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package consensus
import (
"bytes"
"context"
"fmt"
"hash/crc32"
"io"
"reflect"
"time"
abci "github.com/tendermint/tendermint/abci/types"
"github.com/tendermint/tendermint/crypto/merkle"
"github.com/tendermint/tendermint/libs/log"
"github.com/tendermint/tendermint/proxy"
sm "github.com/tendermint/tendermint/state"
"github.com/tendermint/tendermint/types"
)
var crc32c = crc32.MakeTable(crc32.Castagnoli)
// Functionality to replay blocks and messages on recovery from a crash.
// There are two general failure scenarios:
//
// 1. failure during consensus
// 2. failure while applying the block
//
// The former is handled by the WAL, the latter by the proxyApp Handshake on
// restart, which ultimately hands off the work to the WAL.
//-----------------------------------------
// 1. Recover from failure during consensus
// (by replaying messages from the WAL)
//-----------------------------------------
// Unmarshal and apply a single message to the consensus state as if it were
// received in receiveRoutine. Lines that start with "#" are ignored.
// NOTE: receiveRoutine should not be running.
func (cs *State) readReplayMessage(msg *TimedWALMessage, newStepSub types.Subscription) error {
// Skip meta messages which exist for demarcating boundaries.
if _, ok := msg.Msg.(EndHeightMessage); ok {
return nil
}
// for logging
switch m := msg.Msg.(type) {
case types.EventDataRoundState:
cs.Logger.Info("Replay: New Step", "height", m.Height, "round", m.Round, "step", m.Step)
// these are playback checks
ticker := time.After(time.Second * 2)
if newStepSub != nil {
select {
case stepMsg := <-newStepSub.Out():
m2 := stepMsg.Data().(types.EventDataRoundState)
if m.Height != m2.Height || m.Round != m2.Round || m.Step != m2.Step {
return fmt.Errorf("roundState mismatch. Got %v; Expected %v", m2, m)
}
case <-newStepSub.Cancelled():
return fmt.Errorf("failed to read off newStepSub.Out(). newStepSub was cancelled")
case <-ticker:
return fmt.Errorf("failed to read off newStepSub.Out()")
}
}
case msgInfo:
peerID := m.PeerID
if peerID == "" {
peerID = "local"
}
switch msg := m.Msg.(type) {
case *ProposalMessage:
p := msg.Proposal
cs.Logger.Info("Replay: Proposal", "height", p.Height, "round", p.Round, "header",
p.BlockID.PartSetHeader, "pol", p.POLRound, "peer", peerID)
case *BlockPartMessage:
cs.Logger.Info("Replay: BlockPart", "height", msg.Height, "round", msg.Round, "peer", peerID)
case *VoteMessage:
v := msg.Vote
cs.Logger.Info("Replay: Vote", "height", v.Height, "round", v.Round, "type", v.Type,
"blockID", v.BlockID, "peer", peerID)
}
cs.handleMsg(m)
case timeoutInfo:
cs.Logger.Info("Replay: Timeout", "height", m.Height, "round", m.Round, "step", m.Step, "dur", m.Duration)
cs.handleTimeout(m, cs.RoundState)
default:
return fmt.Errorf("replay: Unknown TimedWALMessage type: %v", reflect.TypeOf(msg.Msg))
}
return nil
}
// Replay only those messages since the last block. `timeoutRoutine` should
// run concurrently to read off tickChan.
func (cs *State) catchupReplay(csHeight int64) error {
// Set replayMode to true so we don't log signing errors.
cs.replayMode = true
defer func() { cs.replayMode = false }()
// Ensure that #ENDHEIGHT for this height doesn't exist.
// NOTE: This is just a sanity check. As far as we know things work fine
// without it, and Handshake could reuse State if it weren't for
// this check (since we can crash after writing #ENDHEIGHT).
//
// Ignore data corruption errors since this is a sanity check.
gr, found, err := cs.wal.SearchForEndHeight(csHeight, &WALSearchOptions{IgnoreDataCorruptionErrors: true})
if err != nil {
return err
}
if gr != nil {
if err := gr.Close(); err != nil {
return err
}
}
if found {
return fmt.Errorf("wal should not contain #ENDHEIGHT %d", csHeight)
}
// Search for last height marker.
