package torrent
import (
- "container/heap"
"context"
"encoding/gob"
- "math/rand"
+ "fmt"
"reflect"
"runtime/pprof"
"time"
"unsafe"
- "github.com/RoaringBitmap/roaring"
+ "github.com/anacrolix/generics/heap"
"github.com/anacrolix/log"
"github.com/anacrolix/multiless"
- request_strategy "github.com/anacrolix/torrent/request-strategy"
+ requestStrategy "github.com/anacrolix/torrent/request-strategy"
+ typedRoaring "github.com/anacrolix/torrent/typed-roaring"
)
-func (cl *Client) tickleRequester() {
- cl.updateRequests.Broadcast()
-}
+type (
+ // Since we have to store all the requests in memory, we can't reasonably exceed what could be
+ // indexed with the memory space available.
+ maxRequests = int
+)
-func (cl *Client) getRequestStrategyInput() request_strategy.Input {
- ts := make([]request_strategy.Torrent, 0, len(cl.torrents))
- for _, t := range cl.torrents {
- if !t.haveInfo() {
- // This would be removed if metadata is handled here. We have to guard against not
- // knowing the piece size. If we have no info, we have no pieces too, so the end result
- // is the same.
- continue
- }
- rst := request_strategy.Torrent{
- InfoHash: t.infoHash,
- ChunksPerPiece: t.chunksPerRegularPiece(),
- }
- if t.storage != nil {
- rst.Capacity = t.storage.Capacity
- }
- rst.Pieces = make([]request_strategy.Piece, 0, len(t.pieces))
- for i := range t.pieces {
- p := &t.pieces[i]
- rst.Pieces = append(rst.Pieces, request_strategy.Piece{
- Request: !t.ignorePieceForRequests(i),
- Priority: p.purePriority(),
- Partial: t.piecePartiallyDownloaded(i),
- Availability: p.availability,
- Length: int64(p.length()),
- NumPendingChunks: int(t.pieceNumPendingChunks(i)),
- IterPendingChunks: &p.undirtiedChunksIter,
- })
- }
- t.iterPeers(func(p *Peer) {
- if p.closed.IsSet() {
- return
- }
- if p.piecesReceivedSinceLastRequestUpdate > p.maxPiecesReceivedBetweenRequestUpdates {
- p.maxPiecesReceivedBetweenRequestUpdates = p.piecesReceivedSinceLastRequestUpdate
- }
- p.piecesReceivedSinceLastRequestUpdate = 0
- rst.Peers = append(rst.Peers, request_strategy.Peer{
- Pieces: *p.newPeerPieces(),
- MaxRequests: p.nominalMaxRequests(),
- ExistingRequests: p.actualRequestState.Requests,
- Choking: p.peerChoking,
- PieceAllowedFast: p.peerAllowedFast,
- DownloadRate: p.downloadRate(),
- Age: time.Since(p.completedHandshake),
- Id: peerId{
- Peer: p,
- ptr: uintptr(unsafe.Pointer(p)),
- },
- })
- })
- ts = append(ts, rst)
- }
- return request_strategy.Input{
- Torrents: ts,
- MaxUnverifiedBytes: cl.config.MaxUnverifiedBytes,
+func (t *Torrent) requestStrategyPieceOrderState(i int) requestStrategy.PieceRequestOrderState {
+ return requestStrategy.PieceRequestOrderState{
+ Priority: t.piece(i).purePriority(),
+ Partial: t.piecePartiallyDownloaded(i),
+ Availability: t.piece(i).availability(),
}
}
return nil
}
-type RequestIndex = request_strategy.RequestIndex
-type chunkIndexType = request_strategy.ChunkIndex
-
-type peerRequests struct {
- requestIndexes []RequestIndex
- peer *Peer
- torrentStrategyInput request_strategy.Torrent
-}
+type (
+ RequestIndex = requestStrategy.RequestIndex
+ chunkIndexType = requestStrategy.ChunkIndex
+)
-func (p *peerRequests) Len() int {
- return len(p.requestIndexes)
+type desiredPeerRequests struct {
+ requestIndexes []RequestIndex
+ peer *Peer
+ pieceStates []requestStrategy.PieceRequestOrderState
}
-func (p *peerRequests) Less(i, j int) bool {
- leftRequest := p.requestIndexes[i]
- rightRequest := p.requestIndexes[j]
+func (p *desiredPeerRequests) lessByValue(leftRequest, rightRequest RequestIndex) bool {
t := p.peer.t
- leftPieceIndex := leftRequest / p.torrentStrategyInput.ChunksPerPiece
- rightPieceIndex := rightRequest / p.torrentStrategyInput.ChunksPerPiece
- leftCurrent := p.peer.actualRequestState.Requests.Contains(leftRequest)
- rightCurrent := p.peer.actualRequestState.Requests.Contains(rightRequest)
- pending := func(index RequestIndex, current bool) int {
- ret := t.pendingRequests.Get(index)
- if current {
- ret--
- }
- // I have a hunch that this could trigger for requests for chunks that are choked and not
- // allowed fast, since the current conn shouldn't already be included. It's a very specific
- // circumstance, and if it triggers I will fix it.
