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package blockchain
import (
"errors"
"fmt"
"math"
"sync"
"time"
cmn "github.com/tendermint/tmlibs/common"
flow "github.com/tendermint/tmlibs/flowrate"
"github.com/tendermint/tmlibs/log"
"github.com/tendermint/tendermint/p2p"
"github.com/tendermint/tendermint/types"
)
/*
eg, L = latency = 0.1s
P = num peers = 10
FN = num full nodes
BS = 1kB block size
CB = 1 Mbit/s = 128 kB/s
CB/P = 12.8 kB
B/S = CB/P/BS = 12.8 blocks/s
12.8 * 0.1 = 1.28 blocks on conn
*/
const (
requestIntervalMS = 100
maxTotalRequesters = 1000
maxPendingRequests = maxTotalRequesters
maxPendingRequestsPerPeer = 50
// Minimum recv rate to ensure we're receiving blocks from a peer fast
// enough. If a peer is not sending us data at at least that rate, we
// consider them to have timedout and we disconnect.
//
// Assuming a DSL connection (not a good choice) 128 Kbps (upload) ~ 15 KB/s,
// sending data across atlantic ~ 7.5 KB/s.
minRecvRate = 7680
// Maximum difference between current and new block's height.
maxDiffBetweenCurrentAndReceivedBlockHeight = 100
)
var peerTimeout = 15 * time.Second // not const so we can override with tests
/*
Peers self report their heights when we join the block pool.
Starting from our latest pool.height, we request blocks
in sequence from peers that reported higher heights than ours.
Every so often we ask peers what height they're on so we can keep going.
Requests are continuously made for blocks of higher heights until
the limit is reached. If most of the requests have no available peers, and we
are not at peer limits, we can probably switch to consensus reactor
*/
type BlockPool struct {
cmn.BaseService
startTime time.Time
mtx sync.Mutex
// block requests
requesters map[int64]*bpRequester
height int64 // the lowest key in requesters.
numPending int32 // number of requests pending assignment or block response
// peers
peers map[p2p.ID]*bpPeer
maxPeerHeight int64
requestsCh chan<- BlockRequest
errorsCh chan<- peerError
}
func NewBlockPool(start int64, requestsCh chan<- BlockRequest, errorsCh chan<- peerError) *BlockPool {
bp := &BlockPool{
peers: make(map[p2p.ID]*bpPeer),
requesters: make(map[int64]*bpRequester),
height: start,
numPending: 0,
requestsCh: requestsCh,
errorsCh: errorsCh,
}
bp.BaseService = *cmn.NewBaseService(nil, "BlockPool", bp)
return bp
}
func (pool *BlockPool) OnStart() error {
go pool.makeRequestersRoutine()
pool.startTime = time.Now()
return nil
}
func (pool *BlockPool) OnStop() {}
// Run spawns requesters as needed.
func (pool *BlockPool) makeRequestersRoutine() {
for {
if !pool.IsRunning() {
break
}
_, numPending, lenRequesters := pool.GetStatus()
if numPending >= maxPendingRequests {
// sleep for a bit.
time.Sleep(requestIntervalMS * time.Millisecond)
// check for timed out peers
pool.removeTimedoutPeers()
} else if lenRequesters >= maxTotalRequesters {
// sleep for a bit.
time.Sleep(requestIntervalMS * time.Millisecond)
// check for timed out peers
pool.removeTimedoutPeers()
} else {
// request for more blocks.
