diff options
Diffstat (limited to 'eth/sync.go')
| -rw-r--r-- | eth/sync.go | 36 |
1 files changed, 19 insertions, 17 deletions
diff --git a/eth/sync.go b/eth/sync.go index aa7ebc77b..62d08acb6 100644 --- a/eth/sync.go +++ b/eth/sync.go @@ -10,8 +10,8 @@ import ( "github.com/ethereum/go-ethereum/logger/glog" ) -// Sync contains all synchronisation code for the eth protocol - +// 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) @@ -20,22 +20,16 @@ func (pm *ProtocolManager) update() { for { select { case <-pm.newPeerCh: - // Meet the `minDesiredPeerCount` before we select our best peer - if len(pm.peers) < minDesiredPeerCount { + // Make sure we have peers to select from, then sync + if pm.peers.Len() < 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) + go pm.synchronise(pm.peers.BestPeer()) case <-forceSync: // Force a sync even if not enough peers are present - if peer := getBestPeer(pm.peers); peer != nil { - go pm.synchronise(peer) - } + go pm.synchronise(pm.peers.BestPeer()) + case <-blockProc: // Try to pull some blocks from the downloaded if atomic.CompareAndSwapInt32(&blockProcPend, 0, 1) { @@ -51,10 +45,9 @@ func (pm *ProtocolManager) update() { } } -// 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. +// 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() @@ -79,15 +72,24 @@ func (pm *ProtocolManager) processBlocks() error { 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) |