package blockchain import ( "math" "sync" "time" flow "github.com/tendermint/flowcontrol" . "github.com/tendermint/go-common" "github.com/tendermint/tendermint/types" ) const ( requestIntervalMS = 250 maxTotalRequesters = 300 maxPendingRequests = maxTotalRequesters maxPendingRequestsPerPeer = 75 peerTimeoutSeconds = 15 minRecvRate = 10240 // 10Kb/s ) /* 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 heigher heights until the limits. 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 { QuitService startTime time.Time // block requests mtx sync.Mutex requesters map[int]*bpRequester height int // the lowest key in requesters. numPending int32 // number of requests pending assignment or block response // peers peersMtx sync.Mutex peers map[string]*bpPeer requestsCh chan<- BlockRequest timeoutsCh chan<- string } func NewBlockPool(start int, requestsCh chan<- BlockRequest, timeoutsCh chan<- string) *BlockPool { bp := &BlockPool{ peers: make(map[string]*bpPeer), requesters: make(map[int]*bpRequester), height: start, numPending: 0, requestsCh: requestsCh, timeoutsCh: timeoutsCh, } bp.QuitService = *NewQuitService(log, "BlockPool", bp) return bp } func (pool *BlockPool) OnStart() error { pool.QuitService.OnStart() go pool.makeRequestersRoutine() pool.startTime = time.Now() return nil } func (pool *BlockPool) OnStop() { pool.QuitService.OnStop() } // Run spawns requesters as needed. func (pool *BlockPool) makeRequestersRoutine() { for { if !pool.IsRunning() { break } _, numPending := pool.GetStatus() if numPending >= maxPendingRequests { // sleep for a bit. time.Sleep(requestIntervalMS * time.Millisecond) // check for timed out peers pool.removeTimedoutPeers() } else if len(pool.requesters) >= 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() { for _, peer := range pool.peers { if !peer.didTimeout && peer.numPending > 0 { curRate := peer.recvMonitor.Status().CurRate // XXX remove curRate != 0 if curRate != 0 && curRate < minRecvRate { pool.sendTimeout(peer.id) log.Warn("SendTimeout", "peer", peer.id, "reason", "curRate too low") peer.didTimeout = true } } if peer.didTimeout { pool.peersMtx.Lock() // Lock pool.removePeer(peer.id) pool.peersMtx.Unlock() } } } func (pool *BlockPool) GetStatus() (height int, numPending int32) { pool.mtx.Lock() // Lock defer pool.mtx.Unlock() return pool.height, pool.numPending } // TODO: relax conditions, prevent abuse. func (pool *BlockPool) IsCaughtUp() bool { pool.mtx.Lock() height := pool.height pool.mtx.Unlock() pool.peersMtx.Lock() numPeers := len(pool.peers) maxPeerHeight := 0 for _, peer := range pool.peers { maxPeerHeight = MaxInt(maxPeerHeight, peer.height) } pool.peersMtx.Unlock() return numPeers >= 3 && (height > 0 || time.Now().Sub(pool.startTime) > 30*time.Second) && (maxPeerHeight == 0 || height == maxPeerHeight) } // We need to see the second block's Validation to validate the first block. // So we peek two blocks at a time. func (pool *BlockPool) PeekTwoBlocks() (first *types.Block, second *types.Block) { pool.mtx.Lock() // 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'.Validation from PeekTwoBlocks(). func (pool *BlockPool) PopRequest() { pool.mtx.Lock() // 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 { PanicSanity(Fmt("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. func (pool *BlockPool) RedoRequest(height int) { pool.mtx.Lock() // Lock defer pool.mtx.Unlock() request := pool.requesters[height] if request.block == nil { PanicSanity("Expected block to be non-nil") } // RemovePeer will redo all requesters associated with this peer. // TODO: record this malfeasance pool.RemovePeer(request.peerID) // Lock on peersMtx. } // TODO: ensure that blocks come in order for each peer. func (pool *BlockPool) AddBlock(peerID string, block *types.Block, blockSize int) { pool.mtx.Lock() // Lock defer pool.mtx.Unlock() requester := pool.requesters[block.Height] if requester == nil { return } if requester.setBlock(block, peerID) { pool.numPending-- peer := pool.getPeer(peerID) peer.decrPending(blockSize) } else { // Bad peer? } } // Sets the peer's alleged blockchain height. func (pool *BlockPool) SetPeerHeight(peerID string, height int) { pool.peersMtx.Lock() // Lock defer pool.peersMtx.Unlock() peer := pool.peers[peerID] if peer != nil { peer.height = height } else { peer = newBPPeer(pool, peerID, height) pool.peers[peerID] = peer } } func (pool *BlockPool) RemovePeer(peerID string) { pool.peersMtx.Lock() // Lock defer pool.peersMtx.Unlock() pool.removePeer(peerID) } func (pool *BlockPool) removePeer(peerID string) { for _, requester := range pool.requesters { if requester.getPeerID() == peerID { pool.numPending++ go requester.redo() // pick another peer and ... } } delete(pool.peers, peerID) } func (pool *BlockPool) getPeer(peerID string) *bpPeer { pool.peersMtx.Lock() // Lock defer pool.peersMtx.Unlock() peer := pool.peers[peerID] return peer } // Pick an available peer with at least the given minHeight. // If no peers are available, returns nil. func (pool *BlockPool) pickIncrAvailablePeer(minHeight int) *bpPeer { pool.peersMtx.Lock() defer pool.peersMtx.Unlock() for _, peer := range pool.peers { if peer.isBad() { pool.removePeer(peer.id) continue } else { } if peer.numPending >= maxPendingRequestsPerPeer { continue } if peer.height < minHeight { continue } peer.incrPending() return peer } return nil } func (pool *BlockPool) makeNextRequester() { pool.mtx.Lock() // Lock defer pool.mtx.Unlock() nextHeight := pool.height + len(pool.requesters) request := newBPRequester(pool, nextHeight) pool.requesters[nextHeight] = request pool.numPending++ request.Start() } func (pool *BlockPool) sendRequest(height int, peerID string) { if !pool.IsRunning() { return } pool.requestsCh <- BlockRequest{height, peerID} } func (pool *BlockPool) sendTimeout(peerID string) { if !pool.IsRunning() { return } pool.timeoutsCh <- peerID } func (pool *BlockPool) debug() string { pool.mtx.Lock() // Lock defer pool.mtx.Unlock() str := "" for h := pool.height; h < pool.height+len(pool.requesters); h++ { if pool.requesters[h] == nil { str += Fmt("H(%v):X ", h) } else { str += Fmt("H(%v):", h) str += Fmt("B?(%v) ", pool.requesters[h].block != nil) } } return str } //------------------------------------- type bpPeer struct { pool *BlockPool id string height int numPending int32 recvMonitor *flow.Monitor timeout *time.Timer didTimeout bool } func newBPPeer(pool *BlockPool, peerID string, height int) *bpPeer { peer := &bpPeer{ pool: pool, id: peerID, height: height, numPending: 0, } return peer } func (peer *bpPeer) resetMonitor() { peer.recvMonitor = flow.New(time.Second, time.Second*40) var initialValue = float64(minRecvRate) * math.E peer.recvMonitor.SetREMA(initialValue) } func (peer *bpPeer) resetTimeout() { if peer.timeout == nil { peer.timeout = time.AfterFunc(time.Second*peerTimeoutSeconds, peer.onTimeout) } else { peer.timeout.Reset(time.Second * peerTimeoutSeconds) } } 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.sendTimeout(peer.id) log.Warn("SendTimeout", "peer", peer.id, "reason", "onTimeout") peer.didTimeout = true } func (peer *bpPeer) isBad() bool { return peer.didTimeout } //------------------------------------- type bpRequester struct { QuitService pool *BlockPool height int gotBlockCh chan struct{} redoCh chan struct{} mtx sync.Mutex peerID string block *types.Block } func newBPRequester(pool *BlockPool, height int) *bpRequester { bpr := &bpRequester{ pool: pool, height: height, gotBlockCh: make(chan struct{}), redoCh: make(chan struct{}), peerID: "", block: nil, } bpr.QuitService = *NewQuitService(nil, "bpRequester", bpr) return bpr } func (bpr *bpRequester) OnStart() error { bpr.QuitService.OnStart() go bpr.requestRoutine() return nil } // Returns true if the peer matches func (bpr *bpRequester) setBlock(block *types.Block, peerID string) 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() string { 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 = nil 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 int PeerID string }