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487 lines
11 KiB
487 lines
11 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 = 30000 // Total number of nodes to simulate
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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(100) // Transmission time per peer of 4KB of data.
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const sendQueueCapacity = 5 // Amount of messages to queue between peers.
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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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parts []byte // [32]byte{} bitarray of received block pieces.
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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 + latencyMS == desiredRecvTime
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// when desiredRecvTime == minRecvTime,
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// p.sent += partTxMS
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p.sent = desiredRecvTime - latencyMS
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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.time = 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) sendEventParts(event EventParts) {
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p.node.sendEvent(event)
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}
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// Does the peer's .parts (as received by an EventParts event) contain part?
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func (p *Peer) knownToHave(part uint8) bool {
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return p.parts[part/8]&(1<<(part%8)) > 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
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events *Heap
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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 uint8) bool {
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x := n.parts[part/8]
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nx := x | (1 << (part % 8))
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if x == nx {
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return false
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} else {
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n.parts[part/8] = nx
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return true
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}
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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 _, part := range n.parts {
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if part != byte(0xff) {
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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 uint8, ok bool) {
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peerParts := peer.parts
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nodeParts := n.parts
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randStart := rand.Intn(32)
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for i := 0; i < 32; i++ {
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bytei := uint8((i + randStart) % 32)
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nByte := nodeParts[bytei]
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pByte := peerParts[bytei]
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iHas := nByte & ^pByte
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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 := uint8((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, parts: %X, (%v/%v)", p.sent, p.parts, 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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}
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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 uint8
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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) 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 EventParts 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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parts []byte
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}
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func (e EventParts) RecvTime() int32 {
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return e.time
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}
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func (e EventParts) String() string {
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return fmt.Sprintf("[%d:%d:%d]", e.time, e.src, e.parts)
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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, 32),
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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, &Peer{node: remote, remote: remote_j, parts: make([]byte, 32)})
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remote.peers = append(remote.peers, &Peer{node: n, remote: j, parts: make([]byte, 32)})
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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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func main() {
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// Global vars
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nodes := createNetwork()
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timeMS := int32(0)
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proposer := nodes[0]
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for i := 0; i < 32; i++ {
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proposer.parts[i] = byte(0xff)
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}
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//printNodes(nodes[:])
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// The proposer sends parts to all of its peers.
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for i := 0; i < len(proposer.peers); i++ {
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timeMS := int32(0) // scoped
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peer := proposer.peers[i]
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for j := 0; j < 256; j++ {
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// Send each part to a peer, but each peer starts at a different offset.
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part := uint8((j + i*(256/len(proposer.peers))) % 256)
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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: part,
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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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// 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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fmt.Printf("simulating until %v\n", endTimeMS)
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// Print out the network for debugging
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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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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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if !node.receive(event.part) {
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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 needs this piece.
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for _, peer := range node.peers {
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if !peer.knownToHave(event.part) {
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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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} else {
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continue
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}
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}
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case EventParts:
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event := _event.(EventParts)
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node.peers[event.src].parts = event.parts
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peer := node.peers[event.src]
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// Lets blast the peer with random parts.
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randomSent := 0
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randomSentErr := 0
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for peer.canSendData(event.time) {
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part, ok := node.pickRandomForPeer(peer)
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if ok {
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randomSent += 1
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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: part,
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})
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if !sent {
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randomSentErr += 1
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}
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} else {
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break
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}
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}
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/*
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if randomSent > 0 {
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fmt.Printf("radom sent: %v %v", randomSent, randomSentErr)
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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 network is full, quit.
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if countFull(nodes) == numNodes {
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fmt.Printf("Done! took %v ms", timeMS)
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break
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}
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// Lets increment the timeMS now
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timeMS += latencyMS / 2
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// Debug
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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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}
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// Send EventParts rather frequently. It's cheap.
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for _, node := range nodes {
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for _, peer := range node.peers {
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peer.sendEventParts(EventParts{
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time: timeMS + latencyMS,
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src: peer.remote,
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parts: node.parts,
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})
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}
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newParts := make([]byte, 32)
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copy(newParts, node.parts)
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node.parts = newParts
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}
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}
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}
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// ----------------------------------------------------------------------------
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type Heap struct {
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pq priorityQueue
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}
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func NewHeap() *Heap {
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return &Heap{pq: make([]*pqItem, 0)}
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}
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func (h *Heap) Len() int {
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return len(h.pq)
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}
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func (h *Heap) Peek() interface{} {
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if len(h.pq) == 0 {
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return nil
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}
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return h.pq[0].value
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}
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func (h *Heap) Push(value interface{}, priority int32) {
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heap.Push(&h.pq, &pqItem{value: value, priority: priority})
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}
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func (h *Heap) Pop() interface{} {
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item := heap.Pop(&h.pq).(*pqItem)
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return item.value
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}
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/*
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func main() {
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h := NewHeap()
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h.Push(String("msg1"), 1)
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h.Push(String("msg3"), 3)
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h.Push(String("msg2"), 2)
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fmt.Println(h.Pop())
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fmt.Println(h.Pop())
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fmt.Println(h.Pop())
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}
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*/
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///////////////////////
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// From: http://golang.org/pkg/container/heap/#example__priorityQueue
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type pqItem struct {
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value interface{}
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priority int32
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index int
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}
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type priorityQueue []*pqItem
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func (pq priorityQueue) Len() int { return len(pq) }
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func (pq priorityQueue) Less(i, j int) bool {
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return pq[i].priority < pq[j].priority
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}
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func (pq priorityQueue) Swap(i, j int) {
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pq[i], pq[j] = pq[j], pq[i]
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pq[i].index = i
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pq[j].index = j
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}
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func (pq *priorityQueue) Push(x interface{}) {
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n := len(*pq)
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item := x.(*pqItem)
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item.index = n
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*pq = append(*pq, item)
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}
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func (pq *priorityQueue) Pop() interface{} {
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old := *pq
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n := len(old)
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item := old[n-1]
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item.index = -1 // for safety
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*pq = old[0 : n-1]
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return item
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}
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func (pq *priorityQueue) Update(item *pqItem, value interface{}, priority int32) {
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heap.Remove(pq, item.index)
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item.value = value
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item.priority = priority
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heap.Push(pq, item)
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}
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