pool.makeNextRequester()
}
}
}
func (pool *BlockPool) removeTimedoutPeers() {
pool.mtx.Lock()
defer pool.mtx.Unlock()
for _, peer := range pool.peers {
if !peer.didTimeout && peer.numPending > 0 {
curRate := peer.recvMonitor.Status().CurRate
// curRate can be 0 on start
if curRate != 0 && curRate < minRecvRate {
err := errors.New("peer is not sending us data fast enough")
pool.sendError(err, peer.id)
pool.Logger.Error("SendTimeout", "peer", peer.id,
"reason", err,
"curRate", fmt.Sprintf("%d KB/s", curRate/1024),
"minRate", fmt.Sprintf("%d KB/s", minRecvRate/1024))
peer.didTimeout = true
}
}
if peer.didTimeout {
pool.removePeer(peer.id)
}
}
}
func (pool *BlockPool) GetStatus() (height int64, numPending int32, lenRequesters int) {
pool.mtx.Lock()
defer pool.mtx.Unlock()
return pool.height, pool.numPending, len(pool.requesters)
}
// TODO: relax conditions, prevent abuse.
func (pool *BlockPool) IsCaughtUp() bool {
pool.mtx.Lock()
defer pool.mtx.Unlock()
// Need at least 1 peer to be considered caught up.
if len(pool.peers) == 0 {
pool.Logger.Debug("Blockpool has no peers")
return false
}
// some conditions to determine if we're caught up
receivedBlockOrTimedOut := (pool.height > 0 || time.Since(pool.startTime) > 5*time.Second)
ourChainIsLongestAmongPeers := pool.maxPeerHeight == 0 || pool.height >= pool.maxPeerHeight
isCaughtUp := receivedBlockOrTimedOut && ourChainIsLongestAmongPeers
return isCaughtUp
}
// We need to see the second block's Commit to validate the first block.
// So we peek two blocks at a time.
// The caller will verify the commit.
func (pool *BlockPool) PeekTwoBlocks() (first *types.Block, second *types.Block) {
pool.mtx.Lock()
defer pool.mtx.Unlock()
if r := pool.requesters[pool.height]; r != nil {
first = r.getBlock()
}
if r := pool.requesters[pool.height+1]; r != nil {
second = r.getBlock()
}
return
}
// Pop the first block at pool.height
// It must have been validated by 'second'.Commit from PeekTwoBlocks().
func (pool *BlockPool) PopRequest() {
pool.mtx.Lock()
defer pool.mtx.Unlock()
if r := pool.requesters[pool.height]; r != nil {
/* The block can disappear at any time, due to removePeer().
if r := pool.requesters[pool.height]; r == nil || r.block == nil {
PanicSanity("PopRequest() requires a valid block")
}
*/
r.Stop()
delete(pool.requesters, pool.height)
pool.height++
} else {
panic(fmt.Sprintf("Expected requester to pop, got nothing at height %v", pool.height))
}
}
// Invalidates the block at pool.height,
// Remove the peer and redo request from others.
// Returns the ID of the removed peer.
func (pool *BlockPool) RedoRequest(height int64) p2p.ID {
pool.mtx.Lock()
defer pool.mtx.Unlock()
request := pool.requesters[height]
if request.block == nil {
panic("Expected block to be non-nil")
}
// RemovePeer will redo all requesters associated with this peer.
pool.removePeer(request.peerID)
return request.peerID
}
// TODO: ensure that blocks come in order for each peer.
func (pool *BlockPool) AddBlock(peerID p2p.ID, block *types.Block, blockSize int) {
pool.mtx.Lock()
defer pool.mtx.Unlock()
requester := pool.requesters[block.Height]
if requester == nil {
pool.Logger.Info("peer sent us a block we didn't expect", "peer", peerID, "curHeight", pool.height, "blockHeight", block.Height)
diff := pool.height - block.Height
if diff < 0 {
diff *= -1
}
if diff > maxDiffBetweenCurrentAndReceivedBlockHeight {
pool.sendError(errors.New("peer sent us a block we didn't expect with a height too far ahead/behind"), peerID)
}
return
}
if requester.setBlock(block, peerID) {
pool.numPending--
peer := pool.peers[peerID]
if peer != nil {
peer.decrPending(blockSize)
}
} else {
// Bad peer?
