requesting.go

   1 package torrent
   2
   3 import (
   4         "container/heap"
   5         "context"
   6         "encoding/gob"
   7         "math/rand"
   8         "reflect"
   9         "runtime/pprof"
  10         "time"
  11         "unsafe"
  12
  13         "github.com/anacrolix/log"
  14         "github.com/anacrolix/multiless"
  15
  16         request_strategy "github.com/anacrolix/torrent/request-strategy"
  17 )
  18
  19 func (t *Torrent) requestStrategyPieceOrderState(i int) request_strategy.PieceRequestOrderState {
  20         return request_strategy.PieceRequestOrderState{
  21                 Priority:     t.piece(i).purePriority(),
  22                 Partial:      t.piecePartiallyDownloaded(i),
  23                 Availability: t.piece(i).availability,
  24         }
  25 }
  26
  27 func init() {
  28         gob.Register(peerId{})
  29 }
  30
  31 type peerId struct {
  32         *Peer
  33         ptr uintptr
  34 }
  35
  36 func (p peerId) Uintptr() uintptr {
  37         return p.ptr
  38 }
  39
  40 func (p peerId) GobEncode() (b []byte, _ error) {
  41         *(*reflect.SliceHeader)(unsafe.Pointer(&b)) = reflect.SliceHeader{
  42                 Data: uintptr(unsafe.Pointer(&p.ptr)),
  43                 Len:  int(unsafe.Sizeof(p.ptr)),
  44                 Cap:  int(unsafe.Sizeof(p.ptr)),
  45         }
  46         return
  47 }
  48
  49 func (p *peerId) GobDecode(b []byte) error {
  50         if uintptr(len(b)) != unsafe.Sizeof(p.ptr) {
  51                 panic(len(b))
  52         }
  53         ptr := unsafe.Pointer(&b[0])
  54         p.ptr = *(*uintptr)(ptr)
  55         log.Printf("%p", ptr)
  56         dst := reflect.SliceHeader{
  57                 Data: uintptr(unsafe.Pointer(&p.Peer)),
  58                 Len:  int(unsafe.Sizeof(p.Peer)),
  59                 Cap:  int(unsafe.Sizeof(p.Peer)),
  60         }
  61         copy(*(*[]byte)(unsafe.Pointer(&dst)), b)
  62         return nil
  63 }
  64
  65 type (
  66         RequestIndex   = request_strategy.RequestIndex
  67         chunkIndexType = request_strategy.ChunkIndex
  68 )
  69
  70 type peerRequests struct {
  71         requestIndexes []RequestIndex
  72         peer           *Peer
  73 }
  74
  75 func (p *peerRequests) Len() int {
  76         return len(p.requestIndexes)
  77 }
  78
  79 func (p *peerRequests) Less(i, j int) bool {
  80         leftRequest := p.requestIndexes[i]
  81         rightRequest := p.requestIndexes[j]
  82         t := p.peer.t
  83         leftPieceIndex := leftRequest / t.chunksPerRegularPiece()
  84         rightPieceIndex := rightRequest / t.chunksPerRegularPiece()
  85         leftCurrent := p.peer.actualRequestState.Requests.Contains(leftRequest)
  86         rightCurrent := p.peer.actualRequestState.Requests.Contains(rightRequest)
  87         pending := func(index RequestIndex, current bool) int {
  88                 ret := t.pendingRequests.Get(index)
  89                 if current {
  90                         ret--
  91                 }
  92                 // See https://github.com/anacrolix/torrent/issues/679 for possible issues. This should be
  93                 // resolved.
  94                 if ret < 0 {
  95                         panic(ret)
  96                 }
  97                 return ret
  98         }
  99         ml := multiless.New()
 100         // Push requests that can't be served right now to the end. But we don't throw them away unless
 101         // there's a better alternative. This is for when we're using the fast extension and get choked
 102         // but our requests could still be good when we get unchoked.
