package torrent import ( "sync" "github.com/anacrolix/missinggo/bitmap" "github.com/anacrolix/torrent/metainfo" pp "github.com/anacrolix/torrent/peer_protocol" "github.com/anacrolix/torrent/storage" ) // Piece priority describes the importance of obtaining a particular piece. type piecePriority byte func (pp *piecePriority) Raise(maybe piecePriority) { if maybe > *pp { *pp = maybe } } const ( PiecePriorityNone piecePriority = iota // Not wanted. PiecePriorityNormal // Wanted. PiecePriorityReadahead // May be required soon. PiecePriorityNext // Succeeds a piece where a read occurred. PiecePriorityNow // A Reader is reading in this piece. ) type piece struct { // The completed piece SHA1 hash, from the metainfo "pieces" field. Hash metainfo.Hash t *Torrent index int // Chunks we've written to since the last check. The chunk offset and // length can be determined by the request chunkSize in use. DirtyChunks bitmap.Bitmap Hashing bool QueuedForHash bool EverHashed bool PublicPieceState PieceState priority piecePriority pendingWritesMutex sync.Mutex pendingWrites int noPendingWrites sync.Cond } func (p *piece) Info() metainfo.Piece { return p.t.info.Piece(p.index) } func (p *piece) Storage() storage.Piece { return p.t.storage.Piece(p.Info()) } func (p *piece) pendingChunkIndex(chunkIndex int) bool { return !p.DirtyChunks.Contains(chunkIndex) } func (p *piece) pendingChunk(cs chunkSpec, chunkSize pp.Integer) bool { return p.pendingChunkIndex(chunkIndex(cs, chunkSize)) } func (p *piece) hasDirtyChunks() bool { return p.DirtyChunks.Len() != 0 } func (p *piece) numDirtyChunks() (ret int) { return p.DirtyChunks.Len() } func (p *piece) unpendChunkIndex(i int) { p.DirtyChunks.Add(i) } func (p *piece) pendChunkIndex(i int) { p.DirtyChunks.Remove(i) } func (p *piece) numChunks() int { return p.t.pieceNumChunks(p.index) } func (p *piece) undirtiedChunkIndices() (ret bitmap.Bitmap) { ret = p.DirtyChunks.Copy() ret.FlipRange(0, p.numChunks()) return } func (p *piece) incrementPendingWrites() { p.pendingWritesMutex.Lock() p.pendingWrites++ p.pendingWritesMutex.Unlock() } func (p *piece) decrementPendingWrites() { p.pendingWritesMutex.Lock() if p.pendingWrites == 0 { panic("assertion") } p.pendingWrites-- if p.pendingWrites == 0 { p.noPendingWrites.Broadcast() } p.pendingWritesMutex.Unlock() } func (p *piece) waitNoPendingWrites() { p.pendingWritesMutex.Lock() for p.pendingWrites != 0 { p.noPendingWrites.Wait() } p.pendingWritesMutex.Unlock() } func (p *piece) chunkIndexDirty(chunk int) bool { return p.DirtyChunks.Contains(chunk) } func (p *piece) chunkIndexSpec(chunk int) chunkSpec { return chunkIndexSpec(chunk, p.length(), p.chunkSize()) } func (p *piece) numDirtyBytes() (ret pp.Integer) { defer func() { if ret > p.length() { panic("too many dirty bytes") } }() numRegularDirtyChunks := p.numDirtyChunks() if p.chunkIndexDirty(p.numChunks() - 1) { numRegularDirtyChunks-- ret += p.chunkIndexSpec(p.lastChunkIndex()).Length } ret += pp.Integer(numRegularDirtyChunks) * p.chunkSize() return } func (p *piece) length() pp.Integer { return p.t.pieceLength(p.index) } func (p *piece) chunkSize() pp.Integer { return p.t.chunkSize } func (p *piece) lastChunkIndex() int { return p.numChunks() - 1 } func (p *piece) bytesLeft() (ret pp.Integer) { if p.t.pieceComplete(p.index) { return 0 } return p.length() - p.numDirtyBytes() }