// 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 discv5
import (
"container/heap"
"fmt"
"math"
"math/rand"
"time"
"github.com/ethereum/go-ethereum/common/mclock"
"github.com/ethereum/go-ethereum/log"
)
const (
maxEntries = 10000
maxEntriesPerTopic = 50
fallbackRegistrationExpiry = 1 * time.Hour
)
type Topic string
type topicEntry struct {
topic Topic
fifoIdx uint64
node *Node
expire mclock.AbsTime
}
type topicInfo struct {
entries map[uint64]*topicEntry
fifoHead, fifoTail uint64
rqItem *topicRequestQueueItem
wcl waitControlLoop
}
// removes tail element from the fifo
func (t *topicInfo) getFifoTail() *topicEntry {
for t.entries[t.fifoTail] == nil {
t.fifoTail++
}
tail := t.entries[t.fifoTail]
t.fifoTail++
return tail
}
type nodeInfo struct {
entries map[Topic]*topicEntry
lastIssuedTicket, lastUsedTicket uint32
// you can't register a ticket newer than lastUsedTicket before noRegUntil (absolute time)
noRegUntil mclock.AbsTime
}
type topicTable struct {
db *nodeDB
self *Node
nodes map[*Node]*nodeInfo
topics map[Topic]*topicInfo
globalEntries uint64
requested topicRequestQueue
requestCnt uint64
lastGarbageCollection mclock.AbsTime
}
func newTopicTable(db *nodeDB, self *Node) *topicTable {
if printTestImgLogs {
fmt.Printf("*N %016x\n", self.sha[:8])
}
return &topicTable{
db: db,
nodes: make(map[*Node]*nodeInfo),
topics: make(map[Topic]*topicInfo),
self: self,
}
}
func (t *topicTable) getOrNewTopic(topic Topic) *topicInfo {
ti := t.topics[topic]
if ti == nil {
rqItem := &topicRequestQueueItem{
topic: topic,
priority: t.requestCnt,
}
ti = &topicInfo{
entries: make(map[uint64]*topicEntry),
rqItem: rqItem,
}
t.topics[topic] = ti
heap.Push(&t.requested, rqItem)
}
return ti
}
func (t *topicTable) checkDeleteTopic(topic Topic) {
ti := t.topics[topic]
if ti == nil {
return
}
if len(ti.entries) == 0 && ti.wcl.hasMinimumWaitPeriod() {
delete(t.topics, topic)
heap.Remove(&t.requested, ti.rqItem.index)
}
}
func (t *topicTable) getOrNewNode(node *Node) *nodeInfo {
n := t.nodes[node]
if n == nil {
//fmt.Printf("newNode %016x %016x\n", t.self.sha[:8], node.sha[:8])
var issued, used uint32
if t.db != nil {
issued, used = t.db.fetchTopicRegTickets(node.ID)
}
n = &nodeInfo{
entries: make(map[Topic]*topicEntry),
lastIssuedTicket: issued,
lastUsedTicket: used,
}
t.nodes[node] = n
}
return n
}
func (t *topicTable) checkDeleteNode(node *Node) {
if n, ok := t.nodes[node]; ok && len(n.entries) == 0 && n.noRegUntil < mclock.Now() {
//fmt.Printf("deleteNode %016x %016x\n", t.self.sha[:8], node.sha[:8])
delete(t.nodes, node)
}
}
func (t *topicTable) storeTicketCounters(node *Node) {
n := t.getOrNewNode(node)
if t.db != nil {
t.db.updateTopicRegTickets(node.ID, n.lastIssuedTicket, n.lastUsedTicket)
}
}
func (t *topicTable) getEntries(topic Topic) []*Node {
t.collectGarbage()
te := t.topics[topic]
if te == nil {
return nil
}
nodes := make([]*Node, len(te.entries))
i := 0
for _, e := range te.entries {
nodes[i] = e.node
i++
}
t.requestCnt++
t.requested.update(te.rqItem, t.requestCnt)
return nodes
}
func (t *topicTable) addEntry(node *Node, topic Topic) {
n := t.getOrNewNode(node)
// clear previous entries by the same node
for _, e := range n.entries {
t.deleteEntry(e)
}
// ***
n = t.getOrNewNode(node)
tm := mclock.Now()
te := t.getOrNewTopic(topic)
if len(te.entries) == maxEntriesPerTopic {
t.deleteEntry(te.getFifoTail())
}
if t.globalEntries == maxEntries {
t.deleteEntry(t.leastRequested()) // not empty, no need to check for nil
}
fifoIdx := te.fifoHead
te.fifoHead++
entry := &topicEntry{
topic: topic,
fifoIdx: fifoIdx,
node: node,
expire: tm + mclock.AbsTime(fallbackRegistrationExpiry),
}
if printTestImgLogs {
fmt.Printf("*+ %d %v %016x %016x\n", tm/1000000, topic, t.self.sha[:8], node.sha[:8])
}
te.entries[fifoIdx] = entry
n.entries[topic] = entry
t.globalEntries++
te.wcl.registered(tm)
}
// removes least requested element from the fifo
func (t *topicTable) leastRequested() *topicEntry {
for t.requested.Len() > 0 && t.topics[t.requested[0].topic] == nil {
heap.Pop(&t.requested)
}
if t.requested.Len() == 0 {
return nil
}
return t.topics[t.requested[0].topic].getFifoTail()
}
// entry should exist
func (t *topicTable) deleteEntry(e *topicEntry) {
if printTestImgLogs {
fmt.Printf("*- %d %v %016x %016x\n", mclock.Now()/1000000, e.topic, t.self.sha[:8], e.node.sha[:8])
}
ne := t.nodes[e.node].entries
delete(ne, e.topic)
if len(ne) == 0 {
t.checkDeleteNode(e.node)
}
te := t.topics[e.topic]
delete(te.entries, e.fifoIdx)
if len(te.entries) == 0 {
t.checkDeleteTopic(e.topic)
}
t.globalEntries--
}
// It is assumed that topics and waitPeriods have the same length.
