're caught up.
+	// Ensures we've either received a block or waited some amount of time,
+	// and that we're synced to the highest known height. Note we use maxPeerHeight - 1
+	// because to sync block H requires block H+1 to verify the LastCommit.
+	receivedBlockOrTimedOut := pool.height > 0 || time.Since(pool.startTime) > 5*time.Second
+	ourChainIsLongestAmongPeers := pool.maxPeerHeight == 0 || pool.height >= (pool.maxPeerHeight-1)
 	isCaughtUp := receivedBlockOrTimedOut && ourChainIsLongestAmongPeers
 	return isCaughtUp
 }
@@ -252,7 +255,8 @@ func (pool *BlockPool) AddBlock(peerID p2p.ID, block *types.Block, blockSize int
 			peer.decrPending(blockSize)
 		}
 	} else {
-		// Bad peer?
+		pool.Logger.Info("invalid peer", "peer", peerID, "blockHeight", block.Height)
+		pool.sendError(errors.New("invalid peer"), peerID)
 	}
 }

@@ -292,7 +296,7 @@ func (pool *BlockPool) RemovePeer(peerID p2p.ID) {
 func (pool *BlockPool) removePeer(peerID p2p.ID) {
 	for _, requester := range pool.requesters {
 		if requester.getPeerID() == peerID {
-			requester.redo()
+			requester.redo(peerID)
 		}
 	}
 	delete(pool.peers, peerID)
@@ -326,8 +330,11 @@ func (pool *BlockPool) makeNextRequester() {
 	defer pool.mtx.Unlock()

 	nextHeight := pool.height + pool.requestersLen()
+	if nextHeight > pool.maxPeerHeight {
+		return
+	}
+
 	request := newBPRequester(pool, nextHeight)
-	// request.SetLogger(pool.Logger.With("height", nextHeight))

 	pool.requesters[nextHeight] = request
 	atomic.AddInt32(&pool.numPending, 1)
@@ -453,7 +460,7 @@ type bpRequester struct {
 	pool       *BlockPool
 	height     int64
 	gotBlockCh chan struct{}
-	redoCh     chan struct{}
+	redoCh     chan p2p.ID //redo may send multitime, add peerId to identify repeat

 	mtx    sync.Mutex
 	peerID p2p.ID
@@ -465,7 +472,7 @@ func newBPRequester(pool *BlockPool, height int64) *bpRequester {
 		pool:       pool,
 		height:     height,
 		gotBlockCh: make(chan struct{}, 1),
-		redoCh:     make(chan struct{}, 1),
+		redoCh:     make(chan p2p.ID, 1),

 		peerID: "",
 		block:  nil,
@@ -524,9 +531,9 @@ func (bpr *bpRequester) reset() {
 // Tells bpRequester to pick another peer and try again.
 // NOTE: Nonblocking, and does nothing if another redo
 // was already requested.
-func (bpr *bpRequester) redo() {
+func (bpr *bpRequester) redo(peerId p2p.ID) {
 	select {
-	case bpr.redoCh <- struct{}{}:
+	case bpr.redoCh <- peerId:
 	default:
 	}
 }
@@ -565,9 +572,13 @@ OUTER_LOOP:
 				return
 			case <-bpr.Quit():
 				return
-			case <-bpr.redoCh:
-				bpr.reset()
-				continue OUTER_LOOP
+			case peerID := <-bpr.redoCh:
+				if peerID == bpr.peerID {
+					bpr.reset()
+					continue OUTER_LOOP
+				} else {
+					continue WAIT_LOOP
+				}
 			case <-bpr.gotBlockCh:
 				// We got a block!
 				// Continue the for-loop and wait til Quit.
--- a/blockchain/pool_test.go
+++ b/blockchain/pool_test.go
@@ -16,16 +16,52 @@ func init() {
 }

 type testPeer struct {
-	id     p2p.ID
-	height int64
+	id        p2p.ID
+	height    int64
+	inputChan chan inputData //make sure each peer's data is sequential
 }

-func makePeers(numPeers int, minHeight, maxHeight int64) map[p2p.ID]testPeer {
-	peers := make(map[p2p.ID]testPeer, numPeers)
+type inputData struct {
+	t       *testing.T
+	pool    *BlockPool
+	request BlockRequest
+}
+
+func (p testPeer) runInputRoutine() {
+	go func() {
+		for input := range p.inputChan {
+			p.simulateInput(input)
+		}
+	}()
+}
+
+// Request desired, pretend like we got the block immediately.
+func (p testPeer) simulateInput(input inputData) {
+	block := &types.Block{Header: types.Header{Height: input.request.Height}}
+	input.pool.AddBlock(input.request.PeerID, block, 123)
+	input.t.Logf("Added block from peer %v (height: %v)", input.request.PeerID, input.request.Height)
+}
+
+type testPeers map[p2p.ID]testPeer
+
+func (ps testPeers) start() {
+	for _, v := range ps {
+		v.runInputRoutine()
+	}
+}
+
+func (ps testPeers) stop() {
+	for _, v := range ps {
+		close(v.inputChan)
+	}
+}
+
+func makePeers(numPeers int, minHeight, maxHeight int64) testPeers {
+	peers := make(testPeers, numPeers)
 	for i := 0; i < numPeers; i++ {
 		peerID := p2p.ID(cmn.RandStr(12))
 		height := minHeight + cmn.RandInt63n(maxHeight-minHeight)
-		peers[peerID] = testPeer{peerID, height}
+		peers[peerID] = testPeer{peerID, height, make(chan inputData, 10)}
 	}
 	return peers
 }
@@ -45,6 +81,9 @@ func TestBasic(t *testing.T) {

 	defer pool.Stop()

+	peers.start()
+	defer peers.stop()
+
 	// Introduce each peer.
 	go func() {
 		for _, peer := range peers {
@@ -77,12 +116,8 @@ func TestBasic(t *testing.T) {
 			if request.Height == 300 {
 				return // Done!
 			}
-			// Request desired, pretend like we got the block immediately.
-			go func() {
-				block := &types.Block{Header: types.Header{Height: request.Height}}
-				pool.AddBlock(request.PeerID, block, 123)
-				t.Logf("Added block from peer %v (height: %v)", request.PeerID, request.Height)
-			}()
+
+			peers[request.PeerID].inputChan <- inputData{t, pool, request}
 		}
 	}
 }
--- a/blockchain/reactor.go
+++ b/blockchain/reactor.go
@@ -264,8 +264,12 @@ FOR_LOOP:
 				bcR.Logger.Info("Time to switch to consensus reactor!", "height", height)
 				bcR.pool.Stop()

-				conR := bcR.Switch.Reactor("CONSENSUS").(consensusReactor)
-				conR.SwitchToConsensus(state, blocksSynced)
+				conR, ok := bcR.Switch.Reactor("CONSENSUS").(consensusReactor)
+				if ok {
+					conR.SwitchToConsensus(state, blocksSynced)
+				} else {
+					// should only happen during testing
+				}

 				break FOR_LOOP
 			}
@@ -314,6 +318,13 @@ FOR_LOOP:
 					// still need to clean up the rest.
 					bcR.Switch.StopPeerForError(peer, fmt.Errorf("BlockchainReactor validation error: %v", err))
 				}
+				peerID2 := bcR.pool.RedoRequest(second.Height)
+				peer2 := bcR.Switch.Peers().Get(peerID2)
+				if peer2 != nil && peer2 != peer {
+					// NOTE: we've already removed the peer's request, but we
+					// still need to clean up the rest.
+					bcR.Switch.StopPeerForError(peer2, fmt.Errorf("BlockchainReactor validation error: %v", err))
+				}
 				continue FOR_LOOP
 			} else {
 				bcR.pool.PopRequest()
--- a/blockchain/reactor_test.go
+++ b/blockchain/reactor_test.go
@@ -1,72 +1,151 @@
 package blockchain

 import (
-	"net"
+	"sort"
 	"testing"
+	"time"

+	"github.com/stretchr/testify/assert"
+
+	abci "github.com/tendermint/tendermint/abci/types"
+	cfg "github.com/tendermint/tendermint/config"
 	cmn "github.com/tendermint/tendermint/libs/common"
 	dbm "github.com/tendermint/tendermint/libs/db"
 	"github.com/tendermint/tendermint/libs/log"
-
-	cfg "github.com/tendermint/tendermint/config"
 	"github.com/tendermint/tendermint/p2p"
 	"github.com/tendermint/tendermint/proxy"
 	sm "github.com/tendermint/tendermint/state"
 	"github.com/tendermint/tendermint/types"
+	tmtime "github.com/tendermint/tendermint/types/time"
 )

-func makeStateAndBlockStore(logger log.Logger) (sm.State, *BlockStore) {
-	config := cfg.ResetTestRoot("blockchain_reactor_test")
-	// blockDB := dbm.NewDebugDB("blockDB", dbm.NewMemDB())
-	// stateDB := dbm.NewDebugDB("stateDB", dbm.NewMemDB())
+var config *cfg.Config
+
+func randGenesisDoc(numValidators int, randPower bool, minPower int64) (*types.GenesisDoc, []types.PrivValidator) {
+	validators := make([]types.GenesisValidator, numValidators)
+	privValidators := make([]types.PrivValidator, numValidators)
+	for i := 0; i < numValidators; i++ {
+		val, privVal := types.RandValidator(randPower, minPower)
+		validators[i] = types.GenesisValidator{
+			PubKey: val.PubKey,
+			Power:  val.VotingPower,
+		}
+		privValidators[i] = privVal
+	}
+	sort.Sort(types.PrivValidatorsByAddress(privValidators))
+
+	return &types.GenesisDoc{
+		GenesisTime: tmtime.Now(),
+		ChainID:     config.ChainID(),
+		Validators:  validators,
+	}, privValidators
+}
+
+func makeVote(header *types.Header, blockID types.BlockID, valset *types.ValidatorSet, privVal types.PrivValidator) *types.Vote {
+	addr := privVal.GetAddress()
+	idx, _ := valset.GetByAddress(addr)
+	vote := &types.Vote{
+		ValidatorAddress: addr,
+		ValidatorIndex:   idx,
+		Height:           header.Height,
+		Round:            1,
+		Timestamp:        tmtime.Now(),
+		Type:             types.PrecommitType,
+		BlockID:          blockID,
+	}
+
+	privVal.SignVote(header.ChainID, vote)
+
+	return vote
+}
+
+type BlockchainReactorPair struct {
+	reactor *BlockchainReactor
+	app     proxy.AppConns
+}
+
+func newBlockchainReactor(logger log.Logger, genDoc *types.GenesisDoc, privVals []types.PrivValidator, maxBlockHeight int64) BlockchainReactorPair {
+	if len(privVals) != 1 {
+		panic("only support one validator")
+	}
+
+	app := &testApp{}
+	cc := proxy.NewLocalClientCreator(app)
+	proxyApp := proxy.NewAppConns(cc)
+	err := proxyApp.Start()
+	if err != nil {
+		panic(cmn.ErrorWrap(err, "error start app"))
+	}
+
 	blockDB := dbm.NewMemDB()
 	stateDB := dbm.NewMemDB()
 	blockStore := NewBlockStore(blockDB)
-	state, err := sm.LoadStateFromDBOrGenesisFile(stateDB, config.GenesisFile())
+
+	state, err := sm.LoadStateFromDBOrGenesisDoc(stateDB, genDoc)
 	if err != nil {
 		panic(cmn.ErrorWrap(err, "error constructing state from genesis file"))
 	}
-	return state, blockStore
-}

-func newBlockchainReactor(logger log.Logger, maxBlockHeight int64) *BlockchainReactor {
-	state, blockStore := makeStateAndBlockStore(logger)
-
-	// Make the blockchainReactor itself
+	// Make the BlockchainReactor itself.
+	// NOTE we have to create and commit the blocks first because
+	// pool.height is determined from the store.
 	fastSync := true
-	var nilApp proxy.AppConnConsensus
-	blockExec := sm.NewBlockExecutor(dbm.NewMemDB(), log.TestingLogger(), nilApp,
+	blockExec := sm.NewBlockExecutor(dbm.NewMemDB(), log.TestingLogger(), proxyApp.Consensus(),
 		sm.MockMempool{}, sm.MockEvidencePool{})

+	// let's add some blocks in
+	for blockHeight := int64(1); blockHeight <= maxBlockHeight; blockHeight++ {
+		lastCommit := &types.Commit{}
+		if blockHeight > 1 {
+			lastBlockMeta := blockStore.LoadBlockMeta(blockHeight - 1)
+			lastBlock := blockStore.LoadBlock(blockHeight - 1)
+
+			vote := makeVote(&lastBlock.Header, lastBlockMeta.BlockID, state.Validators, privVals[0])
+			lastCommit = &types.Commit{Precommits: []*types.Vote{vote}, BlockID: lastBlockMeta.BlockID}
+		}
+
+		thisBlock := makeBlock(blockHeight, state, lastCommit)
+
+		thisParts := thisBlock.MakePartSet(types.BlockPartSizeBytes)
+		blockID := types.BlockID{thisBlock.Hash(), thisParts.Header()}
+
+		state, err = blockExec.ApplyBlock(state, blockID, thisBlock)
+		if err != nil {
+			panic(cmn.ErrorWrap(err, "error apply block"))
+		}
+
+		blockStore.SaveBlock(thisBlock, thisParts, lastCommit)
+	}
+
 	bcReactor := NewBlockchainReactor(state.Copy(), blockExec, blockStore, fastSync)
 	bcReactor.SetLogger(logger.With("module", "blockchain"))

-	// Next: we need to set a switch in order for peers to be added in
-	bcReactor.Switch = p2p.NewSwitch(cfg.DefaultP2PConfig(), nil)
-
-	// Lastly: let's add some blocks in
-	for blockHeight := int64(1); blockHeight <= maxBlockHeight; blockHeight++ {
-		firstBlock := makeBlock(blockHeight, state)
-		secondBlock := makeBlock(blockHeight+1, state)
-		firstParts := firstBlock.MakePartSet(types.BlockPartSizeBytes)
-		blockStore.SaveBlock(firstBlock, firstParts, secondBlock.LastCommit)
-	}
-
-	return bcReactor
+	return BlockchainReactorPair{bcReactor, proxyApp}
 }

 func TestNoBlockResponse(t *testing.T) {
-	maxBlockHeight := int64(20)
+	config = cfg.ResetTestRoot("blockchain_reactor_test")
+	genDoc, privVals := randGenesisDoc(1, false, 30)

-	bcr := newBlockchainReactor(log.TestingLogger(), maxBlockHeight)
-	bcr.Start()
-	defer bcr.Stop()
+	maxBlockHeight := int64(65)

-	// Add some peers in
-	peer := newbcrTestPeer(p2p.ID(cmn.RandStr(12)))
-	bcr.AddPeer(peer)
+	reactorPairs := make([]BlockchainReactorPair, 2)

-	chID := byte(0x01)
+	reactorPairs[0] = newBlockchainReactor(log.TestingLogger(), genDoc, privVals, maxBlockHeight)
+	reactorPairs[1] = newBlockchainReactor(log.TestingLogger(), genDoc, privVals, 0)
+
+	p2p.MakeConnectedSwitches(config.P2P, 2, func(i int, s *p2p.Switch) *p2p.Switch {
+		s.AddReactor("BLOCKCHAIN", reactorPairs[i].reactor)
+		return s
+
+	}, p2p.Connect2Switches)
+
+	defer func() {
+		for _, r := range reactorPairs {
+			r.reactor.Stop()
+			r.app.Stop()
+		}
+	}()

 	tests := []struct {
 		height   int64
@@ -78,72 +157,100 @@ func TestNoBlockResponse(t *testing.T) {
 		{100, false},
 	}

