d01c6221e6
It's not trivial to ensure that anyone waiting on the piece Cond will wake on events like the torrent being dropped from the client.
89 lines
2.1 KiB
Go
89 lines
2.1 KiB
Go
package torrent
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import (
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"math/rand"
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"sync"
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pp "github.com/anacrolix/torrent/peer_protocol"
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)
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// Piece priority describes the importance of obtaining a particular piece.
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type piecePriority byte
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const (
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PiecePriorityNone piecePriority = iota // Not wanted.
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PiecePriorityNormal // Wanted.
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PiecePriorityReadahead // May be required soon.
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PiecePriorityNext // Succeeds a piece where a read occurred.
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PiecePriorityNow // A read occurred in this piece.
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)
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type piece struct {
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// The completed piece SHA1 hash, from the metainfo "pieces" field.
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Hash pieceSum
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// Chunks we don't have. The offset and length can be determined by the
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// request chunkSize in use.
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PendingChunkSpecs []bool
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Hashing bool
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QueuedForHash bool
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EverHashed bool
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Priority piecePriority
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PublicPieceState PieceState
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pendingWritesMutex sync.Mutex
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pendingWrites int
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noPendingWrites sync.Cond
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}
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func (p *piece) pendingChunk(cs chunkSpec, chunkSize pp.Integer) bool {
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if p.PendingChunkSpecs == nil {
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return false
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}
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return p.PendingChunkSpecs[chunkIndex(cs, chunkSize)]
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}
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func (p *piece) numPendingChunks() (ret int) {
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for _, pending := range p.PendingChunkSpecs {
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if pending {
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ret++
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}
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}
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return
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}
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func (p *piece) unpendChunkIndex(i int) {
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if p.PendingChunkSpecs == nil {
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return
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}
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p.PendingChunkSpecs[i] = false
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}
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func chunkIndexSpec(index int, pieceLength, chunkSize pp.Integer) chunkSpec {
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ret := chunkSpec{pp.Integer(index) * chunkSize, chunkSize}
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if ret.Begin+ret.Length > pieceLength {
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ret.Length = pieceLength - ret.Begin
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}
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return ret
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}
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func (p *piece) shuffledPendingChunkSpecs(pieceLength, chunkSize pp.Integer) (css []chunkSpec) {
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if p.numPendingChunks() == 0 {
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return
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}
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css = make([]chunkSpec, 0, p.numPendingChunks())
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for i, pending := range p.PendingChunkSpecs {
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if pending {
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css = append(css, chunkIndexSpec(i, pieceLength, chunkSize))
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}
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}
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if len(css) <= 1 {
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return
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}
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for i := range css {
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j := rand.Intn(i + 1)
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css[i], css[j] = css[j], css[i]
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}
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return
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}
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