forked from anacrolix/torrent
/
request_strategy.go
222 lines (196 loc) · 6.49 KB
/
request_strategy.go
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package torrent
import (
"math"
"sync"
"time"
"github.com/anacrolix/missinggo/v2/bitmap"
"github.com/anacrolix/missinggo/v2/prioritybitmap"
pp "github.com/anacrolix/torrent/peer_protocol"
)
type requestStrategyPiece interface {
numChunks() pp.Integer
dirtyChunks() bitmap.Bitmap
chunkIndexRequest(i pp.Integer) request
}
type requestStrategyTorrent interface {
numConns() int
numReaders() int
numPieces() int
readerPiecePriorities() (now, readahead bitmap.Bitmap)
ignorePieces() bitmap.Bitmap
pendingPieces() *prioritybitmap.PriorityBitmap
}
type requestStrategyConnection interface {
torrent() requestStrategyTorrent
peerPieces() bitmap.Bitmap
pieceRequestOrder() *prioritybitmap.PriorityBitmap
fastest() bool
stats() *ConnStats
totalExpectingTime() time.Duration
peerMaxRequests() int
chunksReceivedWhileExpecting() int64
}
type requestStrategy interface {
iterPendingPieces(requestStrategyConnection, func(pieceIndex) bool) bool
iterUndirtiedChunks(requestStrategyPiece, func(chunkSpec) bool) bool
nominalMaxRequests(requestStrategyConnection) int
shouldRequestWithoutBias(requestStrategyConnection) bool
piecePriority(requestStrategyConnection, pieceIndex, piecePriority, int) int
hooks() requestStrategyHooks
}
type requestStrategyHooks struct {
sentRequest func(request)
deletedRequest func(request)
}
type requestStrategyCallbacks interface {
requestTimedOut(request)
}
// Favour higher priority pieces with some fuzzing to reduce overlaps and wastage across
// connections.
type requestStrategyFuzzing struct {
requestStrategyDefaults
}
// The fastest connection downloads strictly in order of priority, while all others adhere to their
// piece inclinations.
type requestStrategyFastest struct {
requestStrategyDefaults
}
func newRequestStrategyMaker(rs requestStrategy) RequestStrategyMaker {
return func(requestStrategyCallbacks, sync.Locker) requestStrategy {
return rs
}
}
func RequestStrategyFastest() RequestStrategyMaker {
return newRequestStrategyMaker(requestStrategyFastest{})
}
func RequestStrategyFuzzing() RequestStrategyMaker {
return newRequestStrategyMaker(requestStrategyFuzzing{})
}
func (requestStrategyFastest) shouldRequestWithoutBias(cn requestStrategyConnection) bool {
if cn.torrent().numReaders() == 0 {
return false
}
if cn.torrent().numConns() == 1 {
return true
}
if cn.fastest() {
return true
}
return false
}
// Requests are strictly by piece priority, and not duplicated until duplicateRequestTimeout is
// reached.
type requestStrategyDuplicateRequestTimeout struct {
requestStrategyDefaults
// How long to avoid duplicating a pending request.
duplicateRequestTimeout time.Duration
callbacks requestStrategyCallbacks
// The last time we requested a chunk. Deleting the request from any connection will clear this
// value.
lastRequested map[request]*time.Timer
// The lock to take when running a request timeout handler.
timeoutLocker sync.Locker
}
type RequestStrategyMaker func(callbacks requestStrategyCallbacks, clientLocker sync.Locker) requestStrategy
func RequestStrategyDuplicateRequestTimeout(duplicateRequestTimeout time.Duration) RequestStrategyMaker {
return func(callbacks requestStrategyCallbacks, clientLocker sync.Locker) requestStrategy {
return requestStrategyDuplicateRequestTimeout{
duplicateRequestTimeout: duplicateRequestTimeout,
callbacks: callbacks,
lastRequested: make(map[request]*time.Timer),
timeoutLocker: clientLocker,
}
}
}
func (rs requestStrategyDuplicateRequestTimeout) hooks() requestStrategyHooks {
return requestStrategyHooks{
deletedRequest: func(r request) {
if t, ok := rs.lastRequested[r]; ok {
t.Stop()
delete(rs.lastRequested, r)
}
},
sentRequest: rs.onSentRequest,
}
}
func (rs requestStrategyDuplicateRequestTimeout) iterUndirtiedChunks(p requestStrategyPiece, f func(chunkSpec) bool) bool {
for i := pp.Integer(0); i < pp.Integer(p.numChunks()); i++ {
if p.dirtyChunks().Get(bitmap.BitIndex(i)) {
continue
}
r := p.chunkIndexRequest(i)
if rs.wouldDuplicateRecent(r) {
continue
}
if !f(r.chunkSpec) {
return false
}
}
return true
}
func (requestStrategyFuzzing) piecePriority(cn requestStrategyConnection, piece pieceIndex, tpp piecePriority, prio int) int {
switch tpp {
case PiecePriorityNormal:
case PiecePriorityReadahead:
prio -= int(cn.torrent().numPieces())
case PiecePriorityNext, PiecePriorityNow:
prio -= 2 * int(cn.torrent().numPieces())
default:
panic(tpp)
}
prio += int(piece / 3)
return prio
}
func (requestStrategyDuplicateRequestTimeout) iterPendingPieces(cn requestStrategyConnection, f func(pieceIndex) bool) bool {
return iterUnbiasedPieceRequestOrder(cn, f)
}
func defaultIterPendingPieces(rs requestStrategy, cn requestStrategyConnection, f func(pieceIndex) bool) bool {
if rs.shouldRequestWithoutBias(cn) {
return iterUnbiasedPieceRequestOrder(cn, f)
} else {
return cn.pieceRequestOrder().IterTyped(func(i int) bool {
return f(pieceIndex(i))
})
}
}
func (rs requestStrategyFuzzing) iterPendingPieces(cn requestStrategyConnection, cb func(pieceIndex) bool) bool {
return defaultIterPendingPieces(rs, cn, cb)
}
func (rs requestStrategyFastest) iterPendingPieces(cn requestStrategyConnection, cb func(pieceIndex) bool) bool {
return defaultIterPendingPieces(rs, cn, cb)
}
func (rs requestStrategyDuplicateRequestTimeout) onSentRequest(r request) {
rs.lastRequested[r] = time.AfterFunc(rs.duplicateRequestTimeout, func() {
rs.timeoutLocker.Lock()
delete(rs.lastRequested, r)
rs.timeoutLocker.Unlock()
rs.callbacks.requestTimedOut(r)
})
}
// The actual value to use as the maximum outbound requests.
func (rs requestStrategyDuplicateRequestTimeout) nominalMaxRequests(cn requestStrategyConnection) (ret int) {
expectingTime := int64(cn.totalExpectingTime())
if expectingTime == 0 {
expectingTime = math.MaxInt64
} else {
expectingTime *= 2
}
return int(clamp(
1,
int64(cn.peerMaxRequests()),
max(
// It makes sense to always pipeline at least one connection, since latency must be
// non-zero.
2,
// Request only as many as we expect to receive in the duplicateRequestTimeout
// window. We are trying to avoid having to duplicate requests.
cn.chunksReceivedWhileExpecting()*int64(rs.duplicateRequestTimeout)/expectingTime,
),
))
}
func (rs requestStrategyDuplicateRequestTimeout) wouldDuplicateRecent(r request) bool {
// This piece has been requested on another connection, and the duplicate request timer is still
// running.
_, ok := rs.lastRequested[r]
return ok
}