}
}
// MaxPeerHeight returns the highest height reported by a peer.
func (pool *BlockPool) MaxPeerHeight() int64 {
pool.mtx.Lock()
defer pool.mtx.Unlock()
return pool.maxPeerHeight
}
// Sets the peer's alleged blockchain height.
func (pool *BlockPool) SetPeerHeight(peerID p2p.ID, height int64) {
pool.mtx.Lock()
defer pool.mtx.Unlock()
peer := pool.peers[peerID]
if peer != nil {
peer.height = height
} else {
peer = newBPPeer(pool, peerID, height)
peer.setLogger(pool.Logger.With("peer", peerID))
pool.peers[peerID] = peer
}
if height > pool.maxPeerHeight {
pool.maxPeerHeight = height
}
}
func (pool *BlockPool) RemovePeer(peerID p2p.ID) {
pool.mtx.Lock()
defer pool.mtx.Unlock()
pool.removePeer(peerID)
}
func (pool *BlockPool) removePeer(peerID p2p.ID) {
for _, requester := range pool.requesters {
if requester.getPeerID() == peerID {
if requester.getBlock() != nil {
pool.numPending++
}
go requester.redo() // pick another peer and ...
}
}
delete(pool.peers, peerID)
}
// Pick an available peer with at least the given minHeight.
// If no peers are available, returns nil.
func (pool *BlockPool) pickIncrAvailablePeer(minHeight int64) *bpPeer {
pool.mtx.Lock()
defer pool.mtx.Unlock()
for _, peer := range pool.peers {
if peer.didTimeout {
pool.removePeer(peer.id)
continue
}
if peer.numPending >= maxPendingRequestsPerPeer {
continue
}
if peer.height < minHeight {
continue
}
peer.incrPending()
return peer
}
return nil
}
func (pool *BlockPool) makeNextRequester() {
pool.mtx.Lock()
defer pool.mtx.Unlock()
nextHeight := pool.height + pool.requestersLen()
request := newBPRequester(pool, nextHeight)
// request.SetLogger(pool.Logger.With("height", nextHeight))
pool.requesters[nextHeight] = request
pool.numPending++
err := request.Start()
if err != nil {
request.Logger.Error("Error starting request", "err", err)
}
}
func (pool *BlockPool) requestersLen() int64 {
return int64(len(pool.requesters))
}
func (pool *BlockPool) sendRequest(height int64, peerID p2p.ID) {
if !pool.IsRunning() {
return
}
pool.requestsCh <- BlockRequest{height, peerID}
}
func (pool *BlockPool) sendError(err error, peerID p2p.ID) {
if !pool.IsRunning() {
return
}
pool.errorsCh <- peerError{err, peerID}
}
// unused by tendermint; left for debugging purposes
func (pool *BlockPool) debug() string {
pool.mtx.Lock() // Lock
defer pool.mtx.Unlock()
str := ""
nextHeight := pool.height + pool.requestersLen()
for h := pool.height; h < nextHeight; h++ {
if pool.requesters[h] == nil {
str += cmn.Fmt("H(%v):X ", h)
} else {
str += cmn.Fmt("H(%v):", h)
str += cmn.Fmt("B?(%v) ", pool.requesters[h].block != nil)
}
}
return str
}
//-------------------------------------
type bpPeer struct {
pool *BlockPool
id p2p.ID
recvMonitor *flow.Monitor
height int64
numPending int32
timeout *time.Timer
didTimeout bool
logger log.Logger
}
func newBPPeer(pool *BlockPool, peerID p2p.ID, height int64) *bpPeer {
peer := &bpPeer{
pool: pool,
id: peerID,
height: height,
numPending: 0,
logger: log.NewNopLogger(),
}
return peer
}
func (peer *bpPeer) setLogger(l log.Logger) {
peer.logger = l
}
func (peer *bpPeer) resetMonitor() {
peer.recvMonitor = flow.New(time.Second, time.Second*40)
initialValue := float64(minRecvRate) * math.E
