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/RoaringBitmap/roaring"
  14         "github.com/anacrolix/log"
  15         "github.com/anacrolix/multiless"
  16
  17         request_strategy "github.com/anacrolix/torrent/request-strategy"
  18 )
  19
  20 func (cl *Client) tickleRequester() {
  21         cl.updateRequests.Broadcast()
  22 }
  23
  24 func (cl *Client) getRequestStrategyInput() request_strategy.Input {
  25         ts := make([]request_strategy.Torrent, 0, len(cl.torrents))
  26         for _, t := range cl.torrents {
  27                 if !t.haveInfo() {
  28                         // This would be removed if metadata is handled here. We have to guard against not
  29                         // knowing the piece size. If we have no info, we have no pieces too, so the end result
  30                         // is the same.
  31                         continue
  32                 }
  33                 rst := request_strategy.Torrent{
  34                         InfoHash:       t.infoHash,
  35                         ChunksPerPiece: t.chunksPerRegularPiece(),
  36                 }
  37                 if t.storage != nil {
  38                         rst.Capacity = t.storage.Capacity
  39                 }
  40                 rst.Pieces = make([]request_strategy.Piece, 0, len(t.pieces))
  41                 for i := range t.pieces {
  42                         p := &t.pieces[i]
  43                         rst.Pieces = append(rst.Pieces, request_strategy.Piece{
  44                                 Request:           !t.ignorePieceForRequests(i),
  45                                 Priority:          p.purePriority(),
  46                                 Partial:           t.piecePartiallyDownloaded(i),
  47                                 Availability:      p.availability,
  48                                 Length:            int64(p.length()),
  49                                 NumPendingChunks:  int(t.pieceNumPendingChunks(i)),
  50                                 IterPendingChunks: &p.undirtiedChunksIter,
  51                         })
  52                 }
  53                 t.iterPeers(func(p *Peer) {
  54                         if p.closed.IsSet() {
  55                                 return
  56                         }
  57                         if p.piecesReceivedSinceLastRequestUpdate > p.maxPiecesReceivedBetweenRequestUpdates {
  58                                 p.maxPiecesReceivedBetweenRequestUpdates = p.piecesReceivedSinceLastRequestUpdate
  59                         }
  60                         p.piecesReceivedSinceLastRequestUpdate = 0
  61                         rst.Peers = append(rst.Peers, request_strategy.Peer{
  62                                 Pieces:           *p.newPeerPieces(),
  63                                 MaxRequests:      p.nominalMaxRequests(),
  64                                 ExistingRequests: p.actualRequestState.Requests,
  65                                 Choking:          p.peerChoking,
  66                                 PieceAllowedFast: p.peerAllowedFast,
  67                                 DownloadRate:     p.downloadRate(),
  68                                 Age:              time.Since(p.completedHandshake),
  69                                 Id: peerId{
  70                                         Peer: p,
  71                                         ptr:  uintptr(unsafe.Pointer(p)),
  72                                 },
  73                         })
  74                 })
  75                 ts = append(ts, rst)
  76         }
  77         return request_strategy.Input{
  78                 Torrents:           ts,
  79                 MaxUnverifiedBytes: cl.config.MaxUnverifiedBytes,
  80         }
  81 }
  82
  83 func init() {
  84         gob.Register(peerId{})
  85 }
  86
  87 type peerId struct {
  88         *Peer
  89         ptr uintptr
  90 }
  91
  92 func (p peerId) Uintptr() uintptr {
  93         return p.ptr
  94 }
  95
  96 func (p peerId) GobEncode() (b []byte, _ error) {
  97         *(*reflect.SliceHeader)(unsafe.Pointer(&b)) = reflect.SliceHeader{
  98                 Data: uintptr(unsafe.Pointer(&p.ptr)),
  99                 Len:  int(unsafe.Sizeof(p.ptr)),
 100                 Cap:  int(unsafe.Sizeof(p.ptr)),
 101         }
 102         return
 103 }
 104
 105 func (p *peerId) GobDecode(b []byte) error {
 106         if uintptr(len(b)) != unsafe.Sizeof(p.ptr) {
 107                 panic(len(b))
 108         }
 109         ptr := unsafe.Pointer(&b[0])
 110         p.ptr = *(*uintptr)(ptr)
 111         log.Printf("%p", ptr)
 112         dst := reflect.SliceHeader{
 113                 Data: uintptr(unsafe.Pointer(&p.Peer)),
 114                 Len:  int(unsafe.Sizeof(p.Peer)),
 115                 Cap:  int(unsafe.Sizeof(p.Peer)),
 116         }
 117         copy(*(*[]byte)(unsafe.Pointer(&dst)), b)
 118         return nil
 119 }
 120
 121 type RequestIndex = request_strategy.RequestIndex
 122 type chunkIndexType = request_strategy.ChunkIndex
