Add write incomplete/consecutive chunks interfaces

storage/interface.go

@@ -38,6 +38,10 @@ type PieceImpl interface {
 	Completion() Completion
 }
 
+type IncompletePieceToWriter interface {
+	WriteIncompleteTo(w io.Writer) error
+}
+
 type Completion struct {
 	Complete bool
 	Ok       bool

storage/piece_resource.go

@@ -13,10 +13,10 @@ import (
 )
 
 type piecePerResource struct {
-	p resource.Provider
+	p PieceProvider
 }
 
-func NewResourcePieces(p resource.Provider) ClientImpl {
+func NewResourcePieces(p PieceProvider) ClientImpl {
 	return &piecePerResource{
 		p: p,
 	}
@@ -41,11 +41,29 @@ func (s piecePerResource) Piece(p metainfo.Piece) PieceImpl {
 	}
 }
 
+type PieceProvider interface {
+	resource.Provider
+}
+
+type ConsecutiveChunkWriter interface {
+	WriteConsecutiveChunks(prefix string, _ io.Writer) error
+}
+
 type piecePerResourcePiece struct {
 	mp metainfo.Piece
 	rp resource.Provider
 }
 
+var _ IncompletePieceToWriter = piecePerResourcePiece{}
+
+func (s piecePerResourcePiece) WriteIncompleteTo(w io.Writer) error {
+	if ccw, ok := s.rp.(ConsecutiveChunkWriter); ok {
+		return ccw.WriteConsecutiveChunks(s.incompleteDirPath()+"/", w)
+	}
+	_, err := io.Copy(w, io.NewSectionReader(s.getChunks(), 0, s.mp.Length()))
+	return err
+}
+
 func (s piecePerResourcePiece) Completion() Completion {
 	fi, err := s.completed().Stat()
 	return Completion{
@@ -73,6 +91,7 @@ func (s piecePerResourcePiece) ReadAt(b []byte, off int64) (int, error) {
 	if s.Completion().Complete {
 		return s.completed().ReadAt(b, off)
 	}
+	//panic("unexpected ReadAt of incomplete piece")
 	return s.getChunks().ReadAt(b, off)
 }
 

storage/sqlite/sqlite-storage.go

@@ -71,10 +71,17 @@ with recursive excess(
 	where usage_with >= (select value from setting where name='capacity')
 ) select * from excess;
 
-CREATE TRIGGER if not exists trim_blobs_to_capacity_after_update after update on blob begin 
+create trigger if not exists trim_blobs_to_capacity_after_update
+after update of data on blob
+when length(new.data)>length(old.data) and (select sum(length(cast(data as blob))) from blob)>(select value from setting where name='capacity')
+begin 
 	delete from blob where rowid in (select blob_rowid from deletable_blob);
 end;
-CREATE TRIGGER if not exists trim_blobs_to_capacity_after_insert after insert on blob begin
+
+create trigger if not exists trim_blobs_to_capacity_after_insert 
+after insert on blob
+when (select sum(length(cast(data as blob))) from blob)>(select value from setting where name='capacity')
+begin
 	delete from blob where rowid in (select blob_rowid from deletable_blob);
 end;
 `)
@@ -188,7 +195,13 @@ func NewProvider(pool ConnPool, opts ProviderOpts) (_ *provider, err error) {
 	}
 	writes := make(chan writeRequest)
 	prov := &provider{pool: pool, writes: writes, opts: opts}
-	go prov.writer(writes)
+	runtime.SetFinalizer(prov, func(p *provider) {
+		// This is done in a finalizer, as it's easier than trying to synchronize on whether the
+		// channel has been closed. It also means that the provider writer can pass back errors from
+		// a closed ConnPool.
+		close(p.writes)
+	})
+	go providerWriter(writes, prov.pool)
 	return prov, nil
 }
 
@@ -227,8 +240,33 @@ type provider struct {
 	opts   ProviderOpts
 }
 
+var _ storage.ConsecutiveChunkWriter = (*provider)(nil)
+
+func (p *provider) WriteConsecutiveChunks(prefix string, w io.Writer) (err error) {
+	p.withConn(func(conn conn) {
+		err = io.EOF
+		err = sqlitex.Exec(conn, `
+				select
+					cast(data as blob),
+					cast(substr(name, ?+1) as integer) as offset
+				from blob
+				where name like ?||'%'
+				order by offset`,
+			func(stmt *sqlite.Stmt) error {
+				r := stmt.ColumnReader(0)
+				//offset := stmt.ColumnInt64(1)
+				//log.Printf("got %v bytes at offset %v", r.Len(), offset)
+				_, err := io.Copy(w, r)
+				return err
+			},
+			len(prefix),
+			prefix,
+		)
+	}, false)
+	return
+}
+
 func (me *provider) Close() error {
-	close(me.writes)
 	return me.pool.Close()
 }
 