peer.recvMonitor.SetREMA(initialValue)
}
func (peer *bpPeer) resetTimeout() {
if peer.timeout == nil {
peer.timeout = time.AfterFunc(peerTimeout, peer.onTimeout)
} else {
peer.timeout.Reset(peerTimeout)
}
}
func (peer *bpPeer) incrPending() {
if peer.numPending == 0 {
peer.resetMonitor()
peer.resetTimeout()
}
peer.numPending++
}
func (peer *bpPeer) decrPending(recvSize int) {
peer.numPending--
if peer.numPending == 0 {
peer.timeout.Stop()
} else {
peer.recvMonitor.Update(recvSize)
peer.resetTimeout()
}
}
func (peer *bpPeer) onTimeout() {
peer.pool.mtx.Lock()
defer peer.pool.mtx.Unlock()
err := errors.New("peer did not send us anything")
peer.pool.sendError(err, peer.id)
peer.logger.Error("SendTimeout", "reason", err, "timeout", peerTimeout)
peer.didTimeout = true
}
//-------------------------------------
type bpRequester struct {
cmn.BaseService
pool *BlockPool
height int64
gotBlockCh chan struct{}
redoCh chan struct{}
mtx sync.Mutex
peerID p2p.ID
block *types.Block
}
func newBPRequester(pool *BlockPool, height int64) *bpRequester {
bpr := &bpRequester{
pool: pool,
height: height,
gotBlockCh: make(chan struct{}),
redoCh: make(chan struct{}),
peerID: "",
block: nil,
}
bpr.BaseService = *cmn.NewBaseService(nil, "bpRequester", bpr)
return bpr
}
func (bpr *bpRequester) OnStart() error {
go bpr.requestRoutine()
return nil
}
// Returns true if the peer matches
func (bpr *bpRequester) setBlock(block *types.Block, peerID p2p.ID) bool {
bpr.mtx.Lock()
if bpr.block != nil || bpr.peerID != peerID {
bpr.mtx.Unlock()
return false
}
bpr.block = block
bpr.mtx.Unlock()
bpr.gotBlockCh <- struct{}{}
return true
}
func (bpr *bpRequester) getBlock() *types.Block {
bpr.mtx.Lock()
defer bpr.mtx.Unlock()
return bpr.block
}
func (bpr *bpRequester) getPeerID() p2p.ID {
bpr.mtx.Lock()
defer bpr.mtx.Unlock()
return bpr.peerID
}
func (bpr *bpRequester) reset() {
bpr.mtx.Lock()
bpr.peerID = ""
bpr.block = nil
bpr.mtx.Unlock()
}
// Tells bpRequester to pick another peer and try again.
// NOTE: blocking
func (bpr *bpRequester) redo() {
bpr.redoCh <- struct{}{}
}
// Responsible for making more requests as necessary
// Returns only when a block is found (e.g. AddBlock() is called)
func (bpr *bpRequester) requestRoutine() {
OUTER_LOOP:
for {
// Pick a peer to send request to.
var peer *bpPeer
PICK_PEER_LOOP:
for {
if !bpr.IsRunning() || !bpr.pool.IsRunning() {
return
}
peer = bpr.pool.pickIncrAvailablePeer(bpr.height)
if peer == nil {
//log.Info("No peers available", "height", height)
time.Sleep(requestIntervalMS * time.Millisecond)
continue PICK_PEER_LOOP
}
break PICK_PEER_LOOP
}
bpr.mtx.Lock()
bpr.peerID = peer.id
bpr.mtx.Unlock()
// Send request and wait.
bpr.pool.sendRequest(bpr.height, peer.id)
select {
case <-bpr.pool.Quit():
bpr.Stop()
return
case <-bpr.Quit():
return
case <-bpr.redoCh:
bpr.reset()
continue OUTER_LOOP // When peer is removed
case <-bpr.gotBlockCh:
// We got the block, now see if it's good.
select {
case <-bpr.pool.Quit():
bpr.Stop()
return
case <-bpr.Quit():
return
case <-bpr.redoCh:
bpr.reset()
continue OUTER_LOOP
}
}
}
}
//-------------------------------------
type BlockRequest struct {
Height int64
PeerID p2p.ID
}