 123
 124 type peerRequests struct {
 125         requestIndexes       []RequestIndex
 126         peer                 *Peer
 127         torrentStrategyInput request_strategy.Torrent
 128 }
 129
 130 func (p *peerRequests) Len() int {
 131         return len(p.requestIndexes)
 132 }
 133
 134 func (p *peerRequests) Less(i, j int) bool {
 135         leftRequest := p.requestIndexes[i]
 136         rightRequest := p.requestIndexes[j]
 137         t := p.peer.t
 138         leftPieceIndex := leftRequest / p.torrentStrategyInput.ChunksPerPiece
 139         rightPieceIndex := rightRequest / p.torrentStrategyInput.ChunksPerPiece
 140         leftCurrent := p.peer.actualRequestState.Requests.Contains(leftRequest)
 141         rightCurrent := p.peer.actualRequestState.Requests.Contains(rightRequest)
 142         pending := func(index RequestIndex, current bool) int {
 143                 ret := t.pendingRequests.Get(index)
 144                 if current {
 145                         ret--
 146                 }
 147                 // I have a hunch that this could trigger for requests for chunks that are choked and not
 148                 // allowed fast, since the current conn shouldn't already be included. It's a very specific
 149                 // circumstance, and if it triggers I will fix it.
 150                 if ret < 0 {
 151                         panic(ret)
 152                 }
 153                 return ret
 154         }
 155         ml := multiless.New()
 156         // Push requests that can't be served right now to the end. But we don't throw them away unless
 157         // there's a better alternative. This is for when we're using the fast extension and get choked
 158         // but our requests could still be good when we get unchoked.
 159         if p.peer.peerChoking {
 160                 ml = ml.Bool(
 161                         !p.peer.peerAllowedFast.Contains(leftPieceIndex),
 162                         !p.peer.peerAllowedFast.Contains(rightPieceIndex),
 163                 )
 164         }
 165         ml = ml.Int(
 166                 pending(leftRequest, leftCurrent),
 167                 pending(rightRequest, rightCurrent))
 168         ml = ml.Bool(!leftCurrent, !rightCurrent)
 169         ml = ml.Int(
 170                 -int(p.torrentStrategyInput.Pieces[leftPieceIndex].Priority),
 171                 -int(p.torrentStrategyInput.Pieces[rightPieceIndex].Priority),
 172         )
 173         ml = ml.Int(
 174                 int(p.torrentStrategyInput.Pieces[leftPieceIndex].Availability),
 175                 int(p.torrentStrategyInput.Pieces[rightPieceIndex].Availability))
 176         ml = ml.Uint32(leftPieceIndex, rightPieceIndex)
 177         ml = ml.Uint32(leftRequest, rightRequest)
 178         return ml.MustLess()
 179 }
 180
 181 func (p *peerRequests) Swap(i, j int) {
 182         p.requestIndexes[i], p.requestIndexes[j] = p.requestIndexes[j], p.requestIndexes[i]
 183 }
 184
 185 func (p *peerRequests) Push(x interface{}) {
 186         p.requestIndexes = append(p.requestIndexes, x.(RequestIndex))
 187 }
 188
 189 func (p *peerRequests) Pop() interface{} {
 190         last := len(p.requestIndexes) - 1
 191         x := p.requestIndexes[last]
 192         p.requestIndexes = p.requestIndexes[:last]
 193         return x
 194 }
 195
 196 func (p *Peer) getDesiredRequestState() (desired requestState) {
 197         input := p.t.cl.getRequestStrategyInput()
 198         requestHeap := peerRequests{
 199                 peer: p,
 200         }
 201         for _, t := range input.Torrents {
 202                 if t.InfoHash == p.t.infoHash {
 203                         requestHeap.torrentStrategyInput = t
 204                         break
 205                 }
 206         }
 207         request_strategy.GetRequestablePieces(
 208                 input,
 209                 func(t *request_strategy.Torrent, rsp *request_strategy.Piece, pieceIndex int) {
 210                         if t.InfoHash != p.t.infoHash {
 211                                 return
 212                         }
 213                         if !p.peerHasPiece(pieceIndex) {
 214                                 return
 215                         }
 216                         allowedFast := p.peerAllowedFast.ContainsInt(pieceIndex)
 217                         rsp.IterPendingChunks.Iter(func(ci request_strategy.ChunkIndex) {
 218                                 if !allowedFast {
 219                                         // We must signal interest to request this
 220                                         desired.Interested = true
 221                                         // We can make or will allow sustaining a request here if we're not choked, or
 222                                         // have made the request previously (presumably while unchoked), and haven't had
 223                                         // the peer respond yet (and the request was retained because we are using the
 224                                         // fast extension).