-	// receive a request message from peer,
-	// wait for our response to be received on the peer
-	for _, tt := range tests {
-		reqBlockMsg := &bcBlockRequestMessage{tt.height}
-		reqBlockBytes := cdc.MustMarshalBinaryBare(reqBlockMsg)
-		bcr.Receive(chID, peer, reqBlockBytes)
-		msg := peer.lastBlockchainMessage()
+	for {
+		if reactorPairs[1].reactor.pool.IsCaughtUp() {
+			break
+		}

+		time.Sleep(10 * time.Millisecond)
+	}
+
+	assert.Equal(t, maxBlockHeight, reactorPairs[0].reactor.store.Height())
+
+	for _, tt := range tests {
+		block := reactorPairs[1].reactor.store.LoadBlock(tt.height)
 		if tt.existent {
-			if blockMsg, ok := msg.(*bcBlockResponseMessage); !ok {
-				t.Fatalf("Expected to receive a block response for height %d", tt.height)
-			} else if blockMsg.Block.Height != tt.height {
-				t.Fatalf("Expected response to be for height %d, got %d", tt.height, blockMsg.Block.Height)
-			}
+			assert.True(t, block != nil)
 		} else {
-			if noBlockMsg, ok := msg.(*bcNoBlockResponseMessage); !ok {
-				t.Fatalf("Expected to receive a no block response for height %d", tt.height)
-			} else if noBlockMsg.Height != tt.height {
-				t.Fatalf("Expected response to be for height %d, got %d", tt.height, noBlockMsg.Height)
-			}
+			assert.True(t, block == nil)
 		}
 	}
 }

-/*
 // NOTE: This is too hard to test without
 // an easy way to add test peer to switch
 // or without significant refactoring of the module.
 // Alternatively we could actually dial a TCP conn but
 // that seems extreme.
 func TestBadBlockStopsPeer(t *testing.T) {
-	maxBlockHeight := int64(20)
+	config = cfg.ResetTestRoot("blockchain_reactor_test")
+	genDoc, privVals := randGenesisDoc(1, false, 30)

-	bcr := newBlockchainReactor(log.TestingLogger(), maxBlockHeight)
-	bcr.Start()
-	defer bcr.Stop()
+	maxBlockHeight := int64(148)

-	// Add some peers in
-	peer := newbcrTestPeer(p2p.ID(cmn.RandStr(12)))
+	otherChain := newBlockchainReactor(log.TestingLogger(), genDoc, privVals, maxBlockHeight)
+	defer func() {
+		otherChain.reactor.Stop()
+		otherChain.app.Stop()
+	}()

-	// XXX: This doesn't add the peer to anything,
-	// so it's hard to check that it's later removed
-	bcr.AddPeer(peer)
-	assert.True(t, bcr.Switch.Peers().Size() > 0)
+	reactorPairs := make([]BlockchainReactorPair, 4)

-	// send a bad block from the peer
-	// default blocks already dont have commits, so should fail
-	block := bcr.store.LoadBlock(3)
-	msg := &bcBlockResponseMessage{Block: block}
-	peer.Send(BlockchainChannel, struct{ BlockchainMessage }{msg})
+	reactorPairs[0] = newBlockchainReactor(log.TestingLogger(), genDoc, privVals, maxBlockHeight)
+	reactorPairs[1] = newBlockchainReactor(log.TestingLogger(), genDoc, privVals, 0)
+	reactorPairs[2] = newBlockchainReactor(log.TestingLogger(), genDoc, privVals, 0)
+	reactorPairs[3] = newBlockchainReactor(log.TestingLogger(), genDoc, privVals, 0)

-	ticker := time.NewTicker(time.Millisecond * 10)
-	timer := time.NewTimer(time.Second * 2)
-LOOP:
-	for {
-		select {
-		case <-ticker.C:
-			if bcr.Switch.Peers().Size() == 0 {
-				break LOOP
-			}
-		case <-timer.C:
-			t.Fatal("Timed out waiting to disconnect peer")
+	switches := p2p.MakeConnectedSwitches(config.P2P, 4, func(i int, s *p2p.Switch) *p2p.Switch {
+		s.AddReactor("BLOCKCHAIN", reactorPairs[i].reactor)
+		return s
+
+	}, p2p.Connect2Switches)
+
+	defer func() {
+		for _, r := range reactorPairs {
+			r.reactor.Stop()
+			r.app.Stop()
 		}
+	}()
+
+	for {
+		if reactorPairs[3].reactor.pool.IsCaughtUp() {
+			break
+		}
+
+		time.Sleep(1 * time.Second)
 	}
+
+	//at this time, reactors[0-3] is the newest
+	assert.Equal(t, 3, reactorPairs[1].reactor.Switch.Peers().Size())
+
+	//mark reactorPairs[3] is an invalid peer
+	reactorPairs[3].reactor.store = otherChain.reactor.store
+
+	lastReactorPair := newBlockchainReactor(log.TestingLogger(), genDoc, privVals, 0)
+	reactorPairs = append(reactorPairs, lastReactorPair)
+
+	switches = append(switches, p2p.MakeConnectedSwitches(config.P2P, 1, func(i int, s *p2p.Switch) *p2p.Switch {
+		s.AddReactor("BLOCKCHAIN", reactorPairs[len(reactorPairs)-1].reactor)
+		return s
+
+	}, p2p.Connect2Switches)...)
+
+	for i := 0; i < len(reactorPairs)-1; i++ {
+		p2p.Connect2Switches(switches, i, len(reactorPairs)-1)
+	}
+
+	for {
+		if lastReactorPair.reactor.pool.IsCaughtUp() || lastReactorPair.reactor.Switch.Peers().Size() == 0 {
+			break
+		}
+
+		time.Sleep(1 * time.Second)
+	}
+
+	assert.True(t, lastReactorPair.reactor.Switch.Peers().Size() < len(reactorPairs)-1)
 }
-*/

 //----------------------------------------------
 // utility funcs
@@ -155,56 +262,41 @@ func makeTxs(height int64) (txs []types.Tx) {
 	return txs
 }

-func makeBlock(height int64, state sm.State) *types.Block {
-	block, _ := state.MakeBlock(height, makeTxs(height), new(types.Commit), nil, state.Validators.GetProposer().Address)
+func makeBlock(height int64, state sm.State, lastCommit *types.Commit) *types.Block {
+	block, _ := state.MakeBlock(height, makeTxs(height), lastCommit, nil, state.Validators.GetProposer().Address)
 	return block
 }

-// The Test peer
-type bcrTestPeer struct {
-	cmn.BaseService
-	id p2p.ID
-	ch chan interface{}
+type testApp struct {
+	abci.BaseApplication
 }

-var _ p2p.Peer = (*bcrTestPeer)(nil)
+var _ abci.Application = (*testApp)(nil)

-func newbcrTestPeer(id p2p.ID) *bcrTestPeer {
-	bcr := &bcrTestPeer{
-		id: id,
-		ch: make(chan interface{}, 2),
-	}
-	bcr.BaseService = *cmn.NewBaseService(nil, "bcrTestPeer", bcr)
-	return bcr
+func (app *testApp) Info(req abci.RequestInfo) (resInfo abci.ResponseInfo) {
+	return abci.ResponseInfo{}
 }

-func (tp *bcrTestPeer) lastBlockchainMessage() interface{} { return <-tp.ch }
-
-func (tp *bcrTestPeer) TrySend(chID byte, msgBytes []byte) bool {
-	var msg BlockchainMessage
-	err := cdc.UnmarshalBinaryBare(msgBytes, &msg)
-	if err != nil {
-		panic(cmn.ErrorWrap(err, "Error while trying to parse a BlockchainMessage"))
-	}
-	if _, ok := msg.(*bcStatusResponseMessage); ok {
-		// Discard status response messages since they skew our results
-		// We only want to deal with:
-		// + bcBlockResponseMessage
-		// + bcNoBlockResponseMessage
-	} else {
-		tp.ch <- msg
-	}
-	return true
+func (app *testApp) BeginBlock(req abci.RequestBeginBlock) abci.ResponseBeginBlock {
+	return abci.ResponseBeginBlock{}
 }

-func (tp *bcrTestPeer) FlushStop()                           {}
-func (tp *bcrTestPeer) Send(chID byte, msgBytes []byte) bool { return tp.TrySend(chID, msgBytes) }
-func (tp *bcrTestPeer) NodeInfo() p2p.NodeInfo               { return p2p.DefaultNodeInfo{} }
-func (tp *bcrTestPeer) Status() p2p.ConnectionStatus         { return p2p.ConnectionStatus{} }
-func (tp *bcrTestPeer) ID() p2p.ID                           { return tp.id }
-func (tp *bcrTestPeer) IsOutbound() bool                     { return false }
-func (tp *bcrTestPeer) IsPersistent() bool                   { return true }
-func (tp *bcrTestPeer) Get(s string) interface{}             { return s }
-func (tp *bcrTestPeer) Set(string, interface{})              {}
-func (tp *bcrTestPeer) RemoteIP() net.IP                     { return []byte{127, 0, 0, 1} }
-func (tp *bcrTestPeer) OriginalAddr() *p2p.NetAddress        { return nil }
+func (app *testApp) EndBlock(req abci.RequestEndBlock) abci.ResponseEndBlock {
+	return abci.ResponseEndBlock{}
+}
+
+func (app *testApp) DeliverTx(tx []byte) abci.ResponseDeliverTx {
+	return abci.ResponseDeliverTx{Tags: []cmn.KVPair{}}
+}
+
+func (app *testApp) CheckTx(tx []byte) abci.ResponseCheckTx {
+	return abci.ResponseCheckTx{}
+}
+
+func (app *testApp) Commit() abci.ResponseCommit {
+	return abci.ResponseCommit{}
+}
+
+func (app *testApp) Query(reqQuery abci.RequestQuery) (resQuery abci.ResponseQuery) {
+	return
+}
--- a/blockchain/store_test.go
+++ b/blockchain/store_test.go
@@ -9,13 +9,30 @@ import (

 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	cfg "github.com/tendermint/tendermint/config"
+	cmn "github.com/tendermint/tendermint/libs/common"
 	"github.com/tendermint/tendermint/libs/db"
+	dbm "github.com/tendermint/tendermint/libs/db"
 	"github.com/tendermint/tendermint/libs/log"
+	sm "github.com/tendermint/tendermint/state"

 	"github.com/tendermint/tendermint/types"
 	tmtime "github.com/tendermint/tendermint/types/time"
 )

+func makeStateAndBlockStore(logger log.Logger) (sm.State, *BlockStore) {
+	config := cfg.ResetTestRoot("blockchain_reactor_test")
+	// blockDB := dbm.NewDebugDB("blockDB", dbm.NewMemDB())
+	// stateDB := dbm.NewDebugDB("stateDB", dbm.NewMemDB())
+	blockDB := dbm.NewMemDB()
+	stateDB := dbm.NewMemDB()
+	state, err := sm.LoadStateFromDBOrGenesisFile(stateDB, config.GenesisFile())
+	if err != nil {
+		panic(cmn.ErrorWrap(err, "error constructing state from genesis file"))
+	}
+	return state, NewBlockStore(blockDB)
+}
+
 func TestLoadBlockStoreStateJSON(t *testing.T) {
 	db := db.NewMemDB()

@@ -65,7 +82,7 @@ func freshBlockStore() (*BlockStore, db.DB) {
 var (
 	state, _ = makeStateAndBlockStore(log.NewTMLogger(new(bytes.Buffer)))

-	block       = makeBlock(1, state)
+	block       = makeBlock(1, state, new(types.Commit))
 	partSet     = block.MakePartSet(2)
 	part1       = partSet.GetPart(0)
 	part2       = partSet.GetPart(1)
@@ -88,7 +105,7 @@ func TestBlockStoreSaveLoadBlock(t *testing.T) {
 	}

 	// save a block
-	block := makeBlock(bs.Height()+1, state)
+	block := makeBlock(bs.Height()+1, state, new(types.Commit))
 	validPartSet := block.MakePartSet(2)
 	seenCommit := &types.Commit{Precommits: []*types.Vote{{Height: 10,
 		Timestamp: tmtime.Now()}}}
@@ -331,7 +348,7 @@ func TestLoadBlockMeta(t *testing.T) {
 func TestBlockFetchAtHeight(t *testing.T) {
 	state, bs := makeStateAndBlockStore(log.NewTMLogger(new(bytes.Buffer)))
 	require.Equal(t, bs.Height(), int64(0), "initially the height should be zero")
-	block := makeBlock(bs.Height()+1, state)
+	block := makeBlock(bs.Height()+1, state, new(types.Commit))

 	partSet := block.MakePartSet(2)
 	seenCommit := &types.Commit{Precommits: []*types.Vote{{Height: 10,
--- a/config/toml.go
+++ b/config/toml.go
@@ -260,6 +260,9 @@ create_empty_blocks_interval = "{{ .Consensus.CreateEmptyBlocksInterval }}"
 peer_gossip_sleep_duration = "{{ .Consensus.PeerGossipSleepDuration }}"
 peer_query_maj23_sleep_duration = "{{ .Consensus.PeerQueryMaj23SleepDuration }}"

+# Block time parameters. Corresponds to the minimum time increment between consecutive blocks.
+blocktime_iota = "{{ .Consensus.BlockTimeIota }}"
+
 ##### transactions indexer configuration options #####
 [tx_index]

--- a/consensus/mempool_test.go
+++ b/consensus/mempool_test.go
@@ -72,18 +72,18 @@ func TestMempoolProgressInHigherRound(t *testing.T) {
 	startTestRound(cs, height, round)

 	ensureNewRound(newRoundCh, height, round) // first round at first height
-	ensureNewEventOnChannel(newBlockCh)           // first block gets committed
+	ensureNewEventOnChannel(newBlockCh)       // first block gets committed

 	height = height + 1 // moving to the next height
 	round = 0

 	ensureNewRound(newRoundCh, height, round) // first round at next height
-	deliverTxsRange(cs, 0, 1)                     // we deliver txs, but dont set a proposal so we get the next round
+	deliverTxsRange(cs, 0, 1)                 // we deliver txs, but dont set a proposal so we get the next round
 	ensureNewTimeout(timeoutCh, height, round, cs.config.TimeoutPropose.Nanoseconds())

-	round = round + 1                             // moving to the next round
+	round = round + 1                         // moving to the next round
 	ensureNewRound(newRoundCh, height, round) // wait for the next round
-	ensureNewEventOnChannel(newBlockCh)           // now we can commit the block
+	ensureNewEventOnChannel(newBlockCh)       // now we can commit the block
 }

 func deliverTxsRange(cs *ConsensusState, start, end int) {
--- a/consensus/replay.go
+++ b/consensus/replay.go
@@ -276,7 +276,12 @@ func (h *Handshaker) ReplayBlocks(