- if ret < 0 {
- panic(ret)
- }
- return ret
- }
+ leftPieceIndex := t.pieceIndexOfRequestIndex(leftRequest)
+ rightPieceIndex := t.pieceIndexOfRequestIndex(rightRequest)
ml := multiless.New()
// Push requests that can't be served right now to the end. But we don't throw them away unless
// there's a better alternative. This is for when we're using the fast extension and get choked
!p.peer.peerAllowedFast.Contains(rightPieceIndex),
)
}
+ leftPiece := &p.pieceStates[leftPieceIndex]
+ rightPiece := &p.pieceStates[rightPieceIndex]
+ // Putting this first means we can steal requests from lesser-performing peers for our first few
+ // new requests.
+ priority := func() piecePriority {
+ // Technically we would be happy with the cached priority here, except we don't actually
+ // cache it anymore, and Torrent.piecePriority just does another lookup of *Piece to resolve
+ // the priority through Piece.purePriority, which is probably slower.
+ leftPriority := leftPiece.Priority
+ rightPriority := rightPiece.Priority
+ ml = ml.Int(
+ -int(leftPriority),
+ -int(rightPriority),
+ )
+ if !ml.Ok() {
+ if leftPriority != rightPriority {
+ panic("expected equal")
+ }
+ }
+ return leftPriority
+ }()
+ if ml.Ok() {
+ return ml.MustLess()
+ }
+ leftRequestState := t.requestState[leftRequest]
+ rightRequestState := t.requestState[rightRequest]
+ leftPeer := leftRequestState.peer
+ rightPeer := rightRequestState.peer
+ // Prefer chunks already requested from this peer.
+ ml = ml.Bool(rightPeer == p.peer, leftPeer == p.peer)
+ // Prefer unrequested chunks.
+ ml = ml.Bool(rightPeer == nil, leftPeer == nil)
+ if ml.Ok() {
+ return ml.MustLess()
+ }
+ if leftPeer != nil {
+ // The right peer should also be set, or we'd have resolved the computation by now.
+ ml = ml.Uint64(
+ rightPeer.requestState.Requests.GetCardinality(),
+ leftPeer.requestState.Requests.GetCardinality(),
+ )
+ // Could either of the lastRequested be Zero? That's what checking an existing peer is for.
+ leftLast := leftRequestState.when
+ rightLast := rightRequestState.when
+ if leftLast.IsZero() || rightLast.IsZero() {
+ panic("expected non-zero last requested times")
+ }
+ // We want the most-recently requested on the left. Clients like Transmission serve requests
+ // in received order, so the most recently-requested is the one that has the longest until
+ // it will be served and therefore is the best candidate to cancel.
+ ml = ml.CmpInt64(rightLast.Sub(leftLast).Nanoseconds())
+ }
ml = ml.Int(
- pending(leftRequest, leftCurrent),
- pending(rightRequest, rightCurrent))
- ml = ml.Bool(!leftCurrent, !rightCurrent)
- ml = ml.Int(
- -int(p.torrentStrategyInput.Pieces[leftPieceIndex].Priority),
- -int(p.torrentStrategyInput.Pieces[rightPieceIndex].Priority),
- )
- ml = ml.Int(
- int(p.torrentStrategyInput.Pieces[leftPieceIndex].Availability),
- int(p.torrentStrategyInput.Pieces[rightPieceIndex].Availability))
- ml = ml.Uint32(leftPieceIndex, rightPieceIndex)
- ml = ml.Uint32(leftRequest, rightRequest)
- return ml.MustLess()
-}
-
-func (p *peerRequests) Swap(i, j int) {
- p.requestIndexes[i], p.requestIndexes[j] = p.requestIndexes[j], p.requestIndexes[i]
-}
-
-func (p *peerRequests) Push(x interface{}) {
- p.requestIndexes = append(p.requestIndexes, x.(RequestIndex))
+ leftPiece.Availability,
+ rightPiece.Availability)
+ if priority == PiecePriorityReadahead {
+ // TODO: For readahead in particular, it would be even better to consider distance from the
+ // reader position so that reads earlier in a torrent don't starve reads later in the
+ // torrent. This would probably require reconsideration of how readahead priority works.
