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package v2
import (
"bytes"
"fmt"
"math"
"sort"
"time"
"github.com/tendermint/tendermint/p2p"
"github.com/tendermint/tendermint/types"
)
// Events generated by the scheduler:
// all blocks have been processed
type scFinishedEv struct {
priorityNormal
reason string
}
// send a blockRequest message
type scBlockRequest struct {
priorityNormal
peerID p2p.ID
height int64
}
// a block has been received and validated by the scheduler
type scBlockReceived struct {
priorityNormal
peerID p2p.ID
block *types.Block
}
// scheduler detected a peer error
type scPeerError struct {
priorityHigh
peerID p2p.ID
reason error
}
func (e scPeerError) String() string {
return fmt.Sprintf("scPeerError - peerID %s, err %s", e.peerID, e.reason)
}
// scheduler removed a set of peers (timed out or slow peer)
type scPeersPruned struct {
priorityHigh
peers []p2p.ID
}
// XXX: make this fatal?
// scheduler encountered a fatal error
type scSchedulerFail struct {
priorityHigh
reason error
}
type blockState int
const (
blockStateUnknown blockState = iota + 1 // no known peer has this block
blockStateNew // indicates that a peer has reported having this block
blockStatePending // indicates that this block has been requested from a peer
blockStateReceived // indicates that this block has been received by a peer
blockStateProcessed // indicates that this block has been applied
)
func (e blockState) String() string {
switch e {
case blockStateUnknown:
return "Unknown"
case blockStateNew:
return "New"
case blockStatePending:
return "Pending"
case blockStateReceived:
return "Received"
case blockStateProcessed:
return "Processed"
default:
return fmt.Sprintf("invalid blockState: %d", e)
}
}
type peerState int
const (
peerStateNew = iota + 1
peerStateReady
peerStateRemoved
)
func (e peerState) String() string {
switch e {
case peerStateNew:
return "New"
case peerStateReady:
return "Ready"
case peerStateRemoved:
return "Removed"
default:
panic(fmt.Sprintf("unknown peerState: %d", e))
}
}
type scPeer struct {
peerID p2p.ID
// initialized as New when peer is added, updated to Ready when statusUpdate is received,
// updated to Removed when peer is removed
state peerState
base int64 // updated when statusResponse is received
height int64 // updated when statusResponse is received
lastTouched time.Time
lastRate int64 // last receive rate in bytes
}
func (p scPeer) String() string {
return fmt.Sprintf("{state %v, base %d, height %d, lastTouched %v, lastRate %d, id %v}",
p.state, p.base, p.height, p.lastTouched, p.lastRate, p.peerID)
}
func newScPeer(peerID p2p.ID) *scPeer {
return &scPeer{
peerID: peerID,
state: peerStateNew,
base: -1,
height: -1,
lastTouched: time.Time{},
}
}
// The scheduler keep track of the state of each block and each peer. The
// scheduler will attempt to schedule new block requests with `trySchedule`
// events and remove slow peers with `tryPrune` events.
type scheduler struct {
initHeight int64
// next block that needs to be processed. All blocks with smaller height are
// in Processed state.
height int64
// lastAdvance tracks the last time a block execution happened.
// syncTimeout is the maximum time the scheduler waits to advance in the fast sync process before finishing.
// This covers the cases where there are no peers or all peers have a lower height.
lastAdvance time.Time
syncTimeout time.Duration
// a map of peerID to scheduler specific peer struct `scPeer` used to keep
// track of peer specific state
peers map[p2p.ID]*scPeer
peerTimeout time.Duration // maximum response time from a peer otherwise prune
minRecvRate int64 // minimum receive rate from peer otherwise prune
// the maximum number of blocks that should be New, Received or Pending at any point
// in time. This is used to enforce a limit on the blockStates map.
targetPending int
// a list of blocks to be scheduled (New), Pending or Received. Its length should be
// smaller than targetPending.
