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619 lines
15 KiB
619 lines
15 KiB
package main
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import (
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"container/heap"
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"fmt"
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"math/rand"
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"strings"
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)
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const seed = 0
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const numNodes = 6400 // Total number of nodes to simulate
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const numNodes8 = (numNodes + 7) / 8
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const minNumPeers = 7 // Each node should be connected to at least this many peers
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const maxNumPeers = 10 // ... and at most this many
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const latencyMS = int32(500) // One way packet latency
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const partTxMS = int32(3) // Transmission time per peer of 100B of data.
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const sendQueueCapacity = 40 // Amount of messages to queue between peers.
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const maxAllowableRank = 2 // After this, the data is considered waste.
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const tryUnsolicited = 0.1 // Chance of sending an unsolicited piece of data.
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func init() {
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rand.Seed(seed)
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}
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//-----------------------------------------------------------------------------
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type Peer struct {
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node *Node // Pointer to node
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sent int32 // Time of last packet send, including transmit time.
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remote int // SomeNode.peers[x].node.peers[remote].node is SomeNode for all x.
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wanted []byte // Bitarray of wanted pieces.
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given []byte // Bitarray of given pieces.
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}
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func newPeer(pNode *Node, remote int) *Peer {
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peer := &Peer{
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node: pNode,
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remote: remote,
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wanted: make([]byte, numNodes8),
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given: make([]byte, numNodes8),
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}
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for i := 0; i < numNodes8; i++ {
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peer.wanted[i] = byte(0xff)
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}
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return peer
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}
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// Send a data event to the peer, or return false if queue is "full".
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// Depending on how many event packets are "queued" for peer,
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// the actual recvTime may be adjusted to be later.
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func (p *Peer) sendEventData(event EventData) bool {
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desiredRecvTime := event.RecvTime()
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minRecvTime := p.sent + partTxMS + latencyMS
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if desiredRecvTime >= minRecvTime {
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p.node.sendEvent(event)
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p.sent += partTxMS
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return true
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} else {
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if (minRecvTime-desiredRecvTime)/partTxMS > sendQueueCapacity {
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return false
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} else {
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event.SetRecvTime(minRecvTime) // Adjust recvTime
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p.node.sendEvent(event)
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p.sent += partTxMS
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return true
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}
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}
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}
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// Returns true if the sendQueue is not "full"
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func (p *Peer) canSendData(now int32) bool {
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return (p.sent - now) < sendQueueCapacity
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}
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// Since EventPart events are much smaller, we don't consider the transmit time,
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// and assume that the sendQueue is always free.
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func (p *Peer) sendEventDataResponse(event EventDataResponse) {
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p.node.sendEvent(event)
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}
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// Does the peer's .wanted (as received by an EventDataResponse event) contain part?
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func (p *Peer) wants(part uint16) bool {
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return p.wanted[part/8]&(1<<(part%8)) > 0
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}
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func (p *Peer) setWants(part uint16, want bool) {
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if want {
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p.wanted[part/8] |= (1 << (part % 8))
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} else {
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p.wanted[part/8] &= ^(1 << (part % 8))
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}
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}
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// Did we give peer a part
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func (p *Peer) gave(part uint16) bool {
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return p.given[part/8]&(1<<(part%8)) > 0
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}
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func (p *Peer) setGave(part uint16) {
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p.given[part/8] |= (1 << (part % 8))
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}
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// Reset state in preparation for new "round"
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func (p *Peer) reset() {
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for i := 0; i < numNodes8; i++ {
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p.given[i] = byte(0x00)
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}
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p.sent = 0
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}
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//-----------------------------------------------------------------------------
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type Node struct {
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index int
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peers []*Peer
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parts []byte // Bitarray of received parts.
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partsCount []uint8 // Count of how many times parts were received.
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events *Heap
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}
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// Reset state in preparation for new "round"
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func (n *Node) reset() {
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for i := 0; i < numNodes8; i++ {
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n.parts[i] = byte(0x00)
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}
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for i := 0; i < numNodes; i++ {
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n.partsCount[i] = uint8(0)
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}
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n.events = NewHeap()
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for _, peer := range n.peers {
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peer.reset()
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}
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}
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func (n *Node) fill() float64 {
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gotten := 0
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for _, count := range n.partsCount {
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if count > 0 {
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gotten += 1
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}
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}
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return float64(gotten) / float64(numNodes)
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}
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func (n *Node) sendEvent(event Event) {
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n.events.Push(event, event.RecvTime())
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}
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func (n *Node) recvEvent() Event {
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return n.events.Pop().(Event)
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}
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func (n *Node) receive(part uint16) uint8 {
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/*
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defer func() {
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e := recover()
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if e != nil {
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fmt.Println(part, len(n.parts), len(n.partsCount), part/8)
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panic(e)
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}
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}()
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*/
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n.parts[part/8] |= (1 << (part % 8))
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n.partsCount[part] += 1
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return n.partsCount[part]
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}
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// returns false if already connected, or remote node has too many connections.
