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package downloader
import (
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
)
// THIS IS PENDING AND TO DO CHANGES FOR MAKING THE DOWNLOADER SYNCHRONOUS
// SynchroniseWithPeer will select the peer and use it for synchronising. If an empty string is given
// it will use the best peer possible and synchronise if it's TD is higher than our own. If any of the
// checks fail an error will be returned. This method is synchronous
func (d *Downloader) SynchroniseWithPeer(id string) (types.Blocks, error) {
// Check if we're busy
if d.isBusy() {
return nil, errBusy
}
// Attempt to select a peer. This can either be nothing, which returns, best peer
// or selected peer. If no peer could be found an error will be returned
var p *peer
if len(id) == 0 {
p = d.peers[id]
if p == nil {
return nil, errUnknownPeer
}
} else {
p = d.peers.bestPeer()
}
// Make sure our td is lower than the peer's td
if p.td.Cmp(d.currentTd()) <= 0 || d.hasBlock(p.recentHash) {
return nil, errLowTd
}
// Get the hash from the peer and initiate the downloading progress.
err := d.getFromPeer(p, p.recentHash, false)
if err != nil {
return nil, err
}
return d.queue.blocks, nil
}
// Synchronise will synchronise using the best peer.
func (d *Downloader) Synchronise() (types.Blocks, error) {
return d.SynchroniseWithPeer("")
}
func (d *Downloader) getFromPeer(p *peer, hash common.Hash, ignoreInitial bool) error {
d.activePeer = p.id
glog.V(logger.Detail).Infoln("Synchronising with the network using:", p.id)
// Start the fetcher. This will block the update entirely
// interupts need to be send to the appropriate channels
// respectively.
if err := d.startFetchingHashes(p, hash, ignoreInitial); err != nil {
// handle error
glog.V(logger.Debug).Infoln("Error fetching hashes:", err)
// XXX Reset
return err
}
// Start fetching blocks in paralel. The strategy is simple
// take any available peers, seserve a chunk for each peer available,
// let the peer deliver the chunkn and periodically check if a peer
// has timedout. When done downloading, process blocks.
if err := d.startFetchingBlocks(p); err != nil {
glog.V(logger.Debug).Infoln("Error downloading blocks:", err)
// XXX reset
return err
}
glog.V(logger.Detail).Infoln("Sync completed")
return nil
}
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