les: light client protocol and API

1 files changed, 84 insertions, 0 deletions

diff --git a/les/sync.go b/les/sync.go
new file mode 100644
index 000000000..f92f8ce04
--- /dev/null
+++ b/les/sync.go
@@ -0,0 +1,84 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package les
+
+import (
+	"time"
+
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/eth/downloader"
+	"github.com/ethereum/go-ethereum/light"
+	"golang.org/x/net/context"
+)
+
+const (
+	//forceSyncCycle      = 10 * time.Second // Time interval to force syncs, even if few peers are available
+	minDesiredPeerCount = 5 // Amount of peers desired to start syncing
+)
+
+// syncer is responsible for periodically synchronising with the network, both
+// downloading hashes and blocks as well as handling the announcement handler.
+func (pm *ProtocolManager) syncer() {
+	// Start and ensure cleanup of sync mechanisms
+	//pm.fetcher.Start()
+	//defer pm.fetcher.Stop()
+	defer pm.downloader.Terminate()
+
+	// Wait for different events to fire synchronisation operations
+	//forceSync := time.Tick(forceSyncCycle)
+	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 <-pm.noMorePeers:
+			return
+		}
+	}
+}
+
+func (pm *ProtocolManager) needToSync(peerHead blockInfo) bool {
+	head := pm.blockchain.CurrentHeader()
+	currentTd := core.GetTd(pm.chainDb, head.Hash(), head.Number.Uint64())
+	return currentTd != nil && peerHead.Td.Cmp(currentTd) > 0
+}
+
+// synchronise tries to sync up our local block chain with a remote peer.
+func (pm *ProtocolManager) synchronise(peer *peer) {
+	// Short circuit if no peers are available
+	if peer == nil {
+		return
+	}
+
+	// Make sure the peer's TD is higher than our own.
+	if !pm.needToSync(peer.headBlockInfo()) {
+		return
+	}
+
+	ctx, _ := context.WithTimeout(context.Background(), time.Second*5)
+	pm.blockchain.(*light.LightChain).SyncCht(ctx)
+
+	pm.downloader.Synchronise(peer.id, peer.Head(), peer.Td(), downloader.LightSync)
+}