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package eth
import (
"math"
"time"
"github.com/ethereum/go-ethereum/eth/downloader"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
)
// Sync contains all synchronisation code for the eth protocol
func (pm *ProtocolManager) update() {
forceSync := time.Tick(forceSyncCycle)
blockProc := time.Tick(blockProcCycle)
for {
select {
case <-pm.newPeerCh:
// Meet the `minDesiredPeerCount` before we select our best peer
if len(pm.peers) < minDesiredPeerCount {
break
}
// Find the best peer and synchronise with it
peer := getBestPeer(pm.peers)
if peer == nil {
glog.V(logger.Debug).Infoln("Sync attempt canceled. No peers available")
}
go pm.synchronise(peer)
case <-forceSync:
// Force a sync even if not enough peers are present
if peer := getBestPeer(pm.peers); peer != nil {
go pm.synchronise(peer)
}
case <-blockProc:
// Try to pull some blocks from the downloaded
go pm.processBlocks()
case <-pm.quitSync:
return
}
}
}
// processBlocks will attempt to reconstruct a chain by checking the first item and check if it's
// a known parent. The first block in the chain may be unknown during downloading. When the
// downloader isn't downloading blocks will be dropped with an unknown parent until either it
// has depleted the list or found a known parent.
func (pm *ProtocolManager) processBlocks() error {
pm.wg.Add(1)
defer pm.wg.Done()
// Take a batch of blocks (will return nil if a previous batch has not reached the chain yet)
blocks := pm.downloader.TakeBlocks()
if len(blocks) == 0 {
return nil
}
glog.V(logger.Debug).Infof("Inserting chain with %d blocks (#%v - #%v)\n", len(blocks), blocks[0].Number(), blocks[len(blocks)-1].Number())
for len(blocks) != 0 && !pm.quit {
max := int(math.Min(float64(len(blocks)), float64(blockProcAmount)))
_, err := pm.chainman.InsertChain(blocks[:max])
if err != nil {
// cancel download process
pm.downloader.Cancel()
return err
}
blocks = blocks[max:]
}
return nil
}
func (pm *ProtocolManager) synchronise(peer *peer) {
// Make sure the peer's TD is higher than our own. If not drop.
if peer.td.Cmp(pm.chainman.Td()) <= 0 {
return
}
// FIXME if we have the hash in our chain and the TD of the peer is
// much higher than ours, something is wrong with us or the peer.
// Check if the hash is on our own chain
if pm.chainman.HasBlock(peer.recentHash) {
return
}
// Get the hashes from the peer (synchronously)
glog.V(logger.Debug).Infof("Attempting synchronisation: %v, 0x%x", peer.id, peer.recentHash)
err := pm.downloader.Synchronise(peer.id, peer.recentHash)
switch err {
case nil:
glog.V(logger.Debug).Infof("Synchronisation completed")
case downloader.ErrBusy:
glog.V(logger.Debug).Infof("Synchronisation already in progress")
case downloader.ErrTimeout:
glog.V(logger.Debug).Infof("Removing peer %v due to sync timeout", peer.id)
pm.removePeer(peer)
case downloader.ErrPendingQueue:
glog.V(logger.Debug).Infoln("Synchronisation aborted:", err)
default:
glog.V(logger.Warn).Infof("Synchronisation failed: %v", err)
}
}
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