github.com/n1ghtfa1l/go-vnt@v0.6.4-alpha.6/vnt/sync.go (about) 1 // Copyright 2015 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 package vnt 18 19 import ( 20 "math/rand" 21 "sync/atomic" 22 "time" 23 24 libp2p "github.com/libp2p/go-libp2p-peer" 25 "github.com/vntchain/go-vnt/common" 26 "github.com/vntchain/go-vnt/core/types" 27 "github.com/vntchain/go-vnt/log" 28 "github.com/vntchain/go-vnt/vnt/downloader" 29 ) 30 31 const ( 32 forceSyncCycle = 10 * time.Second // Time interval to force syncs, even if few peers are available 33 minDesiredPeerCount = 5 // Amount of peers desired to start syncing 34 35 // This is the target size for the packs of transactions sent by txsyncLoop. 36 // A pack can get larger than this if a single transactions exceeds this size. 37 txsyncPackSize = 100 * 1024 38 ) 39 40 type txsync struct { 41 p *peer 42 txs []*types.Transaction 43 } 44 45 // syncTransactions starts sending all currently pending transactions to the given peer. 46 func (pm *ProtocolManager) syncTransactions(p *peer) { 47 var txs types.Transactions 48 pending, _ := pm.txpool.Pending() 49 for _, batch := range pending { 50 txs = append(txs, batch...) 51 } 52 if len(txs) == 0 { 53 return 54 } 55 select { 56 case pm.txsyncCh <- &txsync{p, txs}: 57 case <-pm.quitSync: 58 } 59 } 60 61 // txsyncLoop takes care of the initial transaction sync for each new 62 // connection. When a new peer appears, we relay all currently pending 63 // transactions. In order to minimise egress bandwidth usage, we send 64 // the transactions in small packs to one peer at a time. 65 func (pm *ProtocolManager) txsyncLoop() { 66 log.Debug("sync", "txsyncLoop", "") 67 var ( 68 pending = make(map[libp2p.ID]*txsync) 69 sending = false // whether a send is active 70 pack = new(txsync) // the pack that is being sent 71 done = make(chan error, 1) // result of the send 72 ) 73 74 // send starts a sending a pack of transactions from the sync. 75 send := func(s *txsync) { 76 // Fill pack with transactions up to the target size. 77 size := common.StorageSize(0) 78 pack.p = s.p 79 pack.txs = pack.txs[:0] 80 for i := 0; i < len(s.txs) && size < txsyncPackSize; i++ { 81 pack.txs = append(pack.txs, s.txs[i]) 82 size += s.txs[i].Size() 83 } 84 // Remove the transactions that will be sent. 85 s.txs = s.txs[:copy(s.txs, s.txs[len(pack.txs):])] 86 if len(s.txs) == 0 { 87 delete(pending, s.p.RemoteID()) 88 } 89 // Send the pack in the background. 90 s.p.Log().Trace("Sending batch of transactions", "count", len(pack.txs), "bytes", size) 91 sending = true 92 go func() { done <- pack.p.SendTransactions(pack.txs) }() 93 } 94 95 // pick chooses the next pending sync. 96 pick := func() *txsync { 97 if len(pending) == 0 { 98 return nil 99 } 100 n := rand.Intn(len(pending)) + 1 101 for _, s := range pending { 102 if n--; n == 0 { 103 return s 104 } 105 } 106 return nil 107 } 108 109 for { 110 select { 111 case s := <-pm.txsyncCh: 112 pending[s.p.RemoteID()] = s 113 if !sending { 114 send(s) 115 } 116 case err := <-done: 117 sending = false 118 // Stop tracking peers that cause send failures. 119 if err != nil { 120 pack.p.Log().Debug("Transaction send failed", "err", err) 121 delete(pending, pack.p.RemoteID()) 122 } 123 // Schedule the next send. 124 if s := pick(); s != nil { 125 send(s) 126 } 127 case <-pm.quitSync: 128 return 129 } 130 } 131 } 132 133 // syncer is responsible for periodically synchronising with the network, both 134 // downloading hashes and blocks as well as handling the announcement handler. 