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package eth
import (
"math"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/eth/downloader"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
)
// update periodically tries to synchronise with the network, both downloading
// hashes and blocks as well as retrieving cached ones.
func (pm *ProtocolManager) update() {
forceSync := time.Tick(forceSyncCycle)
blockProc := time.Tick(blockProcCycle)
blockProcPend := int32(0)
for {
select {
case <-pm.newPeerCh:
// Make sure we have peers to select from, then sync
if pm.peers.Len() < minDesiredPeerCount {
break
}
go pm.synchronise(pm.peers.BestPeer())
case <-forceSync:
// Force a sync even if not enough peers are present
go pm.synchronise(pm.peers.BestPeer())
case <-blockProc:
// Try to pull some blocks from the downloaded
if atomic.CompareAndSwapInt32(&blockProcPend, 0, 1) {
go func() {
pm.processBlocks()
atomic.StoreInt32(&blockProcPend, 0)
}()
}
case <-pm.quitSync:
return
}
}
}
// processBlocks retrieves downloaded blocks from the download cache and tries
// to construct the local block chain with it. Note, since the block retrieval
// order matters, access to this function *must* be synchronized/serialized.
func (pm *ProtocolManager) processBlocks() error {
pm.wg.Add(1)
defer pm.wg.Done()
// Short circuit if no blocks are available for insertion
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 {
glog.V(logger.Warn).Infof("Block insertion failed: %v", err)
pm.downloader.Cancel()
return err
}
blocks = blocks[max:]
}
return nil
}
// synchronise tries to sync up our local block chain with a remote peer, both
// adding various sanity checks as well as wrapping it with various log entries.
func (pm *ProtocolManager) synchronise(peer *peer) {
// Short circuit if no peers are available
if peer == nil {
glog.V(logger.Debug).Infoln("Synchronisation canceled: no peers available")
return
}
// Make sure the peer's TD is higher than our own. If not drop.
if peer.td.Cmp(pm.chainman.Td()) <= 0 {
glog.V(logger.Debug).Infoln("Synchronisation canceled: peer TD too small")
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) {
glog.V(logger.Debug).Infoln("Synchronisation canceled: head already known")
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, downloader.ErrBadPeer, downloader.ErrInvalidChain, downloader.ErrCrossCheckFailed:
glog.V(logger.Debug).Infof("Removing peer %v: %v", peer.id, err)
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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