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package consensus
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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"reflect"
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"strconv"
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"strings"
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"time"
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abci "github.com/tendermint/abci/types"
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auto "github.com/tendermint/go-autofile"
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. "github.com/tendermint/go-common"
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cfg "github.com/tendermint/go-config"
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"github.com/tendermint/go-wire"
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"github.com/tendermint/tendermint/proxy"
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sm "github.com/tendermint/tendermint/state"
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"github.com/tendermint/tendermint/types"
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)
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// Functionality to replay blocks and messages on recovery from a crash.
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// There are two general failure scenarios: failure during consensus, and failure while applying the block.
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// The former is handled by the WAL, the latter by the proxyApp Handshake on restart,
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// which ultimately hands off the work to the WAL.
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//-----------------------------------------
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// recover from failure during consensus
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// by replaying messages from the WAL
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// Unmarshal and apply a single message to the consensus state
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// as if it were received in receiveRoutine
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// Lines that start with "#" are ignored.
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// NOTE: receiveRoutine should not be running
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func (cs *ConsensusState) readReplayMessage(msgBytes []byte, newStepCh chan interface{}) error {
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// Skip over empty and meta lines
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if len(msgBytes) == 0 || msgBytes[0] == '#' {
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return nil
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}
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var err error
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var msg TimedWALMessage
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wire.ReadJSON(&msg, msgBytes, &err)
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if err != nil {
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fmt.Println("MsgBytes:", msgBytes, string(msgBytes))
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return fmt.Errorf("Error reading json data: %v", err)
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}
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// for logging
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switch m := msg.Msg.(type) {
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case types.EventDataRoundState:
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log.Notice("Replay: New Step", "height", m.Height, "round", m.Round, "step", m.Step)
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// these are playback checks
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ticker := time.After(time.Second * 2)
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if newStepCh != nil {
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select {
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case mi := <-newStepCh:
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m2 := mi.(types.EventDataRoundState)
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if m.Height != m2.Height || m.Round != m2.Round || m.Step != m2.Step {
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return fmt.Errorf("RoundState mismatch. Got %v; Expected %v", m2, m)
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}
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case <-ticker:
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return fmt.Errorf("Failed to read off newStepCh")
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}
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}
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case msgInfo:
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peerKey := m.PeerKey
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if peerKey == "" {
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peerKey = "local"
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}
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switch msg := m.Msg.(type) {
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case *ProposalMessage:
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p := msg.Proposal
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log.Notice("Replay: Proposal", "height", p.Height, "round", p.Round, "header",
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p.BlockPartsHeader, "pol", p.POLRound, "peer", peerKey)
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case *BlockPartMessage:
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log.Notice("Replay: BlockPart", "height", msg.Height, "round", msg.Round, "peer", peerKey)
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case *VoteMessage:
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v := msg.Vote
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log.Notice("Replay: Vote", "height", v.Height, "round", v.Round, "type", v.Type,
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"blockID", v.BlockID, "peer", peerKey)
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}
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cs.handleMsg(m, cs.RoundState)
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case timeoutInfo:
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log.Notice("Replay: Timeout", "height", m.Height, "round", m.Round, "step", m.Step, "dur", m.Duration)
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cs.handleTimeout(m, cs.RoundState)
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default:
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return fmt.Errorf("Replay: Unknown TimedWALMessage type: %v", reflect.TypeOf(msg.Msg))
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}
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return nil
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}
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// replay only those messages since the last block.
