GasDataLib

Git Source

Library for encoding and decoding GasData and ChainGas structs.

GasData

GasData is a struct to store the "basic information about gas prices", that could be later used to approximate the cost of a message execution, and thus derive the minimal tip values for sending a message to the chain.

• GasData is supposed to be cached by GasOracle contract, allowing to store the approximates instead of the exact values, and thus save on storage costs.
• For instance, if GasOracle only updates the values on +- 10% change, having an 0.4% error on the approximates would be acceptable. GasData is supposed to be included in the Origin's state, which are synced across chains using Agent-signed snapshots and attestations.

GasData stack layout (from highest bits to lowest)

See Number.sol for more details on Number type and BWAD (binary WAD) math.

ChainGas stack layout (from highest bits to lowest)

State Variables

SHIFT_GAS_PRICE

Amount of bits to shift to gasPrice field

uint96 private constant SHIFT_GAS_PRICE = 10 * 8;

SHIFT_DATA_PRICE

Amount of bits to shift to dataPrice field

uint96 private constant SHIFT_DATA_PRICE = 8 * 8;

SHIFT_EXEC_BUFFER

Amount of bits to shift to execBuffer field

uint96 private constant SHIFT_EXEC_BUFFER = 6 * 8;

SHIFT_AMORT_ATT_COST

Amount of bits to shift to amortAttCost field

uint96 private constant SHIFT_AMORT_ATT_COST = 4 * 8;

SHIFT_ETHER_PRICE

Amount of bits to shift to etherPrice field

uint96 private constant SHIFT_ETHER_PRICE = 2 * 8;

SHIFT_GAS_DATA

Amount of bits to shift to gasData field

uint128 private constant SHIFT_GAS_DATA = 4 * 8;

Functions

encodeGasData

Returns an encoded GasData struct with the given fields.

function encodeGasData(
    Number gasPrice_,
    Number dataPrice_,
    Number execBuffer_,
    Number amortAttCost_,
    Number etherPrice_,
    Number markup_
) internal pure returns (GasData);

Parameters

wrapGasData

Wraps padded uint256 value into GasData struct.

function wrapGasData(uint256 paddedGasData) internal pure returns (GasData);

gasPrice

Returns the gas price, in Wei per gas unit.

function gasPrice(GasData data) internal pure returns (Number);

dataPrice

Returns the calldata price, in Wei per byte of content.

function dataPrice(GasData data) internal pure returns (Number);

execBuffer

Returns the tx fee safety buffer for message execution, in Wei.

function execBuffer(GasData data) internal pure returns (Number);

amortAttCost

Returns the amortized cost for attestation submission, in Wei.

function amortAttCost(GasData data) internal pure returns (Number);

etherPrice

Returns the ratio of Chain's Ether Price / Mainnet Ether Price, in BWAD math.

function etherPrice(GasData data) internal pure returns (Number);

markup

Returns the markup for the message execution, in BWAD math.

function markup(GasData data) internal pure returns (Number);

encodeChainGas

Returns an encoded ChainGas struct with the given fields.

function encodeChainGas(GasData gasData_, uint32 domain_) internal pure returns (ChainGas);

Parameters

wrapChainGas

Wraps padded uint256 value into ChainGas struct.

function wrapChainGas(uint256 paddedChainGas) internal pure returns (ChainGas);

gasData

Returns the chain's gas data.

function gasData(ChainGas data) internal pure returns (GasData);

domain

Returns the chain's domain.

function domain(ChainGas data) internal pure returns (uint32);

snapGasHash

Returns the hash for the list of ChainGas structs.

function snapGasHash(ChainGas[] memory snapGas) internal pure returns (bytes32 snapGasHash_);