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 (cl *Client) getRequestStrategyInput() request_strategy.Input {
  20         ts := make([]request_strategy.Torrent, 0, len(cl.torrents))
  21         for _, t := range cl.torrents {
  22                 if !t.haveInfo() {
  23                         // This would be removed if metadata is handled here. We have to guard against not
  24                         // knowing the piece size. If we have no info, we have no pieces too, so the end result
  25                         // is the same.
  26                         continue
  27                 }
  28                 rst := request_strategy.Torrent{
  29                         InfoHash:       t.infoHash,
  30                         ChunksPerPiece: t.chunksPerRegularPiece(),
  31                 }
  32                 if t.storage != nil {
  33                         rst.Capacity = t.storage.Capacity
  34                 }
  35                 rst.Pieces = make([]request_strategy.Piece, 0, len(t.pieces))
  36                 for i := range t.pieces {
  37                         p := &t.pieces[i]
  38                         rst.Pieces = append(rst.Pieces, request_strategy.Piece{
  39                                 Request:           !t.ignorePieceForRequests(i),
  40                                 Priority:          p.purePriority(),
  41                                 Partial:           t.piecePartiallyDownloaded(i),
  42                                 Availability:      p.availability,
  43                                 Length:            int64(p.length()),
  44                                 NumPendingChunks:  int(t.pieceNumPendingChunks(i)),
  45                                 IterPendingChunks: &p.undirtiedChunksIter,
  46                         })
  47                 }
  48                 ts = append(ts, rst)
  49         }
  50         return request_strategy.Input{
  51                 Torrents:           ts,
  52                 MaxUnverifiedBytes: cl.config.MaxUnverifiedBytes,
  53         }
  54 }
  55
  56 func init() {
  57         gob.Register(peerId{})
  58 }
  59
  60 type peerId struct {
  61         *Peer
  62         ptr uintptr
  63 }
  64
  65 func (p peerId) Uintptr() uintptr {
  66         return p.ptr
  67 }
  68
  69 func (p peerId) GobEncode() (b []byte, _ error) {
  70         *(*reflect.SliceHeader)(unsafe.Pointer(&b)) = reflect.SliceHeader{
  71                 Data: uintptr(unsafe.Pointer(&p.ptr)),
  72                 Len:  int(unsafe.Sizeof(p.ptr)),
  73                 Cap:  int(unsafe.Sizeof(p.ptr)),
  74         }
  75         return
  76 }
  77
  78 func (p *peerId) GobDecode(b []byte) error {
  79         if uintptr(len(b)) != unsafe.Sizeof(p.ptr) {
  80                 panic(len(b))
  81         }
  82         ptr := unsafe.Pointer(&b[0])
  83         p.ptr = *(*uintptr)(ptr)
  84         log.Printf("%p", ptr)
  85         dst := reflect.SliceHeader{
  86                 Data: uintptr(unsafe.Pointer(&p.Peer)),
  87                 Len:  int(unsafe.Sizeof(p.Peer)),
  88                 Cap:  int(unsafe.Sizeof(p.Peer)),
  89         }
  90         copy(*(*[]byte)(unsafe.Pointer(&dst)), b)
  91         return nil
  92 }
  93
  94 type (
  95         RequestIndex   = request_strategy.RequestIndex
  96         chunkIndexType = request_strategy.ChunkIndex
  97 )
  98
  99 type peerRequests struct {
 100         requestIndexes       []RequestIndex
 101         peer                 *Peer
 102         torrentStrategyInput *request_strategy.Torrent
 103 }
 104
 105 func (p *peerRequests) Len() int {
 106         return len(p.requestIndexes)
 107 }
 108
 109 func (p *peerRequests) Less(i, j int) bool {
 110         leftRequest := p.requestIndexes[i]
 111         rightRequest := p.requestIndexes[j]
 112         t := p.peer.t
 113         leftPieceIndex := leftRequest / p.torrentStrategyInput.ChunksPerPiece
 114         rightPieceIndex := rightRequest / p.torrentStrategyInput.ChunksPerPiece
 115         leftCurrent := p.peer.actualRequestState.Requests.Contains(leftRequest)
 116         rightCurrent := p.peer.actualRequestState.Requests.Contains(rightRequest)
 117         pending := func(index RequestIndex, current bool) int {
 118                 ret := t.pendingRequests.Get(index)
 119                 if current {
 120                         ret--
 121                 }
 122                 // See https://github.com/anacrolix/torrent/issues/679 for possible issues. This should be
 123                 // resolved.
