feeder

Documentation

Overview

Package feeder provides support for building witness feeder implementations.

Index

• Variables
• func FeedOnce(ctx context.Context, sizeHint uint64, opts FeedOpts) (uint64, error)
• type FeedOpts
• type UpdateFn

Variables

var ErrNoSignaturesAdded = errors.New("no additional signatures added")

ErrNoSignaturesAdded is returned when the witness has already signed the presented checkpoint.

Functions

func FeedOnce

func FeedOnce(ctx context.Context, sizeHint uint64, opts FeedOpts) (uint64, error)

FeedOnce completes one feeding operation for the log and witness in the provided configuration. The provided sizeHint is size of the log that the caller believes is current on the target witness.

Returns a new hint on what the current size of the log on the target witness.

Types

type FeedOpts

type FeedOpts struct {
	// LogID is the ID for the log whose checkpoint is being fed.
	//
	// TODO(al/mhutchinson): should this be an impl detail of Witness
	// rather than present here just to be passed back in to Witness calls?
	LogID string

	// FetchCheckpoint should return a recent checkpoint from the source log.
	FetchCheckpoint func(ctx context.Context) ([]byte, error)

	// FetchProof should return a consistency proof from the source log.
	//
	// Note that if the witness knows the log but has no previous checkpoint stored, this
	// function will be called with a default `from` value - this allows compact-range
	// type proofs to be supported.  Implementations for non-compact-range type proofs
	// should return an empty proof and no error.
	FetchProof func(ctx context.Context, from uint64, to log.Checkpoint) ([][]byte, error)

	// LogSigVerifier a verifier for log checkpoint signatures.
	LogSigVerifier note.Verifier
	// LogOrigin is the expected first line of checkpoints from the source log.
	LogOrigin string

	// Update knows how to update a witness
	Update UpdateFn
}

FeedOpts holds parameters when calling the Feed function.

type UpdateFn

type UpdateFn func(ctx context.Context, oldSize uint64, newCP []byte, proof [][]byte) ([]byte, uint64, error)

UpdateFn is the signature of a function which knows how to update a witness.