135 func (pm *ProtocolManager) syncer() { 136 // Start and ensure cleanup of sync mechanisms 137 pm.fetcher.Start() 138 defer pm.fetcher.Stop() 139 defer pm.downloader.Terminate() 140 141 // Wait for different events to fire synchronisation operations 142 forceSync := time.NewTicker(forceSyncCycle) 143 defer forceSync.Stop() 144 145 for { 146 select { 147 case <-pm.newPeerCh: 148 // Make sure we have peers to select from, then sync 149 if pm.peers.Len() < minDesiredPeerCount { 150 break 151 } 152 go pm.synchronise(pm.peers.BestPeer()) 153 154 case <-forceSync.C: 155 // Force a sync even if not enough peers are present 156 go pm.synchronise(pm.peers.BestPeer()) 157 158 case <-pm.noMorePeers: 159 return 160 } 161 } 162 } 163 164 // synchronise tries to sync up our local block chain with a remote peer. 165 func (pm *ProtocolManager) synchronise(peer *peer) { 166 // Short circuit if no peers are available 167 if peer == nil { 168 return 169 } 170 171 log.Debug("PM update with", "with", peer.id) 172 defer func() { 173 log.Debug("Update end", "with", peer.id) 174 }() 175 176 // Make sure the peer's TD is higher than our own 177 currentBlock := pm.blockchain.CurrentBlock() 178 td := pm.blockchain.GetTd(currentBlock.Hash(), currentBlock.NumberU64()) 179 180 pHead, pTd := peer.Head() 181 if pTd.Cmp(td) <= 0 { 182 return 183 } 184 // Otherwise try to sync with the downloader 185 mode := downloader.FullSync 186 if atomic.LoadUint32(&pm.fastSync) == 1 { 187 // Fast sync was explicitly requested, and explicitly granted 188 mode = downloader.FastSync 189 } else if currentBlock.NumberU64() == 0 && pm.blockchain.CurrentFastBlock().NumberU64() > 0 { 190 // The database seems empty as the current block is the genesis. Yet the fast 191 // block is ahead, so fast sync was enabled for this node at a certain point. 192 // The only scenario where this can happen is if the user manually (or via a 193 // bad block) rolled back a fast sync node below the sync point. In this case 194 // however it's safe to reenable fast sync. 195 atomic.StoreUint32(&pm.fastSync, 1) 196 mode = downloader.FastSync 197 } 198 199 if mode == downloader.FastSync { 200 // Make sure the peer's total difficulty we are synchronizing is higher. 201 if pm.blockchain.GetTdByHash(pm.blockchain.CurrentFastBlock().Hash()).Cmp(pTd) >= 0 { 202 return 203 } 204 } 205 206 // Run the sync cycle, and disable fast sync if we've went past the pivot block 207 if err := pm.downloader.Synchronise(peer.id, pHead, pTd, mode); err != nil { 208 return 209 } 210 if atomic.LoadUint32(&pm.fastSync) == 1 { 211 log.Info("Fast sync complete, auto disabling") 212 atomic.StoreUint32(&pm.fastSync, 0) 213 } 214 atomic.StoreUint32(&pm.acceptTxs, 1) // Mark initial sync done 215 if head := pm.blockchain.CurrentBlock(); head.NumberU64() > 0 { 216 // We've completed a sync cycle, notify all peers of new state. This path is 217 // essential in star-topology networks where a gateway node needs to notify 218 // all its out-of-date peers of the availability of a new block. This failure 219 // scenario will most often crop up in private and hackathon networks with 220 // degenerate connectivity, but it should be healthy for the mainnet too to 221 // more reliably update peers or the local TD state. 222 go pm.BroadcastBlock(head, false) 223 } 224 }