cchain

Documentation

Overview

Package cchain defines the API to interact with the omni consensus chain.

Index

• type Provider
• type ProviderCallback
• type Validator
  • func (v Validator) Verify() error

Types

type Provider

type Provider interface {
	// Subscribe registers a callback function that will be called with all approved
	// attestations (as they become available per versioned cross-chain block) on the consensus chain from
	// the provided source chain ID, confLevel and XBlockOffset (inclusive).
	//
	// Worker name is only used for metrics.
	Subscribe(ctx context.Context, sourceChainID uint64, conf xchain.ConfLevel, xBlockOffset uint64,
		workerName string, callback ProviderCallback)

	// AttestationsFrom returns the subsequent approved attestations for the provided source chain
	// and XBlockOffset (inclusive). It will return max 100 attestations per call.
	AttestationsFrom(ctx context.Context, sourceChainID uint64, conf xchain.ConfLevel, xBlockOffset uint64) ([]xchain.Attestation, error)

	// LatestAttestation returns the latest approved attestation for the provided source chain or false
	// if none exist.
	LatestAttestation(ctx context.Context, sourceChainID uint64, conf xchain.ConfLevel) (xchain.Attestation, bool, error)

	// WindowCompare returns whether the given attestation block header is behind (-1), or in (0), or ahead (1)
	// of the current vote window. The vote window is a configured number of blocks around the latest approved
	// attestation for the provided chain.
	WindowCompare(ctx context.Context, sourceChainID uint64, conf xchain.ConfLevel, xBlockOffset uint64) (int, error)

	// ValidatorSet returns the validators for the given validator set ID or false if none exist or an error.
	// Note the genesis validator set has ID 1.
	ValidatorSet(ctx context.Context, valSetID uint64) ([]Validator, bool, error)

	// XBlock returns the validator sync xblock for the given height/offset (or latest) or false if none exist or an error.
	XBlock(ctx context.Context, heightAndOffset uint64, latest bool) (xchain.Block, bool, error)
}

Provider abstracts connecting to the omni consensus chain and streaming approved attestations for each source chain block from a specific height.

It provides exactly once-delivery guarantees for the callback function. It will exponentially backoff and retry forever while the callback function returns an error.

type ProviderCallback

type ProviderCallback func(ctx context.Context, approved xchain.Attestation) error

ProviderCallback is the callback function signature that will be called with each approved attestation per source chain block in strictly sequential order.

type Validator

type Validator struct {
	Address common.Address
	Power   int64
}

Validator is a consensus chain validator in a validator set.

func (Validator) Verify

func (v Validator) Verify() error

Verify returns an error if the validator is invalid.