 	// If appBlockHeight == 0 it means that we are at genesis and hence should send InitChain.
 	if appBlockHeight == 0 {
-		nextVals := types.TM2PB.ValidatorUpdates(state.NextValidators) // state.Validators would work too.
+		validators := make([]*types.Validator, len(h.genDoc.Validators))
+		for i, val := range h.genDoc.Validators {
+			validators[i] = types.NewValidator(val.PubKey, val.Power)
+		}
+		validatorSet := types.NewValidatorSet(validators)
+		nextVals := types.TM2PB.ValidatorUpdates(validatorSet)
 		csParams := types.TM2PB.ConsensusParams(h.genDoc.ConsensusParams)
 		req := abci.RequestInitChain{
 			Time:            h.genDoc.GenesisTime,
--- a/consensus/replay_test.go
+++ b/consensus/replay_test.go
@@ -315,28 +315,21 @@ func testHandshakeReplay(t *testing.T, nBlocks int, mode uint) {
 	config := ResetConfig("proxy_test_")

 	walBody, err := WALWithNBlocks(NUM_BLOCKS)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)
 	walFile := tempWALWithData(walBody)
 	config.Consensus.SetWalFile(walFile)

 	privVal := privval.LoadFilePV(config.PrivValidatorFile())

 	wal, err := NewWAL(walFile)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)
 	wal.SetLogger(log.TestingLogger())
-	if err := wal.Start(); err != nil {
-		t.Fatal(err)
-	}
+	err = wal.Start()
+	require.NoError(t, err)
 	defer wal.Stop()

 	chain, commits, err := makeBlockchainFromWAL(wal)
-	if err != nil {
-		t.Fatalf(err.Error())
-	}
+	require.NoError(t, err)

 	stateDB, state, store := stateAndStore(config, privVal.GetPubKey(), kvstore.ProtocolVersion)
 	store.chain = chain
--- a/consensus/state.go
+++ b/consensus/state.go
@@ -324,10 +324,11 @@ func (cs *ConsensusState) startRoutines(maxSteps int) {
 	go cs.receiveRoutine(maxSteps)
 }

-// OnStop implements cmn.Service. It stops all routines and waits for the WAL to finish.
+// OnStop implements cmn.Service.
 func (cs *ConsensusState) OnStop() {
 	cs.evsw.Stop()
 	cs.timeoutTicker.Stop()
+	// WAL is stopped in receiveRoutine.
 }

 // Wait waits for the the main routine to return.
--- a/consensus/state_test.go
+++ b/consensus/state_test.go
@@ -1043,7 +1043,7 @@ func TestNoHearbeatWhenNotValidator(t *testing.T) {
 	cs.Stop()

 	// if a faulty implementation sends an event, we should wait here a little bit to make sure we don't miss it by prematurely leaving the test method
-	time.Sleep((proposalHeartbeatIntervalSeconds  + 1) * time.Second)
+	time.Sleep((proposalHeartbeatIntervalSeconds + 1) * time.Second)
 }

 // regression for #2518
--- a/consensus/types/peer_round_state.go
+++ b/consensus/types/peer_round_state.go
@@ -55,3 +55,31 @@ func (prs PeerRoundState) StringIndented(indent string) string {
 		indent, prs.CatchupCommit, prs.CatchupCommitRound,
 		indent)
 }
+
+//-----------------------------------------------------------
+// These methods are for Protobuf Compatibility
+
+// Size returns the size of the amino encoding, in bytes.
+func (ps *PeerRoundState) Size() int {
+	bs, _ := ps.Marshal()
+	return len(bs)
+}
+
+// Marshal returns the amino encoding.
+func (ps *PeerRoundState) Marshal() ([]byte, error) {
+	return cdc.MarshalBinaryBare(ps)
+}
+
+// MarshalTo calls Marshal and copies to the given buffer.
+func (ps *PeerRoundState) MarshalTo(data []byte) (int, error) {
+	bs, err := ps.Marshal()
+	if err != nil {
+		return -1, err
+	}
+	return copy(data, bs), nil
+}
+
+// Unmarshal deserializes from amino encoded form.
+func (ps *PeerRoundState) Unmarshal(bs []byte) error {
+	return cdc.UnmarshalBinaryBare(bs, ps)
+}
--- a/consensus/types/round_state.go
+++ b/consensus/types/round_state.go
@@ -201,3 +201,31 @@ func (rs *RoundState) StringShort() string {
 	return fmt.Sprintf(`RoundState{H:%v R:%v S:%v ST:%v}`,
 		rs.Height, rs.Round, rs.Step, rs.StartTime)
 }
+
+//-----------------------------------------------------------
+// These methods are for Protobuf Compatibility
+
+// Size returns the size of the amino encoding, in bytes.
+func (rs *RoundStateSimple) Size() int {
+	bs, _ := rs.Marshal()
+	return len(bs)
+}
+
+// Marshal returns the amino encoding.
+func (rs *RoundStateSimple) Marshal() ([]byte, error) {
+	return cdc.MarshalBinaryBare(rs)
+}
+
+// MarshalTo calls Marshal and copies to the given buffer.
+func (rs *RoundStateSimple) MarshalTo(data []byte) (int, error) {
+	bs, err := rs.Marshal()
+	if err != nil {
+		return -1, err
+	}
+	return copy(data, bs), nil
+}
+
+// Unmarshal deserializes from amino encoded form.
+func (rs *RoundStateSimple) Unmarshal(bs []byte) error {
+	return cdc.UnmarshalBinaryBare(bs, rs)
+}
--- a/consensus/wal_test.go
+++ b/consensus/wal_test.go
@@ -7,13 +7,13 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-
 	// "sync"
 	"testing"
 	"time"

 	"github.com/tendermint/tendermint/consensus/types"
 	"github.com/tendermint/tendermint/libs/autofile"
+	"github.com/tendermint/tendermint/libs/log"
 	tmtypes "github.com/tendermint/tendermint/types"
 	tmtime "github.com/tendermint/tendermint/types/time"

@@ -23,29 +23,27 @@ import (

 func TestWALTruncate(t *testing.T) {
 	walDir, err := ioutil.TempDir("", "wal")
-	if err != nil {
-		panic(fmt.Errorf("failed to create temp WAL file: %v", err))
-	}
+	require.NoError(t, err)
 	defer os.RemoveAll(walDir)

 	walFile := filepath.Join(walDir, "wal")

 	//this magic number 4K can truncate the content when RotateFile. defaultHeadSizeLimit(10M) is hard to simulate.
 	//this magic number 1 * time.Millisecond make RotateFile check frequently. defaultGroupCheckDuration(5s) is hard to simulate.
-	wal, err := NewWAL(walFile, autofile.GroupHeadSizeLimit(4096), autofile.GroupCheckDuration(1*time.Millisecond))
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	wal.Start()
+	wal, err := NewWAL(walFile,
+		autofile.GroupHeadSizeLimit(4096),
+		autofile.GroupCheckDuration(1*time.Millisecond),
+	)
+	require.NoError(t, err)
+	wal.SetLogger(log.TestingLogger())
+	err = wal.Start()
+	require.NoError(t, err)
 	defer wal.Stop()

 	//60 block's size nearly 70K, greater than group's headBuf size(4096 * 10), when headBuf is full, truncate content will Flush to the file.
 	//at this time, RotateFile is called, truncate content exist in each file.
 	err = WALGenerateNBlocks(wal.Group(), 60)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)

 	time.Sleep(1 * time.Millisecond) //wait groupCheckDuration, make sure RotateFile run

@@ -99,9 +97,8 @@ func TestWALSearchForEndHeight(t *testing.T) {
 	walFile := tempWALWithData(walBody)

 	wal, err := NewWAL(walFile)
-	if err != nil {
-		t.Fatal(err)
-	}
+	require.NoError(t, err)
+	wal.SetLogger(log.TestingLogger())

 	h := int64(3)
 	gr, found, err := wal.SearchForEndHeight(h, &WALSearchOptions{})
--- a/docs/architecture/adr-008-priv-validator.md
+++ b/docs/architecture/adr-008-priv-validator.md
@@ -5,14 +5,17 @@ implementations:

 - FilePV uses an unencrypted private key in a "priv_validator.json" file - no
  configuration required (just `tendermint init`).
- SocketPV uses a socket to send signing requests to another process - user is
-  responsible for starting that process themselves.
+- TCPVal and IPCVal use TCP and Unix sockets respectively to send signing requests
+  to another process - the user is responsible for starting that process themselves.

-The SocketPV address can be provided via flags at the command line - doing so
-will cause Tendermint to ignore any "priv_validator.json" file and to listen on
-the given address for incoming connections from an external priv_validator
-process. It will halt any operation until at least one external process
-succesfully connected.
+Both TCPVal and IPCVal addresses can be provided via flags at the command line
+or in the configuration file; TCPVal addresses must be of the form
+`tcp://<ip_address>:<port>` and IPCVal addresses `unix:///path/to/file.sock` -
+doing so will cause Tendermint to ignore any private validator files.
+
+TCPVal will listen on the given address for incoming connections from an external
+private validator process. It will halt any operation until at least one external
+process successfully connected.

 The external priv_validator process will dial the address to connect to
 Tendermint, and then Tendermint will send requests on the ensuing connection to
@@ -21,6 +24,9 @@ but the Tendermint process makes all requests. In a later stage we're going to
 support multiple validators for fault tolerance. To prevent double signing they
 need to be synced, which is deferred to an external solution (see #1185).

+Conversely, IPCVal will make an outbound connection to an existing socket opened
+by the external validator process.
+
 In addition, Tendermint will provide implementations that can be run in that
 external process. These include:

--- a/docs/introduction/install.md
+++ b/docs/introduction/install.md
@@ -95,9 +95,9 @@ wget https://github.com/google/leveldb/archive/v1.20.tar.gz && \
  tar -zxvf v1.20.tar.gz && \
  cd leveldb-1.20/ && \
  make && \
-  cp -r out-static/lib* out-shared/lib* /usr/local/lib/ && \
+  sudo cp -r out-static/lib* out-shared/lib* /usr/local/lib/ && \
  cd include/ && \
-  cp -r leveldb /usr/local/include/ && \
+  sudo cp -r leveldb /usr/local/include/ && \
  sudo ldconfig && \
  rm -f v1.20.tar.gz
 ```
@@ -109,8 +109,8 @@ Set database backend to cleveldb:
 db_backend = "cleveldb"
 ```

-To build Tendermint, run
+To install Tendermint, run

 ```
-CGO_LDFLAGS="-lsnappy" go build -ldflags "-X github.com/tendermint/tendermint/version.GitCommit=`git rev-parse --short=8 HEAD`" -tags "tendermint gcc" -o build/tendermint ./cmd/tendermint/
+CGO_LDFLAGS="-lsnappy" go install -ldflags "-X github.com/tendermint/tendermint/version.GitCommit=`git rev-parse --short=8 HEAD`" -tags "tendermint gcc" -o build/tendermint ./cmd/tendermint/
 ```
--- a/docs/spec/abci/abci.md
+++ b/docs/spec/abci/abci.md
@@ -45,7 +45,9 @@ include a `Tags` field in their `Response*`. Each tag is key-value pair denoting
 something about what happened during the methods execution.

 Tags can be used to index transactions and blocks according to what happened
-during their execution.
+during their execution. Note that the set of tags returned for a block from
+`BeginBlock` and `EndBlock` are merged. In case both methods return the same
+tag, only the value defined in `EndBlock` is used.

 Keys and values in tags must be UTF-8 encoded strings (e.g.
 "account.owner": "Bob", "balance": "100.0",
--- a/docs/spec/blockchain/encoding.md
+++ b/docs/spec/blockchain/encoding.md
@@ -59,22 +59,14 @@ You can simply use below table and concatenate Prefix || Length (of raw bytes) |
 | PubKeySecp256k1    | tendermint/PubKeySecp256k1    | 0xEB5AE987 | 0x21     |       |
 | PrivKeyEd25519     | tendermint/PrivKeyEd25519     | 0xA3288910 | 0x40     |       |
 | PrivKeySecp256k1   | tendermint/PrivKeySecp256k1   | 0xE1B0F79B | 0x20     |       |
-| SignatureEd25519   | tendermint/SignatureEd25519   | 0x2031EA53 | 0x40     |       |
-| SignatureSecp256k1 | tendermint/SignatureSecp256k1 | 0x7FC4A495 | variable |
+| PubKeyMultisigThreshold | tendermint/PubKeyMultisigThreshold | 0x22C1F7E2 | variable |  |

-|
+### Example

-### Examples
-
-1. For example, the 33-byte (or 0x21-byte in hex) Secp256k1 pubkey
+For example, the 33-byte (or 0x21-byte in hex) Secp256k1 pubkey
   `020BD40F225A57ED383B440CF073BC5539D0341F5767D2BF2D78406D00475A2EE9`
   would be encoded as
-   `EB5AE98221020BD40F225A57ED383B440CF073BC5539D0341F5767D2BF2D78406D00475A2EE9`
-
-2. For example, the variable size Secp256k1 signature (in this particular example 70 or 0x46 bytes)
-   `304402201CD4B8C764D2FD8AF23ECFE6666CA8A53886D47754D951295D2D311E1FEA33BF02201E0F906BB1CF2C30EAACFFB032A7129358AFF96B9F79B06ACFFB18AC90C2ADD7`
-   would be encoded as
-   `16E1FEEA46304402201CD4B8C764D2FD8AF23ECFE6666CA8A53886D47754D951295D2D311E1FEA33BF02201E0F906BB1CF2C30EAACFFB032A7129358AFF96B9F79B06ACFFB18AC90C2ADD7`
+   `EB5AE98721020BD40F225A57ED383B440CF073BC5539D0341F5767D2BF2D78406D00475A2EE9`

 ### Addresses

--- a/docs/spec/reactors/block_sync/reactor.md
+++ b/docs/spec/reactors/block_sync/reactor.md
@@ -65,24 +65,24 @@ type Requester {
  mtx          Mutex
  block        Block
  height       int64
-  peerID       p2p.ID
-  redoChannel  chan struct{}
+   peerID       p2p.ID
+  redoChannel  chan p2p.ID //redo may send multi-time; peerId is used to identify repeat
 }
 ```

-Pool is core data structure that stores last executed block (`height`), assignment of requests to peers (`requesters`), current height for each peer and number of pending requests for each peer (`peers`), maximum peer height, etc.
+Pool is a core data structure that stores last executed block (`height`), assignment of requests to peers (`requesters`), current height for each peer and number of pending requests for each peer (`peers`), maximum peer height, etc.

 ```go
 type Pool {
-  mtx Mutex
-  requesters       map[int64]*Requester
-  height           int64
-  peers            map[p2p.ID]*Peer
-  maxPeerHeight    int64
-  numPending       int32
-  store            BlockStore
-  requestsChannel  chan<- BlockRequest
-  errorsChannel    chan<- peerError
+  mtx                Mutex
+  requesters         map[int64]*Requester
+  height             int64
+  peers              map[p2p.ID]*Peer
+  maxPeerHeight      int64
+  numPending         int32
+  store              BlockStore
+  requestsChannel    chan<- BlockRequest
+  errorsChannel      chan<- peerError
 }
 ```

@@ -90,11 +90,11 @@ Peer data structure stores for each peer current `height` and number of pending

 ```go
 type Peer struct {
-  id         p2p.ID
-  height     int64
-  numPending int32
-  timeout    *time.Timer
-  didTimeout bool
+  id           p2p.ID
+  height       int64
+  numPending   int32
+  timeout      *time.Timer
+  didTimeout   bool
 }
 ```

@@ -169,11 +169,11 @@ Requester task is responsible for fetching a single block at position `height`.

