car

README

go-car (go!)

go-car is a simple way of packing a merkledag into a single file

Table of Contents

• Install
• Contribute
• License

Contribute

PRs are welcome!

Small note: If editing the Readme, please conform to the standard-readme specification.

License

Apache-2.0/MIT © Protocol Labs

Documentation

Index

• func DefaultWalkFunc(nd format.Node) ([]*format.Link, error)
• func HeaderSize(h *CarHeader) (uint64, error)
• func WriteCar(ctx context.Context, ds format.NodeGetter, roots []cid.Cid, w io.Writer) error
• func WriteCarWithWalker(ctx context.Context, ds format.NodeGetter, roots []cid.Cid, w io.Writer, ...) error
• func WriteHeader(h *CarHeader, w io.Writer) error
• type Block
• type CarHeader
  • func LoadCar(s Store, r io.Reader) (*CarHeader, error)
  • func ReadHeader(br *bufio.Reader) (*CarHeader, error)
• type CarReader
  • func NewCarReader(r io.Reader) (*CarReader, error)
  • func (cr *CarReader) Next() (blocks.Block, error)
• type Dag
• type OnCarHeaderFunc
• type OnNewCarBlockFunc
• type ReadStore
• type SelectiveCar
  • func NewSelectiveCar(ctx context.Context, store ReadStore, dags []Dag) SelectiveCar
  • func (sc SelectiveCar) Prepare(userOnNewCarBlocks ...OnNewCarBlockFunc) (SelectiveCarPrepared, error)
  • func (sc SelectiveCar) Write(w io.Writer, userOnNewCarBlocks ...OnNewCarBlockFunc) error
• type SelectiveCarPrepared
  • func (sc SelectiveCarPrepared) Cids() []cid.Cid
  • func (sc SelectiveCarPrepared) Dump(w io.Writer) error
  • func (sc SelectiveCarPrepared) Header() CarHeader
  • func (sc SelectiveCarPrepared) Size() uint64
• type Store
• type WalkFunc

Functions

func DefaultWalkFunc

func DefaultWalkFunc(nd format.Node) ([]*format.Link, error)

func HeaderSize

func HeaderSize(h *CarHeader) (uint64, error)

func WriteCar

func WriteCar(ctx context.Context, ds format.NodeGetter, roots []cid.Cid, w io.Writer) error

func WriteCarWithWalker

func WriteCarWithWalker(ctx context.Context, ds format.NodeGetter, roots []cid.Cid, w io.Writer, walk WalkFunc) error

func WriteHeader

func WriteHeader(h *CarHeader, w io.Writer) error

Types

type Block

type Block struct {
	BlockCID cid.Cid
	Data     []byte
	Offset   uint64
	Size     uint64
}

Block is all information and metadata about a block that is part of a car file

type CarHeader

type CarHeader struct {
	Roots   []cid.Cid
	Version uint64
}

func LoadCar

func LoadCar(s Store, r io.Reader) (*CarHeader, error)

func ReadHeader

func ReadHeader(br *bufio.Reader) (*CarHeader, error)

type CarReader

type CarReader struct {
	Header *CarHeader
	// contains filtered or unexported fields
}

func NewCarReader

func NewCarReader(r io.Reader) (*CarReader, error)

func (*CarReader) Next

func (cr *CarReader) Next() (blocks.Block, error)

type Dag

type Dag struct {
	Root     cid.Cid
	Selector ipld.Node
}

Dag is a root/selector combo to put into a car

type OnCarHeaderFunc

type OnCarHeaderFunc func(CarHeader) error

OnCarHeaderFunc is called during traversal when the header is created

type OnNewCarBlockFunc

type OnNewCarBlockFunc func(Block) error

OnNewCarBlockFunc is called during traveral when a new unique block is encountered

type ReadStore

type ReadStore interface {
	Get(cid.Cid) (blocks.Block, error)
}

type SelectiveCar

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

SelectiveCar is a car file based on root + selector combos instead of just a single root and complete dag walk

func NewSelectiveCar

func NewSelectiveCar(ctx context.Context, store ReadStore, dags []Dag) SelectiveCar

NewSelectiveCar creates a new SelectiveCar for the given car file based a block store and set of root+selector pairs

func (SelectiveCar) Prepare

func (sc SelectiveCar) Prepare(userOnNewCarBlocks ...OnNewCarBlockFunc) (SelectiveCarPrepared, error)

Prepare traverse a car file and collects data on what is about to be written, but does not actually write the file

func (SelectiveCar) Write

func (sc SelectiveCar) Write(w io.Writer, userOnNewCarBlocks ...OnNewCarBlockFunc) error

type SelectiveCarPrepared

type SelectiveCarPrepared struct {
	SelectiveCar
	// contains filtered or unexported fields
}

SelectiveCarPrepared is a SelectiveCar that has already been traversed, such that it can be written quicker with Dump. It also contains metadata already collection about the Car file like size and number of blocks that go into it

func (SelectiveCarPrepared) Cids

func (sc SelectiveCarPrepared) Cids() []cid.Cid

Cids returns the list of unique block cids that will be written to the car file

func (SelectiveCarPrepared) Dump

func (sc SelectiveCarPrepared) Dump(w io.Writer) error

Dump writes the car file as quickly as possible based on information already collected

func (SelectiveCarPrepared) Header

func (sc SelectiveCarPrepared) Header() CarHeader

Header returns the header for the car file that will be written

func (SelectiveCarPrepared) Size

func (sc SelectiveCarPrepared) Size() uint64

Size returns the total size in bytes of the car file that will be written

type Store

type Store interface {
	Put(blocks.Block) error
}

type WalkFunc

type WalkFunc func(format.Node) ([]*format.Link, error)