request-strategy/order.go

   1 package request_strategy
   2
   3 import (
   4         "bytes"
   5         "fmt"
   6         "sort"
   7         "sync"
   8
   9         "github.com/anacrolix/multiless"
  10         "github.com/anacrolix/torrent/metainfo"
  11         "github.com/anacrolix/torrent/storage"
  12
  13         pp "github.com/anacrolix/torrent/peer_protocol"
  14         "github.com/anacrolix/torrent/types"
  15 )
  16
  17 type (
  18         Request       = types.Request
  19         pieceIndex    = types.PieceIndex
  20         piecePriority = types.PiecePriority
  21         // This can be made into a type-param later, will be great for testing.
  22         ChunkSpec = types.ChunkSpec
  23 )
  24
  25 type ClientPieceOrder struct{}
  26
  27 type filterTorrent struct {
  28         *Torrent
  29         unverifiedBytes int64
  30         // Potentially shared with other torrents.
  31         storageLeft *int64
  32 }
  33
  34 func sortFilterPieces(pieces []filterPiece) {
  35         sort.Slice(pieces, func(_i, _j int) bool {
  36                 i := &pieces[_i]
  37                 j := &pieces[_j]
  38                 return multiless.New().Int(
  39                         int(j.Priority), int(i.Priority),
  40                 ).Bool(
  41                         j.Partial, i.Partial,
  42                 ).Int64(
  43                         i.Availability, j.Availability,
  44                 ).Int(
  45                         i.index, j.index,
  46                 ).Lazy(func() multiless.Computation {
  47                         return multiless.New().Cmp(bytes.Compare(
  48                                 i.t.InfoHash[:],
  49                                 j.t.InfoHash[:],
  50                         ))
  51                 }).MustLess()
  52         })
  53 }
  54
  55 type requestsPeer struct {
  56         Peer
  57         nextState                  PeerNextRequestState
  58         requestablePiecesRemaining int
  59 }
  60
  61 func (rp *requestsPeer) canFitRequest() bool {
  62         return len(rp.nextState.Requests) < rp.MaxRequests
  63 }
  64
  65 func (rp *requestsPeer) addNextRequest(r Request) {
  66         _, ok := rp.nextState.Requests[r]
  67         if ok {
  68                 panic("should only add once")
  69         }
  70         rp.nextState.Requests[r] = struct{}{}
  71 }
  72
  73 type peersForPieceRequests struct {
  74         requestsInPiece int
  75         *requestsPeer
  76 }
  77
  78 func (me *peersForPieceRequests) addNextRequest(r Request) {
  79         me.requestsPeer.addNextRequest(r)
  80         me.requestsInPiece++
  81 }
  82
  83 type requestablePiece struct {
  84         index             pieceIndex
  85         t                 *Torrent
  86         alwaysReallocate  bool
  87         NumPendingChunks  int
  88         IterPendingChunks ChunksIter
  89 }
  90
  91 type filterPiece struct {
  92         t     *filterTorrent
  93         index pieceIndex
  94         *Piece
  95 }
  96
  97 // Calls f with requestable pieces in order.
  98 func GetRequestablePieces(input Input, f func(t *Torrent, p *Piece, pieceIndex int)) {
  99         maxPieces := 0
 100         for i := range input.Torrents {
 101                 maxPieces += len(input.Torrents[i].Pieces)
 102         }
 103         pieces := make([]filterPiece, 0, maxPieces)
 104         // Storage capacity left for this run, keyed by the storage capacity pointer on the storage
 105         // TorrentImpl. A nil value means no capacity limit.
 106         storageLeft := make(map[storage.TorrentCapacity]*int64)
 107         for _t := range input.Torrents {
 108                 // TODO: We could do metainfo requests here.