 ```go
 fetchBlock(height, pool):
-  while true do
+  while true do {
    peerID = nil
    block = nil
    peer = pickAvailablePeer(height)
-    peerId = peer.id
+    peerID = peer.id

    enqueue BlockRequest(height, peerID) to pool.requestsChannel
    redo = false
@@ -181,12 +181,15 @@ fetchBlock(height, pool):
      select {
        upon receiving Quit message do
          return
-        upon receiving message on redoChannel do
-          mtx.Lock()
-          pool.numPending++
-          redo = true
-          mtx.UnLock()
+        upon receiving redo message with id on redoChannel do
+          if peerID == id {
+            mtx.Lock()
+            pool.numPending++
+            redo = true
+            mtx.UnLock()	
+          }
      }
+    }

 pickAvailablePeer(height):
  selectedPeer = nil
@@ -244,7 +247,7 @@ createRequesters(pool):
 main(pool):
  create trySyncTicker with interval trySyncIntervalMS
  create statusUpdateTicker with interval statusUpdateIntervalSeconds
-  create switchToConsensusTicker with interbal switchToConsensusIntervalSeconds
+  create switchToConsensusTicker with interval switchToConsensusIntervalSeconds

  while true do
    select {
--- a/docs/tendermint-core/configuration.md
+++ b/docs/tendermint-core/configuration.md
@@ -203,6 +203,9 @@ create_empty_blocks_interval = "0s"
 peer_gossip_sleep_duration = "100ms"
 peer_query_maj23_sleep_duration = "2000ms"

+# Block time parameters. Corresponds to the minimum time increment between consecutive blocks.
+blocktime_iota = "1000ms"
+
 ##### transactions indexer configuration options #####
 [tx_index]

--- a/evidence/reactor.go
+++ b/evidence/reactor.go
@@ -163,7 +163,7 @@ func (evR EvidenceReactor) checkSendEvidenceMessage(peer p2p.Peer, ev types.Evid
 	// make sure the peer is up to date
 	evHeight := ev.Height()
 	peerState, ok := peer.Get(types.PeerStateKey).(PeerState)
-	if !ok { 
+	if !ok {
 		// Peer does not have a state yet. We set it in the consensus reactor, but
 		// when we add peer in Switch, the order we call reactors#AddPeer is
 		// different every time due to us using a map. Sometimes other reactors
--- a/libs/autofile/autofile_test.go
+++ b/libs/autofile/autofile_test.go
@@ -119,4 +119,4 @@ func TestAutoFileSize(t *testing.T) {

 	// Cleanup
 	_ = os.Remove(f.Name())
-}
+}
--- a/libs/cli/flags/log_level_test.go
+++ b/libs/cli/flags/log_level_test.go
@@ -51,7 +51,7 @@ func TestParseLogLevel(t *testing.T) {

 		buf.Reset()

-		logger.With("module", "wire").Debug("Kingpin")
+		logger.With("module", "mempool").With("module", "wire").Debug("Kingpin")
 		if have := strings.TrimSpace(buf.String()); c.expectedLogLines[0] != have {
 			t.Errorf("\nwant '%s'\nhave '%s'\nlevel '%s'", c.expectedLogLines[0], have, c.lvl)
 		}
--- a/libs/log/filter.go
+++ b/libs/log/filter.go
@@ -11,9 +11,10 @@ const (
 )

 type filter struct {
-	next           Logger
-	allowed        level            // XOR'd levels for default case
-	allowedKeyvals map[keyval]level // When key-value match, use this level
+	next             Logger
+	allowed          level            // XOR'd levels for default case
+	initiallyAllowed level            // XOR'd levels for initial case
+	allowedKeyvals   map[keyval]level // When key-value match, use this level
 }

 type keyval struct {
@@ -33,6 +34,7 @@ func NewFilter(next Logger, options ...Option) Logger {
 	for _, option := range options {
 		option(l)
 	}
+	l.initiallyAllowed = l.allowed
 	return l
 }

@@ -76,14 +78,45 @@ func (l *filter) Error(msg string, keyvals ...interface{}) {
 //     logger = log.NewFilter(logger, log.AllowError(), log.AllowInfoWith("module", "crypto"), log.AllowNoneWith("user", "Sam"))
 //		 logger.With("user", "Sam").With("module", "crypto").Info("Hello") # produces "I... Hello module=crypto user=Sam"
 func (l *filter) With(keyvals ...interface{}) Logger {
+	keyInAllowedKeyvals := false
+
 	for i := len(keyvals) - 2; i >= 0; i -= 2 {
 		for kv, allowed := range l.allowedKeyvals {
-			if keyvals[i] == kv.key && keyvals[i+1] == kv.value {
-				return &filter{next: l.next.With(keyvals...), allowed: allowed, allowedKeyvals: l.allowedKeyvals}
+			if keyvals[i] == kv.key {
+				keyInAllowedKeyvals = true
+				// Example:
+				//		logger = log.NewFilter(logger, log.AllowError(), log.AllowInfoWith("module", "crypto"))
+				//		logger.With("module", "crypto")
+				if keyvals[i+1] == kv.value {
+					return &filter{
+						next:             l.next.With(keyvals...),
+						allowed:          allowed, // set the desired level
+						allowedKeyvals:   l.allowedKeyvals,
+						initiallyAllowed: l.initiallyAllowed,
+					}
+				}
 			}
 		}
 	}
-	return &filter{next: l.next.With(keyvals...), allowed: l.allowed, allowedKeyvals: l.allowedKeyvals}
+
+	// Example:
+	//		logger = log.NewFilter(logger, log.AllowError(), log.AllowInfoWith("module", "crypto"))
+	//		logger.With("module", "main")
+	if keyInAllowedKeyvals {
+		return &filter{
+			next:             l.next.With(keyvals...),
+			allowed:          l.initiallyAllowed, // return back to initially allowed
+			allowedKeyvals:   l.allowedKeyvals,
+			initiallyAllowed: l.initiallyAllowed,
+		}
+	}
+
+	return &filter{
+		next:             l.next.With(keyvals...),
+		allowed:          l.allowed, // simply continue with the current level
+		allowedKeyvals:   l.allowedKeyvals,
+		initiallyAllowed: l.initiallyAllowed,
+	}
 }

 //--------------------------------------------------------------------------------
--- a/mempool/mempool.go
+++ b/mempool/mempool.go
@@ -131,7 +131,6 @@ type Mempool struct {
 	proxyMtx             sync.Mutex
 	proxyAppConn         proxy.AppConnMempool
 	txs                  *clist.CList    // concurrent linked-list of good txs
-	counter              int64           // simple incrementing counter
 	height               int64           // the last block Update()'d to
 	rechecking           int32           // for re-checking filtered txs on Update()
 	recheckCursor        *clist.CElement // next expected response
@@ -167,7 +166,6 @@ func NewMempool(
 		config:        config,
 		proxyAppConn:  proxyAppConn,
 		txs:           clist.New(),
-		counter:       0,
 		height:        height,
 		rechecking:    0,
 		recheckCursor: nil,
@@ -365,9 +363,7 @@ func (mem *Mempool) resCbNormal(req *abci.Request, res *abci.Response) {
 			postCheckErr = mem.postCheck(tx, r.CheckTx)
 		}
 		if (r.CheckTx.Code == abci.CodeTypeOK) && postCheckErr == nil {
-			mem.counter++
 			memTx := &mempoolTx{
-				counter:   mem.counter,
 				height:    mem.height,
 				gasWanted: r.CheckTx.GasWanted,
 				tx:        tx,
@@ -378,7 +374,6 @@ func (mem *Mempool) resCbNormal(req *abci.Request, res *abci.Response) {
 				"res", r,
 				"height", memTx.height,
 				"total", mem.Size(),
-				"counter", memTx.counter,
 			)
 			mem.metrics.TxSizeBytes.Observe(float64(len(tx)))
 			mem.notifyTxsAvailable()
@@ -534,12 +529,6 @@ func (mem *Mempool) Update(
 	preCheck PreCheckFunc,
 	postCheck PostCheckFunc,
 ) error {
-	// First, create a lookup map of txns in new txs.
-	txsMap := make(map[string]struct{}, len(txs))
-	for _, tx := range txs {
-		txsMap[string(tx)] = struct{}{}
-	}
-
 	// Set height
 	mem.height = height
 	mem.notifiedTxsAvailable = false
@@ -551,12 +540,18 @@ func (mem *Mempool) Update(
 		mem.postCheck = postCheck
 	}

-	// Remove transactions that are already in txs.
-	goodTxs := mem.filterTxs(txsMap)
+	// Add committed transactions to cache (if missing).
+	for _, tx := range txs {
+		_ = mem.cache.Push(tx)
+	}
+
+	// Remove committed transactions.
+	txsLeft := mem.removeTxs(txs)
+
 	// Recheck mempool txs if any txs were committed in the block
-	if mem.config.Recheck && len(goodTxs) > 0 {
-		mem.logger.Info("Recheck txs", "numtxs", len(goodTxs), "height", height)
-		mem.recheckTxs(goodTxs)
+	if mem.config.Recheck && len(txsLeft) > 0 {
+		mem.logger.Info("Recheck txs", "numtxs", len(txsLeft), "height", height)
+		mem.recheckTxs(txsLeft)
 		// At this point, mem.txs are being rechecked.
 		// mem.recheckCursor re-scans mem.txs and possibly removes some txs.
 		// Before mem.Reap(), we should wait for mem.recheckCursor to be nil.
@@ -568,12 +563,18 @@ func (mem *Mempool) Update(
 	return nil
 }

-func (mem *Mempool) filterTxs(blockTxsMap map[string]struct{}) []types.Tx {
-	goodTxs := make([]types.Tx, 0, mem.txs.Len())
+func (mem *Mempool) removeTxs(txs types.Txs) []types.Tx {
+	// Build a map for faster lookups.
+	txsMap := make(map[string]struct{}, len(txs))
+	for _, tx := range txs {
+		txsMap[string(tx)] = struct{}{}
+	}
+
+	txsLeft := make([]types.Tx, 0, mem.txs.Len())
 	for e := mem.txs.Front(); e != nil; e = e.Next() {
 		memTx := e.Value.(*mempoolTx)
-		// Remove the tx if it's alredy in a block.
-		if _, ok := blockTxsMap[string(memTx.tx)]; ok {
+		// Remove the tx if it's already in a block.
+		if _, ok := txsMap[string(memTx.tx)]; ok {
 			// remove from clist
 			mem.txs.Remove(e)
 			e.DetachPrev()
@@ -581,15 +582,14 @@ func (mem *Mempool) filterTxs(blockTxsMap map[string]struct{}) []types.Tx {
 			// NOTE: we don't remove committed txs from the cache.
 			continue
 		}
-		// Good tx!
-		goodTxs = append(goodTxs, memTx.tx)
+		txsLeft = append(txsLeft, memTx.tx)
 	}
-	return goodTxs
+	return txsLeft
 }

-// NOTE: pass in goodTxs because mem.txs can mutate concurrently.
-func (mem *Mempool) recheckTxs(goodTxs []types.Tx) {
-	if len(goodTxs) == 0 {
+// NOTE: pass in txs because mem.txs can mutate concurrently.
+func (mem *Mempool) recheckTxs(txs []types.Tx) {
+	if len(txs) == 0 {
 		return
 	}
 	atomic.StoreInt32(&mem.rechecking, 1)
@@ -598,7 +598,7 @@ func (mem *Mempool) recheckTxs(goodTxs []types.Tx) {

 	// Push txs to proxyAppConn
 	// NOTE: resCb() may be called concurrently.
-	for _, tx := range goodTxs {
+	for _, tx := range txs {
 		mem.proxyAppConn.CheckTxAsync(tx)
 	}
 	mem.proxyAppConn.FlushAsync()
@@ -608,7 +608,6 @@ func (mem *Mempool) recheckTxs(goodTxs []types.Tx) {

 // mempoolTx is a transaction that successfully ran
 type mempoolTx struct {
-	counter   int64    // a simple incrementing counter
 	height    int64    // height that this tx had been validated in
 	gasWanted int64    // amount of gas this tx states it will require
 	tx        types.Tx //
--- a/mempool/mempool_test.go
+++ b/mempool/mempool_test.go
@@ -163,6 +163,17 @@ func TestMempoolFilters(t *testing.T) {
 	}
 }

+func TestMempoolUpdateAddsTxsToCache(t *testing.T) {
+	app := kvstore.NewKVStoreApplication()
+	cc := proxy.NewLocalClientCreator(app)
+	mempool := newMempoolWithApp(cc)
+	mempool.Update(1, []types.Tx{[]byte{0x01}}, nil, nil)
+	err := mempool.CheckTx([]byte{0x01}, nil)
+	if assert.Error(t, err) {
+		assert.Equal(t, ErrTxInCache, err)
+	}
+}
+
 func TestTxsAvailable(t *testing.T) {
 	app := kvstore.NewKVStoreApplication()
 	cc := proxy.NewLocalClientCreator(app)
--- a/node/node.go
+++ b/node/node.go
@@ -3,7 +3,6 @@ package node
 import (
 	"bytes"
 	"context"
-	"errors"
 	"fmt"
 	"net"
 	"net/http"
@@ -11,11 +10,12 @@ import (
 	"strings"
 	"time"

+	"github.com/pkg/errors"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/rs/cors"

-	"github.com/tendermint/go-amino"
+	amino "github.com/tendermint/go-amino"
 	abci "github.com/tendermint/tendermint/abci/types"
 	bc "github.com/tendermint/tendermint/blockchain"
 	cfg "github.com/tendermint/tendermint/config"
@@ -220,25 +220,14 @@ func NewNode(config *cfg.Config,
 		)
 	}

-	// If an address is provided, listen on the socket for a
-	// connection from an external signing process.
 	if config.PrivValidatorListenAddr != "" {
-		var (
-			// TODO: persist this key so external signer
-			// can actually authenticate us
-			privKey = ed25519.GenPrivKey()
-			pvsc    = privval.NewTCPVal(
-				logger.With("module", "privval"),
-				config.PrivValidatorListenAddr,
-				privKey,
-			)
-		)
-
-		if err := pvsc.Start(); err != nil {
-			return nil, fmt.Errorf("Error starting private validator client: %v", err)
+		// If an address is provided, listen on the socket for a connection from an
+		// external signing process.
+		// FIXME: we should start services inside OnStart
+		privValidator, err = createAndStartPrivValidatorSocketClient(config.PrivValidatorListenAddr, logger)
+		if err != nil {
+			return nil, errors.Wrap(err, "Error with private validator socket client")
 		}
-
-		privValidator = pvsc
 	}

 	// Decide whether to fast-sync or not
@@ -600,10 +589,8 @@ func (n *Node) OnStop() {
 		}
 	}

