status-go/vendor/github.com/anacrolix/torrent/requesting.go

287 lines
8.9 KiB
Go

package torrent
import (
"container/heap"
"context"
"encoding/gob"
"fmt"
"reflect"
"runtime/pprof"
"time"
"unsafe"
"github.com/anacrolix/log"
"github.com/anacrolix/multiless"
request_strategy "github.com/anacrolix/torrent/request-strategy"
)
func (t *Torrent) requestStrategyPieceOrderState(i int) request_strategy.PieceRequestOrderState {
return request_strategy.PieceRequestOrderState{
Priority: t.piece(i).purePriority(),
Partial: t.piecePartiallyDownloaded(i),
Availability: t.piece(i).availability(),
}
}
func init() {
gob.Register(peerId{})
}
type peerId struct {
*Peer
ptr uintptr
}
func (p peerId) Uintptr() uintptr {
return p.ptr
}
func (p peerId) GobEncode() (b []byte, _ error) {
*(*reflect.SliceHeader)(unsafe.Pointer(&b)) = reflect.SliceHeader{
Data: uintptr(unsafe.Pointer(&p.ptr)),
Len: int(unsafe.Sizeof(p.ptr)),
Cap: int(unsafe.Sizeof(p.ptr)),
}
return
}
func (p *peerId) GobDecode(b []byte) error {
if uintptr(len(b)) != unsafe.Sizeof(p.ptr) {
panic(len(b))
}
ptr := unsafe.Pointer(&b[0])
p.ptr = *(*uintptr)(ptr)
log.Printf("%p", ptr)
dst := reflect.SliceHeader{
Data: uintptr(unsafe.Pointer(&p.Peer)),
Len: int(unsafe.Sizeof(p.Peer)),
Cap: int(unsafe.Sizeof(p.Peer)),
}
copy(*(*[]byte)(unsafe.Pointer(&dst)), b)
return nil
}
type (
RequestIndex = request_strategy.RequestIndex
chunkIndexType = request_strategy.ChunkIndex
)
type peerRequests struct {
requestIndexes []RequestIndex
peer *Peer
}
func (p *peerRequests) Len() int {
return len(p.requestIndexes)
}
func (p *peerRequests) Less(i, j int) bool {
leftRequest := p.requestIndexes[i]
rightRequest := p.requestIndexes[j]
t := p.peer.t
leftPieceIndex := leftRequest / t.chunksPerRegularPiece()
rightPieceIndex := rightRequest / t.chunksPerRegularPiece()
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
// but our requests could still be good when we get unchoked.
if p.peer.peerChoking {
ml = ml.Bool(
!p.peer.peerAllowedFast.Contains(leftPieceIndex),
!p.peer.peerAllowedFast.Contains(rightPieceIndex),
)
}
leftPiece := t.piece(int(leftPieceIndex))
rightPiece := t.piece(int(rightPieceIndex))
// Putting this first means we can steal requests from lesser-performing peers for our first few
// new requests.
ml = ml.Int(
// 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.
-int(leftPiece.purePriority()),
-int(rightPiece.purePriority()),
)
leftPeer := t.pendingRequests[leftRequest]
rightPeer := t.pendingRequests[rightRequest]
ml = ml.Bool(rightPeer == p.peer, leftPeer == p.peer)
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 := t.lastRequested[leftRequest]
rightLast := t.lastRequested[rightRequest]
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(
int(leftPiece.relativeAvailability),
int(rightPiece.relativeAvailability))
return ml.Less()
}
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))
}
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 peerRequests
Interested bool
}
func (p *Peer) getDesiredRequestState() (desired desiredRequestState) {
if !p.t.haveInfo() {
return
}
if p.t.closed.IsSet() {
return
}
input := p.t.getRequestStrategyInput()
requestHeap := peerRequests{
peer: p,
}
request_strategy.GetRequestablePieces(
input,
p.t.getPieceRequestOrder(),
func(ih InfoHash, pieceIndex int) {
if ih != p.t.infoHash {
return
}
if !p.peerHasPiece(pieceIndex) {
return
}
allowedFast := p.peerAllowedFast.ContainsInt(pieceIndex)
p.t.piece(pieceIndex).undirtiedChunksIter.Iter(func(ci request_strategy.ChunkIndex) {
r := p.t.pieceRequestIndexOffset(pieceIndex) + ci
if !allowedFast {
// 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.requestState.Requests.Contains(r) {
// We can't request this right now.
return
}
}
if p.requestState.Cancelled.Contains(r) {
// Can't re-request while awaiting acknowledgement.
return
}
requestHeap.requestIndexes = append(requestHeap.requestIndexes, r)
})
},
)
p.t.assertPendingRequests()
desired.Requests = requestHeap
return
}
func (p *Peer) maybeUpdateActualRequestState() {
if p.closed.IsSet() {
return
}
if p.needRequestUpdate == "" {
return
}
if p.needRequestUpdate == peerUpdateRequestsTimerReason {
since := time.Since(p.lastRequestUpdate)
if since < updateRequestsTimerDuration {
panic(since)
}
}
pprof.Do(
context.Background(),
pprof.Labels("update request", p.needRequestUpdate),
func(_ context.Context) {
next := p.getDesiredRequestState()
p.applyRequestState(next)
},
)
}
// Transmit/action the request state to the peer.
func (p *Peer) applyRequestState(next desiredRequestState) {
current := &p.requestState
if !p.setInterested(next.Interested) {
panic("insufficient write buffer")
}
more := true
requestHeap := &next.Requests
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))
}
heap.Init(requestHeap)
for requestHeap.Len() != 0 && maxRequests(current.Requests.GetCardinality()+current.Cancelled.GetCardinality()) < p.nominalMaxRequests() {
req := heap.Pop(requestHeap).(RequestIndex)
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
}
}
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()
p.updateRequestsTimer.Reset(updateRequestsTimerDuration)
}
// 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