//
// Ignore data corruption errors in previous heights because we only care about last height
if csHeight < cs.state.InitialHeight {
return fmt.Errorf("cannot replay height %v, below initial height %v", csHeight, cs.state.InitialHeight)
}
endHeight := csHeight - 1
if csHeight == cs.state.InitialHeight {
endHeight = 0
}
gr, found, err = cs.wal.SearchForEndHeight(endHeight, &WALSearchOptions{IgnoreDataCorruptionErrors: true})
if err == io.EOF {
cs.Logger.Error("Replay: wal.group.Search returned EOF", "#ENDHEIGHT", endHeight)
} else if err != nil {
return err
}
if !found {
return fmt.Errorf("cannot replay height %d. WAL does not contain #ENDHEIGHT for %d", csHeight, endHeight)
}
defer gr.Close()
cs.Logger.Info("Catchup by replaying consensus messages", "height", csHeight)
var msg *TimedWALMessage
dec := WALDecoder{gr}
LOOP:
for {
msg, err = dec.Decode()
switch {
case err == io.EOF:
break LOOP
case IsDataCorruptionError(err):
cs.Logger.Error("data has been corrupted in last height of consensus WAL", "err", err, "height", csHeight)
return err
case err != nil:
return err
}
// NOTE: since the priv key is set when the msgs are received
// it will attempt to eg double sign but we can just ignore it
// since the votes will be replayed and we'll get to the next step
if err := cs.readReplayMessage(msg, nil); err != nil {
return err
}
}
cs.Logger.Info("Replay: Done")
return nil
}
//--------------------------------------------------------------------------------
// Parses marker lines of the form:
// #ENDHEIGHT: 12345
/*
func makeHeightSearchFunc(height int64) auto.SearchFunc {
return func(line string) (int, error) {
line = strings.TrimRight(line, "\n")
parts := strings.Split(line, " ")
if len(parts) != 2 {
return -1, errors.New("line did not have 2 parts")
}
i, err := strconv.Atoi(parts[1])
if err != nil {
return -1, errors.New("failed to parse INFO: " + err.Error())
}
if height < i {
return 1, nil
} else if height == i {
return 0, nil
} else {
return -1, nil
}
}
}*/
//---------------------------------------------------
// 2. Recover from failure while applying the block.
// (by handshaking with the app to figure out where
// we were last, and using the WAL to recover there.)
//---------------------------------------------------
type Handshaker struct {
stateStore sm.Store
initialState sm.State
store sm.BlockStore
eventBus types.BlockEventPublisher
genDoc *types.GenesisDoc
logger log.Logger
nBlocks int // number of blocks applied to the state
}
func NewHandshaker(stateStore sm.Store, state sm.State,
store sm.BlockStore, genDoc *types.GenesisDoc) *Handshaker {
return &Handshaker{
stateStore: stateStore,
initialState: state,
store: store,
eventBus: types.NopEventBus{},
genDoc: genDoc,
logger: log.NewNopLogger(),
nBlocks: 0,
}
}
func (h *Handshaker) SetLogger(l log.Logger) {
h.logger = l
}
// SetEventBus - sets the event bus for publishing block related events.
// If not called, it defaults to types.NopEventBus.
func (h *Handshaker) SetEventBus(eventBus types.BlockEventPublisher) {
h.eventBus = eventBus
}
// NBlocks returns the number of blocks applied to the state.
func (h *Handshaker) NBlocks() int {
return h.nBlocks
}
// TODO: retry the handshake/replay if it fails ?
func (h *Handshaker) Handshake(proxyApp proxy.AppConns) error {
// Handshake is done via ABCI Info on the query conn.
res, err := proxyApp.Query().InfoSync(context.Background(), proxy.RequestInfo)
if err != nil {
return fmt.Errorf("error calling Info: %v", err)
}
blockHeight := res.LastBlockHeight
if blockHeight < 0 {
return fmt.Errorf("got a negative last block height (%d) from the app", blockHeight)
}
appHash := res.LastBlockAppHash
h.logger.Info("ABCI Handshake App Info",
"height", blockHeight,
"hash", appHash,
"software-version", res.Version,
"protocol-version", res.AppVersion,
)
// Only set the version if there is no existing state.
if h.initialState.LastBlockHeight == 0 {
h.initialState.Version.Consensus.App = res.AppVersion
}
// Replay blocks up to the latest in the blockstore.
_, err = h.ReplayBlocks(h.initialState, appHash, blockHeight, proxyApp)
if err != nil {
return fmt.Errorf("error on replay: %v", err)
}
h.logger.Info("Completed ABCI Handshake - Tendermint and App are synced",
"appHeight", blockHeight, "appHash", appHash)
// TODO: (on restart) replay mempool
return nil
}
// ReplayBlocks replays all blocks since appBlockHeight and ensures the result
// matches the current state.