blockStates map[int64]blockState
// a map of heights to the peer we are waiting a response from
pendingBlocks map[int64]p2p.ID
// the time at which a block was put in blockStatePending
pendingTime map[int64]time.Time
// a map of heights to the peers that put the block in blockStateReceived
receivedBlocks map[int64]p2p.ID
}
func (sc scheduler) String() string {
return fmt.Sprintf("ih: %d, bst: %v, peers: %v, pblks: %v, ptm %v, rblks: %v",
sc.initHeight, sc.blockStates, sc.peers, sc.pendingBlocks, sc.pendingTime, sc.receivedBlocks)
}
func newScheduler(initHeight int64, startTime time.Time) *scheduler {
sc := scheduler{
initHeight: initHeight,
lastAdvance: startTime,
syncTimeout: 60 * time.Second,
height: initHeight + 1,
blockStates: make(map[int64]blockState),
peers: make(map[p2p.ID]*scPeer),
pendingBlocks: make(map[int64]p2p.ID),
pendingTime: make(map[int64]time.Time),
receivedBlocks: make(map[int64]p2p.ID),
targetPending: 10, // TODO - pass as param
peerTimeout: 15 * time.Second, // TODO - pass as param
minRecvRate: 0, //int64(7680), TODO - pass as param
}
return &sc
}
func (sc *scheduler) addPeer(peerID p2p.ID) error {
if _, ok := sc.peers[peerID]; ok {
// In the future we should be able to add a previously removed peer
return fmt.Errorf("cannot add duplicate peer %s", peerID)
}
sc.peers[peerID] = newScPeer(peerID)
return nil
}
func (sc *scheduler) touchPeer(peerID p2p.ID, time time.Time) error {
peer, ok := sc.peers[peerID]
if !ok {
return fmt.Errorf("couldn't find peer %s", peerID)
}
if peer.state != peerStateReady {
return fmt.Errorf("tried to touch peer in state %s, must be Ready", peer.state)
}
peer.lastTouched = time
return nil
}
func (sc *scheduler) removePeer(peerID p2p.ID) error {
peer, ok := sc.peers[peerID]
if !ok {
return fmt.Errorf("couldn't find peer %s", peerID)
}
if peer.state == peerStateRemoved {
return fmt.Errorf("tried to remove peer %s in peerStateRemoved", peerID)
}
for height, pendingPeerID := range sc.pendingBlocks {
if pendingPeerID == peerID {
sc.setStateAtHeight(height, blockStateNew)
delete(sc.pendingTime, height)
delete(sc.pendingBlocks, height)
}
}
for height, rcvPeerID := range sc.receivedBlocks {
if rcvPeerID == peerID {
sc.setStateAtHeight(height, blockStateNew)
delete(sc.receivedBlocks, height)
}
}
// remove the blocks from blockStates if the peer removal causes the max peer height to be lower.
peer.state = peerStateRemoved
maxPeerHeight := int64(0)
for _, otherPeer := range sc.peers {
if otherPeer.state != peerStateReady {
continue
}
if otherPeer.peerID != peer.peerID && otherPeer.height > maxPeerHeight {
maxPeerHeight = otherPeer.height
}
}
for h := range sc.blockStates {
if h > maxPeerHeight {
delete(sc.blockStates, h)
}
}
return nil
}
// check if the blockPool is running low and add new blocks in New state to be requested.
// This function is called when there is an increase in the maximum peer height or when
// blocks are processed.