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// timeoutRoutine should run concurrently to read off tickChan
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func (cs *ConsensusState) catchupReplay(csHeight int) error {
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// set replayMode
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cs.replayMode = true
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defer func() { cs.replayMode = false }()
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// Ensure that height+1 doesn't exist
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gr, found, err := cs.wal.group.Search("#HEIGHT: ", makeHeightSearchFunc(csHeight+1))
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if found {
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return errors.New(Fmt("WAL should not contain height %d.", csHeight+1))
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}
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if gr != nil {
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gr.Close()
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}
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// Search for height marker
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gr, found, err = cs.wal.group.Search("#HEIGHT: ", makeHeightSearchFunc(csHeight))
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if err == io.EOF {
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log.Warn("Replay: wal.group.Search returned EOF", "height", csHeight)
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return nil
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} else if err != nil {
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return err
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}
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if !found {
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return errors.New(Fmt("WAL does not contain height %d.", csHeight))
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}
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defer gr.Close()
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log.Notice("Catchup by replaying consensus messages", "height", csHeight)
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for {
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line, err := gr.ReadLine()
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if err != nil {
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if err == io.EOF {
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break
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} else {
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return err
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}
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}
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// NOTE: since the priv key is set when the msgs are received
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// it will attempt to eg double sign but we can just ignore it
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// since the votes will be replayed and we'll get to the next step
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if err := cs.readReplayMessage([]byte(line), nil); err != nil {
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return err
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}
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}
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log.Notice("Replay: Done")
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return nil
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}
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//--------------------------------------------------------------------------------
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// Parses marker lines of the form:
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// #HEIGHT: 12345
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func makeHeightSearchFunc(height int) auto.SearchFunc {
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return func(line string) (int, error) {
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line = strings.TrimRight(line, "\n")
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parts := strings.Split(line, " ")
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if len(parts) != 2 {
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return -1, errors.New("Line did not have 2 parts")
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}
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i, err := strconv.Atoi(parts[1])
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if err != nil {
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return -1, errors.New("Failed to parse INFO: " + err.Error())
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}
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if height < i {
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return 1, nil
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} else if height == i {
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return 0, nil
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} else {
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return -1, nil
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}
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}
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}
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//----------------------------------------------
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// Recover from failure during block processing
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// by handshaking with the app to figure out where
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// we were last and using the WAL to recover there
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type Handshaker struct {
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config cfg.Config
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state *sm.State
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store types.BlockStore
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nBlocks int // number of blocks applied to the state
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}
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func NewHandshaker(config cfg.Config, state *sm.State, store types.BlockStore) *Handshaker {
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return &Handshaker{config, state, store, 0}
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}
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func (h *Handshaker) NBlocks() int {
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return h.nBlocks
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}
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var ErrReplayLastBlockTimeout = errors.New("Timed out waiting for last block to be replayed")
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// TODO: retry the handshake/replay if it fails ?
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func (h *Handshaker) Handshake(proxyApp proxy.AppConns) error {
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// handshake is done via info request on the query conn
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res, err := proxyApp.Query().InfoSync()
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if err != nil {
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return errors.New(Fmt("Error calling Info: %v", err))
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}
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blockHeight := int(res.LastBlockHeight) // XXX: beware overflow
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appHash := res.LastBlockAppHash
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log.Notice("ABCI Handshake", "appHeight", blockHeight, "appHash", appHash)
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// TODO: check version
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// replay blocks up to the latest in the blockstore
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_, err = h.ReplayBlocks(appHash, blockHeight, proxyApp)
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if err == ErrReplayLastBlockTimeout {
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log.Warn("Failed to sync via handshake. Trying other means. If they fail, please increase the timeout_handshake parameter")
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return nil
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} else if err != nil {
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return errors.New(Fmt("Error on replay: %v", err))
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}
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log.Notice("Completed ABCI Handshake - Tendermint and App are synced", "appHeight", blockHeight, "appHash", appHash)
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// TODO: (on restart) replay mempool
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return nil
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}
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// Replay all blocks since appBlockHeight and ensure the result matches the current state.
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// Returns the final AppHash or an error
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func (h *Handshaker) ReplayBlocks(appHash []byte, appBlockHeight int, proxyApp proxy.AppConns) ([]byte, error) {
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storeBlockHeight := h.store.Height()
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stateBlockHeight := h.state.LastBlockHeight
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log.Notice("ABCI Replay Blocks", "appHeight", appBlockHeight, "storeHeight", storeBlockHeight, "stateHeight", stateBlockHeight)
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// First handle edge cases and constraints on the storeBlockHeight
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if storeBlockHeight == 0 {
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return appHash, h.checkAppHash(appHash)
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} else if storeBlockHeight < appBlockHeight {
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// the app should never be ahead of the store (but this is under app's control)
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return appHash, sm.ErrAppBlockHeightTooHigh{storeBlockHeight, appBlockHeight}
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} else if storeBlockHeight < stateBlockHeight {
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// the state should never be ahead of the store (this is under tendermint's control)
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PanicSanity(Fmt("StateBlockHeight (%d) > StoreBlockHeight (%d)", stateBlockHeight, storeBlockHeight))
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} else if storeBlockHeight > stateBlockHeight+1 {
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// store should be at most one ahead of the state (this is under tendermint's control)
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PanicSanity(Fmt("StoreBlockHeight (%d) > StateBlockHeight + 1 (%d)", storeBlockHeight, stateBlockHeight+1))
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}
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// Now either store is equal to state, or one ahead.
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// For each, consider all cases of where the app could be, given app <= store
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if storeBlockHeight == stateBlockHeight {
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// Tendermint ran Commit and saved the state.
