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", fmt.Sprintf("%X", 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", fmt.Sprintf("%X", 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) csParams := types.TM2PB.ConsensusParams(h.genDoc.ConsensusParams) req := abci.RequestInitChain{ Time: h.genDoc.GenesisTime, ChainId: h.genDoc.ChainID, InitialHeight: h.genDoc.InitialHeight, ConsensusParams: csParams, 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 = types.UpdateConsensusParams(state.ConsensusParams, 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)) } }