package consensus import ( "bytes" "errors" "fmt" "io" "reflect" "strconv" "strings" "time" abci "github.com/tendermint/abci/types" wire "github.com/tendermint/go-wire" auto "github.com/tendermint/tmlibs/autofile" cmn "github.com/tendermint/tmlibs/common" "github.com/tendermint/tmlibs/log" "github.com/tendermint/tendermint/proxy" sm "github.com/tendermint/tendermint/state" "github.com/tendermint/tendermint/types" "github.com/tendermint/tendermint/version" ) // Functionality to replay blocks and messages on recovery from a crash. // There are two general failure scenarios: failure during consensus, and 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. //----------------------------------------- // 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 *ConsensusState) readReplayMessage(msgBytes []byte, newStepCh chan interface{}) error { // Skip over empty and meta lines if len(msgBytes) == 0 || msgBytes[0] == '#' { return nil } var err error var msg TimedWALMessage wire.ReadJSON(&msg, msgBytes, &err) if err != nil { fmt.Println("MsgBytes:", msgBytes, string(msgBytes)) return fmt.Errorf("Error reading json data: %v", err) } // 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 newStepCh != nil { select { case mi := <-newStepCh: m2 := mi.(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 <-ticker: return fmt.Errorf("Failed to read off newStepCh") } } case msgInfo: peerKey := m.PeerKey if peerKey == "" { peerKey = "local" } switch msg := m.Msg.(type) { case *ProposalMessage: p := msg.Proposal cs.Logger.Info("Replay: Proposal", "height", p.Height, "round", p.Round, "header", p.BlockPartsHeader, "pol", p.POLRound, "peer", peerKey) case *BlockPartMessage: cs.Logger.Info("Replay: BlockPart", "height", msg.Height, "round", msg.Round, "peer", peerKey) case *VoteMessage: v := msg.Vote cs.Logger.Info("Replay: Vote", "height", v.Height, "round", v.Round, "type", v.Type, "blockID", v.BlockID, "peer", peerKey) } 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 *ConsensusState) catchupReplay(csHeight int) error { // set replayMode 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 ConsensusState if it weren't for this check (since we can crash after writing ENDHEIGHT). gr, found, err := cs.wal.group.Search("#ENDHEIGHT: ", makeHeightSearchFunc(csHeight)) if gr != nil { gr.Close() } if found { return errors.New(cmn.Fmt("WAL should not contain #ENDHEIGHT %d.", csHeight)) } // Search for last height marker gr, found, err = cs.wal.group.Search("#ENDHEIGHT: ", makeHeightSearchFunc(csHeight-1)) if err == io.EOF { cs.Logger.Error("Replay: wal.group.Search returned EOF", "#ENDHEIGHT", csHeight-1) } else if err != nil { return err } else { defer gr.Close() } if !found { return errors.New(cmn.Fmt("Cannot replay height %d. WAL does not contain #ENDHEIGHT for %d.", csHeight, csHeight-1)) } cs.Logger.Info("Catchup by replaying consensus messages", "height", csHeight) for { line, err := gr.ReadLine() if err != nil { if err == io.EOF { break } else { 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([]byte(line), nil); err != nil { return err } } cs.Logger.Info("Replay: Done") return nil } //-------------------------------------------------------------------------------- // Parses marker lines of the form: // #ENDHEIGHT: 12345 func makeHeightSearchFunc(height int) 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 } } } //---------------------------------------------- // Recover from failure during block processing // by handshaking with the app to figure out where // we were last and using the WAL to recover there type Handshaker struct { state *sm.State store types.BlockStore logger log.Logger nBlocks int // number of blocks applied to the state } func NewHandshaker(state *sm.State, store types.BlockStore) *Handshaker { return &Handshaker{state, store, log.NewNopLogger(), 0} } func (h *Handshaker) SetLogger(l log.Logger) { h.logger = l } 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 info request on the query conn res, err := proxyApp.Query().InfoSync(abci.RequestInfo{version.Version}) if err != nil { return errors.New(cmn.Fmt("Error calling Info: %v", err)) } blockHeight := int(res.LastBlockHeight) // XXX: beware overflow appHash := res.LastBlockAppHash h.logger.Info("ABCI Handshake", "appHeight", blockHeight, "appHash", fmt.Sprintf("%X", appHash)) // TODO: check version // replay blocks up to the latest in the blockstore _, err = h.ReplayBlocks(appHash, blockHeight, proxyApp) if err != nil { return errors.New(cmn.Fmt("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 } // Replay all blocks since appBlockHeight and ensure the result matches the current state. // Returns the final AppHash or an error func (h *Handshaker) ReplayBlocks(appHash []byte, appBlockHeight int, proxyApp proxy.AppConns) ([]byte, error) { storeBlockHeight := h.store.Height() stateBlockHeight := h.