-	if pvsc, ok := n.privValidator.(*privval.TCPVal); ok {
-		if err := pvsc.Stop(); err != nil {
-			n.Logger.Error("Error stopping priv validator socket client", "err", err)
-		}
+	if pvsc, ok := n.privValidator.(cmn.Service); ok {
+		pvsc.Stop()
 	}

 	if n.prometheusSrv != nil {
@@ -857,6 +844,36 @@ func saveGenesisDoc(db dbm.DB, genDoc *types.GenesisDoc) {
 	db.SetSync(genesisDocKey, bytes)
 }

+func createAndStartPrivValidatorSocketClient(
+	listenAddr string,
+	logger log.Logger,
+) (types.PrivValidator, error) {
+	var pvsc types.PrivValidator
+
+	protocol, address := cmn.ProtocolAndAddress(listenAddr)
+	switch protocol {
+	case "unix":
+		pvsc = privval.NewIPCVal(logger.With("module", "privval"), address)
+	case "tcp":
+		// TODO: persist this key so external signer
+		// can actually authenticate us
+		pvsc = privval.NewTCPVal(logger.With("module", "privval"), listenAddr, ed25519.GenPrivKey())
+	default:
+		return nil, fmt.Errorf(
+			"Wrong listen address: expected either 'tcp' or 'unix' protocols, got %s",
+			protocol,
+		)
+	}
+
+	if pvsc, ok := pvsc.(cmn.Service); ok {
+		if err := pvsc.Start(); err != nil {
+			return nil, errors.Wrap(err, "failed to start")
+		}
+	}
+
+	return pvsc, nil
+}
+
 // splitAndTrimEmpty slices s into all subslices separated by sep and returns a
 // slice of the string s with all leading and trailing Unicode code points
 // contained in cutset removed. If sep is empty, SplitAndTrim splits after each
--- a/node/node_test.go
+++ b/node/node_test.go
@@ -3,23 +3,26 @@ package node
 import (
 	"context"
 	"fmt"
+	"net"
 	"os"
 	"syscall"
 	"testing"
 	"time"

 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"

 	"github.com/tendermint/tendermint/abci/example/kvstore"
+	cfg "github.com/tendermint/tendermint/config"
+	"github.com/tendermint/tendermint/crypto/ed25519"
+	cmn "github.com/tendermint/tendermint/libs/common"
 	"github.com/tendermint/tendermint/libs/log"
 	"github.com/tendermint/tendermint/p2p"
+	"github.com/tendermint/tendermint/privval"
 	sm "github.com/tendermint/tendermint/state"
-	"github.com/tendermint/tendermint/version"
-
-	cfg "github.com/tendermint/tendermint/config"
 	"github.com/tendermint/tendermint/types"
-
 	tmtime "github.com/tendermint/tendermint/types/time"
+	"github.com/tendermint/tendermint/version"
 )

 func TestNodeStartStop(t *testing.T) {
@@ -27,17 +30,16 @@ func TestNodeStartStop(t *testing.T) {

 	// create & start node
 	n, err := DefaultNewNode(config, log.TestingLogger())
-	assert.NoError(t, err, "expected no err on DefaultNewNode")
-	err1 := n.Start()
-	if err1 != nil {
-		t.Error(err1)
-	}
+	require.NoError(t, err)
+	err = n.Start()
+	require.NoError(t, err)
+
 	t.Logf("Started node %v", n.sw.NodeInfo())

 	// wait for the node to produce a block
 	blockCh := make(chan interface{})
 	err = n.EventBus().Subscribe(context.Background(), "node_test", types.EventQueryNewBlock, blockCh)
-	assert.NoError(t, err)
+	require.NoError(t, err)
 	select {
 	case <-blockCh:
 	case <-time.After(10 * time.Second):
@@ -89,7 +91,7 @@ func TestNodeDelayedStop(t *testing.T) {
 	// create & start node
 	n, err := DefaultNewNode(config, log.TestingLogger())
 	n.GenesisDoc().GenesisTime = now.Add(5 * time.Second)
-	assert.NoError(t, err)
+	require.NoError(t, err)

 	n.Start()
 	startTime := tmtime.Now()
@@ -101,7 +103,7 @@ func TestNodeSetAppVersion(t *testing.T) {

 	// create & start node
 	n, err := DefaultNewNode(config, log.TestingLogger())
-	assert.NoError(t, err, "expected no err on DefaultNewNode")
+	require.NoError(t, err)

 	// default config uses the kvstore app
 	var appVersion version.Protocol = kvstore.ProtocolVersion
@@ -113,3 +115,80 @@ func TestNodeSetAppVersion(t *testing.T) {
 	// check version is set in node info
 	assert.Equal(t, n.nodeInfo.(p2p.DefaultNodeInfo).ProtocolVersion.App, appVersion)
 }
+
+func TestNodeSetPrivValTCP(t *testing.T) {
+	addr := "tcp://" + testFreeAddr(t)
+
+	config := cfg.ResetTestRoot("node_priv_val_tcp_test")
+	config.BaseConfig.PrivValidatorListenAddr = addr
+
+	rs := privval.NewRemoteSigner(
+		log.TestingLogger(),
+		config.ChainID(),
+		addr,
+		types.NewMockPV(),
+		ed25519.GenPrivKey(),
+	)
+	privval.RemoteSignerConnDeadline(5 * time.Millisecond)(rs)
+	go func() {
+		err := rs.Start()
+		if err != nil {
+			panic(err)
+		}
+	}()
+	defer rs.Stop()
+
+	n, err := DefaultNewNode(config, log.TestingLogger())
+	require.NoError(t, err)
+	assert.IsType(t, &privval.TCPVal{}, n.PrivValidator())
+}
+
+// address without a protocol must result in error
+func TestPrivValidatorListenAddrNoProtocol(t *testing.T) {
+	addrNoPrefix := testFreeAddr(t)
+
+	config := cfg.ResetTestRoot("node_priv_val_tcp_test")
+	config.BaseConfig.PrivValidatorListenAddr = addrNoPrefix
+
+	_, err := DefaultNewNode(config, log.TestingLogger())
+	assert.Error(t, err)
+}
+
+func TestNodeSetPrivValIPC(t *testing.T) {
+	tmpfile := "/tmp/kms." + cmn.RandStr(6) + ".sock"
+	defer os.Remove(tmpfile) // clean up
+
+	config := cfg.ResetTestRoot("node_priv_val_tcp_test")
+	config.BaseConfig.PrivValidatorListenAddr = "unix://" + tmpfile
+
+	rs := privval.NewIPCRemoteSigner(
+		log.TestingLogger(),
+		config.ChainID(),
+		tmpfile,
+		types.NewMockPV(),
+	)
+	privval.IPCRemoteSignerConnDeadline(3 * time.Second)(rs)
+
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		n, err := DefaultNewNode(config, log.TestingLogger())
+		require.NoError(t, err)
+		assert.IsType(t, &privval.IPCVal{}, n.PrivValidator())
+	}()
+
+	err := rs.Start()
+	require.NoError(t, err)
+	defer rs.Stop()
+
+	<-done
+}
+
+// testFreeAddr claims a free port so we don't block on listener being ready.
+func testFreeAddr(t *testing.T) string {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	defer ln.Close()
+
+	return fmt.Sprintf("127.0.0.1:%d", ln.Addr().(*net.TCPAddr).Port)
+}
--- a/p2p/node_info.go
+++ b/p2p/node_info.go
@@ -230,3 +230,31 @@ func (info DefaultNodeInfo) NetAddress() *NetAddress {
 	}
 	return netAddr
 }
+
+//-----------------------------------------------------------
+// These methods are for Protobuf Compatibility
+
+// Size returns the size of the amino encoding, in bytes.
+func (info *DefaultNodeInfo) Size() int {
+	bs, _ := info.Marshal()
+	return len(bs)
+}
+
+// Marshal returns the amino encoding.
+func (info *DefaultNodeInfo) Marshal() ([]byte, error) {
+	return cdc.MarshalBinaryBare(info)
+}
+
+// MarshalTo calls Marshal and copies to the given buffer.
+func (info *DefaultNodeInfo) MarshalTo(data []byte) (int, error) {
+	bs, err := info.Marshal()
+	if err != nil {
+		return -1, err
+	}
+	return copy(data, bs), nil
+}
+
+// Unmarshal deserializes from amino encoded form.
+func (info *DefaultNodeInfo) Unmarshal(bs []byte) error {
+	return cdc.UnmarshalBinaryBare(bs, info)
+}
--- a/privval/ipc_server.go
+++ b/privval/ipc_server.go
@@ -69,6 +69,7 @@ func (rs *IPCRemoteSigner) OnStart() error {
 		for {
 			conn, err := rs.listener.AcceptUnix()
 			if err != nil {
+				rs.Logger.Error("AcceptUnix", "err", err)
 				return
 			}
 			go rs.handleConnection(conn)
--- a/rpc/client/rpc_test.go
+++ b/rpc/client/rpc_test.go
@@ -370,20 +370,27 @@ func TestTxSearch(t *testing.T) {
 		}

 		// query by height
-		result, err = c.TxSearch(fmt.Sprintf("tx.height >= %d", txHeight), true, 1, 30)
+		result, err = c.TxSearch(fmt.Sprintf("tx.height=%d", txHeight), true, 1, 30)
 		require.Nil(t, err, "%+v", err)
 		require.Len(t, result.Txs, 1)

-		// we query for non existing tx
+		// query for non existing tx
 		result, err = c.TxSearch(fmt.Sprintf("tx.hash='%X'", anotherTxHash), false, 1, 30)
 		require.Nil(t, err, "%+v", err)
 		require.Len(t, result.Txs, 0)

-		// we query using a tag (see kvstore application)
+		// query using a tag (see kvstore application)
 		result, err = c.TxSearch("app.creator='Cosmoshi Netowoko'", false, 1, 30)
 		require.Nil(t, err, "%+v", err)
 		if len(result.Txs) == 0 {
 			t.Fatal("expected a lot of transactions")
 		}
+
+		// query using a tag (see kvstore application) and height
+		result, err = c.TxSearch("app.creator='Cosmoshi Netowoko' AND tx.height<10000", true, 1, 30)
+		require.Nil(t, err, "%+v", err)
+		if len(result.Txs) == 0 {
+			t.Fatal("expected a lot of transactions")
+		}
 	}
 }
--- a/rpc/core/events.go
+++ b/rpc/core/events.go
@@ -2,6 +2,7 @@ package core

 import (
 	"context"
+	"fmt"

 	"github.com/pkg/errors"

@@ -104,7 +105,7 @@ func Subscribe(wsCtx rpctypes.WSRPCContext, query string) (*ctypes.ResultSubscri
 	go func() {
 		for event := range ch {
 			tmResult := &ctypes.ResultEvent{query, event.(tmtypes.TMEventData)}
-			wsCtx.TryWriteRPCResponse(rpctypes.NewRPCSuccessResponse(wsCtx.Codec(), wsCtx.Request.ID+"#event", tmResult))
+			wsCtx.TryWriteRPCResponse(rpctypes.NewRPCSuccessResponse(wsCtx.Codec(), rpctypes.JSONRPCStringID(fmt.Sprintf("%v#event", wsCtx.Request.ID)), tmResult))
 		}
 	}()

--- a/rpc/lib/client/http_client.go
+++ b/rpc/lib/client/http_client.go
@@ -99,7 +99,7 @@ func NewJSONRPCClient(remote string) *JSONRPCClient {
 }

 func (c *JSONRPCClient) Call(method string, params map[string]interface{}, result interface{}) (interface{}, error) {
-	request, err := types.MapToRequest(c.cdc, "jsonrpc-client", method, params)
+	request, err := types.MapToRequest(c.cdc, types.JSONRPCStringID("jsonrpc-client"), method, params)
 	if err != nil {
 		return nil, err
 	}
--- a/rpc/lib/client/ws_client.go
+++ b/rpc/lib/client/ws_client.go
@@ -214,7 +214,7 @@ func (c *WSClient) Send(ctx context.Context, request types.RPCRequest) error {

 // Call the given method. See Send description.
 func (c *WSClient) Call(ctx context.Context, method string, params map[string]interface{}) error {
-	request, err := types.MapToRequest(c.cdc, "ws-client", method, params)
+	request, err := types.MapToRequest(c.cdc, types.JSONRPCStringID("ws-client"), method, params)
 	if err != nil {
 		return err
 	}
@@ -224,7 +224,7 @@ func (c *WSClient) Call(ctx context.Context, method string, params map[string]in
 // CallWithArrayParams the given method with params in a form of array. See
 // Send description.
 func (c *WSClient) CallWithArrayParams(ctx context.Context, method string, params []interface{}) error {
-	request, err := types.ArrayToRequest(c.cdc, "ws-client", method, params)
+	request, err := types.ArrayToRequest(c.cdc, types.JSONRPCStringID("ws-client"), method, params)
 	if err != nil {
 		return err
 	}
--- a/rpc/lib/server/handlers.go
+++ b/rpc/lib/server/handlers.go
@@ -103,7 +103,7 @@ func makeJSONRPCHandler(funcMap map[string]*RPCFunc, cdc *amino.Codec, logger lo
 	return func(w http.ResponseWriter, r *http.Request) {
 		b, err := ioutil.ReadAll(r.Body)
 		if err != nil {
-			WriteRPCResponseHTTP(w, types.RPCInvalidRequestError("", errors.Wrap(err, "Error reading request body")))
+			WriteRPCResponseHTTP(w, types.RPCInvalidRequestError(types.JSONRPCStringID(""), errors.Wrap(err, "Error reading request body")))
 			return
 		}
 		// if its an empty request (like from a browser),
@@ -116,12 +116,12 @@ func makeJSONRPCHandler(funcMap map[string]*RPCFunc, cdc *amino.Codec, logger lo
 		var request types.RPCRequest
 		err = json.Unmarshal(b, &request)
 		if err != nil {
-			WriteRPCResponseHTTP(w, types.RPCParseError("", errors.Wrap(err, "Error unmarshalling request")))
+			WriteRPCResponseHTTP(w, types.RPCParseError(types.JSONRPCStringID(""), errors.Wrap(err, "Error unmarshalling request")))
 			return
 		}
 		// A Notification is a Request object without an "id" member.
 		// The Server MUST NOT reply to a Notification, including those that are within a batch request.
-		if request.ID == "" {
+		if request.ID == types.JSONRPCStringID("") {
 			logger.Debug("HTTPJSONRPC received a notification, skipping... (please send a non-empty ID if you want to call a method)")
 			return
 		}
@@ -255,7 +255,7 @@ func makeHTTPHandler(rpcFunc *RPCFunc, cdc *amino.Codec, logger log.Logger) func
 	// Exception for websocket endpoints
 	if rpcFunc.ws {
 		return func(w http.ResponseWriter, r *http.Request) {
-			WriteRPCResponseHTTP(w, types.RPCMethodNotFoundError(""))
+			WriteRPCResponseHTTP(w, types.RPCMethodNotFoundError(types.JSONRPCStringID("")))
 		}
 	}
 	// All other endpoints
@@ -263,17 +263,17 @@ func makeHTTPHandler(rpcFunc *RPCFunc, cdc *amino.Codec, logger log.Logger) func
 		logger.Debug("HTTP HANDLER", "req", r)
 		args, err := httpParamsToArgs(rpcFunc, cdc, r)
 		if err != nil {
-			WriteRPCResponseHTTP(w, types.RPCInvalidParamsError("", errors.Wrap(err, "Error converting http params to arguments")))
+			WriteRPCResponseHTTP(w, types.RPCInvalidParamsError(types.JSONRPCStringID(""), errors.Wrap(err, "Error converting http params to arguments")))
 			return
 		}
 		returns := rpcFunc.f.Call(args)
 		logger.Info("HTTPRestRPC", "method", r.URL.Path, "args", args, "returns", returns)
 		result, err := unreflectResult(returns)
 		if err != nil {
-			WriteRPCResponseHTTP(w, types.RPCInternalError("", err))
+			WriteRPCResponseHTTP(w, types.RPCInternalError(types.JSONRPCStringID(""), err))
 			return
 		}
-		WriteRPCResponseHTTP(w, types.NewRPCSuccessResponse(cdc, "", result))
+		WriteRPCResponseHTTP(w, types.NewRPCSuccessResponse(cdc, types.JSONRPCStringID(""), result))
 	}
 }