 103         if p.peer.peerChoking {
 104                 ml = ml.Bool(
 105                         !p.peer.peerAllowedFast.Contains(leftPieceIndex),
 106                         !p.peer.peerAllowedFast.Contains(rightPieceIndex),
 107                 )
 108         }
 109         ml = ml.Int(
 110                 pending(leftRequest, leftCurrent),
 111                 pending(rightRequest, rightCurrent))
 112         ml = ml.Bool(!leftCurrent, !rightCurrent)
 113         leftPiece := t.piece(int(leftPieceIndex))
 114         rightPiece := t.piece(int(rightPieceIndex))
 115         ml = ml.Int(
 116                 -int(leftPiece.purePriority()),
 117                 -int(rightPiece.purePriority()),
 118         )
 119         ml = ml.Int(
 120                 int(leftPiece.availability),
 121                 int(rightPiece.availability))
 122         ml = ml.Uint32(leftPieceIndex, rightPieceIndex)
 123         ml = ml.Uint32(leftRequest, rightRequest)
 124         return ml.MustLess()
 125 }
 126
 127 func (p *peerRequests) Swap(i, j int) {
 128         p.requestIndexes[i], p.requestIndexes[j] = p.requestIndexes[j], p.requestIndexes[i]
 129 }
 130
 131 func (p *peerRequests) Push(x interface{}) {
 132         p.requestIndexes = append(p.requestIndexes, x.(RequestIndex))
 133 }
 134
 135 func (p *peerRequests) Pop() interface{} {
 136         last := len(p.requestIndexes) - 1
 137         x := p.requestIndexes[last]
 138         p.requestIndexes = p.requestIndexes[:last]
 139         return x
 140 }
 141
 142 type desiredRequestState struct {
 143         Requests   []RequestIndex
 144         Interested bool
 145 }
 146
 147 func (p *Peer) getDesiredRequestState() (desired desiredRequestState) {
 148         input := p.t.getRequestStrategyInput()
 149         requestHeap := peerRequests{
 150                 peer: p,
 151         }
 152         request_strategy.GetRequestablePieces(
 153                 input,
 154                 p.t.cl.pieceRequestOrder[p.t.storage.Capacity],
 155                 func(ih InfoHash, pieceIndex int) {
 156                         if ih != p.t.infoHash {
 157                                 return
 158                         }
 159                         if !p.peerHasPiece(pieceIndex) {
 160                                 return
 161                         }
 162                         allowedFast := p.peerAllowedFast.ContainsInt(pieceIndex)
 163                         p.t.piece(pieceIndex).undirtiedChunksIter.Iter(func(ci request_strategy.ChunkIndex) {
 164                                 r := p.t.pieceRequestIndexOffset(pieceIndex) + ci
 165                                 // if p.t.pendingRequests.Get(r) != 0 && !p.actualRequestState.Requests.Contains(r) {
 166                                 //      return
 167                                 // }
 168                                 if !allowedFast {
 169                                         // We must signal interest to request this
 170                                         desired.Interested = true
 171                                         // We can make or will allow sustaining a request here if we're not choked, or
 172                                         // have made the request previously (presumably while unchoked), and haven't had
 173                                         // the peer respond yet (and the request was retained because we are using the
 174                                         // fast extension).
 175                                         if p.peerChoking && !p.actualRequestState.Requests.Contains(r) {
 176                                                 // We can't request this right now.
