package v1 import ( "errors" "fmt" "sync" "time" "github.com/tendermint/tendermint/libs/log" "github.com/tendermint/tendermint/p2p" "github.com/tendermint/tendermint/types" ) // Blockchain Reactor State type bcReactorFSMState struct { name string // called when transitioning out of current state handle func(*BcReactorFSM, bReactorEvent, bReactorEventData) (next *bcReactorFSMState, err error) // called when entering the state enter func(fsm *BcReactorFSM) // timeout to ensure FSM is not stuck in a state forever // the timer is owned and run by the fsm instance timeout time.Duration } func (s *bcReactorFSMState) String() string { return s.name } // BcReactorFSM is the datastructure for the Blockchain Reactor State Machine type BcReactorFSM struct { logger log.Logger mtx sync.Mutex startTime time.Time state *bcReactorFSMState stateTimer *time.Timer pool *BlockPool // interface used to call the Blockchain reactor to send StatusRequest, BlockRequest, reporting errors, etc. toBcR bcReactor } // NewFSM creates a new reactor FSM. func NewFSM(height int64, toBcR bcReactor) *BcReactorFSM { return &BcReactorFSM{ state: unknown, startTime: time.Now(), pool: NewBlockPool(height, toBcR), toBcR: toBcR, } } // bReactorEventData is part of the message sent by the reactor to the FSM and used by the state handlers. type bReactorEventData struct { peerID p2p.ID err error // for peer error: timeout, slow; for processed block event if error occurred height int64 // for status response; for processed block event block *types.Block // for block response stateName string // for state timeout events length int // for block response event, length of received block, used to detect slow peers maxNumRequests int // for request needed event, maximum number of pending requests } // Blockchain Reactor Events (the input to the state machine) type bReactorEvent uint const ( // message type events startFSMEv = iota + 1 statusResponseEv blockResponseEv processedBlockEv makeRequestsEv stopFSMEv // other events peerRemoveEv = iota + 256 stateTimeoutEv ) func (msg *bcReactorMessage) String() string { var dataStr string switch msg.event { case startFSMEv: dataStr = "" case statusResponseEv: dataStr = fmt.Sprintf("peer=%v height=%v", msg.data.peerID, msg.data.height) case blockResponseEv: dataStr = fmt.Sprintf("peer=%v block.height=%v length=%v", msg.data.peerID, msg.data.block.Height, msg.data.length) case processedBlockEv: dataStr = fmt.Sprintf("error=%v", msg.data.err) case makeRequestsEv: dataStr = "" case stopFSMEv: dataStr = "" case peerRemoveEv: dataStr = fmt.Sprintf("peer: %v is being removed by the switch", msg.data.peerID) case stateTimeoutEv: dataStr = fmt.Sprintf("state=%v", msg.data.stateName) default: dataStr = fmt.Sprintf("cannot interpret message data") } return fmt.Sprintf("%v: %v", msg.event, dataStr) } func (ev bReactorEvent) String() string { switch ev { case startFSMEv: return "startFSMEv" case statusResponseEv: return "statusResponseEv" case blockResponseEv: return "blockResponseEv" case processedBlockEv: return "processedBlockEv" case makeRequestsEv: return "makeRequestsEv" case stopFSMEv: return "stopFSMEv" case peerRemoveEv: return "peerRemoveEv" case stateTimeoutEv: return "stateTimeoutEv" default: return "event unknown" } } // states var ( unknown *bcReactorFSMState waitForPeer *bcReactorFSMState waitForBlock *bcReactorFSMState finished *bcReactorFSMState ) // timeouts for state timers const ( waitForPeerTimeout = 3 * time.Second waitForBlockAtCurrentHeightTimeout = 10 * time.Second ) // errors var ( // internal to the package errNoErrorFinished = errors.New("fast sync is finished") errInvalidEvent = errors.New("invalid event in current state") errMissingBlock = errors.New("missing blocks") errNilPeerForBlockRequest = errors.New("peer for block request does not exist in the switch") errSendQueueFull = errors.New("block request not made, send-queue is full") errPeerTooShort = errors.New("peer height too low, old peer removed/ new peer not added") errSwitchRemovesPeer = errors.New("switch is removing peer") errTimeoutEventWrongState = errors.New("timeout