func (sc *scheduler) addNewBlocks() {
if len(sc.blockStates) >= sc.targetPending {
return
}
for i := sc.height; i < int64(sc.targetPending)+sc.height; i++ {
if i > sc.maxHeight() {
break
}
if sc.getStateAtHeight(i) == blockStateUnknown {
sc.setStateAtHeight(i, blockStateNew)
}
}
}
func (sc *scheduler) setPeerRange(peerID p2p.ID, base int64, height int64) error {
peer, ok := sc.peers[peerID]
if !ok {
return fmt.Errorf("cannot find peer %s", peerID)
}
if peer.state == peerStateRemoved {
return fmt.Errorf("cannot set peer height for a peer in peerStateRemoved")
}
if height < peer.height {
sc.removePeer(peerID)
return fmt.Errorf("cannot move peer height lower. from %d to %d", peer.height, height)
}
if base > height {
return fmt.Errorf("cannot set peer base higher than its height")
}
peer.base = base
peer.height = height
peer.state = peerStateReady
sc.addNewBlocks()
return nil
}
func (sc *scheduler) getStateAtHeight(height int64) blockState {
if height < sc.height {
return blockStateProcessed
} else if state, ok := sc.blockStates[height]; ok {
return state
} else {
return blockStateUnknown
}
}
func (sc *scheduler) getPeersWithHeight(height int64) []p2p.ID {
peers := make([]p2p.ID, 0)
for _, peer := range sc.peers {
if peer.state != peerStateReady {
continue
}
if peer.base <= height && peer.height >= height {
peers = append(peers, peer.peerID)
}
}
return peers
}
func (sc *scheduler) prunablePeers(peerTimout time.Duration, minRecvRate int64, now time.Time) []p2p.ID {
prunable := make([]p2p.ID, 0)
for peerID, peer := range sc.peers {
if peer.state != peerStateReady {
continue
}
if now.Sub(peer.lastTouched) > peerTimout || peer.lastRate < minRecvRate {
prunable = append(prunable, peerID)
}
}
// Tests for handleTryPrunePeer() may fail without sort due to range non-determinism
sort.Sort(PeerByID(prunable))
return prunable
}
func (sc *scheduler) setStateAtHeight(height int64, state blockState) {
sc.blockStates[height] = state
}
func (sc *scheduler) markReceived(peerID p2p.ID, height int64, size int64, now time.Time) error {
peer, ok := sc.peers[peerID]
if !ok {
return fmt.Errorf("couldn't find peer %s", peerID)
}
if peer.state != peerStateReady {
return fmt.Errorf("cannot receive blocks from not ready peer %s", peerID)
}
if state := sc.getStateAtHeight(height); state != blockStatePending || sc.pendingBlocks[height] != peerID {
return fmt.Errorf("received block %d from peer %s without being requested", height, peerID)
}
pendingTime, ok := sc.pendingTime[height]
if !ok || now.Sub(pendingTime) <= 0 {
return fmt.Errorf("clock error: block %d received at %s but requested at %s",
height, pendingTime, now)
}
peer.lastRate = size / now.Sub(pendingTime).Nanoseconds()
sc.setStateAtHeight(height, blockStateReceived)
delete(sc.pendingBlocks, height)
delete(sc.pendingTime, height)
sc.receivedBlocks[height] = peerID
return nil
}
func (sc *scheduler) markPending(peerID p2p.ID, height int64, time time.Time) error {
state := sc.getStateAtHeight(height)
if state != blockStateNew {
return fmt.Errorf("block %d should be in blockStateNew but is %s", height, state)
}
peer, ok := sc.peers[peerID]
if !ok {
return fmt.Errorf("cannot find peer %s", peerID)
}
if peer.state != peerStateReady {
return fmt.Errorf("cannot schedule %d from %s in %s", height, peerID, peer.state)
}
if height > peer.height {
return fmt.Errorf("cannot request height %d from peer %s that is at height %d",
height, peerID, peer.height)
}
if height < peer.base {
return fmt.Errorf("cannot request height %d for peer %s with base %d",
height, peerID, peer.base)
}
sc.setStateAtHeight(height, blockStatePending)
sc.pendingBlocks[height] = peerID
sc.pendingTime[height] = time
return nil
}
func (sc *scheduler) markProcessed(height int64) error {
sc.lastAdvance = time.Now()
state := sc.getStateAtHeight(height)
if state != blockStateReceived {
return fmt.Errorf("cannot mark height %d received from block state %s", height, state)
}
sc.height++
delete(sc.receivedBlocks, height)
delete(sc.blockStates, height)
sc.addNewBlocks()
return nil
}
func (sc *scheduler) allBlocksProcessed() bool {
if len(sc.peers) == 0 {
return false
}
return sc.height >= sc.maxHeight()
}
// returns max peer height or the last processed block, i.e. sc.height
func (sc *scheduler) maxHeight() int64 {
max := sc.height - 1
for _, peer := range sc.peers {
if peer.state != peerStateReady {
continue
}
if max < peer.height {
max = peer.height
}
}
return max
}
// lowest block in sc.blockStates with state == blockStateNew or -1 if no new blocks
func (sc *scheduler) nextHeightToSchedule() int64 {
var min int64 = math.MaxInt64
for height, state := range sc.blockStates {
if state == blockStateNew && height < min {
min = height
}
}
if min == math.MaxInt64 {
min = -1
}
return min
}
func (sc *scheduler) pendingFrom(peerID p2p.ID) []int64 {
var heights []int64
for height, pendingPeerID := range sc.pendingBlocks {
if pendingPeerID == peerID {
heights = append(heights, height)
}
}
return heights
}
func (sc *scheduler) selectPeer(height int64) (p2p.ID, error) {
peers := sc.getPeersWithHeight(height)
if len(peers) == 0 {
return "", fmt.Errorf("cannot find peer for height %d", height)
}
// create a map from number of pending requests to a list
// of peers having that number of pending requests.