+ ml = ml.Int(leftPieceIndex, rightPieceIndex)
+ } else {
+ ml = ml.Int(t.pieceRequestOrder[leftPieceIndex], t.pieceRequestOrder[rightPieceIndex])
+ }
+ return ml.Less()
}
-func (p *peerRequests) Pop() interface{} {
- last := len(p.requestIndexes) - 1
- x := p.requestIndexes[last]
- p.requestIndexes = p.requestIndexes[:last]
- return x
+type desiredRequestState struct {
+ Requests desiredPeerRequests
+ Interested bool
}
-func (p *Peer) getDesiredRequestState() (desired requestState) {
- input := p.t.cl.getRequestStrategyInput()
- requestHeap := peerRequests{
- peer: p,
+func (p *Peer) getDesiredRequestState() (desired desiredRequestState) {
+ t := p.t
+ if !t.haveInfo() {
+ return
}
- for _, t := range input.Torrents {
- if t.InfoHash == p.t.infoHash {
- requestHeap.torrentStrategyInput = t
- break
- }
+ if t.closed.IsSet() {
+ return
}
- request_strategy.GetRequestablePieces(
+ input := t.getRequestStrategyInput()
+ requestHeap := desiredPeerRequests{
+ peer: p,
+ pieceStates: t.requestPieceStates,
+ requestIndexes: t.requestIndexes,
+ }
+ // Caller-provided allocation for roaring bitmap iteration.
+ var it typedRoaring.Iterator[RequestIndex]
+ requestStrategy.GetRequestablePieces(
input,
- func(t *request_strategy.Torrent, rsp *request_strategy.Piece, pieceIndex int) {
- if t.InfoHash != p.t.infoHash {
+ t.getPieceRequestOrder(),
+ func(ih InfoHash, pieceIndex int, pieceExtra requestStrategy.PieceRequestOrderState) {
+ if ih != t.infoHash {
return
}
if !p.peerHasPiece(pieceIndex) {
return
}
- allowedFast := p.peerAllowedFast.ContainsInt(pieceIndex)
- rsp.IterPendingChunks.Iter(func(ci request_strategy.ChunkIndex) {
+ requestHeap.pieceStates[pieceIndex] = pieceExtra
+ allowedFast := p.peerAllowedFast.Contains(pieceIndex)
+ t.iterUndirtiedRequestIndexesInPiece(&it, pieceIndex, func(r requestStrategy.RequestIndex) {
if !allowedFast {
- // We must signal interest to request this
+ // We must signal interest to request this. TODO: We could set interested if the
+ // peers pieces (minus the allowed fast set) overlap with our missing pieces if
+ // there are any readers, or any pending pieces.
desired.Interested = true
// We can make or will allow sustaining a request here if we're not choked, or
// have made the request previously (presumably while unchoked), and haven't had
// the peer respond yet (and the request was retained because we are using the
// fast extension).
- if p.peerChoking && !p.actualRequestState.Requests.Contains(ci) {
+ if p.peerChoking && !p.requestState.Requests.Contains(r) {
// We can't request this right now.
return
}
}
- requestHeap.requestIndexes = append(
- requestHeap.requestIndexes,
- p.t.pieceRequestIndexOffset(pieceIndex)+ci)
+ if p.requestState.Cancelled.Contains(r) {
+ // Can't re-request while awaiting acknowledgement.
+ return
+ }
+ requestHeap.requestIndexes = append(requestHeap.requestIndexes, r)
})
},
)
- heap.Init(&requestHeap)
- for requestHeap.Len() != 0 && desired.Requests.GetCardinality() < uint64(p.nominalMaxRequests()) {
- requestIndex := heap.Pop(&requestHeap).(RequestIndex)
- desired.Requests.Add(requestIndex)
- }
+ t.assertPendingRequests()
+ desired.Requests = requestHeap
return
}
-func (p *Peer) maybeUpdateActualRequestState() bool {
+func (p *Peer) maybeUpdateActualRequestState() {
+ if p.closed.IsSet() {
+ return
+ }
if p.needRequestUpdate == "" {
- return true
+ return
+ }
+ if p.needRequestUpdate == peerUpdateRequestsTimerReason {
+ since := time.Since(p.lastRequestUpdate)
+ if since < updateRequestsTimerDuration {
+ panic(since)
+ }
}
- var more bool
pprof.Do(
context.Background(),
pprof.Labels("update request", p.needRequestUpdate),
func(_ context.Context) {
next := p.getDesiredRequestState()
- more = p.applyRequestState(next)
+ p.applyRequestState(next)
+ p.t.requestIndexes = next.Requests.requestIndexes[:0]
},
)
- return more
}
// Transmit/action the request state to the peer.
