12 "github.com/anacrolix/log"
13 "github.com/anacrolix/multiless"
14 "github.com/anacrolix/torrent/typed-roaring"
15 "github.com/lispad/go-generics-tools/binheap"
17 "github.com/anacrolix/torrent/request-strategy"
20 func (t *Torrent) requestStrategyPieceOrderState(i int) request_strategy.PieceRequestOrderState {
21 return request_strategy.PieceRequestOrderState{
22 Priority: t.piece(i).purePriority(),
23 Partial: t.piecePartiallyDownloaded(i),
24 Availability: t.piece(i).availability(),
29 gob.Register(peerId{})
37 func (p peerId) Uintptr() uintptr {
41 func (p peerId) GobEncode() (b []byte, _ error) {
42 *(*reflect.SliceHeader)(unsafe.Pointer(&b)) = reflect.SliceHeader{
43 Data: uintptr(unsafe.Pointer(&p.ptr)),
44 Len: int(unsafe.Sizeof(p.ptr)),
45 Cap: int(unsafe.Sizeof(p.ptr)),
50 func (p *peerId) GobDecode(b []byte) error {
51 if uintptr(len(b)) != unsafe.Sizeof(p.ptr) {
54 ptr := unsafe.Pointer(&b[0])
55 p.ptr = *(*uintptr)(ptr)
57 dst := reflect.SliceHeader{
58 Data: uintptr(unsafe.Pointer(&p.Peer)),
59 Len: int(unsafe.Sizeof(p.Peer)),
60 Cap: int(unsafe.Sizeof(p.Peer)),
62 copy(*(*[]byte)(unsafe.Pointer(&dst)), b)
67 RequestIndex = request_strategy.RequestIndex
68 chunkIndexType = request_strategy.ChunkIndex
71 type desiredPeerRequests struct {
72 requestIndexes []RequestIndex
74 pieceStates []request_strategy.PieceRequestOrderState
77 func (p *desiredPeerRequests) Len() int {
78 return len(p.requestIndexes)
81 func (p *desiredPeerRequests) Less(i, j int) bool {
82 return p.lessByValue(p.requestIndexes[i], p.requestIndexes[j])
85 func (p *desiredPeerRequests) lessByValue(leftRequest, rightRequest RequestIndex) bool {
87 leftPieceIndex := t.pieceIndexOfRequestIndex(leftRequest)
88 rightPieceIndex := t.pieceIndexOfRequestIndex(rightRequest)
90 // Push requests that can't be served right now to the end. But we don't throw them away unless
91 // there's a better alternative. This is for when we're using the fast extension and get choked
92 // but our requests could still be good when we get unchoked.
93 if p.peer.peerChoking {
95 !p.peer.peerAllowedFast.Contains(leftPieceIndex),
96 !p.peer.peerAllowedFast.Contains(rightPieceIndex),
99 leftPiece := &p.pieceStates[leftPieceIndex]
100 rightPiece := &p.pieceStates[rightPieceIndex]
101 // Putting this first means we can steal requests from lesser-performing peers for our first few
103 priority := func() piecePriority {
104 // Technically we would be happy with the cached priority here, except we don't actually
105 // cache it anymore, and Torrent.piecePriority just does another lookup of *Piece to resolve
106 // the priority through Piece.purePriority, which is probably slower.
107 leftPriority := leftPiece.Priority
108 rightPriority := rightPiece.Priority
114 if leftPriority != rightPriority {
115 panic("expected equal")
123 leftRequestState := t.requestState[leftRequest]
124 rightRequestState := t.requestState[rightRequest]
125 leftPeer := leftRequestState.peer
126 rightPeer := rightRequestState.peer
127 // Prefer chunks already requested from this peer.
128 ml = ml.Bool(rightPeer == p.peer, leftPeer == p.peer)
129 // Prefer unrequested chunks.
130 ml = ml.Bool(rightPeer == nil, leftPeer == nil)
135 // The right peer should also be set, or we'd have resolved the computation by now.
137 rightPeer.requestState.Requests.GetCardinality(),
138 leftPeer.requestState.Requests.GetCardinality(),
140 // Could either of the lastRequested be Zero? That's what checking an existing peer is for.
141 leftLast := leftRequestState.when
142 rightLast := rightRequestState.when
143 if leftLast.IsZero() || rightLast.IsZero() {
144 panic("expected non-zero last requested times")
146 // We want the most-recently requested on the left. Clients like Transmission serve requests
147 // in received order, so the most recently-requested is the one that has the longest until
148 // it will be served and therefore is the best candidate to cancel.
149 ml = ml.CmpInt64(rightLast.Sub(leftLast).Nanoseconds())
152 leftPiece.Availability,
153 rightPiece.Availability)
154 if priority == PiecePriorityReadahead {
155 // TODO: For readahead in particular, it would be even better to consider distance from the
156 // reader position so that reads earlier in a torrent don't starve reads later in the
157 // torrent. This would probably require reconsideration of how readahead priority works.