@@ -580,7 +580,7 @@ func (wsc *wsConnection) readRoutine() {
 				err = fmt.Errorf("WSJSONRPC: %v", r)
 			}
 			wsc.Logger.Error("Panic in WSJSONRPC handler", "err", err, "stack", string(debug.Stack()))
-			wsc.WriteRPCResponse(types.RPCInternalError("unknown", err))
+			wsc.WriteRPCResponse(types.RPCInternalError(types.JSONRPCStringID("unknown"), err))
 			go wsc.readRoutine()
 		} else {
 			wsc.baseConn.Close() // nolint: errcheck
@@ -615,13 +615,13 @@ func (wsc *wsConnection) readRoutine() {
 			var request types.RPCRequest
 			err = json.Unmarshal(in, &request)
 			if err != nil {
-				wsc.WriteRPCResponse(types.RPCParseError("", errors.Wrap(err, "Error unmarshaling request")))
+				wsc.WriteRPCResponse(types.RPCParseError(types.JSONRPCStringID(""), errors.Wrap(err, "Error unmarshaling request")))
 				continue
 			}

 			// A Notification is a Request object without an "id" member.
 			// The Server MUST NOT reply to a Notification, including those that are within a batch request.
-			if request.ID == "" {
+			if request.ID == types.JSONRPCStringID("") {
 				wsc.Logger.Debug("WSJSONRPC received a notification, skipping... (please send a non-empty ID if you want to call a method)")
 				continue
 			}
--- a/rpc/lib/server/handlers_test.go
+++ b/rpc/lib/server/handlers_test.go
@@ -47,21 +47,22 @@ func statusOK(code int) bool { return code >= 200 && code <= 299 }
 func TestRPCParams(t *testing.T) {
 	mux := testMux()
 	tests := []struct {
-		payload string
-		wantErr string
+		payload    string
+		wantErr    string
+		expectedId interface{}
 	}{
 		// bad
-		{`{"jsonrpc": "2.0", "id": "0"}`, "Method not found"},
-		{`{"jsonrpc": "2.0", "method": "y", "id": "0"}`, "Method not found"},
-		{`{"method": "c", "id": "0", "params": a}`, "invalid character"},
-		{`{"method": "c", "id": "0", "params": ["a"]}`, "got 1"},
-		{`{"method": "c", "id": "0", "params": ["a", "b"]}`, "invalid character"},
-		{`{"method": "c", "id": "0", "params": [1, 1]}`, "of type string"},
+		{`{"jsonrpc": "2.0", "id": "0"}`, "Method not found", types.JSONRPCStringID("0")},
+		{`{"jsonrpc": "2.0", "method": "y", "id": "0"}`, "Method not found", types.JSONRPCStringID("0")},
+		{`{"method": "c", "id": "0", "params": a}`, "invalid character", types.JSONRPCStringID("")}, // id not captured in JSON parsing failures
+		{`{"method": "c", "id": "0", "params": ["a"]}`, "got 1", types.JSONRPCStringID("0")},
+		{`{"method": "c", "id": "0", "params": ["a", "b"]}`, "invalid character", types.JSONRPCStringID("0")},
+		{`{"method": "c", "id": "0", "params": [1, 1]}`, "of type string", types.JSONRPCStringID("0")},

 		// good
-		{`{"jsonrpc": "2.0", "method": "c", "id": "0", "params": null}`, ""},
-		{`{"method": "c", "id": "0", "params": {}}`, ""},
-		{`{"method": "c", "id": "0", "params": ["a", "10"]}`, ""},
+		{`{"jsonrpc": "2.0", "method": "c", "id": "0", "params": null}`, "", types.JSONRPCStringID("0")},
+		{`{"method": "c", "id": "0", "params": {}}`, "", types.JSONRPCStringID("0")},
+		{`{"method": "c", "id": "0", "params": ["a", "10"]}`, "", types.JSONRPCStringID("0")},
 	}

 	for i, tt := range tests {
@@ -80,7 +81,7 @@ func TestRPCParams(t *testing.T) {
 		recv := new(types.RPCResponse)
 		assert.Nil(t, json.Unmarshal(blob, recv), "#%d: expecting successful parsing of an RPCResponse:\nblob: %s", i, blob)
 		assert.NotEqual(t, recv, new(types.RPCResponse), "#%d: not expecting a blank RPCResponse", i)
-
+		assert.Equal(t, tt.expectedId, recv.ID, "#%d: expected ID not matched in RPCResponse", i)
 		if tt.wantErr == "" {
 			assert.Nil(t, recv.Error, "#%d: not expecting an error", i)
 		} else {
@@ -91,9 +92,56 @@ func TestRPCParams(t *testing.T) {
 	}
 }

+func TestJSONRPCID(t *testing.T) {
+	mux := testMux()
+	tests := []struct {
+		payload    string
+		wantErr    bool
+		expectedId interface{}
+	}{
+		// good id
+		{`{"jsonrpc": "2.0", "method": "c", "id": "0", "params": ["a", "10"]}`, false, types.JSONRPCStringID("0")},
+		{`{"jsonrpc": "2.0", "method": "c", "id": "abc", "params": ["a", "10"]}`, false, types.JSONRPCStringID("abc")},
+		{`{"jsonrpc": "2.0", "method": "c", "id": 0, "params": ["a", "10"]}`, false, types.JSONRPCIntID(0)},
+		{`{"jsonrpc": "2.0", "method": "c", "id": 1, "params": ["a", "10"]}`, false, types.JSONRPCIntID(1)},
+		{`{"jsonrpc": "2.0", "method": "c", "id": 1.3, "params": ["a", "10"]}`, false, types.JSONRPCIntID(1)},
+		{`{"jsonrpc": "2.0", "method": "c", "id": -1, "params": ["a", "10"]}`, false, types.JSONRPCIntID(-1)},
+		{`{"jsonrpc": "2.0", "method": "c", "id": null, "params": ["a", "10"]}`, false, nil},
+
+		// bad id
+		{`{"jsonrpc": "2.0", "method": "c", "id": {}, "params": ["a", "10"]}`, true, nil},
+		{`{"jsonrpc": "2.0", "method": "c", "id": [], "params": ["a", "10"]}`, true, nil},
+	}
+
+	for i, tt := range tests {
+		req, _ := http.NewRequest("POST", "http://localhost/", strings.NewReader(tt.payload))
+		rec := httptest.NewRecorder()
+		mux.ServeHTTP(rec, req)
+		res := rec.Result()
+		// Always expecting back a JSONRPCResponse
+		assert.True(t, statusOK(res.StatusCode), "#%d: should always return 2XX", i)
+		blob, err := ioutil.ReadAll(res.Body)
+		if err != nil {
+			t.Errorf("#%d: err reading body: %v", i, err)
+			continue
+		}
+
+		recv := new(types.RPCResponse)
+		err = json.Unmarshal(blob, recv)
+		assert.Nil(t, err, "#%d: expecting successful parsing of an RPCResponse:\nblob: %s", i, blob)
+		if !tt.wantErr {
+			assert.NotEqual(t, recv, new(types.RPCResponse), "#%d: not expecting a blank RPCResponse", i)
+			assert.Equal(t, tt.expectedId, recv.ID, "#%d: expected ID not matched in RPCResponse", i)
+			assert.Nil(t, recv.Error, "#%d: not expecting an error", i)
+		} else {
+			assert.True(t, recv.Error.Code < 0, "#%d: not expecting a positive JSONRPC code", i)
+		}
+	}
+}
+
 func TestRPCNotification(t *testing.T) {
 	mux := testMux()
-	body := strings.NewReader(`{"jsonrpc": "2.0"}`)
+	body := strings.NewReader(`{"jsonrpc": "2.0", "id": ""}`)
 	req, _ := http.NewRequest("POST", "http://localhost/", body)
 	rec := httptest.NewRecorder()
 	mux.ServeHTTP(rec, req)
@@ -134,7 +182,7 @@ func TestWebsocketManagerHandler(t *testing.T) {
 	}

 	// check basic functionality works
-	req, err := types.MapToRequest(amino.NewCodec(), "TestWebsocketManager", "c", map[string]interface{}{"s": "a", "i": 10})
+	req, err := types.MapToRequest(amino.NewCodec(), types.JSONRPCStringID("TestWebsocketManager"), "c", map[string]interface{}{"s": "a", "i": 10})
 	require.NoError(t, err)
 	err = c.WriteJSON(req)
 	require.NoError(t, err)
--- a/rpc/lib/server/http_server.go
+++ b/rpc/lib/server/http_server.go
@@ -132,7 +132,7 @@ func RecoverAndLogHandler(handler http.Handler, logger log.Logger) http.Handler
 						"Panic in RPC HTTP handler", "err", e, "stack",
 						string(debug.Stack()),
 					)
-					WriteRPCResponseHTTPError(rww, http.StatusInternalServerError, types.RPCInternalError("", e.(error)))
+					WriteRPCResponseHTTPError(rww, http.StatusInternalServerError, types.RPCInternalError(types.JSONRPCStringID(""), e.(error)))
 				}
 			}

--- a/rpc/lib/types/types.go
+++ b/rpc/lib/types/types.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"reflect"
 	"strings"

 	"github.com/pkg/errors"
@@ -13,17 +14,75 @@ import (
 	tmpubsub "github.com/tendermint/tendermint/libs/pubsub"
 )

+// a wrapper to emulate a sum type: jsonrpcid = string | int
+// TODO: refactor when Go 2.0 arrives https://github.com/golang/go/issues/19412
+type jsonrpcid interface {
+	isJSONRPCID()
+}
+
+// JSONRPCStringID a wrapper for JSON-RPC string IDs
+type JSONRPCStringID string
+
+func (JSONRPCStringID) isJSONRPCID() {}
+
+// JSONRPCIntID a wrapper for JSON-RPC integer IDs
+type JSONRPCIntID int
+
+func (JSONRPCIntID) isJSONRPCID() {}
+
+func idFromInterface(idInterface interface{}) (jsonrpcid, error) {
+	switch id := idInterface.(type) {
+	case string:
+		return JSONRPCStringID(id), nil
+	case float64:
+		// json.Unmarshal uses float64 for all numbers
+		// (https://golang.org/pkg/encoding/json/#Unmarshal),
+		// but the JSONRPC2.0 spec says the id SHOULD NOT contain
+		// decimals - so we truncate the decimals here.
+		return JSONRPCIntID(int(id)), nil
+	default:
+		typ := reflect.TypeOf(id)
+		return nil, fmt.Errorf("JSON-RPC ID (%v) is of unknown type (%v)", id, typ)
+	}
+}
+
 //----------------------------------------
 // REQUEST

 type RPCRequest struct {
 	JSONRPC string          `json:"jsonrpc"`
-	ID      string          `json:"id"`
+	ID      jsonrpcid       `json:"id"`
 	Method  string          `json:"method"`
 	Params  json.RawMessage `json:"params"` // must be map[string]interface{} or []interface{}
 }

-func NewRPCRequest(id string, method string, params json.RawMessage) RPCRequest {
+// UnmarshalJSON custom JSON unmarshalling due to jsonrpcid being string or int
+func (request *RPCRequest) UnmarshalJSON(data []byte) error {
+	unsafeReq := &struct {
+		JSONRPC string          `json:"jsonrpc"`
+		ID      interface{}     `json:"id"`
+		Method  string          `json:"method"`
+		Params  json.RawMessage `json:"params"` // must be map[string]interface{} or []interface{}
+	}{}
+	err := json.Unmarshal(data, &unsafeReq)
+	if err != nil {
+		return err
+	}
+	request.JSONRPC = unsafeReq.JSONRPC
+	request.Method = unsafeReq.Method
+	request.Params = unsafeReq.Params
+	if unsafeReq.ID == nil {
+		return nil
+	}
+	id, err := idFromInterface(unsafeReq.ID)
+	if err != nil {
+		return err
+	}
+	request.ID = id
+	return nil
+}
+
+func NewRPCRequest(id jsonrpcid, method string, params json.RawMessage) RPCRequest {
 	return RPCRequest{
 		JSONRPC: "2.0",
 		ID:      id,
@@ -36,7 +95,7 @@ func (req RPCRequest) String() string {
 	return fmt.Sprintf("[%s %s]", req.ID, req.Method)
 }

-func MapToRequest(cdc *amino.Codec, id string, method string, params map[string]interface{}) (RPCRequest, error) {
+func MapToRequest(cdc *amino.Codec, id jsonrpcid, method string, params map[string]interface{}) (RPCRequest, error) {
 	var params_ = make(map[string]json.RawMessage, len(params))
 	for name, value := range params {
 		valueJSON, err := cdc.MarshalJSON(value)
@@ -53,7 +112,7 @@ func MapToRequest(cdc *amino.Codec, id string, method string, params map[string]
 	return request, nil
 }

-func ArrayToRequest(cdc *amino.Codec, id string, method string, params []interface{}) (RPCRequest, error) {
+func ArrayToRequest(cdc *amino.Codec, id jsonrpcid, method string, params []interface{}) (RPCRequest, error) {
 	var params_ = make([]json.RawMessage, len(params))
 	for i, value := range params {
 		valueJSON, err := cdc.MarshalJSON(value)
@@ -89,12 +148,38 @@ func (err RPCError) Error() string {

 type RPCResponse struct {
 	JSONRPC string          `json:"jsonrpc"`
-	ID      string          `json:"id"`
+	ID      jsonrpcid       `json:"id"`
 	Result  json.RawMessage `json:"result,omitempty"`
 	Error   *RPCError       `json:"error,omitempty"`
 }

-func NewRPCSuccessResponse(cdc *amino.Codec, id string, res interface{}) RPCResponse {
+// UnmarshalJSON custom JSON unmarshalling due to jsonrpcid being string or int
+func (response *RPCResponse) UnmarshalJSON(data []byte) error {
+	unsafeResp := &struct {
+		JSONRPC string          `json:"jsonrpc"`
+		ID      interface{}     `json:"id"`
+		Result  json.RawMessage `json:"result,omitempty"`
+		Error   *RPCError       `json:"error,omitempty"`
+	}{}
+	err := json.Unmarshal(data, &unsafeResp)
+	if err != nil {
+		return err
+	}
+	response.JSONRPC = unsafeResp.JSONRPC
+	response.Error = unsafeResp.Error
+	response.Result = unsafeResp.Result
+	if unsafeResp.ID == nil {
+		return nil
+	}
+	id, err := idFromInterface(unsafeResp.ID)
+	if err != nil {
+		return err
+	}
+	response.ID = id
+	return nil
+}
+
+func NewRPCSuccessResponse(cdc *amino.Codec, id jsonrpcid, res interface{}) RPCResponse {
 	var rawMsg json.RawMessage

 	if res != nil {
@@ -109,7 +194,7 @@ func NewRPCSuccessResponse(cdc *amino.Codec, id string, res interface{}) RPCResp
 	return RPCResponse{JSONRPC: "2.0", ID: id, Result: rawMsg}
 }