@@ -237,7 +275,9 @@ type writeRequest struct {
 	done  chan<- struct{}
 }
 
-func (me *provider) writer(writes <-chan writeRequest) {
+// Intentionally avoids holding a reference to *provider to allow it to use a finalizer, and to have
+// stronger typing on the writes channel.
+func providerWriter(writes <-chan writeRequest, pool ConnPool) {
 	for {
 		first, ok := <-writes
 		if !ok {
@@ -258,8 +298,8 @@ func (me *provider) writer(writes <-chan writeRequest) {
 		}
 		var cantFail error
 		func() {
-			conn := me.pool.Get(context.TODO())
-			defer me.pool.Put(conn)
+			conn := pool.Get(context.TODO())
+			defer pool.Put(conn)
 			defer sqlitex.Save(conn)(&cantFail)
 			for _, wr := range buf {
 				wr.query(conn)
@@ -271,7 +311,7 @@ func (me *provider) writer(writes <-chan writeRequest) {
 		for _, wr := range buf {
 			close(wr.done)
 		}
-		log.Printf("batched %v write queries", len(buf))
+		//log.Printf("batched %v write queries", len(buf))
 	}
 }
 
@@ -284,21 +324,25 @@ type instance struct {
 	p        *provider
 }
 
-func (i instance) withConn(with func(conn conn), write bool) {
-	if write && i.p.opts.BatchWrites {
+func (p *provider) withConn(with func(conn conn), write bool) {
+	if write && p.opts.BatchWrites {
 		done := make(chan struct{})
-		i.p.writes <- writeRequest{
+		p.writes <- writeRequest{
 			query: with,
 			done:  done,
 		}
 		<-done
 	} else {
-		conn := i.p.pool.Get(context.TODO())
-		defer i.p.pool.Put(conn)
+		conn := p.pool.Get(context.TODO())
+		defer p.pool.Put(conn)
 		with(conn)
 	}
 }
 
+func (i instance) withConn(with func(conn conn), write bool) {
+	i.p.withConn(with, write)
+}
+
 func (i instance) getConn() *sqlite.Conn {
 	return i.p.pool.Get(context.TODO())
 }

storage/wrappers.go

@@ -38,6 +38,16 @@ type Piece struct {
 	mip metainfo.Piece
 }
 
+func (p Piece) WriteIncompleteTo(w io.Writer) error {
+	if i, ok := p.PieceImpl.(IncompletePieceToWriter); ok {
+		return i.WriteIncompleteTo(w)
+	}
+	n := p.mip.Length()
+	r := io.NewSectionReader(p, 0, n)
+	_, err := io.CopyN(w, r, n)
+	return err
+}
+
 func (p Piece) WriteAt(b []byte, off int64) (n int, err error) {
 	// Callers should not be writing to completed pieces, but it's too
 	// expensive to be checking this on every single write using uncached

torrent.go

@@ -787,27 +787,18 @@ func (t *Torrent) pieceLength(piece pieceIndex) pp.Integer {
 	return pp.Integer(t.info.PieceLength)
 }
 
-func (t *Torrent) hashPiece(piece pieceIndex) (ret metainfo.Hash, copyErr error) {
+func (t *Torrent) hashPiece(piece pieceIndex) (ret metainfo.Hash, err error) {
 	hash := pieceHash.New()
 	p := t.piece(piece)
 	p.waitNoPendingWrites()
-	ip := t.info.Piece(int(piece))
-	pl := ip.Length()
-	pieceReader := io.NewSectionReader(t.pieces[piece].Storage(), 0, pl)
-	var hashSource io.Reader
-	doCopy := func() {
-		// Return no error iff pl bytes are copied.
-		_, copyErr = io.CopyN(hash, hashSource, pl)
-	}
+	storagePiece := t.pieces[piece].Storage()
 	const logPieceContents = false
 	if logPieceContents {
 		var examineBuf bytes.Buffer
-		hashSource = io.TeeReader(pieceReader, &examineBuf)
-		doCopy()
-		log.Printf("hashed %q with copy err %v", examineBuf.Bytes(), copyErr)
+		err = storagePiece.WriteIncompleteTo(io.MultiWriter(hash, &examineBuf))
+		log.Printf("hashed %q with copy err %v", examineBuf.Bytes(), err)
 	} else {
-		hashSource = pieceReader
-		doCopy()
+		err = storagePiece.WriteIncompleteTo(hash)
 	}
 	missinggo.CopyExact(&ret, hash.Sum(nil))
 	return