github.com/gochain-io/gochain@v2.2.26+incompatible/les/sync.go (about)

     1  // Copyright 2016 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 les
    18  
    19  import (
    20  	"context"
    21  	"time"
    22  
    23  	"github.com/gochain-io/gochain/core/rawdb"
    24  	"github.com/gochain-io/gochain/eth/downloader"
    25  	"github.com/gochain-io/gochain/light"
    26  	"github.com/gochain-io/gochain/log"
    27  )
    28  
    29  const (
    30  	//forceSyncCycle      = 10 * time.Second // Time interval to force syncs, even if few peers are available
    31  	minDesiredPeerCount = 5 // Amount of peers desired to start syncing
    32  )
    33  
    34  // syncer is responsible for periodically synchronising with the network, both
    35  // downloading hashes and blocks as well as handling the announcement handler.
    36  func (pm *ProtocolManager) syncer() {
    37  	// Start and ensure cleanup of sync mechanisms
    38  	//pm.fetcher.Start()
    39  	//defer pm.fetcher.Stop()
    40  	defer pm.downloader.Terminate()
    41  
    42  	// Wait for different events to fire synchronisation operations
    43  	//forceSync := time.Tick(forceSyncCycle)
    44  	for {
    45  		select {
    46  		case <-pm.newPeerCh:
    47  			/*			// Make sure we have peers to select from, then sync
    48  						if pm.peers.Len() < minDesiredPeerCount {
    49  							break
    50  						}
    51  						go pm.synchronise(pm.peers.BestPeer())
    52  			*/
    53  		/*case <-forceSync:
    54  		// Force a sync even if not enough peers are present
    55  		go pm.synchronise(pm.peers.BestPeer())
    56  		*/
    57  		case <-pm.noMorePeers:
    58  			return
    59  		}
    60  	}
    61  }
    62  
    63  func (pm *ProtocolManager) needToSync(peerHead blockInfo) bool {
    64  	head := pm.blockchain.CurrentHeader()
    65  	currentTd := rawdb.ReadTd(pm.chainDb.GlobalTable(), head.Hash(), head.Number.Uint64())
    66  	return currentTd != nil && peerHead.Td.Cmp(currentTd) > 0
    67  }
    68  
    69  // synchronise tries to sync up our local block chain with a remote peer.
    70  func (pm *ProtocolManager) synchronise(peer *peer) {
    71  	// Short circuit if no peers are available
    72  	if peer == nil {
    73  		return
    74  	}
    75  
    76  	// Make sure the peer's TD is higher than our own.
    77  	if !pm.needToSync(peer.headBlockInfo()) {
    78  		return
    79  	}
    80  
    81  	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
    82  	defer cancel()
    83  	pm.blockchain.(*light.LightChain).SyncCht(ctx)
    84  	if err := pm.downloader.Synchronise(ctx, peer.id, peer.Head(), peer.Td(), downloader.LightSync); err != nil {
    85  		log.Error("Cannot synchronise downloader", "id", peer.id, "head", peer.Head(), "err", err)
    86  	}
    87  }