 124                 if ret < 0 {
 125                         panic(ret)
 126                 }
 127                 return ret
 128         }
 129         ml := multiless.New()
 130         // Push requests that can't be served right now to the end. But we don't throw them away unless
 131         // there's a better alternative. This is for when we're using the fast extension and get choked
 132         // but our requests could still be good when we get unchoked.
 133         if p.peer.peerChoking {
 134                 ml = ml.Bool(
 135                         !p.peer.peerAllowedFast.Contains(leftPieceIndex),
 136                         !p.peer.peerAllowedFast.Contains(rightPieceIndex),
 137                 )
 138         }
 139         ml = ml.Int(
 140                 pending(leftRequest, leftCurrent),
 141                 pending(rightRequest, rightCurrent))
 142         ml = ml.Bool(!leftCurrent, !rightCurrent)
 143         ml = ml.Int(
 144                 -int(p.torrentStrategyInput.Pieces[leftPieceIndex].Priority),
 145                 -int(p.torrentStrategyInput.Pieces[rightPieceIndex].Priority),
 146         )
 147         ml = ml.Int(
 148                 int(p.torrentStrategyInput.Pieces[leftPieceIndex].Availability),
 149                 int(p.torrentStrategyInput.Pieces[rightPieceIndex].Availability))
 150         ml = ml.Uint32(leftPieceIndex, rightPieceIndex)
 151         ml = ml.Uint32(leftRequest, rightRequest)
 152         return ml.MustLess()
 153 }
 154
 155 func (p *peerRequests) Swap(i, j int) {
 156         p.requestIndexes[i], p.requestIndexes[j] = p.requestIndexes[j], p.requestIndexes[i]
 157 }
 158
 159 func (p *peerRequests) Push(x interface{}) {
 160         p.requestIndexes = append(p.requestIndexes, x.(RequestIndex))
 161 }
 162
 163 func (p *peerRequests) Pop() interface{} {
 164         last := len(p.requestIndexes) - 1
 165         x := p.requestIndexes[last]
 166         p.requestIndexes = p.requestIndexes[:last]
 167         return x
 168 }
 169
 170 type desiredRequestState struct {
 171         Requests   []RequestIndex
 172         Interested bool
 173 }
 174
 175 func (p *Peer) getDesiredRequestState() (desired desiredRequestState) {
 176         input := p.t.cl.getRequestStrategyInput()
 177         requestHeap := peerRequests{
 178                 peer: p,
 179         }
 180         for i := range input.Torrents {
 181                 t := &input.Torrents[i]
 182                 if t.InfoHash == p.t.infoHash {
 183                         requestHeap.torrentStrategyInput = t
 184                         break
 185                 }
 186         }
 187         request_strategy.GetRequestablePieces(
 188                 input,
 189                 func(t *request_strategy.Torrent, rsp *request_strategy.Piece, pieceIndex int) {
 190                         if t.InfoHash != p.t.infoHash {
 191                                 return
 192                         }
 193                         if !p.peerHasPiece(pieceIndex) {
 194                                 return
 195                         }
 196                         allowedFast := p.peerAllowedFast.ContainsInt(pieceIndex)
 197                         rsp.IterPendingChunks.Iter(func(ci request_strategy.ChunkIndex) {
 198                                 r := p.t.pieceRequestIndexOffset(pieceIndex) + ci
 199                                 // if p.t.pendingRequests.Get(r) != 0 && !p.actualRequestState.Requests.Contains(r) {
 200                                 //      return
 201                                 // }
 202                                 if !allowedFast {
 203                                         // We must signal interest to request this
 204                                         desired.Interested = true
 205                                         // We can make or will allow sustaining a request here if we're not choked, or
 206                                         // have made the request previously (presumably while unchoked), and haven't had
 207                                         // the peer respond yet (and the request was retained because we are using the
 208                                         // fast extension).
 209                                         if p.peerChoking && !p.actualRequestState.Requests.Contains(r) {
 210                                                 // We can't request this right now.
