79 lines
2.4 KiB
Go
79 lines
2.4 KiB
Go
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// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package les
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import (
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"time"
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"github.com/ethereum/go-ethereum/eth/downloader"
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)
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const (
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forceSyncCycle = 10 * time.Second // Time interval to force syncs, even if few peers are available
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minDesiredPeerCount = 5 // Amount of peers desired to start syncing
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)
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// syncer is responsible for periodically synchronising with the network, both
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// downloading hashes and blocks as well as handling the announcement handler.
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func (pm *ProtocolManager) syncer() {
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// Start and ensure cleanup of sync mechanisms
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//pm.fetcher.Start()
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//defer pm.fetcher.Stop()
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defer pm.downloader.Terminate()
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// Wait for different events to fire synchronisation operations
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forceSync := time.Tick(forceSyncCycle)
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for {
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select {
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case <-pm.newPeerCh:
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// Make sure we have peers to select from, then sync
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if pm.peers.Len() < minDesiredPeerCount {
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break
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}
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go pm.synchronise(pm.peers.BestPeer(), false)
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case <-forceSync:
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// Force a sync even if not enough peers are present
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go pm.synchronise(pm.peers.BestPeer(), false)
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case <-pm.noMorePeers:
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return
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}
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}
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}
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// synchronise tries to sync up our local block chain with a remote peer.
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func (pm *ProtocolManager) synchronise(peer *peer, exit bool) {
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// Short circuit if no peers are available
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if peer == nil {
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return
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}
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// Make sure the peer's TD is higher than our own.
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td := pm.blockchain.GetTd(pm.blockchain.LastBlockHash())
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if peer.Td().Cmp(td) > 0 {
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for {
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if pm.downloader.Synchronise(peer.id, peer.Head(), peer.Td(), downloader.LightSync) != nil {
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return
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}
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if exit {
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return
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}
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time.Sleep(time.Second * 5)
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}
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}
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}
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