pendingFrom := make(map[int][]p2p.ID)
for _, peerID := range peers {
numPending := len(sc.pendingFrom(peerID))
pendingFrom[numPending] = append(pendingFrom[numPending], peerID)
}
// find the set of peers with minimum number of pending requests.
var minPending int64 = math.MaxInt64
for mp := range pendingFrom {
if int64(mp) < minPending {
minPending = int64(mp)
}
}
sort.Sort(PeerByID(pendingFrom[int(minPending)]))
return pendingFrom[int(minPending)][0], nil
}
// PeerByID is a list of peers sorted by peerID.
type PeerByID []p2p.ID
func (peers PeerByID) Len() int {
return len(peers)
}
func (peers PeerByID) Less(i, j int) bool {
return bytes.Compare([]byte(peers[i]), []byte(peers[j])) == -1
}
func (peers PeerByID) Swap(i, j int) {
it := peers[i]
peers[i] = peers[j]
peers[j] = it
}
// Handlers
// This handler gets the block, performs some validation and then passes it on to the processor.
func (sc *scheduler) handleBlockResponse(event bcBlockResponse) (Event, error) {
err := sc.touchPeer(event.peerID, event.time)
if err != nil {
return scPeerError{peerID: event.peerID, reason: err}, nil
}
err = sc.markReceived(event.peerID, event.block.Height, event.size, event.time)
if err != nil {
_ = sc.removePeer(event.peerID)
return scPeerError{peerID: event.peerID, reason: err}, nil
}
return scBlockReceived{peerID: event.peerID, block: event.block}, nil
}
func (sc *scheduler) handleNoBlockResponse(event bcNoBlockResponse) (Event, error) {
if len(sc.peers) == 0 {
return noOp, nil
}
peer, ok := sc.peers[event.peerID]
if !ok || peer.state == peerStateRemoved {
return noOp, nil
}
// The peer may have been just removed due to errors, low speed or timeouts.
_ = sc.removePeer(event.peerID)
return scPeerError{peerID: event.peerID,
reason: fmt.Errorf("peer %v with base %d height %d claims no block for %d",
event.peerID, peer.base, peer.height, event.height)}, nil
}
func (sc *scheduler) handleBlockProcessed(event pcBlockProcessed) (Event, error) {
if event.height != sc.height {
panic(fmt.Sprintf("processed height %d but expected height %d", event.height, sc.height))
}
err := sc.markProcessed(event.height)
if err != nil {
// It is possible that a peer error or timeout is handled after the processor
// has processed the block but before the scheduler received this event,
// so when pcBlockProcessed event is received the block had been requested again.
return scSchedulerFail{reason: err}, nil
}
if sc.allBlocksProcessed() {
return scFinishedEv{reason: "processed all blocks"}, nil
}
return noOp, nil
}
// Handles an error from the processor. The processor had already cleaned the blocks from
// the peers included in this event. Just attempt to remove the peers.
func (sc *scheduler) handleBlockProcessError(event pcBlockVerificationFailure) (Event, error) {
if len(sc.peers) == 0 {
return noOp, nil
}
// The peers may have been just removed due to errors, low speed or timeouts.