-func (p *Peer) applyRequestState(next requestState) bool {
- current := &p.actualRequestState
+func (p *Peer) applyRequestState(next desiredRequestState) {
+ current := &p.requestState
if !p.setInterested(next.Interested) {
- return false
+ return
}
more := true
- cancel := roaring.AndNot(¤t.Requests, &next.Requests)
- cancel.Iterate(func(req uint32) bool {
- more = p.cancel(req)
- return more
- })
- if !more {
- return false
+ requestHeap := heap.InterfaceForSlice(&next.Requests.requestIndexes, next.Requests.lessByValue)
+ heap.Init(requestHeap)
+
+ t := p.t
+ originalRequestCount := current.Requests.GetCardinality()
+ // We're either here on a timer, or because we ran out of requests. Both are valid reasons to
+ // alter peakRequests.
+ if originalRequestCount != 0 && p.needRequestUpdate != peerUpdateRequestsTimerReason {
+ panic(fmt.Sprintf(
+ "expected zero existing requests (%v) for update reason %q",
+ originalRequestCount, p.needRequestUpdate))
}
- // We randomize the order in which requests are issued, to reduce the overlap with requests to
- // other peers. Note that although it really depends on what order the peer services the
- // requests, if we are only able to issue some requests before buffering, or the peer starts
- // handling our requests before they've all arrived, then this randomization should reduce
- // overlap. Note however that if we received the desired requests in priority order, then
- // randomizing would throw away that benefit.
- for _, x := range rand.Perm(int(next.Requests.GetCardinality())) {
- req, err := next.Requests.Select(uint32(x))
- if err != nil {
- panic(err)
- }
- if p.cancelledRequests.Contains(req) {
- // Waiting for a reject or piece message, which will suitably trigger us to update our
- // requests, so we can skip this one with no additional consideration.
- continue
- }
- // The cardinality of our desired requests shouldn't exceed the max requests since it's used
- // in the calculation of the requests. However if we cancelled requests and they haven't
- // been rejected or serviced yet with the fast extension enabled, we can end up with more
- // extra outstanding requests. We could subtract the number of outstanding cancels from the
- // next request cardinality, but peers might not like that.
- if maxRequests(current.Requests.GetCardinality()) >= p.nominalMaxRequests() {
- //log.Printf("not assigning all requests [desired=%v, cancelled=%v, current=%v, max=%v]",
- // next.Requests.GetCardinality(),
- // p.cancelledRequests.GetCardinality(),
- // current.Requests.GetCardinality(),
- // p.nominalMaxRequests(),
- //)
- break
- }
- more, err = p.request(req)
- if err != nil {
- panic(err)
+ for requestHeap.Len() != 0 && maxRequests(current.Requests.GetCardinality()+current.Cancelled.GetCardinality()) < p.nominalMaxRequests() {
+ req := heap.Pop(requestHeap)
+ existing := t.requestingPeer(req)
+ if existing != nil && existing != p {
+ // Don't steal from the poor.
+ diff := int64(current.Requests.GetCardinality()) + 1 - (int64(existing.uncancelledRequests()) - 1)
+ // Steal a request that leaves us with one more request than the existing peer
+ // connection if the stealer more recently received a chunk.
+ if diff > 1 || (diff == 1 && p.lastUsefulChunkReceived.Before(existing.lastUsefulChunkReceived)) {
+ continue
+ }
+ t.cancelRequest(req)
}
+ more = p.mustRequest(req)
if !more {
break
}
}
- p.updateRequestsTimer.Stop()
- if more {
- p.needRequestUpdate = ""
- if !current.Requests.IsEmpty() {
- p.updateRequestsTimer.Reset(3 * time.Second)
- }
+ if !more {
+ // This might fail if we incorrectly determine that we can fit up to the maximum allowed
+ // requests into the available write buffer space. We don't want that to happen because it
+ // makes our peak requests dependent on how much was already in the buffer.
+ panic(fmt.Sprintf(
+ "couldn't fill apply entire request state [newRequests=%v]",
+ current.Requests.GetCardinality()-originalRequestCount))
+ }
+ newPeakRequests := maxRequests(current.Requests.GetCardinality() - originalRequestCount)
+ // log.Printf(
+ // "requests %v->%v (peak %v->%v) reason %q (peer %v)",
+ // originalRequestCount, current.Requests.GetCardinality(), p.peakRequests, newPeakRequests, p.needRequestUpdate, p)
+ p.peakRequests = newPeakRequests
+ p.needRequestUpdate = ""
+ p.lastRequestUpdate = time.Now()
+ if enableUpdateRequestsTimer {
+ p.updateRequestsTimer.Reset(updateRequestsTimerDuration)
}
- return more
}
+
+// This could be set to 10s to match the unchoke/request update interval recommended by some
+// specifications. I've set it shorter to trigger it more often for testing for now.
+const (
+ updateRequestsTimerDuration = 3 * time.Second
+ enableUpdateRequestsTimer = false
+)