// Returns the final AppHash or an error.
func (h *Handshaker) ReplayBlocks(
state sm.State,
appHash []byte,
appBlockHeight int64,
proxyApp proxy.AppConns,
) ([]byte, error) {
storeBlockBase := h.store.Base()
storeBlockHeight := h.store.Height()
stateBlockHeight := state.LastBlockHeight
h.logger.Info(
"ABCI Replay Blocks",
"appHeight",
appBlockHeight,
"storeHeight",
storeBlockHeight,
"stateHeight",
stateBlockHeight)
// If appBlockHeight == 0 it means that we are at genesis and hence should send InitChain.
if appBlockHeight == 0 {
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)
pbParams := h.genDoc.ConsensusParams.ToProto()
req := abci.RequestInitChain{
Time: h.genDoc.GenesisTime,
ChainId: h.genDoc.ChainID,
InitialHeight: h.genDoc.InitialHeight,
ConsensusParams: &pbParams,
Validators: nextVals,
AppStateBytes: h.genDoc.AppState,
}
res, err := proxyApp.Consensus().InitChainSync(context.Background(), req)
if err != nil {
return nil, err
}
appHash = res.AppHash
if stateBlockHeight == 0 { // we only update state when we are in initial state
// If the app did not return an app hash, we keep the one set from the genesis doc in
// the state. We don't set appHash since we don't want the genesis doc app hash
// recorded in the genesis block. We should probably just remove GenesisDoc.AppHash.
if len(res.AppHash) > 0 {
state.AppHash = res.AppHash
}
// If the app returned validators or consensus params, update the state.
if len(res.Validators) > 0 {
vals, err := types.PB2TM.ValidatorUpdates(res.Validators)
if err != nil {
return nil, err
}
state.Validators = types.NewValidatorSet(vals)
state.NextValidators = types.NewValidatorSet(vals).CopyIncrementProposerPriority(1)
} else if len(h.genDoc.Validators) == 0 {
// If validator set is not set in genesis and still empty after InitChain, exit.
return nil, fmt.Errorf("validator set is nil in genesis and still empty after InitChain")
}
if res.ConsensusParams != nil {
state.ConsensusParams = state.ConsensusParams.UpdateConsensusParams(res.ConsensusParams)
state.Version.Consensus.App = state.ConsensusParams.Version.AppVersion
}
// We update the last results hash with the empty hash, to conform with RFC-6962.
state.LastResultsHash = merkle.HashFromByteSlices(nil)
if err := h.stateStore.Save(state); err != nil {
return nil, err
}
}
}
// First handle edge cases and constraints on the storeBlockHeight and storeBlockBase.
switch {
case storeBlockHeight == 0:
assertAppHashEqualsOneFromState(appHash, state)
return appHash, nil
case appBlockHeight == 0 && state.InitialHeight < storeBlockBase:
// the app has no state, and the block store is truncated above the initial height
return appHash, sm.ErrAppBlockHeightTooLow{AppHeight: appBlockHeight, StoreBase: storeBlockBase}
case appBlockHeight > 0 && appBlockHeight < storeBlockBase-1:
// the app is too far behind truncated store (can be 1 behind since we replay the next)
return appHash, sm.ErrAppBlockHeightTooLow{AppHeight: appBlockHeight, StoreBase: storeBlockBase}
case storeBlockHeight < appBlockHeight:
// the app should never be ahead of the store (but this is under app's control)
return appHash, sm.ErrAppBlockHeightTooHigh{CoreHeight: storeBlockHeight, AppHeight: appBlockHeight}
case storeBlockHeight < stateBlockHeight:
// the state should never be ahead of the store (this is under tendermint's control)
panic(fmt.Sprintf("StateBlockHeight (%d) > StoreBlockHeight (%d)", stateBlockHeight, storeBlockHeight))
case storeBlockHeight > stateBlockHeight+1:
// store should be at most one ahead of the state (this is under tendermint's control)
panic(fmt.Sprintf("StoreBlockHeight (%d) > StateBlockHeight + 1 (%d)", storeBlockHeight, stateBlockHeight+1))
}
var err error
// Now either store is equal to state, or one ahead.
// For each, consider all cases of where the app could be, given app <= store
if storeBlockHeight == stateBlockHeight {
// Tendermint ran Commit and saved the state.
