executor

README

Executor

The Executor is an agent responsible for executing messages on the Destination.sol contract. It verifies that the message has been accepted by verifying a merkle proof, as well as the message's optimistic period.

Components

The Executor operates with two main components:

Run

streamLogs is the data-getter for the Executor. It works by instantiating a gRPC connection to Scribe, and puts logs in a channel for the origin and destination contracts on each chain in the config. From here, it verifies the logs' order since the order of logs are very important for merkle tree construction.
Additionally, if the Executor unexpectedly stops in the middle of streaming logs, it will use the current database state to reconstruct the tree up to where the last log was, then continue to use gRPC.

receiveLogs is the data-processor for the Executor. It works by taking the logs streamed from streamLogs and parsing the logs into either a Message on the Origin.sol contract, or a Attestation on the Destination.sol contract. It then stores the data into the Executor's database and builds the tree accordingly.

Execute

Execute works in 3 parts.

1. Verify that the optimistic period for the message has passed. This is done by checking the timestamp that the attestation was accepted on the Destination, then checking the timestamp of the last block.
2. Verify that the message is in the merkle tree.
3. Call the Execute function on the Destination.sol contract.

Directory Structure

TODO: fill this out

Executor
├── config
├── db
│   ├── sql
├── types
├── config
└── consumer

Documentation

Overview

Package executor is the executor agent.

Index

• type Backend
• type Executor
  • func NewExecutor(ctx context.Context, config config.Config, executorDB db.ExecutorDB, ...) (*Executor, error)
  • func (e Executor) Execute(ctx context.Context, message types.Message) (bool, error)
  • func (e Executor) Run(ctx context.Context) error
  • func (e Executor) Stop(chainID uint32)

Types

type Backend

type Backend interface {
	// HeaderByNumber returns the block header with the given block number.
	HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error)
}

Backend is the backend for the executor.

type Executor

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

Executor is the executor agent.

func NewExecutor

func NewExecutor(ctx context.Context, config config.Config, executorDB db.ExecutorDB, scribeClient client.ScribeClient, clients map[uint32]Backend) (*Executor, error)

NewExecutor creates a new executor agent.

func (Executor) Execute

func (e Executor) Execute(ctx context.Context, message types.Message) (bool, error)

Execute calls execute on `destination.sol` on the destination chain, after verifying the message.

func (Executor) Run

func (e Executor) Run(ctx context.Context) error

Run starts the executor agent. It calls `Start` and `Listen`.

func (Executor) Stop

func (e Executor) Stop(chainID uint32)

Stop stops the executor agent.