 177                                                 return
 178                                         }
 179                                 }
 180                                 requestHeap.requestIndexes = append(requestHeap.requestIndexes, r)
 181                         })
 182                 },
 183         )
 184         p.t.assertPendingRequests()
 185         heap.Init(&requestHeap)
 186         for requestHeap.Len() != 0 && len(desired.Requests) < p.nominalMaxRequests() {
 187                 requestIndex := heap.Pop(&requestHeap).(RequestIndex)
 188                 desired.Requests = append(desired.Requests, requestIndex)
 189         }
 190         return
 191 }
 192
 193 func (p *Peer) maybeUpdateActualRequestState() bool {
 194         if p.needRequestUpdate == "" {
 195                 return true
 196         }
 197         var more bool
 198         pprof.Do(
 199                 context.Background(),
 200                 pprof.Labels("update request", p.needRequestUpdate),
 201                 func(_ context.Context) {
 202                         next := p.getDesiredRequestState()
 203                         more = p.applyRequestState(next)
 204                 },
 205         )
 206         return more
 207 }
 208
 209 // Transmit/action the request state to the peer.
 210 func (p *Peer) applyRequestState(next desiredRequestState) bool {
 211         current := &p.actualRequestState
 212         if !p.setInterested(next.Interested) {
 213                 return false
 214         }
 215         more := true
 216         cancel := current.Requests.Clone()
 217         for _, ri := range next.Requests {
 218                 cancel.Remove(ri)
 219         }
 220         cancel.Iterate(func(req uint32) bool {
 221                 more = p.cancel(req)
 222                 return more
 223         })
 224         if !more {
 225                 return false
 226         }
 227         shuffled := false
 228         lastPending := 0
 229         for i := 0; i < len(next.Requests); i++ {
 230                 req := next.Requests[i]
 231                 if p.cancelledRequests.Contains(req) {
 232                         // Waiting for a reject or piece message, which will suitably trigger us to update our
 233                         // requests, so we can skip this one with no additional consideration.
 234                         continue
 235                 }
 236                 // The cardinality of our desired requests shouldn't exceed the max requests since it's used
 237                 // in the calculation of the requests. However, if we cancelled requests and they haven't
 238                 // been rejected or serviced yet with the fast extension enabled, we can end up with more
 239                 // extra outstanding requests. We could subtract the number of outstanding cancels from the
 240                 // next request cardinality, but peers might not like that.
 241                 if maxRequests(current.Requests.GetCardinality()) >= p.nominalMaxRequests() {
 242                         // log.Printf("not assigning all requests [desired=%v, cancelled=%v, current=%v, max=%v]",
 243                         //      next.Requests.GetCardinality(),
 244                         //      p.cancelledRequests.GetCardinality(),
 245                         //      current.Requests.GetCardinality(),
 246                         //      p.nominalMaxRequests(),
 247                         // )
 248                         break
 249                 }
 250                 otherPending := p.t.pendingRequests.Get(next.Requests[0])
 251                 if p.actualRequestState.Requests.Contains(next.Requests[0]) {
 252                         otherPending--
 253                 }
 254                 if otherPending < lastPending {
 255                         // Pending should only rise. It's supposed to be the strongest ordering criteria. If it
 256                         // doesn't, our shuffling condition could be wrong.
 257                         panic(lastPending)
 258                 }
 259                 // If the request has already been requested by another peer, shuffle this and the rest of
 260                 // the requests (since according to the increasing condition, the rest of the indices
 261                 // already have an outstanding request with another peer).
 262                 if !shuffled && otherPending > 0 {
 263                         shuffleReqs := next.Requests[i:]
 264                         rand.Shuffle(len(shuffleReqs), func(i, j int) {
 265                                 shuffleReqs[i], shuffleReqs[j] = shuffleReqs[j], shuffleReqs[i]
 266                         })
 267                         // log.Printf("shuffled reqs [%v:%v]", i, len(next.Requests))
 268                         shuffled = true
 269                         // Repeat this index
 270                         i--
 271                         continue
 272                 }
 273
 274                 more = p.mustRequest(req)
 275                 if !more {
 276                         break
 277                 }
 278         }
 279         p.updateRequestsTimer.Stop()
 280         if more {
 281                 p.needRequestUpdate = ""
 282                 if !current.Requests.IsEmpty() {
 283                         p.updateRequestsTimer.Reset(3 * time.Second)
 284                 }
 285         }
 286         return more
 287 }