 109                 t := &filterTorrent{
 110                         Torrent:         &input.Torrents[_t],
 111                         unverifiedBytes: 0,
 112                 }
 113                 key := t.Capacity
 114                 if key != nil {
 115                         if _, ok := storageLeft[key]; !ok {
 116                                 capacity, ok := (*key)()
 117                                 if ok {
 118                                         storageLeft[key] = &capacity
 119                                 } else {
 120                                         storageLeft[key] = nil
 121                                 }
 122                         }
 123                         t.storageLeft = storageLeft[key]
 124                 }
 125                 for i := range t.Pieces {
 126                         pieces = append(pieces, filterPiece{
 127                                 t:     t,
 128                                 index: i,
 129                                 Piece: &t.Pieces[i],
 130                         })
 131                 }
 132         }
 133         sortFilterPieces(pieces)
 134         var allTorrentsUnverifiedBytes int64
 135         for _, piece := range pieces {
 136                 if left := piece.t.storageLeft; left != nil {
 137                         if *left < int64(piece.Length) {
 138                                 continue
 139                         }
 140                         *left -= int64(piece.Length)
 141                 }
 142                 if !piece.Request || piece.NumPendingChunks == 0 {
 143                         // TODO: Clarify exactly what is verified. Stuff that's being hashed should be
 144                         // considered unverified and hold up further requests.
 145                         continue
 146                 }
 147                 if piece.t.MaxUnverifiedBytes != 0 && piece.t.unverifiedBytes+piece.Length > piece.t.MaxUnverifiedBytes {
 148                         continue
 149                 }
 150                 if input.MaxUnverifiedBytes != 0 && allTorrentsUnverifiedBytes+piece.Length > input.MaxUnverifiedBytes {
 151                         continue
 152                 }
 153                 piece.t.unverifiedBytes += piece.Length
 154                 allTorrentsUnverifiedBytes += piece.Length
 155                 f(piece.t.Torrent, piece.Piece, piece.index)
 156         }
 157         return
 158 }
 159
 160 type Input struct {
 161         Torrents           []Torrent
 162         MaxUnverifiedBytes int64
 163 }
 164
 165 // TODO: We could do metainfo requests here.
 166 func Run(input Input) map[PeerId]PeerNextRequestState {
 167         var requestPieces []requestablePiece
 168         GetRequestablePieces(input, func(t *Torrent, piece *Piece, pieceIndex int) {
 169                 requestPieces = append(requestPieces, requestablePiece{
 170                         index:             pieceIndex,
 171                         t:                 t,
 172                         NumPendingChunks:  piece.NumPendingChunks,
 173                         IterPendingChunks: piece.iterPendingChunksWrapper,
 174                         alwaysReallocate:  piece.Priority >= types.PiecePriorityNext,
 175                 })
 176         })
 177         torrents := input.Torrents
 178         allPeers := make(map[metainfo.Hash][]*requestsPeer, len(torrents))
 179         for _, t := range torrents {
 180                 peers := make([]*requestsPeer, 0, len(t.Peers))
 181                 for _, p := range t.Peers {
 182                         peers = append(peers, &requestsPeer{
 183                                 Peer: p,
 184                                 nextState: PeerNextRequestState{
 185                                         Requests: make(map[Request]struct{}, p.MaxRequests),
 186                                 },
 187                         })
 188                 }
 189                 allPeers[t.InfoHash] = peers
 190         }
 191         for _, piece := range requestPieces {
 192                 for _, peer := range allPeers[piece.t.InfoHash] {
 193                         if peer.canRequestPiece(piece.index) {
 194                                 peer.requestablePiecesRemaining++
 195                         }
 196                 }
 197         }
 198         for _, piece := range requestPieces {
 199                 allocatePendingChunks(piece, allPeers[piece.t.InfoHash])
 200         }
 201         ret := make(map[PeerId]PeerNextRequestState)
 202         for _, peers := range allPeers {
 203                 for _, rp := range peers {
 204                         if rp.requestablePiecesRemaining != 0 {
 205                                 panic(rp.requestablePiecesRemaining)
 206                         }
 207                         if _, ok := ret[rp.Id]; ok {
 208                                 panic(fmt.Sprintf("duplicate peer id: %v", rp.Id))
 209                         }
 210                         ret[rp.Id] = rp.nextState
 211                 }
 212         }
 213         return ret
 214 }
 215
 216 // Checks that a sorted peersForPiece slice makes sense.