-func NewRPCErrorResponse(id string, code int, msg string, data string) RPCResponse {
+func NewRPCErrorResponse(id jsonrpcid, code int, msg string, data string) RPCResponse {
 	return RPCResponse{
 		JSONRPC: "2.0",
 		ID:      id,
@@ -124,27 +209,27 @@ func (resp RPCResponse) String() string {
 	return fmt.Sprintf("[%s %s]", resp.ID, resp.Error)
 }

-func RPCParseError(id string, err error) RPCResponse {
+func RPCParseError(id jsonrpcid, err error) RPCResponse {
 	return NewRPCErrorResponse(id, -32700, "Parse error. Invalid JSON", err.Error())
 }

-func RPCInvalidRequestError(id string, err error) RPCResponse {
+func RPCInvalidRequestError(id jsonrpcid, err error) RPCResponse {
 	return NewRPCErrorResponse(id, -32600, "Invalid Request", err.Error())
 }

-func RPCMethodNotFoundError(id string) RPCResponse {
+func RPCMethodNotFoundError(id jsonrpcid) RPCResponse {
 	return NewRPCErrorResponse(id, -32601, "Method not found", "")
 }

-func RPCInvalidParamsError(id string, err error) RPCResponse {
+func RPCInvalidParamsError(id jsonrpcid, err error) RPCResponse {
 	return NewRPCErrorResponse(id, -32602, "Invalid params", err.Error())
 }

-func RPCInternalError(id string, err error) RPCResponse {
+func RPCInternalError(id jsonrpcid, err error) RPCResponse {
 	return NewRPCErrorResponse(id, -32603, "Internal error", err.Error())
 }

-func RPCServerError(id string, err error) RPCResponse {
+func RPCServerError(id jsonrpcid, err error) RPCResponse {
 	return NewRPCErrorResponse(id, -32000, "Server error", err.Error())
 }

--- a/rpc/lib/types/types_test.go
+++ b/rpc/lib/types/types_test.go
@@ -15,24 +15,57 @@ type SampleResult struct {
 	Value string
 }

+type responseTest struct {
+	id       jsonrpcid
+	expected string
+}
+
+var responseTests = []responseTest{
+	{JSONRPCStringID("1"), `"1"`},
+	{JSONRPCStringID("alphabet"), `"alphabet"`},
+	{JSONRPCStringID(""), `""`},
+	{JSONRPCStringID("àáâ"), `"àáâ"`},
+	{JSONRPCIntID(-1), "-1"},
+	{JSONRPCIntID(0), "0"},
+	{JSONRPCIntID(1), "1"},
+	{JSONRPCIntID(100), "100"},
+}
+
 func TestResponses(t *testing.T) {
 	assert := assert.New(t)
 	cdc := amino.NewCodec()
+	for _, tt := range responseTests {
+		jsonid := tt.id
+		a := NewRPCSuccessResponse(cdc, jsonid, &SampleResult{"hello"})
+		b, _ := json.Marshal(a)
+		s := fmt.Sprintf(`{"jsonrpc":"2.0","id":%v,"result":{"Value":"hello"}}`, tt.expected)
+		assert.Equal(string(s), string(b))

-	a := NewRPCSuccessResponse(cdc, "1", &SampleResult{"hello"})
-	b, _ := json.Marshal(a)
-	s := `{"jsonrpc":"2.0","id":"1","result":{"Value":"hello"}}`
-	assert.Equal(string(s), string(b))
+		d := RPCParseError(jsonid, errors.New("Hello world"))
+		e, _ := json.Marshal(d)
+		f := fmt.Sprintf(`{"jsonrpc":"2.0","id":%v,"error":{"code":-32700,"message":"Parse error. Invalid JSON","data":"Hello world"}}`, tt.expected)
+		assert.Equal(string(f), string(e))

-	d := RPCParseError("1", errors.New("Hello world"))
-	e, _ := json.Marshal(d)
-	f := `{"jsonrpc":"2.0","id":"1","error":{"code":-32700,"message":"Parse error. Invalid JSON","data":"Hello world"}}`
-	assert.Equal(string(f), string(e))
+		g := RPCMethodNotFoundError(jsonid)
+		h, _ := json.Marshal(g)
+		i := fmt.Sprintf(`{"jsonrpc":"2.0","id":%v,"error":{"code":-32601,"message":"Method not found"}}`, tt.expected)
+		assert.Equal(string(h), string(i))
+	}
+}

-	g := RPCMethodNotFoundError("2")
-	h, _ := json.Marshal(g)
-	i := `{"jsonrpc":"2.0","id":"2","error":{"code":-32601,"message":"Method not found"}}`
-	assert.Equal(string(h), string(i))
+func TestUnmarshallResponses(t *testing.T) {
+	assert := assert.New(t)
+	cdc := amino.NewCodec()
+	for _, tt := range responseTests {
+		response := &RPCResponse{}
+		err := json.Unmarshal([]byte(fmt.Sprintf(`{"jsonrpc":"2.0","id":%v,"result":{"Value":"hello"}}`, tt.expected)), response)
+		assert.Nil(err)
+		a := NewRPCSuccessResponse(cdc, tt.id, &SampleResult{"hello"})
+		assert.Equal(*response, a)
+	}
+	response := &RPCResponse{}
+	err := json.Unmarshal([]byte(`{"jsonrpc":"2.0","id":true,"result":{"Value":"hello"}}`), response)
+	assert.NotNil(err)
 }

 func TestRPCError(t *testing.T) {
--- a/state/execution.go
+++ b/state/execution.go
@@ -226,8 +226,9 @@ func execBlockOnProxyApp(

 	commitInfo, byzVals := getBeginBlockValidatorInfo(block, lastValSet, stateDB)

-	// Begin block.
-	_, err := proxyAppConn.BeginBlockSync(abci.RequestBeginBlock{
+	// Begin block
+	var err error
+	abciResponses.BeginBlock, err = proxyAppConn.BeginBlockSync(abci.RequestBeginBlock{
 		Hash:                block.Hash(),
 		Header:              types.TM2PB.Header(&block.Header),
 		LastCommitInfo:      commitInfo,
@@ -417,8 +418,16 @@ func updateState(
 // Fire TxEvent for every tx.
 // NOTE: if Tendermint crashes before commit, some or all of these events may be published again.
 func fireEvents(logger log.Logger, eventBus types.BlockEventPublisher, block *types.Block, abciResponses *ABCIResponses) {
-	eventBus.PublishEventNewBlock(types.EventDataNewBlock{block})
-	eventBus.PublishEventNewBlockHeader(types.EventDataNewBlockHeader{block.Header})
+	eventBus.PublishEventNewBlock(types.EventDataNewBlock{
+		Block:            block,
+		ResultBeginBlock: *abciResponses.BeginBlock,
+		ResultEndBlock:   *abciResponses.EndBlock,
+	})
+	eventBus.PublishEventNewBlockHeader(types.EventDataNewBlockHeader{
+		Header:           block.Header,
+		ResultBeginBlock: *abciResponses.BeginBlock,
+		ResultEndBlock:   *abciResponses.EndBlock,
+	})

 	for i, tx := range block.Data.Txs {
 		eventBus.PublishEventTx(types.EventDataTx{types.TxResult{
--- a/state/state.go
+++ b/state/state.go
@@ -64,7 +64,8 @@ type State struct {
 	// Validators are persisted to the database separately every time they change,
 	// so we can query for historical validator sets.
 	// Note that if s.LastBlockHeight causes a valset change,
-	// we set s.LastHeightValidatorsChanged = s.LastBlockHeight + 1
+	// we set s.LastHeightValidatorsChanged = s.LastBlockHeight + 1 + 1
+	// Extra +1 due to nextValSet delay.
 	NextValidators              *types.ValidatorSet
 	Validators                  *types.ValidatorSet
 	LastValidators              *types.ValidatorSet
--- a/state/state_test.go
+++ b/state/state_test.go
@@ -3,9 +3,10 @@ package state
 import (
 	"bytes"
 	"fmt"
-	"github.com/tendermint/tendermint/libs/log"
 	"testing"

+	"github.com/tendermint/tendermint/libs/log"
+
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	abci "github.com/tendermint/tendermint/abci/types"
@@ -260,6 +261,27 @@ func TestOneValidatorChangesSaveLoad(t *testing.T) {
 	}
 }

+func TestStoreLoadValidatorsIncrementsAccum(t *testing.T) {
+	const valSetSize = 2
+	tearDown, stateDB, state := setupTestCase(t)
+	state.Validators = genValSet(valSetSize)
+	state.NextValidators = state.Validators.CopyIncrementAccum(1)
+	SaveState(stateDB, state)
+	defer tearDown(t)
+
+	nextHeight := state.LastBlockHeight + 1
+
+	v0, err := LoadValidators(stateDB, nextHeight)
+	assert.Nil(t, err)
+	acc0 := v0.Validators[0].Accum
+
+	v1, err := LoadValidators(stateDB, nextHeight+1)
+	assert.Nil(t, err)
+	acc1 := v1.Validators[0].Accum
+
+	assert.NotEqual(t, acc1, acc0, "expected Accum value to change between heights")
+}
+
 // TestValidatorChangesSaveLoad tests saving and loading a validator set with
 // changes.
 func TestManyValidatorChangesSaveLoad(t *testing.T) {
--- a/state/store.go
+++ b/state/store.go
@@ -89,7 +89,9 @@ func saveState(db dbm.DB, state State, key []byte) {
 	nextHeight := state.LastBlockHeight + 1
 	// If first block, save validators for block 1.
 	if nextHeight == 1 {
-		lastHeightVoteChanged := int64(1) // Due to Tendermint validator set changes being delayed 1 block.
+		// This extra logic due to Tendermint validator set changes being delayed 1 block.
+		// It may get overwritten due to InitChain validator updates.
+		lastHeightVoteChanged := int64(1)
 		saveValidatorsInfo(db, nextHeight, lastHeightVoteChanged, state.Validators)
 	}
 	// Save next validators.
@@ -105,8 +107,9 @@ func saveState(db dbm.DB, state State, key []byte) {
 // of the various ABCI calls during block processing.
 // It is persisted to disk for each height before calling Commit.
 type ABCIResponses struct {
-	DeliverTx []*abci.ResponseDeliverTx
-	EndBlock  *abci.ResponseEndBlock
+	DeliverTx  []*abci.ResponseDeliverTx
+	EndBlock   *abci.ResponseEndBlock
+	BeginBlock *abci.ResponseBeginBlock
 }

 // NewABCIResponses returns a new ABCIResponses
@@ -191,12 +194,14 @@ func LoadValidators(db dbm.DB, height int64) (*types.ValidatorSet, error) {
 				),
 			)
 		}
+		valInfo2.ValidatorSet.IncrementAccum(int(height - valInfo.LastHeightChanged)) // mutate
 		valInfo = valInfo2
 	}

 	return valInfo.ValidatorSet, nil
 }

+// CONTRACT: Returned ValidatorsInfo can be mutated.
 func loadValidatorsInfo(db dbm.DB, height int64) *ValidatorsInfo {
 	buf := db.Get(calcValidatorsKey(height))
 	if len(buf) == 0 {
@@ -215,18 +220,22 @@ func loadValidatorsInfo(db dbm.DB, height int64) *ValidatorsInfo {
 	return v
 }

-// saveValidatorsInfo persists the validator set for the next block to disk.
+// saveValidatorsInfo persists the validator set.
+// `height` is the effective height for which the validator is responsible for signing.
 // It should be called from s.Save(), right before the state itself is persisted.
 // If the validator set did not change after processing the latest block,
 // only the last height for which the validators changed is persisted.
-func saveValidatorsInfo(db dbm.DB, nextHeight, changeHeight int64, valSet *types.ValidatorSet) {
-	valInfo := &ValidatorsInfo{
-		LastHeightChanged: changeHeight,
+func saveValidatorsInfo(db dbm.DB, height, lastHeightChanged int64, valSet *types.ValidatorSet) {
+	if lastHeightChanged > height {
+		panic("LastHeightChanged cannot be greater than ValidatorsInfo height")
 	}
-	if changeHeight == nextHeight {
+	valInfo := &ValidatorsInfo{
+		LastHeightChanged: lastHeightChanged,
+	}
+	if lastHeightChanged == height {
 		valInfo.ValidatorSet = valSet
 	}
-	db.Set(calcValidatorsKey(nextHeight), valInfo.Bytes())
+	db.Set(calcValidatorsKey(height), valInfo.Bytes())
 }

 //-----------------------------------------------------------------------------
--- a/state/txindex/kv/kv.go
+++ b/state/txindex/kv/kv.go
@@ -207,8 +207,11 @@ func (txi *TxIndex) Search(q *query.Query) ([]*types.TxResult, error) {
 		i++
 	}

-	// sort by height by default
+	// sort by height & index by default
 	sort.Slice(results, func(i, j int) bool {
+		if results[i].Height == results[j].Height {
+			return results[i].Index < results[j].Index
+		}
 		return results[i].Height < results[j].Height
 	})

@@ -225,9 +228,10 @@ func lookForHash(conditions []query.Condition) (hash []byte, err error, ok bool)
 	return
 }

+// lookForHeight returns a height if there is an "height=X" condition.
 func lookForHeight(conditions []query.Condition) (height int64) {
 	for _, c := range conditions {
-		if c.Tag == types.TxHeightKey {
+		if c.Tag == types.TxHeightKey && c.Op == query.OpEqual {
 			return c.Operand.(int64)
 		}
 	}
@@ -408,9 +412,9 @@ LOOP:
 func startKey(c query.Condition, height int64) []byte {
 	var key string
 	if height > 0 {
-		key = fmt.Sprintf("%s/%v/%d", c.Tag, c.Operand, height)
+		key = fmt.Sprintf("%s/%v/%d/", c.Tag, c.Operand, height)
 	} else {
-		key = fmt.Sprintf("%s/%v", c.Tag, c.Operand)
+		key = fmt.Sprintf("%s/%v/", c.Tag, c.Operand)
 	}
 	return []byte(key)
 }
--- a/state/txindex/kv/kv_test.go
+++ b/state/txindex/kv/kv_test.go
@@ -73,6 +73,8 @@ func TestTxSearch(t *testing.T) {
 		{"account.number = 1 AND account.owner = 'Ivan'", 1},
 		// search by exact match (two tags)
 		{"account.number = 1 AND account.owner = 'Vlad'", 0},
+		// search using a prefix of the stored value
+		{"account.owner = 'Iv'", 0},
 		// search by range
 		{"account.number >= 1 AND account.number <= 5", 1},
 		// search by range (lower bound)
@@ -133,6 +135,7 @@ func TestTxSearchMultipleTxs(t *testing.T) {
 	})
 	txResult.Tx = types.Tx("Bob's account")
 	txResult.Height = 2
+	txResult.Index = 1
 	err := indexer.Index(txResult)
 	require.NoError(t, err)

