les: implement request distributor, fix blocking issues (#3660)

* les: implement request distributor, fix blocking issues
* core: moved header validation before chain mutex lock

les/distributor_test.go

@@ -0,0 +1,192 @@
+// Copyright 2016 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 light implements on-demand retrieval capable state and chain objects
+// for the Ethereum Light Client.
+package les
+
+import (
+	"math/rand"
+	"sync"
+	"testing"
+	"time"
+)
+
+type testDistReq struct {
+	cost, procTime, order uint64
+	canSendTo             map[*testDistPeer]struct{}
+}
+
+func (r *testDistReq) getCost(dp distPeer) uint64 {
+	return r.cost
+}
+
+func (r *testDistReq) canSend(dp distPeer) bool {
+	_, ok := r.canSendTo[dp.(*testDistPeer)]
+	return ok
+}
+
+func (r *testDistReq) request(dp distPeer) func() {
+	return func() { dp.(*testDistPeer).send(r) }
+}
+
+type testDistPeer struct {
+	sent    []*testDistReq
+	sumCost uint64
+	lock    sync.RWMutex
+}
+
+func (p *testDistPeer) send(r *testDistReq) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	p.sent = append(p.sent, r)
+	p.sumCost += r.cost
+}
+
+func (p *testDistPeer) worker(t *testing.T, checkOrder bool, stop chan struct{}) {
+	var last uint64
+	for {
+		wait := time.Millisecond
+		p.lock.Lock()
+		if len(p.sent) > 0 {
+			rq := p.sent[0]
+			wait = time.Duration(rq.procTime)
+			p.sumCost -= rq.cost
+			if checkOrder {
+				if rq.order <= last {
+					t.Errorf("Requests processed in wrong order")
+				}
+				last = rq.order
+			}
+			p.sent = p.sent[1:]
+		}
+		p.lock.Unlock()
+		select {
+		case <-stop:
+			return
+		case <-time.After(wait):
+		}
+	}
+}
+
+const (
+	testDistBufLimit       = 10000000
+	testDistMaxCost        = 1000000
+	testDistPeerCount      = 5
+	testDistReqCount       = 50000
+	testDistMaxResendCount = 3
+)
+
+func (p *testDistPeer) waitBefore(cost uint64) (time.Duration, float64) {
+	p.lock.RLock()
+	sumCost := p.sumCost + cost
+	p.lock.RUnlock()
+	if sumCost < testDistBufLimit {
+		return 0, float64(testDistBufLimit-sumCost) / float64(testDistBufLimit)
+	} else {
+		return time.Duration(sumCost - testDistBufLimit), 0
+	}
+}
+
+func (p *testDistPeer) canQueue() bool {
+	return true
+}
+
+func (p *testDistPeer) queueSend(f func()) {
+	f()
+}
+
+func TestRequestDistributor(t *testing.T) {
+	testRequestDistributor(t, false)
+}
+
+func TestRequestDistributorResend(t *testing.T) {
+	testRequestDistributor(t, true)
+}
+
+func testRequestDistributor(t *testing.T, resend bool) {
+	stop := make(chan struct{})
+	defer close(stop)
+
+	var peers [testDistPeerCount]*testDistPeer
+	for i, _ := range peers {
+		peers[i] = &testDistPeer{}
+		go peers[i].worker(t, !resend, stop)
+	}
+
+	dist := newRequestDistributor(func() map[distPeer]struct{} {
+		m := make(map[distPeer]struct{})
+		for _, peer := range peers {
+			m[peer] = struct{}{}
+		}
+		return m
+	}, stop)
+
+	var wg sync.WaitGroup
+
+	for i := 1; i <= testDistReqCount; i++ {
+		cost := uint64(rand.Int63n(testDistMaxCost))
+		procTime := uint64(rand.Int63n(int64(cost + 1)))
+		rq := &testDistReq{
+			cost:      cost,
+			procTime:  procTime,
+			order:     uint64(i),
+			canSendTo: make(map[*testDistPeer]struct{}),
+		}
+		for _, peer := range peers {
+			if rand.Intn(2) != 0 {
+				rq.canSendTo[peer] = struct{}{}
+			}
+		}
+
+		wg.Add(1)
+		req := &distReq{
+			getCost: rq.getCost,
+			canSend: rq.canSend,
+			request: rq.request,
+		}
+		chn := dist.queue(req)
+		go func() {
+			cnt := 1
+			if resend && len(rq.canSendTo) != 0 {
+				cnt = rand.Intn(testDistMaxResendCount) + 1
+			}
+			for i := 0; i < cnt; i++ {
+				if i != 0 {
+					chn = dist.queue(req)
+				}
+				p := <-chn
+				if p == nil {
+					if len(rq.canSendTo) != 0 {
+						t.Errorf("Request that could have been sent was dropped")
+					}
+				} else {
+					peer := p.(*testDistPeer)
+					if _, ok := rq.canSendTo[peer]; !ok {
+						t.Errorf("Request sent to wrong peer")
+					}
+				}
+			}
+			wg.Done()
+		}()
+		if rand.Intn(1000) == 0 {
+			time.Sleep(time.Duration(rand.Intn(5000000)))
+		}
+	}
+
+	wg.Wait()
+}