les: light client protocol and API

les/odr_peerset.go

@@ -0,0 +1,119 @@
+// 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 (
+	"sync"
+)
+
+const dropTimeoutRatio = 20
+
+type odrPeerInfo struct {
+	reqTimeSum, reqTimeCnt, reqCnt, timeoutCnt uint64
+}
+
+// odrPeerSet represents the collection of active peer participating in the block
+// download procedure.
+type odrPeerSet struct {
+	peers map[*peer]*odrPeerInfo
+	lock  sync.RWMutex
+}
+
+// newPeerSet creates a new peer set top track the active download sources.
+func newOdrPeerSet() *odrPeerSet {
+	return &odrPeerSet{
+		peers: make(map[*peer]*odrPeerInfo),
+	}
+}
+
+// Register injects a new peer into the working set, or returns an error if the
+// peer is already known.
+func (ps *odrPeerSet) register(p *peer) error {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	if _, ok := ps.peers[p]; ok {
+		return errAlreadyRegistered
+	}
+	ps.peers[p] = &odrPeerInfo{}
+	return nil
+}
+
+// Unregister removes a remote peer from the active set, disabling any further
+// actions to/from that particular entity.
+func (ps *odrPeerSet) unregister(p *peer) error {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	if _, ok := ps.peers[p]; !ok {
+		return errNotRegistered
+	}
+	delete(ps.peers, p)
+	return nil
+}
+
+func (ps *odrPeerSet) peerPriority(p *peer, info *odrPeerInfo, req LesOdrRequest) uint64 {
+	tm := p.fcServer.CanSend(req.GetCost(p))
+	if info.reqTimeCnt > 0 {
+		tm += info.reqTimeSum / info.reqTimeCnt
+	}
+	return tm
+}
+
+func (ps *odrPeerSet) bestPeer(req LesOdrRequest, exclude map[*peer]struct{}) *peer {
+	var best *peer
+	var bpv uint64
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	for p, info := range ps.peers {
+		if _, ok := exclude[p]; !ok {
+			pv := ps.peerPriority(p, info, req)
+			if best == nil || pv < bpv {
+				best = p
+				bpv = pv
+			}
+		}
+	}
+	return best
+}
+
+func (ps *odrPeerSet) updateTimeout(p *peer, timeout bool) (drop bool) {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	if info, ok := ps.peers[p]; ok {
+		info.reqCnt++
+		if timeout {
+			// check ratio before increase to allow an extra timeout
+			if info.timeoutCnt*dropTimeoutRatio >= info.reqCnt {
+				return true
+			}
+			info.timeoutCnt++
+		}
+	}
+	return false
+}
+
+func (ps *odrPeerSet) updateServTime(p *peer, servTime uint64) {
+	ps.lock.Lock()
+	defer ps.lock.Unlock()
+
+	if info, ok := ps.peers[p]; ok {
+		info.reqTimeSum += servTime
+		info.reqTimeCnt++
+	}
+}