@@ -142,14 +145,26 @@ func TestTxSearchMultipleTxs(t *testing.T) {
 	})
 	txResult2.Tx = types.Tx("Alice's account")
 	txResult2.Height = 1
+	txResult2.Index = 2
+
 	err = indexer.Index(txResult2)
 	require.NoError(t, err)

+	// indexed third (to test the order of transactions)
+	txResult3 := txResultWithTags([]cmn.KVPair{
+		{Key: []byte("account.number"), Value: []byte("3")},
+	})
+	txResult3.Tx = types.Tx("Jack's account")
+	txResult3.Height = 1
+	txResult3.Index = 1
+	err = indexer.Index(txResult3)
+	require.NoError(t, err)
+
 	results, err := indexer.Search(query.MustParse("account.number >= 1"))
 	assert.NoError(t, err)

-	require.Len(t, results, 2)
-	assert.Equal(t, []*types.TxResult{txResult2, txResult}, results)
+	require.Len(t, results, 3)
+	assert.Equal(t, []*types.TxResult{txResult3, txResult2, txResult}, results)
 }

 func TestIndexAllTags(t *testing.T) {
--- a/tools/tm-bench/transacter.go
+++ b/tools/tm-bench/transacter.go
@@ -191,7 +191,7 @@ func (t *transacter) sendLoop(connIndex int) {
 				c.SetWriteDeadline(now.Add(sendTimeout))
 				err = c.WriteJSON(rpctypes.RPCRequest{
 					JSONRPC: "2.0",
-					ID:      "tm-bench",
+					ID:      rpctypes.JSONRPCStringID("tm-bench"),
 					Method:  t.BroadcastTxMethod,
 					Params:  rawParamsJSON,
 				})
--- a/tools/tm-monitor/monitor/node_test.go
+++ b/tools/tm-monitor/monitor/node_test.go
@@ -34,7 +34,7 @@ func TestNodeNewBlockReceived(t *testing.T) {
 	n.SendBlocksTo(blockCh)

 	blockHeader := tmtypes.Header{Height: 5}
-	emMock.Call("eventCallback", &em.EventMetric{}, tmtypes.EventDataNewBlockHeader{blockHeader})
+	emMock.Call("eventCallback", &em.EventMetric{}, tmtypes.EventDataNewBlockHeader{Header: blockHeader})

 	assert.Equal(t, int64(5), n.Height)
 	assert.Equal(t, blockHeader, <-blockCh)
--- a/types/block.go
+++ b/types/block.go
@@ -275,6 +275,28 @@ func (b *Block) StringShort() string {
 	return fmt.Sprintf("Block#%v", b.Hash())
 }

+//-----------------------------------------------------------
+// These methods are for Protobuf Compatibility
+
+// Marshal returns the amino encoding.
+func (b *Block) Marshal() ([]byte, error) {
+	return cdc.MarshalBinaryBare(b)
+}
+
+// MarshalTo calls Marshal and copies to the given buffer.
+func (b *Block) MarshalTo(data []byte) (int, error) {
+	bs, err := b.Marshal()
+	if err != nil {
+		return -1, err
+	}
+	return copy(data, bs), nil
+}
+
+// Unmarshal deserializes from amino encoded form.
+func (b *Block) Unmarshal(bs []byte) error {
+	return cdc.UnmarshalBinaryBare(bs, b)
+}
+
 //-----------------------------------------------------------------------------

 // MaxDataBytes returns the maximum size of block's data.
--- a/types/block_meta.go
+++ b/types/block_meta.go
@@ -13,3 +13,31 @@ func NewBlockMeta(block *Block, blockParts *PartSet) *BlockMeta {
 		Header:  block.Header,
 	}
 }
+
+//-----------------------------------------------------------
+// These methods are for Protobuf Compatibility
+
+// Size returns the size of the amino encoding, in bytes.
+func (bm *BlockMeta) Size() int {
+	bs, _ := bm.Marshal()
+	return len(bs)
+}
+
+// Marshal returns the amino encoding.
+func (bm *BlockMeta) Marshal() ([]byte, error) {
+	return cdc.MarshalBinaryBare(bm)
+}
+
+// MarshalTo calls Marshal and copies to the given buffer.
+func (bm *BlockMeta) MarshalTo(data []byte) (int, error) {
+	bs, err := bm.Marshal()
+	if err != nil {
+		return -1, err
+	}
+	return copy(data, bs), nil
+}
+
+// Unmarshal deserializes from amino encoded form.
+func (bm *BlockMeta) Unmarshal(bs []byte) error {
+	return cdc.UnmarshalBinaryBare(bs, bm)
+}
--- a/types/event_bus.go
+++ b/types/event_bus.go
@@ -71,12 +71,48 @@ func (b *EventBus) Publish(eventType string, eventData TMEventData) error {
 	return nil
 }

+func (b *EventBus) validateAndStringifyTags(tags []cmn.KVPair, logger log.Logger) map[string]string {
+	result := make(map[string]string)
+	for _, tag := range tags {
+		// basic validation
+		if len(tag.Key) == 0 {
+			logger.Debug("Got tag with an empty key (skipping)", "tag", tag)
+			continue
+		}
+		result[string(tag.Key)] = string(tag.Value)
+	}
+	return result
+}
+
 func (b *EventBus) PublishEventNewBlock(data EventDataNewBlock) error {
-	return b.Publish(EventNewBlock, data)
+	// no explicit deadline for publishing events
+	ctx := context.Background()
+
+	resultTags := append(data.ResultBeginBlock.Tags, data.ResultEndBlock.Tags...)
+	tags := b.validateAndStringifyTags(resultTags, b.Logger.With("block", data.Block.StringShort()))
+
+	// add predefined tags
+	logIfTagExists(EventTypeKey, tags, b.Logger)
+	tags[EventTypeKey] = EventNewBlock
+
+	b.pubsub.PublishWithTags(ctx, data, tmpubsub.NewTagMap(tags))
+	return nil
 }

 func (b *EventBus) PublishEventNewBlockHeader(data EventDataNewBlockHeader) error {
-	return b.Publish(EventNewBlockHeader, data)
+	// no explicit deadline for publishing events
+	ctx := context.Background()
+
+	resultTags := append(data.ResultBeginBlock.Tags, data.ResultEndBlock.Tags...)
+	// TODO: Create StringShort method for Header and use it in logger.
+	tags := b.validateAndStringifyTags(resultTags, b.Logger.With("header", data.Header))
+
+	// add predefined tags
+	logIfTagExists(EventTypeKey, tags, b.Logger)
+	tags[EventTypeKey] = EventNewBlockHeader
+
+	b.pubsub.PublishWithTags(ctx, data, tmpubsub.NewTagMap(tags))
+	return nil
 }

 func (b *EventBus) PublishEventVote(data EventDataVote) error {
@@ -94,17 +130,7 @@ func (b *EventBus) PublishEventTx(data EventDataTx) error {
 	// no explicit deadline for publishing events
 	ctx := context.Background()

-	tags := make(map[string]string)
-
-	// validate and fill tags from tx result
-	for _, tag := range data.Result.Tags {
-		// basic validation
-		if len(tag.Key) == 0 {
-			b.Logger.Info("Got tag with an empty key (skipping)", "tag", tag, "tx", data.Tx)
-			continue
-		}
-		tags[string(tag.Key)] = string(tag.Value)
-	}
+	tags := b.validateAndStringifyTags(data.Result.Tags, b.Logger.With("tx", data.Tx))

 	// add predefined tags
 	logIfTagExists(EventTypeKey, tags, b.Logger)
--- a/types/event_bus_test.go
+++ b/types/event_bus_test.go
@@ -58,6 +58,90 @@ func TestEventBusPublishEventTx(t *testing.T) {
 	}
 }

+func TestEventBusPublishEventNewBlock(t *testing.T) {
+	eventBus := NewEventBus()
+	err := eventBus.Start()
+	require.NoError(t, err)
+	defer eventBus.Stop()
+
+	block := MakeBlock(0, []Tx{}, nil, []Evidence{})
+	resultBeginBlock := abci.ResponseBeginBlock{Tags: []cmn.KVPair{{Key: []byte("baz"), Value: []byte("1")}}}
+	resultEndBlock := abci.ResponseEndBlock{Tags: []cmn.KVPair{{Key: []byte("foz"), Value: []byte("2")}}}
+
+	txEventsCh := make(chan interface{})
+
+	// PublishEventNewBlock adds the tm.event tag, so the query below should work
+	query := "tm.event='NewBlock' AND baz=1 AND foz=2"
+	err = eventBus.Subscribe(context.Background(), "test", tmquery.MustParse(query), txEventsCh)
+	require.NoError(t, err)
+
+	done := make(chan struct{})
+	go func() {
+		for e := range txEventsCh {
+			edt := e.(EventDataNewBlock)
+			assert.Equal(t, block, edt.Block)
+			assert.Equal(t, resultBeginBlock, edt.ResultBeginBlock)
+			assert.Equal(t, resultEndBlock, edt.ResultEndBlock)
+			close(done)
+		}
+	}()
+
+	err = eventBus.PublishEventNewBlock(EventDataNewBlock{
+		Block:            block,
+		ResultBeginBlock: resultBeginBlock,
+		ResultEndBlock:   resultEndBlock,
+	})
+	assert.NoError(t, err)
+
+	select {
+	case <-done:
+	case <-time.After(1 * time.Second):
+		t.Fatal("did not receive a block after 1 sec.")
+	}
+}
+
+func TestEventBusPublishEventNewBlockHeader(t *testing.T) {
+	eventBus := NewEventBus()
+	err := eventBus.Start()
+	require.NoError(t, err)
+	defer eventBus.Stop()
+
+	block := MakeBlock(0, []Tx{}, nil, []Evidence{})
+	resultBeginBlock := abci.ResponseBeginBlock{Tags: []cmn.KVPair{{Key: []byte("baz"), Value: []byte("1")}}}
+	resultEndBlock := abci.ResponseEndBlock{Tags: []cmn.KVPair{{Key: []byte("foz"), Value: []byte("2")}}}
+
+	txEventsCh := make(chan interface{})
+
+	// PublishEventNewBlockHeader adds the tm.event tag, so the query below should work
+	query := "tm.event='NewBlockHeader' AND baz=1 AND foz=2"
+	err = eventBus.Subscribe(context.Background(), "test", tmquery.MustParse(query), txEventsCh)
+	require.NoError(t, err)
+
+	done := make(chan struct{})
+	go func() {
+		for e := range txEventsCh {
+			edt := e.(EventDataNewBlockHeader)
+			assert.Equal(t, block.Header, edt.Header)
+			assert.Equal(t, resultBeginBlock, edt.ResultBeginBlock)
+			assert.Equal(t, resultEndBlock, edt.ResultEndBlock)
+			close(done)
+		}
+	}()
+
+	err = eventBus.PublishEventNewBlockHeader(EventDataNewBlockHeader{
+		Header:           block.Header,
+		ResultBeginBlock: resultBeginBlock,
+		ResultEndBlock:   resultEndBlock,
+	})
+	assert.NoError(t, err)
+
+	select {
+	case <-done:
+	case <-time.After(1 * time.Second):
+		t.Fatal("did not receive a block header after 1 sec.")
+	}
+}
+
 func TestEventBusPublish(t *testing.T) {
 	eventBus := NewEventBus()
 	err := eventBus.Start()
--- a/types/events.go
+++ b/types/events.go
@@ -4,6 +4,7 @@ import (
 	"fmt"

 	amino "github.com/tendermint/go-amino"
+	abci "github.com/tendermint/tendermint/abci/types"
 	tmpubsub "github.com/tendermint/tendermint/libs/pubsub"
 	tmquery "github.com/tendermint/tendermint/libs/pubsub/query"
 )
@@ -56,11 +57,17 @@ func RegisterEventDatas(cdc *amino.Codec) {

 type EventDataNewBlock struct {
 	Block *Block `json:"block"`
+
+	ResultBeginBlock abci.ResponseBeginBlock `json:"result_begin_block"`
+	ResultEndBlock   abci.ResponseEndBlock   `json:"result_end_block"`
 }

 // light weight event for benchmarking
 type EventDataNewBlockHeader struct {
 	Header Header `json:"header"`
+
+	ResultBeginBlock abci.ResponseBeginBlock `json:"result_begin_block"`
+	ResultEndBlock   abci.ResponseEndBlock   `json:"result_end_block"`
 }

 // All txs fire EventDataTx
@@ -100,7 +107,7 @@ type EventDataCompleteProposal struct {
 	Round  int    `json:"round"`
 	Step   string `json:"step"`

-	BlockID         BlockID `json:"block_id"`
+	BlockID BlockID `json:"block_id"`
 }

 type EventDataVote struct {
--- a/types/part_set.go
+++ b/types/part_set.go
@@ -200,6 +200,9 @@ func (ps *PartSet) Total() int {
 }

 func (ps *PartSet) AddPart(part *Part) (bool, error) {
+	if ps == nil {
+		return false, nil
+	}
 	ps.mtx.Lock()
 	defer ps.mtx.Unlock()

--- a/types/validator_set.go
+++ b/types/validator_set.go
@@ -62,7 +62,11 @@ func (vals *ValidatorSet) CopyIncrementAccum(times int) *ValidatorSet {

 // IncrementAccum increments accum of each validator and updates the
 // proposer. Panics if validator set is empty.
+// `times` must be positive.
 func (vals *ValidatorSet) IncrementAccum(times int) {
+	if times <= 0 {
+		panic("Cannot call IncrementAccum with non-positive times")
+	}

 	// Add VotingPower * times to each validator and order into heap.
 	validatorsHeap := cmn.NewHeap()
--- a/types/validator_set_test.go
+++ b/types/validator_set_test.go
@@ -86,6 +86,19 @@ func TestCopy(t *testing.T) {
 	}
 }

+// Test that IncrementAccum requires positive times.
+func TestIncrementAccumPositiveTimes(t *testing.T) {
+	vset := NewValidatorSet([]*Validator{
+		newValidator([]byte("foo"), 1000),
+		newValidator([]byte("bar"), 300),
+		newValidator([]byte("baz"), 330),
+	})
+
+	assert.Panics(t, func() { vset.IncrementAccum(-1) })
+	assert.Panics(t, func() { vset.IncrementAccum(0) })
+	vset.IncrementAccum(1)
+}
+
 func BenchmarkValidatorSetCopy(b *testing.B) {
 	b.StopTimer()
 	vset := NewValidatorSet([]*Validator{})
@@ -239,7 +252,7 @@ func TestProposerSelection3(t *testing.T) {
 		mod := (cmn.RandInt() % 5) + 1
 		if cmn.RandInt()%mod > 0 {
 			// sometimes its up to 5
-			times = cmn.RandInt() % 5
+			times = (cmn.RandInt() % 4) + 1
 		}
 		vset.IncrementAccum(times)

--- a/version/version.go
+++ b/version/version.go
@@ -18,7 +18,7 @@ const (
 	// TMCoreSemVer is the current version of Tendermint Core.
 	// It's the Semantic Version of the software.
 	// Must be a string because scripts like dist.sh read this file.
-	TMCoreSemVer = "0.26.3"
+	TMCoreSemVer = "0.26.4"

 	// ABCISemVer is the semantic version of the ABCI library
 	ABCISemVer  = "0.15.0"