_ = sc.removePeer(event.firstPeerID)
if event.firstPeerID != event.secondPeerID {
_ = sc.removePeer(event.secondPeerID)
}
if sc.allBlocksProcessed() {
return scFinishedEv{reason: "error on last block"}, nil
}
return noOp, nil
}
func (sc *scheduler) handleAddNewPeer(event bcAddNewPeer) (Event, error) {
err := sc.addPeer(event.peerID)
if err != nil {
return scSchedulerFail{reason: err}, nil
}
return noOp, nil
}
func (sc *scheduler) handleRemovePeer(event bcRemovePeer) (Event, error) {
err := sc.removePeer(event.peerID)
if err != nil {
// XXX - It is possible that the removePeer fails here for legitimate reasons
// for example if a peer timeout or error was handled just before this.
return scSchedulerFail{reason: err}, nil
}
if sc.allBlocksProcessed() {
return scFinishedEv{reason: "removed peer"}, nil
}
return noOp, nil
}
func (sc *scheduler) handleTryPrunePeer(event rTryPrunePeer) (Event, error) {
// Check behavior of peer responsible to deliver block at sc.height.
timeHeightAsked, ok := sc.pendingTime[sc.height]
if ok && time.Since(timeHeightAsked) > sc.peerTimeout {
// A request was sent to a peer for block at sc.height but a response was not received
// from that peer within sc.peerTimeout. Remove the peer. This is to ensure that a peer
// will be timed out even if it sends blocks at higher heights but prevents progress by
// not sending the block at current height.
sc.removePeer(sc.pendingBlocks[sc.height])
}
prunablePeers := sc.prunablePeers(sc.peerTimeout, sc.minRecvRate, event.time)
if len(prunablePeers) == 0 {
return noOp, nil
}
for _, peerID := range prunablePeers {
err := sc.removePeer(peerID)
if err != nil {
// Should never happen as prunablePeers() returns only existing peers in Ready state.
panic("scheduler data corruption")
}
}
// If all blocks are processed we should finish.
if sc.allBlocksProcessed() {
return scFinishedEv{reason: "after try prune"}, nil
}
return scPeersPruned{peers: prunablePeers}, nil
}
func (sc *scheduler) handleTrySchedule(event rTrySchedule) (Event, error) {
if time.Since(sc.lastAdvance) > sc.syncTimeout {
return scFinishedEv{reason: "timeout, no advance"}, nil
}
nextHeight := sc.nextHeightToSchedule()
if nextHeight == -1 {
return noOp, nil
}
bestPeerID, err := sc.selectPeer(nextHeight)
if err != nil {
return scSchedulerFail{reason: err}, nil
}
if err := sc.markPending(bestPeerID, nextHeight, event.time); err != nil {
return scSchedulerFail{reason: err}, nil // XXX: peerError might be more appropriate
}
return scBlockRequest{peerID: bestPeerID, height: nextHeight}, nil
}
func (sc *scheduler) handleStatusResponse(event bcStatusResponse) (Event, error) {
err := sc.setPeerRange(event.peerID, event.base, event.height)
if err != nil {
return scPeerError{peerID: event.peerID, reason: err}, nil
}
return noOp, nil
}
func (sc *scheduler) handle(event Event) (Event, error) {
switch event := event.(type) {
case bcStatusResponse:
nextEvent, err := sc.handleStatusResponse(event)
return nextEvent, err
case bcBlockResponse:
nextEvent, err := sc.handleBlockResponse(event)
return nextEvent, err
case bcNoBlockResponse:
nextEvent, err := sc.handleNoBlockResponse(event)
return nextEvent, err
case rTrySchedule:
nextEvent, err := sc.handleTrySchedule(event)
return nextEvent, err
case bcAddNewPeer:
nextEvent, err := sc.handleAddNewPeer(event)
return nextEvent, err
case bcRemovePeer:
nextEvent, err := sc.handleRemovePeer(event)
return nextEvent, err
case rTryPrunePeer:
nextEvent, err := sc.handleTryPrunePeer(event)
return nextEvent, err
case pcBlockProcessed:
nextEvent, err := sc.handleBlockProcessed(event)
return nextEvent, err
case pcBlockVerificationFailure:
nextEvent, err := sc.handleBlockProcessError(event)
return nextEvent, err
default:
return scSchedulerFail{reason: fmt.Errorf("unknown event %v", event)}, nil
}
}