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package consensus
import (
"bytes"
"errors"
"fmt"
"io"
"reflect"
"strconv"
"strings"
"time"
abci "github.com/tendermint/abci/types"
auto "github.com/tendermint/go-autofile"
. "github.com/tendermint/go-common"
cfg "github.com/tendermint/go-config"
"github.com/tendermint/go-wire"
"github.com/tendermint/tendermint/proxy"
sm "github.com/tendermint/tendermint/state"
"github.com/tendermint/tendermint/types"
)
// 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:
log.Notice("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
log.Notice("Replay: Proposal", "height", p.Height, "round", p.Round, "header",
p.BlockPartsHeader, "pol", p.POLRound, "peer", peerKey)
case *BlockPartMessage:
log.Notice("Replay: BlockPart", "height", msg.Height, "round", msg.Round, "peer", peerKey)
case *VoteMessage:
v := msg.Vote
log.Notice("Replay: Vote", "height", v.Height, "round", v.Round, "type", v.Type,
"blockID", v.BlockID, "peer", peerKey)
}
cs.handleMsg(m, cs.RoundState)
case timeoutInfo:
log.Notice("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(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 {
log.Warn("Replay: wal.group.Search returned EOF", "#ENDHEIGHT", csHeight-1)
// if we upgraded from 0.9 to 0.9.1, we may have #HEIGHT instead
// TODO (0.10.0): remove this
gr, found, err = cs.wal.group.Search("#HEIGHT: ", makeHeightSearchFunc(csHeight))
if err == io.EOF {
log.Warn("Replay: wal.group.Search returned EOF", "#HEIGHT", csHeight)
return nil
} else if err != nil {
return err
}
} else if err != nil {
return err
} else {
defer gr.Close()
}
if !found {
// if we upgraded from 0.9 to 0.9.1, we may have #HEIGHT instead
// TODO (0.10.0): remove this
gr, found, err = cs.wal.group.Search("#HEIGHT: ", makeHeightSearchFunc(csHeight))
if err == io.EOF {
log.Warn("Replay: wal.group.Search returned EOF", "#HEIGHT", csHeight)
return nil
} else if err != nil {
return err
} else {
defer gr.Close()
}
// TODO (0.10.0): uncomment
// return errors.New(Fmt("Cannot replay height %d. WAL does not contain #ENDHEIGHT for %d.", csHeight, csHeight-1))
}
log.Notice("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
}
}
log.Notice("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 {
config cfg.Config
state *sm.State
store types.BlockStore
nBlocks int // number of blocks applied to the state
}
func NewHandshaker(config cfg.Config, state *sm.State, store types.BlockStore) *Handshaker {
return &Handshaker{config, state, store, 0}
}
func (h *Handshaker) NBlocks() int {
return h.nBlocks
}
var ErrReplayLastBlockTimeout = errors.New("Timed out waiting for last block to be replayed")
// 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()
if err != nil {
return errors.New(Fmt("Error calling Info: %v", err))
}
blockHeight := int(res.LastBlockHeight) // XXX: beware overflow
appHash := res.LastBlockAppHash
log.Notice("ABCI Handshake", "appHeight", blockHeight, "appHash", appHash)
// TODO: check version
// replay blocks up to the latest in the blockstore
_, err = h.ReplayBlocks(appHash, blockHeight, proxyApp)
if err == ErrReplayLastBlockTimeout {
log.Warn("Failed to sync via handshake. Trying other means. If they fail, please increase the timeout_handshake parameter")
return nil
} else if err != nil {
return errors.New(Fmt("Error on replay: %v", err))
}
log.Notice("Completed ABCI Handshake - Tendermint and App are synced", "appHeight", blockHeight, "appHash", 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
log.Notice("ABCI Replay Blocks", "appHeight", appBlockHeight, "storeHeight", storeBlockHeight, "stateHeight", stateBlockHeight)
// 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)
PanicSanity(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)
PanicSanity(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
log.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)
log.Info("Replay last block using mock app")
return h.replayBlock(storeBlockHeight, mockApp)
}
}
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.
// 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++ {
log.Info("Applying block", "height", i)
block := h.store.LoadBlock(i)
appHash, err = sm.ExecCommitBlock(proxyApp.Consensus(), block)
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(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()
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, "")
}