// Either the app is asking for replay, or we're all synced up.
if appBlockHeight < storeBlockHeight {
// the app is behind, so replay blocks, but no need to go through WAL (state is already synced to store)
return h.replayBlocks(state, proxyApp, appBlockHeight, storeBlockHeight, false)
} else if appBlockHeight == storeBlockHeight {
// We're good!
assertAppHashEqualsOneFromState(appHash, state)
return appHash, nil
}
} else if storeBlockHeight == stateBlockHeight+1 {
// We saved the block in the store but haven't updated the state,
// so we'll need to replay a block using the WAL.
switch {
case appBlockHeight < stateBlockHeight:
// the app is further behind than it should be, so replay blocks
// but leave the last block to go through the WAL
return h.replayBlocks(state, proxyApp, appBlockHeight, storeBlockHeight, true)
case appBlockHeight == stateBlockHeight:
// We haven't run Commit (both the state and app are one block behind),
// so replayBlock with the real app.
// NOTE: We could instead use the cs.WAL on cs.Start,
// but we'd have to allow the WAL to replay a block that wrote it's #ENDHEIGHT
h.logger.Info("Replay last block using real app")
state, err = h.replayBlock(state, storeBlockHeight, proxyApp.Consensus())
return state.AppHash, err
case appBlockHeight == storeBlockHeight:
// We ran Commit, but didn't save the state, so replayBlock with mock app.
abciResponses, err := h.stateStore.LoadABCIResponses(storeBlockHeight)
if err != nil {
return nil, err
}
mockApp := newMockProxyApp(appHash, abciResponses)
h.logger.Info("Replay last block using mock app")
state, err = h.replayBlock(state, storeBlockHeight, mockApp)
return state.AppHash, err
}
}
panic(fmt.Sprintf("uncovered case! appHeight: %d, storeHeight: %d, stateHeight: %d",
appBlockHeight, storeBlockHeight, stateBlockHeight))
}
func (h *Handshaker) replayBlocks(
state sm.State,
proxyApp proxy.AppConns,
appBlockHeight,
storeBlockHeight int64,
mutateState bool) ([]byte, error) {
// App is further behind than it should be, so we need to replay blocks.
// We replay all blocks from appBlockHeight+1.
//
// Note that we don't have an old version of the state,
// so we by-pass state validation/mutation using sm.ExecCommitBlock.
// This also means we won't be saving validator sets if they change during this period.
// TODO: Load the historical information to fix this and just use state.ApplyBlock
//
// If mutateState == true, the final block is replayed with h.replayBlock()
var appHash []byte
var err error
finalBlock := storeBlockHeight
if mutateState {
finalBlock--
}
firstBlock := appBlockHeight + 1
if firstBlock == 1 {
firstBlock = state.InitialHeight
}
for i := firstBlock; i <= finalBlock; i++ {
h.logger.Info("Applying block", "height", i)
block := h.store.LoadBlock(i)
// Extra check to ensure the app was not changed in a way it shouldn't have.
if len(appHash) > 0 {
assertAppHashEqualsOneFromBlock(appHash, block)
}
appHash, err = sm.ExecCommitBlock(proxyApp.Consensus(), block, h.logger, h.stateStore, h.genDoc.InitialHeight)
if err != nil {
return nil, err
}
h.nBlocks++
}
if mutateState {
// sync the final block
state, err = h.replayBlock(state, storeBlockHeight, proxyApp.Consensus())
if err != nil {
return nil, err
}
appHash = state.AppHash
}
assertAppHashEqualsOneFromState(appHash, state)
return appHash, nil
}
// ApplyBlock on the proxyApp with the last block.
func (h *Handshaker) replayBlock(state sm.State, height int64, proxyApp proxy.AppConnConsensus) (sm.State, error) {
block := h.store.LoadBlock(height)
meta := h.store.LoadBlockMeta(height)
// Use stubs for both mempool and evidence pool since no transactions nor
// evidence are needed here - block already exists.
blockExec := sm.NewBlockExecutor(h.stateStore, h.logger, proxyApp, emptyMempool{}, sm.EmptyEvidencePool{})
blockExec.SetEventBus(h.eventBus)
var err error
state, _, err = blockExec.ApplyBlock(state, meta.BlockID, block)
if err != nil {
return sm.State{}, err
}
h.nBlocks++
return state, nil
}
func assertAppHashEqualsOneFromBlock(appHash []byte, block *types.Block) {
if !bytes.Equal(appHash, block.AppHash) {
panic(fmt.Sprintf(`block.AppHash does not match AppHash after replay. Got %X, expected %X.
Block: %v
`,
appHash, block.AppHash, block))
}
}
func assertAppHashEqualsOneFromState(appHash []byte, state sm.State) {
if !bytes.Equal(appHash, state.AppHash) {
panic(fmt.Sprintf(`state.AppHash does not match AppHash after replay. Got
%X, expected %X.
State: %v
Did you reset Tendermint without resetting your application's data?`,
appHash, state.AppHash, state))
}
}