158 ml = ml.Int(leftPieceIndex, rightPieceIndex)
160 ml = ml.Int(t.pieceRequestOrder[leftPieceIndex], t.pieceRequestOrder[rightPieceIndex])
165 func (p *desiredPeerRequests) Swap(i, j int) {
166 p.requestIndexes[i], p.requestIndexes[j] = p.requestIndexes[j], p.requestIndexes[i]
169 func (p *desiredPeerRequests) Push(x interface{}) {
170 p.requestIndexes = append(p.requestIndexes, x.(RequestIndex))
173 func (p *desiredPeerRequests) Pop() interface{} {
174 last := len(p.requestIndexes) - 1
175 x := p.requestIndexes[last]
176 p.requestIndexes = p.requestIndexes[:last]
180 type desiredRequestState struct {
181 Requests desiredPeerRequests
185 func (p *Peer) getDesiredRequestState() (desired desiredRequestState) {
190 if t.closed.IsSet() {
193 input := t.getRequestStrategyInput()
194 requestHeap := desiredPeerRequests{
196 pieceStates: t.requestPieceStates,
197 requestIndexes: t.requestIndexes,
199 // Caller-provided allocation for roaring bitmap iteration.
200 var it typedRoaring.Iterator[RequestIndex]
201 request_strategy.GetRequestablePieces(
203 t.getPieceRequestOrder(),
204 func(ih InfoHash, pieceIndex int, pieceExtra request_strategy.PieceRequestOrderState) {
205 if ih != t.infoHash {
208 if !p.peerHasPiece(pieceIndex) {
211 requestHeap.pieceStates[pieceIndex] = pieceExtra
212 allowedFast := p.peerAllowedFast.Contains(pieceIndex)
213 t.iterUndirtiedRequestIndexesInPiece(&it, pieceIndex, func(r request_strategy.RequestIndex) {
215 // We must signal interest to request this. TODO: We could set interested if the
216 // peers pieces (minus the allowed fast set) overlap with our missing pieces if
217 // there are any readers, or any pending pieces.
218 desired.Interested = true
219 // We can make or will allow sustaining a request here if we're not choked, or
220 // have made the request previously (presumably while unchoked), and haven't had
221 // the peer respond yet (and the request was retained because we are using the
223 if p.peerChoking && !p.requestState.Requests.Contains(r) {
224 // We can't request this right now.
228 if p.requestState.Cancelled.Contains(r) {
229 // Can't re-request while awaiting acknowledgement.
232 requestHeap.requestIndexes = append(requestHeap.requestIndexes, r)
236 t.assertPendingRequests()
237 desired.Requests = requestHeap
241 func (p *Peer) maybeUpdateActualRequestState() {
242 if p.closed.IsSet() {
245 if p.needRequestUpdate == "" {
248 if p.needRequestUpdate == peerUpdateRequestsTimerReason {
249 since := time.Since(p.lastRequestUpdate)
250 if since < updateRequestsTimerDuration {
255 context.Background(),
256 pprof.Labels("update request", p.needRequestUpdate),
257 func(_ context.Context) {
258 next := p.getDesiredRequestState()
259 p.applyRequestState(next)
260 p.t.requestIndexes = next.Requests.requestIndexes[:0]
265 // Transmit/action the request state to the peer.
266 func (p *Peer) applyRequestState(next desiredRequestState) {
267 current := &p.requestState
268 if !p.setInterested(next.Interested) {
269 panic("insufficient write buffer")
272 requestHeap := binheap.FromSlice(next.Requests.requestIndexes, next.Requests.lessByValue)
274 originalRequestCount := current.Requests.GetCardinality()
275 // We're either here on a timer, or because we ran out of requests. Both are valid reasons to
276 // alter peakRequests.
277 if originalRequestCount != 0 && p.needRequestUpdate != peerUpdateRequestsTimerReason {
279 "expected zero existing requests (%v) for update reason %q",
280 originalRequestCount, p.needRequestUpdate))
282 for requestHeap.Len() != 0 && maxRequests(current.Requests.GetCardinality()+current.Cancelled.GetCardinality()) < p.nominalMaxRequests() {
283 req := requestHeap.Pop()
284 existing := t.requestingPeer(req)
285 if existing != nil && existing != p {
286 // Don't steal from the poor.
287 diff := int64(current.Requests.GetCardinality()) + 1 - (int64(existing.uncancelledRequests()) - 1)
288 // Steal a request that leaves us with one more request than the existing peer
289 // connection if the stealer more recently received a chunk.
290 if diff > 1 || (diff == 1 && p.lastUsefulChunkReceived.Before(existing.lastUsefulChunkReceived)) {
295 more = p.mustRequest(req)
301 // This might fail if we incorrectly determine that we can fit up to the maximum allowed
302 // requests into the available write buffer space. We don't want that to happen because it
303 // makes our peak requests dependent on how much was already in the buffer.
305 "couldn't fill apply entire request state [newRequests=%v]",
306 current.Requests.GetCardinality()-originalRequestCount))
308 newPeakRequests := maxRequests(current.Requests.GetCardinality() - originalRequestCount)
310 // "requests %v->%v (peak %v->%v) reason %q (peer %v)",
311 // originalRequestCount, current.Requests.GetCardinality(), p.peakRequests, newPeakRequests, p.needRequestUpdate, p)
312 p.peakRequests = newPeakRequests
313 p.needRequestUpdate = ""
314 p.lastRequestUpdate = time.Now()
315 if enableUpdateRequestsTimer {
316 p.updateRequestsTimer.Reset(updateRequestsTimerDuration)
320 // This could be set to 10s to match the unchoke/request update interval recommended by some
321 // specifications. I've set it shorter to trigger it more often for testing for now.
323 updateRequestsTimerDuration = 3 * time.Second
324 enableUpdateRequestsTimer = false