 225                                         if p.peerChoking && !p.actualRequestState.Requests.Contains(ci) {
 226                                                 // We can't request this right now.
 227                                                 return
 228                                         }
 229                                 }
 230                                 requestHeap.requestIndexes = append(
 231                                         requestHeap.requestIndexes,
 232                                         p.t.pieceRequestIndexOffset(pieceIndex)+ci)
 233                         })
 234                 },
 235         )
 236         p.t.assertPendingRequests()
 237         heap.Init(&requestHeap)
 238         for requestHeap.Len() != 0 && desired.Requests.GetCardinality() < uint64(p.nominalMaxRequests()) {
 239                 requestIndex := heap.Pop(&requestHeap).(RequestIndex)
 240                 desired.Requests.Add(requestIndex)
 241         }
 242         return
 243 }
 244
 245 func (p *Peer) maybeUpdateActualRequestState() bool {
 246         if p.needRequestUpdate == "" {
 247                 return true
 248         }
 249         var more bool
 250         pprof.Do(
 251                 context.Background(),
 252                 pprof.Labels("update request", p.needRequestUpdate),
 253                 func(_ context.Context) {
 254                         next := p.getDesiredRequestState()
 255                         more = p.applyRequestState(next)
 256                 },
 257         )
 258         return more
 259 }
 260
 261 // Transmit/action the request state to the peer.
 262 func (p *Peer) applyRequestState(next requestState) bool {
 263         current := &p.actualRequestState
 264         if !p.setInterested(next.Interested) {
 265                 return false
 266         }
 267         more := true
 268         cancel := roaring.AndNot(&current.Requests, &next.Requests)
 269         cancel.Iterate(func(req uint32) bool {
 270                 more = p.cancel(req)
 271                 return more
 272         })
 273         if !more {
 274                 return false
 275         }
 276         // We randomize the order in which requests are issued, to reduce the overlap with requests to
 277         // other peers. Note that although it really depends on what order the peer services the
 278         // requests, if we are only able to issue some requests before buffering, or the peer starts
 279         // handling our requests before they've all arrived, then this randomization should reduce
 280         // overlap. Note however that if we received the desired requests in priority order, then
 281         // randomizing would throw away that benefit.
 282         for _, x := range rand.Perm(int(next.Requests.GetCardinality())) {
 283                 req, err := next.Requests.Select(uint32(x))
 284                 if err != nil {
 285                         panic(err)
 286                 }
 287                 if p.cancelledRequests.Contains(req) {
 288                         // Waiting for a reject or piece message, which will suitably trigger us to update our
 289                         // requests, so we can skip this one with no additional consideration.
 290                         continue
 291                 }
 292                 // The cardinality of our desired requests shouldn't exceed the max requests since it's used
 293                 // in the calculation of the requests. However if we cancelled requests and they haven't
 294                 // been rejected or serviced yet with the fast extension enabled, we can end up with more
 295                 // extra outstanding requests. We could subtract the number of outstanding cancels from the
 296                 // next request cardinality, but peers might not like that.
 297                 if maxRequests(current.Requests.GetCardinality()) >= p.nominalMaxRequests() {
 298                         //log.Printf("not assigning all requests [desired=%v, cancelled=%v, current=%v, max=%v]",
 299                         //      next.Requests.GetCardinality(),
 300                         //      p.cancelledRequests.GetCardinality(),
 301                         //      current.Requests.GetCardinality(),
 302                         //      p.nominalMaxRequests(),
 303                         //)
 304                         break
 305                 }
 306                 more, err = p.request(req)
 307                 if err != nil {
 308                         panic(err)
 309                 }
 310                 if !more {
 311                         break
 312                 }
 313         }
 314         p.updateRequestsTimer.Stop()
 315         if more {
 316                 p.needRequestUpdate = ""
 317                 if !current.Requests.IsEmpty() {
 318                         p.updateRequestsTimer.Reset(3 * time.Second)
 319                 }
 320         }
 321         return more
 322 }