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func (n *Node) canConnectTo(node *Node) bool {
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if len(n.peers) > maxNumPeers {
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return false
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}
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for _, peer := range n.peers {
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if peer.node == node {
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return false
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}
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}
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return true
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}
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func (n *Node) isFull() bool {
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for _, count := range n.partsCount {
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if count == 0 {
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return false
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}
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}
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return true
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}
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func (n *Node) pickRandomForPeer(peer *Peer) (part uint16, ok bool) {
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// Pick a random piece that node has and give it to peer.
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// Do not pick a piece that has already been given.
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peerGiven := peer.given
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nodeParts := n.parts
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randStart := rand.Intn(numNodes8)
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for i := 0; i < numNodes8; i++ {
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bytei := uint16((i + randStart) % numNodes8)
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pByte := peerGiven[bytei]
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nByte := nodeParts[bytei]
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iHas := nByte & ^pByte // iHas something to give :)
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if iHas > 0 {
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randBitStart := rand.Intn(8)
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//fmt.Println("//--")
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for j := 0; j < 8; j++ {
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biti := uint16((j + randBitStart) % 8)
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//fmt.Printf("%X %v %v %v\n", iHas, j, biti, randBitStart)
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if (iHas & (1 << biti)) > 0 {
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return 8*bytei + biti, true
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}
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}
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panic("should not happen")
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}
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}
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return 0, false
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}
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func (n *Node) debug() {
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lines := []string{}
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lines = append(lines, n.String())
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lines = append(lines, fmt.Sprintf("events: %v, parts: %X", n.events.Len(), n.parts))
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for _, p := range n.peers {
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part, ok := n.pickRandomForPeer(p)
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lines = append(lines, fmt.Sprintf("peer sent: %v, given: %X, (%v/%v)", p.sent, p.given, part, ok))
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}
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fmt.Println("//---------------")
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fmt.Println(strings.Join(lines, "\n"))
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fmt.Println("//---------------")
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}
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func (n *Node) String() string {
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return fmt.Sprintf("{N:%d}", n.index)
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}
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//-----------------------------------------------------------------------------
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type Event interface {
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RecvTime() int32
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SetRecvTime(int32)
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}
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type EventData struct {
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time int32 // time of receipt.
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src int // src node's peer index on destination node
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part uint16
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}
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func (e EventData) RecvTime() int32 {
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return e.time
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}
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func (e EventData) SetRecvTime(time int32) {
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e.time = time
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}
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func (e EventData) String() string {
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return fmt.Sprintf("[%d:%d:%d]", e.time, e.src, e.part)
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}
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type EventDataResponse struct {
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time int32 // time of receipt.
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src int // src node's peer index on destination node.
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part uint16 // in response to given part
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rank uint8 // if this is 1, node was first to give peer part.
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}
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func (e EventDataResponse) RecvTime() int32 {
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return e.time
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}
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func (e EventDataResponse) SetRecvTime(time int32) {
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e.time = time
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}
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func (e EventDataResponse) String() string {
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return fmt.Sprintf("[%d:%d:%d:%d]", e.time, e.src, e.part, e.rank)
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}
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//-----------------------------------------------------------------------------
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func createNetwork() []*Node {
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nodes := make([]*Node, numNodes)
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for i := 0; i < numNodes; i++ {
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n := &Node{
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index: i,
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peers: []*Peer{},
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parts: make([]byte, numNodes8),
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partsCount: make([]uint8, numNodes),
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events: NewHeap(),
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}
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nodes[i] = n
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}
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for i := 0; i < numNodes; i++ {
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n := nodes[i]
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for j := 0; j < minNumPeers; j++ {
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if len(n.peers) > j {
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// Already set, continue
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continue
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}
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pidx := rand.Intn(numNodes)
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for !n.canConnectTo(nodes[pidx]) {
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pidx = rand.Intn(numNodes)
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}
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// connect to nodes[pidx]
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remote := nodes[pidx]
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remote_j := len(remote.peers)
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n.peers = append(n.peers, newPeer(remote, remote_j))
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remote.peers = append(remote.peers, newPeer(n, j))
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}
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}
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return nodes
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}
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func printNodes(nodes []*Node) {
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for _, node := range nodes {
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peerStr := ""
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for _, peer := range node.peers {
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peerStr += fmt.Sprintf(" %v", peer.node.index)
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}
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fmt.Printf("[%v] peers: %v\n", node.index, peerStr)
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}
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}
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func countFull(nodes []*Node) (fullCount int) {
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for _, node := range nodes {
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if node.isFull() {
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fullCount += 1
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}
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}
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return fullCount
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}
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type runStat struct {
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time int32 // time for all events to propagate
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fill float64 // avg % of pieces gotten
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full float64 // % of times the sendQueue was full
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}
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func (s runStat) String() string {
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return fmt.Sprintf("{t:%v/fi:%.5f/fu:%.5f}", s.time, s.fill, s.full)
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}
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func main() {
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// Global vars
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nodes := createNetwork()
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runStats := []runStat{}
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//printNodes(nodes[:])
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// Keep iterating and improving .wanted
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for {
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timeMS := int32(0)
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// Each node sends a part to its peers.