 211                                                 return
 212                                         }
 213                                 }
 214                                 requestHeap.requestIndexes = append(requestHeap.requestIndexes, r)
 215                         })
 216                 },
 217         )
 218         p.t.assertPendingRequests()
 219         heap.Init(&requestHeap)
 220         for requestHeap.Len() != 0 && len(desired.Requests) < p.nominalMaxRequests() {
 221                 requestIndex := heap.Pop(&requestHeap).(RequestIndex)
 222                 desired.Requests = append(desired.Requests, requestIndex)
 223         }
 224         return
 225 }
 226
 227 func (p *Peer) maybeUpdateActualRequestState() bool {
 228         if p.needRequestUpdate == "" {
 229                 return true
 230         }
 231         var more bool
 232         pprof.Do(
 233                 context.Background(),
 234                 pprof.Labels("update request", p.needRequestUpdate),
 235                 func(_ context.Context) {
 236                         next := p.getDesiredRequestState()
 237                         more = p.applyRequestState(next)
 238                 },
 239         )
 240         return more
 241 }
 242
 243 // Transmit/action the request state to the peer.
 244 func (p *Peer) applyRequestState(next desiredRequestState) bool {
 245         current := &p.actualRequestState
 246         if !p.setInterested(next.Interested) {
 247                 return false
 248         }
 249         more := true
 250         cancel := current.Requests.Clone()
 251         for _, ri := range next.Requests {
 252                 cancel.Remove(ri)
 253         }
 254         cancel.Iterate(func(req uint32) bool {
 255                 more = p.cancel(req)
 256                 return more
 257         })
 258         if !more {
 259                 return false
 260         }
 261         shuffled := false
 262         lastPending := 0
 263         for i := 0; i < len(next.Requests); i++ {
 264                 req := next.Requests[i]
 265                 if p.cancelledRequests.Contains(req) {
 266                         // Waiting for a reject or piece message, which will suitably trigger us to update our
 267                         // requests, so we can skip this one with no additional consideration.
 268                         continue
 269                 }
 270                 // The cardinality of our desired requests shouldn't exceed the max requests since it's used
 271                 // in the calculation of the requests. However, if we cancelled requests and they haven't
 272                 // been rejected or serviced yet with the fast extension enabled, we can end up with more
 273                 // extra outstanding requests. We could subtract the number of outstanding cancels from the
 274                 // next request cardinality, but peers might not like that.
 275                 if maxRequests(current.Requests.GetCardinality()) >= p.nominalMaxRequests() {
 276                         // log.Printf("not assigning all requests [desired=%v, cancelled=%v, current=%v, max=%v]",
 277                         //      next.Requests.GetCardinality(),
 278                         //      p.cancelledRequests.GetCardinality(),
 279                         //      current.Requests.GetCardinality(),
 280                         //      p.nominalMaxRequests(),
 281                         // )
 282                         break
 283                 }
 284                 otherPending := p.t.pendingRequests.Get(next.Requests[0])
 285                 if p.actualRequestState.Requests.Contains(next.Requests[0]) {
 286                         otherPending--
 287                 }
 288                 if otherPending < lastPending {
 289                         // Pending should only rise. It's supposed to be the strongest ordering criteria. If it
 290                         // doesn't, our shuffling condition could be wrong.
 291                         panic(lastPending)
 292                 }
 293                 // If the request has already been requested by another peer, shuffle this and the rest of
 294                 // the requests (since according to the increasing condition, the rest of the indices
 295                 // already have an outstanding request with another peer).
 296                 if !shuffled && otherPending > 0 {
 297                         shuffleReqs := next.Requests[i:]
 298                         rand.Shuffle(len(shuffleReqs), func(i, j int) {
 299                                 shuffleReqs[i], shuffleReqs[j] = shuffleReqs[j], shuffleReqs[i]
 300                         })
 301                         // log.Printf("shuffled reqs [%v:%v]", i, len(next.Requests))
 302                         shuffled = true
 303                         // Repeat this index
 304                         i--
 305                         continue
 306                 }
 307
 308                 more = p.mustRequest(req)
 309                 if !more {
 310                         break
 311                 }
 312         }
 313         p.updateRequestsTimer.Stop()
 314         if more {
 315                 p.needRequestUpdate = ""
 316                 if !current.Requests.IsEmpty() {
 317                         p.updateRequestsTimer.Reset(3 * time.Second)
 318                 }
 319         }
 320         return more
 321 }