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 := types.TM2PB.Validators(h.state.Validators) proxyApp.Consensus().InitChainSync(abci.RequestInitChain{validators}) } // First handle edge cases and constraints on the storeBlockHeight if storeBlockHeight == 0 { return appHash, h.checkAppHash(appHash) } else if storeBlockHeight < appBlockHeight { // the app should never be ahead of the store (but this is under app's control) return appHash, sm.ErrAppBlockHeightTooHigh{storeBlockHeight, appBlockHeight} } else if storeBlockHeight < stateBlockHeight { // the state should never be ahead of the store (this is under tendermint's control) cmn.PanicSanity(cmn.Fmt("StateBlockHeight (%d) > StoreBlockHeight (%d)", stateBlockHeight, storeBlockHeight)) } else if storeBlockHeight > stateBlockHeight+1 { // store should be at most one ahead of the state (this is under tendermint's control) cmn.PanicSanity(cmn.Fmt("StoreBlockHeight (%d) > StateBlockHeight + 1 (%d)", storeBlockHeight, stateBlockHeight+1)) } // 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(proxyApp, appBlockHeight, storeBlockHeight, false) } else if appBlockHeight == storeBlockHeight { // We're good! return appHash, h.checkAppHash(appHash) } } 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. if 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(proxyApp, appBlockHeight, storeBlockHeight, true) } else if 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") return h.replayBlock(storeBlockHeight, proxyApp.Consensus()) } else if appBlockHeight == storeBlockHeight { // We ran Commit, but didn't save the state, so replayBlock with mock app abciResponses := h.state.LoadABCIResponses() mockApp := newMockProxyApp(appHash, abciResponses) h.logger.Info("Replay last block using mock app") return h.replayBlock(storeBlockHeight, mockApp) } } cmn.PanicSanity("Should never happen") return nil, nil } func (h *Handshaker) replayBlocks(proxyApp proxy.AppConns, appBlockHeight, storeBlockHeight int, 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. // // If mutateState == true, the final block is replayed with h.replayBlock() var appHash []byte var err error finalBlock := storeBlockHeight if mutateState { finalBlock -= 1 } for i := appBlockHeight + 1; i <= finalBlock; i++ { h.logger.Info("Applying block", "height", i) block := h.store.LoadBlock(i) appHash, err = sm.ExecCommitBlock(proxyApp.Consensus(), block, h.logger) if err != nil { return nil, err } h.nBlocks += 1 } if mutateState { // sync the final block return h.replayBlock(storeBlockHeight, proxyApp.Consensus()) } return appHash, h.checkAppHash(appHash) } // ApplyBlock on the proxyApp with the last block. func (h *Handshaker) replayBlock(height int, proxyApp proxy.AppConnConsensus) ([]byte, error) { mempool := types.MockMempool{} var eventCache types.Fireable // nil block := h.store.LoadBlock(height) meta := h.store.LoadBlockMeta(height) if err := h.state.ApplyBlock(eventCache, proxyApp, block, meta.BlockID.PartsHeader, mempool); err != nil { return nil, err } h.nBlocks += 1 return h.state.AppHash, nil } func (h *Handshaker) checkAppHash(appHash []byte) error { if !bytes.Equal(h.state.AppHash, appHash) { panic(errors.New(cmn.Fmt("Tendermint state.AppHash does not match AppHash after replay. Got %X, expected %X", appHash, h.state.AppHash)).Error()) return nil } return nil } //-------------------------------------------------------------------------------- // mockProxyApp uses ABCIResponses to give the right results // Useful because we don't want to call Commit() twice for the same block on the real app. func newMockProxyApp(appHash []byte, abciResponses *sm.ABCIResponses) proxy.AppConnConsensus { clientCreator := proxy.NewLocalClientCreator(&mockProxyApp{ appHash: appHash, abciResponses: abciResponses, }) cli, _ := clientCreator.NewABCIClient() cli.Start() return proxy.NewAppConnConsensus(cli) } type mockProxyApp struct { abci.BaseApplication appHash []byte txCount int abciResponses *sm.ABCIResponses } func (mock *mockProxyApp) DeliverTx(tx []byte) abci.Result { r := mock.abciResponses.DeliverTx[mock.txCount] mock.txCount += 1 return abci.Result{ r.Code, r.Data, r.Log, } } func (mock *mockProxyApp) EndBlock(height uint64) abci.ResponseEndBlock { mock.txCount = 0 return mock.abciResponses.EndBlock } func (mock *mockProxyApp) Commit() abci.Result { return abci.NewResultOK(mock.appHash, "") }