func (t *topicTable) useTicket(node *Node, serialNo uint32, topics []Topic, idx int, issueTime uint64, waitPeriods []uint32) (registered bool) {
log.Trace("Using discovery ticket", "serial", serialNo, "topics", topics, "waits", waitPeriods)
//fmt.Println("useTicket", serialNo, topics, waitPeriods)
t.collectGarbage()
n := t.getOrNewNode(node)
if serialNo < n.lastUsedTicket {
return false
}
tm := mclock.Now()
if serialNo > n.lastUsedTicket && tm < n.noRegUntil {
return false
}
if serialNo != n.lastUsedTicket {
n.lastUsedTicket = serialNo
n.noRegUntil = tm + mclock.AbsTime(noRegTimeout())
t.storeTicketCounters(node)
}
currTime := uint64(tm / mclock.AbsTime(time.Second))
regTime := issueTime + uint64(waitPeriods[idx])
relTime := int64(currTime - regTime)
if relTime >= -1 && relTime <= regTimeWindow+1 { // give clients a little security margin on both ends
if e := n.entries[topics[idx]]; e == nil {
t.addEntry(node, topics[idx])
} else {
// if there is an active entry, don't move to the front of the FIFO but prolong expire time
e.expire = tm + mclock.AbsTime(fallbackRegistrationExpiry)
}
return true
}
return false
}
func (t *topicTable) getTicket(node *Node, topics []Topic) *ticket {
t.collectGarbage()
now := mclock.Now()
n := t.getOrNewNode(node)
n.lastIssuedTicket++
t.storeTicketCounters(node)
tic := &ticket{
issueTime: now,
topics: topics,
serial: n.lastIssuedTicket,
regTime: make([]mclock.AbsTime, len(topics)),
}
for i, topic := range topics {
var waitPeriod time.Duration
if topic := t.topics[topic]; topic != nil {
waitPeriod = topic.wcl.waitPeriod
} else {
waitPeriod = minWaitPeriod
}
tic.regTime[i] = now + mclock.AbsTime(waitPeriod)
}
return tic
}
const gcInterval = time.Minute
func (t *topicTable) collectGarbage() {
tm := mclock.Now()
if time.Duration(tm-t.lastGarbageCollection) < gcInterval {
return
}
t.lastGarbageCollection = tm
for node, n := range t.nodes {
for _, e := range n.entries {
if e.expire <= tm {
t.deleteEntry(e)
}
}
t.checkDeleteNode(node)
}
for topic := range t.topics {
t.checkDeleteTopic(topic)
}
}
const (
minWaitPeriod = time.Minute
regTimeWindow = 10 // seconds
avgnoRegTimeout = time.Minute * 10
// target average interval between two incoming ad requests
wcTargetRegInterval = time.Minute * 10 / maxEntriesPerTopic
//
wcTimeConst = time.Minute * 10
)
// initialization is not required, will set to minWaitPeriod at first registration
type waitControlLoop struct {
lastIncoming mclock.AbsTime
waitPeriod time.Duration
}
func (w *waitControlLoop) registered(tm mclock.AbsTime) {
w.waitPeriod = w.nextWaitPeriod(tm)
w.lastIncoming = tm
}
func (w *waitControlLoop) nextWaitPeriod(tm mclock.AbsTime) time.Duration {
period := tm - w.lastIncoming
wp := time.Duration(float64(w.waitPeriod) * math.Exp((float64(wcTargetRegInterval)-float64(period))/float64(wcTimeConst)))
if wp < minWaitPeriod {
wp = minWaitPeriod
}
return wp
}
func (w *waitControlLoop) hasMinimumWaitPeriod() bool {
return w.nextWaitPeriod(mclock.Now()) == minWaitPeriod
}
func noRegTimeout() time.Duration {
e := rand.ExpFloat64()
if e > 100 {
e = 100
}
return time.Duration(float64(avgnoRegTimeout) * e)
}
type topicRequestQueueItem struct {
topic Topic
priority uint64
index int
}
// A topicRequestQueue implements heap.Interface and holds topicRequestQueueItems.
type topicRequestQueue []*topicRequestQueueItem
func (tq topicRequestQueue) Len() int { return len(tq) }
func (tq topicRequestQueue) Less(i, j int) bool {
return tq[i].priority < tq[j].priority
}
func (tq topicRequestQueue) Swap(i, j int) {
tq[i], tq[j] = tq[j], tq[i]
tq[i].index = i
tq[j].index = j
}
func (tq *topicRequestQueue) Push(x interface{}) {
n := len(*tq)
item := x.(*topicRequestQueueItem)
item.index = n
*tq = append(*tq, item)
}
func (tq *topicRequestQueue) Pop() interface{} {
old := *tq
n := len(old)
item := old[n-1]
item.index = -1
*tq = old[0 : n-1]
return item
}
func (tq *topicRequestQueue) update(item *topicRequestQueueItem, priority uint64) {
item.priority = priority
heap.Fix(tq, item.index)
}