 217 func ensureValidSortedPeersForPieceRequests(peers *peersForPieceSorter) {
 218         if !sort.IsSorted(peers) {
 219                 panic("not sorted")
 220         }
 221         peerMap := make(map[*peersForPieceRequests]struct{}, peers.Len())
 222         for _, p := range peers.peersForPiece {
 223                 if _, ok := peerMap[p]; ok {
 224                         panic(p)
 225                 }
 226                 peerMap[p] = struct{}{}
 227         }
 228 }
 229
 230 var peersForPiecesPool sync.Pool
 231
 232 func makePeersForPiece(cap int) []*peersForPieceRequests {
 233         got := peersForPiecesPool.Get()
 234         if got == nil {
 235                 return make([]*peersForPieceRequests, 0, cap)
 236         }
 237         return got.([]*peersForPieceRequests)[:0]
 238 }
 239
 240 type peersForPieceSorter struct {
 241         peersForPiece []*peersForPieceRequests
 242         req           *Request
 243         p             requestablePiece
 244 }
 245
 246 func (me *peersForPieceSorter) Len() int {
 247         return len(me.peersForPiece)
 248 }
 249
 250 func (me *peersForPieceSorter) Swap(i, j int) {
 251         me.peersForPiece[i], me.peersForPiece[j] = me.peersForPiece[j], me.peersForPiece[i]
 252 }
 253
 254 func (me *peersForPieceSorter) Less(_i, _j int) bool {
 255         i := me.peersForPiece[_i]
 256         j := me.peersForPiece[_j]
 257         req := me.req
 258         p := &me.p
 259         byHasRequest := func() multiless.Computation {
 260                 ml := multiless.New()
 261                 if req != nil {
 262                         _, iHas := i.nextState.Requests[*req]
 263                         _, jHas := j.nextState.Requests[*req]
 264                         ml = ml.Bool(jHas, iHas)
 265                 }
 266                 return ml
 267         }()
 268         ml := multiless.New()
 269         // We always "reallocate", that is force even striping amongst peers that are either on
 270         // the last piece they can contribute too, or for pieces marked for this behaviour.
 271         // Striping prevents starving peers of requests, and will always re-balance to the
 272         // fastest known peers.
 273         if !p.alwaysReallocate {
 274                 ml = ml.Bool(
 275                         j.requestablePiecesRemaining == 1,
 276                         i.requestablePiecesRemaining == 1)
 277         }
 278         if p.alwaysReallocate || j.requestablePiecesRemaining == 1 {
 279                 ml = ml.Int(
 280                         i.requestsInPiece,
 281                         j.requestsInPiece)
 282         } else {
 283                 ml = ml.AndThen(byHasRequest)
 284         }
 285         ml = ml.Int(
 286                 i.requestablePiecesRemaining,
 287                 j.requestablePiecesRemaining,
 288         ).Float64(
 289                 j.DownloadRate,
 290                 i.DownloadRate,
 291         )
 292         if ml.Ok() {
 293                 return ml.Less()
 294         }
 295         ml = ml.AndThen(byHasRequest)
 296         return ml.Int64(
 297                 int64(j.Age), int64(i.Age),
 298                 // TODO: Probably peer priority can come next
 299         ).Uintptr(
 300                 i.Id.Uintptr(),
 301                 j.Id.Uintptr(),
 302         ).MustLess()
 303 }
 304
 305 func allocatePendingChunks(p requestablePiece, peers []*requestsPeer) {
 306         peersForPiece := makePeersForPiece(len(peers))
 307         for _, peer := range peers {
 308                 if !peer.canRequestPiece(p.index) {
 309                         continue
 310                 }
 311                 if !peer.canFitRequest() {
 312                         peer.requestablePiecesRemaining--
 313                         continue
 314                 }
 315                 peersForPiece = append(peersForPiece, &peersForPieceRequests{
 316                         requestsInPiece: 0,
 317                         requestsPeer:    peer,
 318                 })
 319         }
 320         defer func() {
