car

type Block ¶

type Block struct {
	Length int
	Cid    cid.Cid
	Data   []byte
}

Block is a length-cid-data tuple. These make up most of CARv1.

See https://ipld.io/specs/transport/car/carv1/#data

func NewBlockFromCBOR(node datamodel.Node, contentType uint64) (Block, error)

func NewBlockFromRaw(data []byte, contentType uint64) Block

func (b Block) TotalLen() int

type OutStream ¶

type OutStream interface {
	WriteBlock(Block) error
}

type Writer ¶

type Writer struct {
	// contains filtered or unexported fields
}

Writer produces CARv1 files with size tracking.

The implementation is kinda memory-efficient. Needs up to IPLD block size plus peanuts of memory.

Rationale ¶

github.com/ipld/go-car/v2 is not helpful because it wants to traverse a complete IPLD link system. However we create an IPLD link system (Merkle-DAG) on the fly in a single pass as we read the chain. CARv1 is simple enough that we can roll a custom block writer, so no big deal.

func NewWriter(out io.Writer) (*Writer, error)

func (w *Writer) Write(data []byte) (n int, err error)

func (w *Writer) WriteBlock(b Block) (err error)

func (w *Writer) Written() int64