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for _, node := range nodes {
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// reset all node state.
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node.reset()
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}
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// Each node sends a part to its peers.
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for i, node := range nodes {
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// TODO: make it staggered.
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timeMS := int32(0) // scoped
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for _, peer := range node.peers {
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recvTime := timeMS + latencyMS + partTxMS
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event := EventData{
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time: recvTime,
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src: peer.remote,
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part: uint16(i),
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}
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peer.sendEventData(event)
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//timeMS += partTxMS
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}
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}
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numEventsZero := 0 // times no events have occured
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numSendSuccess := 0 // times data send was successful
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numSendFailure := 0 // times data send failed due to queue being full
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// Run simulation
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for {
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// Lets run the simulation for each user until endTimeMS
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// We use latencyMS/2 since causality has at least this much lag.
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endTimeMS := timeMS + latencyMS/2
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// Print out the network for debugging
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/*
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fmt.Printf("simulating until %v\n", endTimeMS)
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if true {
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for i := 0; i < 40; i++ {
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node := nodes[i]
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fmt.Printf("[%v] parts: %X\n", node.index, node.parts)
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}
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}
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*/
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numEvents := 0
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for _, node := range nodes {
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// Iterate over the events of this node until event.time >= endTimeMS
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for {
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_event, ok := node.events.Peek().(Event)
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if !ok || _event.RecvTime() >= endTimeMS {
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break
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} else {
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node.events.Pop()
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}
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switch _event.(type) {
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case EventData:
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event := _event.(EventData)
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// Process this event
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rank := node.receive(event.part)
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// Send rank back to peer
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// NOTE: in reality, maybe this doesn't always happen.
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srcPeer := node.peers[event.src]
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srcPeer.setGave(event.part) // HACK
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srcPeer.sendEventDataResponse(EventDataResponse{
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time: event.time + latencyMS, // TODO: responseTxMS ?
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src: srcPeer.remote,
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part: event.part,
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rank: rank,
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})
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numEvents++
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if rank > 1 {
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// Already has this part, ignore this event.
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continue
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}
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// Let's iterate over peers & see which wants this piece.
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for _, peer := range node.peers {
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if peer.wants(event.part) {
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//fmt.Print("w")
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sent := peer.sendEventData(EventData{
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time: event.time + latencyMS + partTxMS,
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src: peer.remote,
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part: event.part,
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})
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if sent {
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peer.setGave(event.part)
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numSendSuccess++
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} else {
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numSendFailure++
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}
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} else {
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//fmt.Print("!")
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// Peer doesn't want it, but sporadically we'll try sending it anyways.
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if peer.canSendData(event.time) &&
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rand.Float32() < tryUnsolicited {
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sent := peer.sendEventData(EventData{
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time: event.time + latencyMS + partTxMS,
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src: peer.remote,
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part: event.part,
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})
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if sent {
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peer.setGave(event.part)
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numSendSuccess++
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} else {
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numSendFailure++
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}
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}
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}
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}
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case EventDataResponse:
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event := _event.(EventDataResponse)
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peer := node.peers[event.src]
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|
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// Adjust peer.wanted accordingly
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if event.rank <= maxAllowableRank {
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peer.setWants(event.part, true)
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} else {
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peer.setWants(event.part, false)
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}
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}
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}
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}
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|
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if numEvents == 0 {
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numEventsZero++
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} else {
|
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numEventsZero = 0
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}
|
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// If network is full or numEventsZero > 3, quit.