 321                 for _, peer := range peersForPiece {
 322                         peer.requestablePiecesRemaining--
 323                 }
 324                 peersForPiecesPool.Put(peersForPiece)
 325         }()
 326         peersForPieceSorter := peersForPieceSorter{
 327                 peersForPiece: peersForPiece,
 328                 p:             p,
 329         }
 330         sortPeersForPiece := func(req *Request) {
 331                 peersForPieceSorter.req = req
 332                 sort.Sort(&peersForPieceSorter)
 333                 //ensureValidSortedPeersForPieceRequests(&peersForPieceSorter)
 334         }
 335         // Chunks can be preassigned several times, if peers haven't been able to update their "actual"
 336         // with "next" request state before another request strategy run occurs.
 337         preallocated := make(map[ChunkSpec][]*peersForPieceRequests, p.NumPendingChunks)
 338         p.IterPendingChunks(func(spec ChunkSpec) {
 339                 req := Request{pp.Integer(p.index), spec}
 340                 for _, peer := range peersForPiece {
 341                         if h := peer.HasExistingRequest; h == nil || !h(req) {
 342                                 continue
 343                         }
 344                         if !peer.canFitRequest() {
 345                                 continue
 346                         }
 347                         preallocated[spec] = append(preallocated[spec], peer)
 348                         peer.addNextRequest(req)
 349                 }
 350         })
 351         pendingChunksRemaining := int(p.NumPendingChunks)
 352         p.IterPendingChunks(func(chunk types.ChunkSpec) {
 353                 if _, ok := preallocated[chunk]; ok {
 354                         return
 355                 }
 356                 req := Request{pp.Integer(p.index), chunk}
 357                 defer func() { pendingChunksRemaining-- }()
 358                 sortPeersForPiece(nil)
 359                 for _, peer := range peersForPiece {
 360                         if !peer.canFitRequest() {
 361                                 continue
 362                         }
 363                         if !peer.pieceAllowedFastOrDefault(p.index) {
 364                                 // TODO: Verify that's okay to stay uninterested if we request allowed fast pieces.
 365                                 peer.nextState.Interested = true
 366                                 if peer.Choking {
 367                                         continue
 368                                 }
 369                         }
 370                         peer.addNextRequest(req)
 371                         break
 372                 }
 373         })
 374 chunk:
 375         for chunk, prePeers := range preallocated {
 376                 pendingChunksRemaining--
 377                 req := Request{pp.Integer(p.index), chunk}
 378                 for _, pp := range prePeers {
 379                         pp.requestsInPiece--
 380                 }
 381                 sortPeersForPiece(&req)
 382                 for _, pp := range prePeers {
 383                         delete(pp.nextState.Requests, req)
 384                 }
 385                 for _, peer := range peersForPiece {
 386                         if !peer.canFitRequest() {
 387                                 continue
 388                         }
 389                         if !peer.pieceAllowedFastOrDefault(p.index) {
 390                                 // TODO: Verify that's okay to stay uninterested if we request allowed fast pieces.
 391                                 peer.nextState.Interested = true
 392                                 if peer.Choking {
 393                                         continue
 394                                 }
 395                         }
 396                         peer.addNextRequest(req)
 397                         continue chunk
 398                 }
 399         }
 400         if pendingChunksRemaining != 0 {
 401                 panic(pendingChunksRemaining)
 402         }
 403 }