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// Either the app is asking for replay, or we're all synced up.
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if appBlockHeight < storeBlockHeight {
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// the app is behind, so replay blocks, but no need to go through WAL (state is already synced to store)
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return h.replayBlocks(proxyApp, appBlockHeight, storeBlockHeight, false)
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} else if appBlockHeight == storeBlockHeight {
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// We're good!
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return appHash, h.checkAppHash(appHash)
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}
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} else if storeBlockHeight == stateBlockHeight+1 {
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// We saved the block in the store but haven't updated the state,
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// so we'll need to replay a block using the WAL.
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if appBlockHeight < stateBlockHeight {
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// the app is further behind than it should be, so replay blocks
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// but leave the last block to go through the WAL
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return h.replayBlocks(proxyApp, appBlockHeight, storeBlockHeight, true)
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} else if appBlockHeight == stateBlockHeight {
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// We haven't run Commit (both the state and app are one block behind),
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// so run through consensus with the real app
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log.Info("Replay last block using real app")
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return h.replayLastBlock(proxyApp.Consensus())
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} else if appBlockHeight == storeBlockHeight {
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// We ran Commit, but didn't save the state, so run through consensus with mock app
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mockApp := newMockProxyApp(appHash)
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log.Info("Replay last block using mock app")
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return h.replayLastBlock(mockApp)
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}
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}
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PanicSanity("Should never happen")
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return nil, nil
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}
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func (h *Handshaker) replayBlocks(proxyApp proxy.AppConns, appBlockHeight, storeBlockHeight int, useReplayFunc bool) ([]byte, error) {
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// App is further behind than it should be, so we need to replay blocks.
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// We replay all blocks from appBlockHeight+1 to storeBlockHeight-1,
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// and let the final block be replayed through ReplayBlocks.
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// Note that we don't have an old version of the state,
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// so we by-pass state validation using applyBlock here.
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var appHash []byte
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var err error
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finalBlock := storeBlockHeight
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if useReplayFunc {
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finalBlock -= 1
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}
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for i := appBlockHeight + 1; i <= finalBlock; i++ {
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log.Info("Applying block", "height", i)
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block := h.store.LoadBlock(i)
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appHash, err = sm.ApplyBlock(proxyApp.Consensus(), block)
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if err != nil {
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return nil, err
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}
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h.nBlocks += 1
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}
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if useReplayFunc {
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// sync the final block
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return h.ReplayBlocks(appHash, finalBlock, proxyApp)
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}
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return appHash, h.checkAppHash(appHash)
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}
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// Replay the last block through the consensus and return the AppHash from after Commit.
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func (h *Handshaker) replayLastBlock(proxyApp proxy.AppConnConsensus) ([]byte, error) {
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mempool := types.MockMempool{}
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cs := NewConsensusState(h.config, h.state, proxyApp, h.store, mempool)
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evsw := types.NewEventSwitch()
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evsw.Start()
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defer evsw.Stop()
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cs.SetEventSwitch(evsw)
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newBlockCh := subscribeToEvent(evsw, "consensus-replay", types.EventStringNewBlock(), 1)
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// run through the WAL, commit new block, stop
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if _, err := cs.Start(); err != nil {
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return nil, err
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}
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defer cs.Stop()
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timeout := h.config.GetInt("timeout_handshake")
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timer := time.NewTimer(time.Duration(timeout) * time.Millisecond)
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log.Notice("Attempting to replay last block", "height", h.store.Height(), "timeout", timeout)
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select {
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case <-newBlockCh:
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case <-timer.C:
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return nil, ErrReplayLastBlockTimeout
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}
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h.nBlocks += 1
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return cs.state.AppHash, nil
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}
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func (h *Handshaker) checkAppHash(appHash []byte) error {
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if !bytes.Equal(h.state.AppHash, appHash) {
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panic(errors.New(Fmt("Tendermint state.AppHash does not match AppHash after replay. Got %X, expected %X", appHash, h.state.AppHash)).Error())
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return nil
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}
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return nil
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}
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//--------------------------------------------------------------------------------
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func newMockProxyApp(appHash []byte) proxy.AppConnConsensus {
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clientCreator := proxy.NewLocalClientCreator(&mockProxyApp{appHash: appHash})
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cli, _ := clientCreator.NewABCIClient()
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return proxy.NewAppConnConsensus(cli)
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}
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type mockProxyApp struct {
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abci.BaseApplication
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appHash []byte
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}
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func (mock *mockProxyApp) Commit() abci.Result {
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return abci.NewResultOK(mock.appHash, "")
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}
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