package blockchain import ( "errors" "fmt" "math" "sync" "sync/atomic" "time" cmn "github.com/tendermint/tendermint/libs/common" flow "github.com/tendermint/tendermint/libs/flowrate" "github.com/tendermint/tendermint/libs/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 = 2 maxTotalRequesters = 600 maxPendingRequests = maxTotalRequesters maxPendingRequestsPerPeer = 20 // 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. // peers peers map[p2p.ID]*bpPeer maxPeerHeight int64 // atomic numPending int32 // number of requests pending assignment or block response 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, atomic.LoadInt32(&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. // Ensures we've either received a block or waited some amount of time, // and that we're synced to the highest known height. Note we use maxPeerHeight - 1 // because to sync block H requires block H+1 to verify the LastCommit. receivedBlockOrTimedOut := pool.height > 0 || time.Since(pool.startTime) > 5*time.Second ourChainIsLongestAmongPeers := pool.maxPeerHeight == 0 || pool.height >= (pool.maxPeerHeight-1) 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] peerID := request.getPeerID() if peerID != p2p.ID("") { // RemovePeer will redo all requesters associated with this peer. pool.removePeer(peerID) } return 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) { atomic.AddInt32(&pool.numPending, -1) peer := pool.peers[peerID] if peer != nil { peer.decrPending(blockSize) } } else { pool.Logger.Info("invalid peer", "peer", peerID, "blockHeight", block.Height) pool.sendError(errors.New("invalid peer"), peerID) } } // 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 { requester.redo(peerID) } } 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() if nextHeight > pool.maxPeerHeight { return } request := newBPRequester(pool, nextHeight) pool.requesters[nextHeight] = request atomic.AddInt32(&pool.numPending, 1) 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() defer pool.mtx.Unlock() str := "" nextHeight := pool.height + pool.requestersLen() for h := pool.height; h < nextHeight; h++ { if pool.requesters[h] == nil { str += fmt.Sprintf("H(%v):X ", h) } else { str += fmt.Sprintf("H(%v):", h) str += fmt.Sprintf("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 p2p.ID //redo may send multitime, add peerId to identify repeat 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{}, 1), redoCh: make(chan p2p.ID, 1), 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 and block doesn't already exist. 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() select { case bpr.gotBlockCh <- struct{}{}: default: } 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 } // This is called from the requestRoutine, upon redo(). func (bpr *bpRequester) reset() { bpr.mtx.Lock() defer bpr.mtx.Unlock() if bpr.block != nil { atomic.AddInt32(&bpr.pool.numPending, 1) } bpr.peerID = "" bpr.block = nil } // Tells bpRequester to pick another peer and try again. // NOTE: Nonblocking, and does nothing if another redo // was already requested. func (bpr *bpRequester) redo(peerId p2p.ID) { select { case bpr.redoCh <- peerId: default: } } // 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) WAIT_LOOP: for { select { case <-bpr.pool.Quit(): bpr.Stop() return case <-bpr.Quit(): return case peerID := <-bpr.redoCh: if peerID == bpr.peerID { bpr.reset() continue OUTER_LOOP } else { continue WAIT_LOOP } case <-bpr.gotBlockCh: // We got a block! // Continue the for-loop and wait til Quit. continue WAIT_LOOP } } } } //------------------------------------- type BlockRequest struct { Height int64 PeerID p2p.ID }