event for a state different than the current one") errNoTallerPeer = errors.New("fast sync timed out on waiting for a peer taller than this node") // reported eventually to the switch errPeerLowersItsHeight = errors.New("fast sync peer reports a height lower than previous") // handle return errNoPeerResponseForCurrentHeights = errors.New("fast sync timed out on peer block response for current heights") // handle return errNoPeerResponse = errors.New("fast sync timed out on peer block response") // xx errBadDataFromPeer = errors.New("fast sync received block from wrong peer or block is bad") // xx errDuplicateBlock = errors.New("fast sync received duplicate block from peer") errBlockVerificationFailure = errors.New("fast sync block verification failure") // xx errSlowPeer = errors.New("fast sync peer is not sending us data fast enough") // xx ) func init() { unknown = &bcReactorFSMState{ name: "unknown", handle: func(fsm *BcReactorFSM, ev bReactorEvent, data bReactorEventData) (*bcReactorFSMState, error) { switch ev { case startFSMEv: // Broadcast Status message. Currently doesn't return non-nil error. fsm.toBcR.sendStatusRequest() return waitForPeer, nil case stopFSMEv: return finished, errNoErrorFinished default: return unknown, errInvalidEvent } }, } waitForPeer = &bcReactorFSMState{ name: "waitForPeer", timeout: waitForPeerTimeout, enter: func(fsm *BcReactorFSM) { // Stop when leaving the state. fsm.resetStateTimer() }, handle: func(fsm *BcReactorFSM, ev bReactorEvent, data bReactorEventData) (*bcReactorFSMState, error) { switch ev { case stateTimeoutEv: if data.stateName != "waitForPeer" { fsm.logger.Error("received a state timeout event for different state", "state", data.stateName) return waitForPeer, errTimeoutEventWrongState } // There was no statusResponse received from any peer. // Should we send status request again? return finished, errNoTallerPeer case statusResponseEv: if err := fsm.pool.UpdatePeer(data.peerID, data.height); err != nil { if fsm.pool.NumPeers() == 0 { return waitForPeer, err } } if fsm.stateTimer != nil { fsm.stateTimer.Stop() } return waitForBlock, nil case stopFSMEv: if fsm.stateTimer != nil { fsm.stateTimer.Stop() } return finished, errNoErrorFinished default: return waitForPeer, errInvalidEvent } }, } waitForBlock = &bcReactorFSMState{ name: "waitForBlock", timeout: waitForBlockAtCurrentHeightTimeout, enter: func(fsm *BcReactorFSM) { // Stop when leaving the state. fsm.resetStateTimer() }, handle: func(fsm *BcReactorFSM, ev bReactorEvent, data bReactorEventData) (*bcReactorFSMState, error) { switch ev { case statusResponseEv: err := fsm.pool.UpdatePeer(data.peerID, data.height) if fsm.pool.NumPeers() == 0 { return waitForPeer, err } if fsm.pool.ReachedMaxHeight() { return finished, err } return waitForBlock, err case blockResponseEv: fsm.logger.Debug("blockResponseEv", "H", data.block.Height) err := fsm.pool.AddBlock(data.peerID, data.block, data.length) if err != nil { // A block was received that was unsolicited, from unexpected peer, or that we already have it. // Ignore block, remove peer and send error to switch. fsm.pool.RemovePeer(data.peerID, err) fsm.toBcR.sendPeerError(err, data.peerID) } if fsm.pool.NumPeers() == 0 { return waitForPeer, err } return waitForBlock, err case processedBlockEv: if data.err != nil { first, second, _ := fsm.pool.FirstTwoBlocksAndPeers() fsm.logger.Error("error processing block", "err", data.err, "first", first.block.Height, "second", second.block.Height) fsm.logger.Error("send peer error for", "peer", first.peer.ID) fsm.toBcR.sendPeerError(data.err, first.peer.ID) fsm.logger.Error("send peer error for", "peer", second.peer.ID) fsm.toBcR.sendPeerError(data.err, second.peer.ID) // Remove the first two blocks. This will also remove the peers fsm.pool.InvalidateFirstTwoBlocks(data.err) } else { fsm.pool.ProcessedCurrentHeightBlock() // Since we advanced one block reset the state timer fsm.resetStateTimer() } // Both cases above may result in achieving maximum height. if fsm.pool.ReachedMaxHeight() { return finished, nil } return waitForBlock, data.err case peerRemoveEv: // This