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