|
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if countFull(nodes) == numNodes || numEventsZero > 3 {
|
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fmt.Printf("Done! took %v ms. Past: %v\n", timeMS, runStats)
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fillSum := 0.0
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for _, node := range nodes {
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fillSum += node.fill()
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}
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runStats = append(runStats, runStat{timeMS, fillSum / float64(numNodes), float64(numSendSuccess) / float64(numSendSuccess+numSendFailure)})
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for i := 0; i < 20; i++ {
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node := nodes[i]
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fmt.Printf("[%v] parts: %X (%f)\n", node.index, node.parts[:80], node.fill())
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}
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break
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} else {
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fmt.Printf("simulated %v ms. numEvents: %v Past: %v\n", timeMS, numEvents, runStats)
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for i := 0; i < 2; i++ {
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peer := nodes[0].peers[i]
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fmt.Printf("[0].[%v] wanted: %X\n", i, peer.wanted[:80])
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fmt.Printf("[0].[%v] given: %X\n", i, peer.given[:80])
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}
|
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for i := 0; i < 5; i++ {
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node := nodes[i]
|
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fmt.Printf("[%v] parts: %X (%f)\n", node.index, node.parts[:80], node.fill())
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}
|
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}
|
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|
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// Lets increment the timeMS now
|
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timeMS += latencyMS / 2
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|
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/*
|
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// Debug
|
|
if timeMS >= 25000 {
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nodes[1].debug()
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for e := nodes[1].events.Pop(); e != nil; e = nodes[1].events.Pop() {
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fmt.Println(e)
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}
|
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return
|
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} */
|
|
} // end simulation
|
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} // forever loop
|
|
}
|
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|
|
// ----------------------------------------------------------------------------
|
|
|
|
type Heap struct {
|
|
pq priorityQueue
|
|
}
|
|
|
|
func NewHeap() *Heap {
|
|
return &Heap{pq: make([]*pqItem, 0)}
|
|
}
|
|
|
|
func (h *Heap) Len() int {
|
|
return len(h.pq)
|
|
}
|
|
|
|
func (h *Heap) Peek() interface{} {
|
|
if len(h.pq) == 0 {
|
|
return nil
|
|
}
|
|
return h.pq[0].value
|
|
}
|
|
|
|
func (h *Heap) Push(value interface{}, priority int32) {
|
|
heap.Push(&h.pq, &pqItem{value: value, priority: priority})
|
|
}
|
|
|
|
func (h *Heap) Pop() interface{} {
|
|
if len(h.pq) == 0 {
|
|
return nil
|
|
}
|
|
item := heap.Pop(&h.pq).(*pqItem)
|
|
return item.value
|
|
}
|
|
|
|
/*
|
|
func main() {
|
|
h := NewHeap()
|
|
|
|
h.Push(String("msg1"), 1)
|
|
h.Push(String("msg3"), 3)
|
|
h.Push(String("msg2"), 2)
|
|
|
|
fmt.Println(h.Pop())
|
|
fmt.Println(h.Pop())
|
|
fmt.Println(h.Pop())
|
|
}
|
|
*/
|
|
|
|
///////////////////////
|
|
// From: http://golang.org/pkg/container/heap/#example__priorityQueue
|
|
|
|
type pqItem struct {
|
|
value interface{}
|
|
priority int32
|
|
index int
|
|
}
|
|
|
|
type priorityQueue []*pqItem
|
|
|
|
func (pq priorityQueue) Len() int { return len(pq) }
|
|
|
|
func (pq priorityQueue) Less(i, j int) bool {
|
|
return pq[i].priority < pq[j].priority
|
|
}
|
|
|
|
func (pq priorityQueue) Swap(i, j int) {
|
|
pq[i], pq[j] = pq[j], pq[i]
|
|
pq[i].index = i
|
|
pq[j].index = j
|
|
}
|
|
|
|
func (pq *priorityQueue) Push(x interface{}) {
|
|
n := len(*pq)
|
|
item := x.(*pqItem)
|
|
item.index = n
|
|
*pq = append(*pq, item)
|
|
}
|
|
|
|
func (pq *priorityQueue) Pop() interface{} {
|
|
old := *pq
|
|
n := len(old)
|
|
item := old[n-1]
|
|
item.index = -1 // for safety
|
|
*pq = old[0 : n-1]
|
|
return item
|
|
}
|
|
|
|
func (pq *priorityQueue) Update(item *pqItem, value interface{}, priority int32) {
|
|
heap.Remove(pq, item.index)
|
|
item.value = value
|
|
item.priority = priority
|
|
heap.Push(pq, item)
|
|
}
|