event is sent by the switch to remove disconnected and errored peers. fsm.pool.RemovePeer(data.peerID, data.err) if fsm.pool.NumPeers() == 0 { return waitForPeer, nil } if fsm.pool.ReachedMaxHeight() { return finished, nil } return waitForBlock, nil case makeRequestsEv: fsm.makeNextRequests(data.maxNumRequests) return waitForBlock, nil case stateTimeoutEv: if data.stateName != "waitForBlock" { fsm.logger.Error("received a state timeout event for different state", "state", data.stateName) return waitForBlock, errTimeoutEventWrongState } // We haven't received the block at current height or height+1. Remove peer. fsm.pool.RemovePeerAtCurrentHeights(errNoPeerResponseForCurrentHeights) fsm.resetStateTimer() if fsm.pool.NumPeers() == 0 { return waitForPeer, errNoPeerResponseForCurrentHeights } if fsm.pool.ReachedMaxHeight() { return finished, nil } return waitForBlock, errNoPeerResponseForCurrentHeights case stopFSMEv: if fsm.stateTimer != nil { fsm.stateTimer.Stop() } return finished, errNoErrorFinished default: return waitForBlock, errInvalidEvent } }, } finished = &bcReactorFSMState{ name: "finished", enter: func(fsm *BcReactorFSM) { fsm.logger.Info("Time to switch to consensus reactor!", "height", fsm.pool.Height) fsm.toBcR.switchToConsensus() fsm.cleanup() }, handle: func(fsm *BcReactorFSM, ev bReactorEvent, data bReactorEventData) (*bcReactorFSMState, error) { return finished, nil }, } } // Interface used by FSM for sending Block and Status requests, // informing of peer errors and state timeouts // Implemented by BlockchainReactor and tests type bcReactor interface { sendStatusRequest() sendBlockRequest(peerID p2p.ID, height int64) error sendPeerError(err error, peerID p2p.ID) resetStateTimer(name string, timer **time.Timer, timeout time.Duration) switchToConsensus() } // SetLogger sets the FSM logger. func (fsm *BcReactorFSM) SetLogger(l log.Logger) { fsm.logger = l fsm.pool.SetLogger(l) } // Start starts the FSM. func (fsm *BcReactorFSM) Start() { _ = fsm.Handle(&bcReactorMessage{event: startFSMEv}) } // Handle processes messages and events sent to the FSM. func (fsm *BcReactorFSM) Handle(msg *bcReactorMessage) error { fsm.mtx.Lock() defer fsm.mtx.Unlock() fsm.logger.Debug("FSM received", "event", msg, "state", fsm.state) if fsm.state == nil { fsm.state = unknown } next, err := fsm.state.handle(fsm, msg.event, msg.data) if err != nil { fsm.logger.Error("FSM event handler returned", "err", err, "state", fsm.state, "event", msg.event) } oldState := fsm.state.name fsm.transition(next) if oldState != fsm.state.name { fsm.logger.Info("FSM changed state", "new_state", fsm.state) } return err } func (fsm *BcReactorFSM) transition(next *bcReactorFSMState) { if next == nil { return } if fsm.state != next { fsm.state = next if next.enter != nil { next.enter(fsm) } } } // Called when entering an FSM state in order to detect lack of progress in the state machine. // Note the use of the 'bcr' interface to facilitate testing without timer expiring. func (fsm *BcReactorFSM) resetStateTimer() { fsm.toBcR.resetStateTimer(fsm.state.name, &fsm.stateTimer, fsm.state.timeout) } func (fsm *BcReactorFSM) isCaughtUp() bool { return fsm.state == finished } func (fsm *BcReactorFSM) makeNextRequests(maxNumRequests int) { fsm.pool.MakeNextRequests(maxNumRequests) } func (fsm *BcReactorFSM) cleanup() { fsm.pool.Cleanup() } // NeedsBlocks checks if more block requests are required. func (fsm *BcReactorFSM) NeedsBlocks() bool { fsm.mtx.Lock() defer fsm.mtx.Unlock() return fsm.state.name == "waitForBlock" && fsm.pool.NeedsBlocks() } // FirstTwoBlocks returns the two blocks at pool height and height+1 func (fsm *BcReactorFSM) FirstTwoBlocks() (first, second *types.Block, err error) { fsm.mtx.Lock() defer fsm.mtx.Unlock() firstBP, secondBP, err := fsm.pool.FirstTwoBlocksAndPeers() if err == nil { first = firstBP.block second = secondBP.block } return } // Status returns the pool's height and the maximum peer height. func (fsm *BcReactorFSM) Status() (height, maxPeerHeight int64) { fsm.mtx.Lock() defer fsm.mtx.Unlock() return fsm.pool.Height, fsm.pool.MaxPeerHeight }