gas

Documentation for eth_defi.gas Python module.

Gas price strategies.

Web3.py no longer support gas price strategies post London hard work.

Module Attributes

GAS_PRICE_BUFFER_MULTIPLIER

Safety buffer multiplier applied to maxFeePerGas in EIP-1559 transactions.

Functions

`apply_gas`(tx, suggestion)	Apply gas fees to a raw transaction dict.
`estimate_gas_fees`(web3[, method, ...])	Get a good gas price for a transaction.
`estimate_gas_price`(web3[, method, ...])	Get a good gas price for a transaction.
`node_default_gas_price_strategy`(web3, ...)	Gas price strategy for blockchains not supporting dynamic gas fees.

Classes

`GasPriceMethod`	What method we did use for setting the gas price.
`GasPriceSuggestion`	Gas price details.

GAS_PRICE_BUFFER_MULTIPLIER = 1.12

Safety buffer multiplier applied to maxFeePerGas in EIP-1559 transactions.

On L2 chains like Arbitrum, the base fee can fluctuate between the time gas is estimated and the time the signed transaction reaches the sequencer. Without a buffer, this race condition causes rejections with:

max fee per gas less than block base fee

A 12% buffer absorbs typical L2 base fee volatility while keeping overpayment minimal (unused gas fee is refunded by the protocol).

For more information see:

class GasPriceMethod

Bases: enum.Enum

What method we did use for setting the gas price.

legacy = 'legacy': Legacy chains

london = 'london': Post London hard work

class GasPriceSuggestion

Bases: object

Gas price details.

Capture the necessary information for the gas price to used during the transaction building.

EIP-1559 London hard fork chains (Ethereumm mainnet)
Legacy EVM: Polygon, BNB Chain

method: eth_defi.gas.GasPriceMethod: How the gas price was determined

legacy_gas_price: Optional[int] = None: Non London hard fork chains

base_fee: Optional[int] = None: London hard fork chains

max_priority_fee_per_gas: Optional[int] = None: London hard fork chains

max_fee_per_gas: Optional[int] = None: London hard fork chains

get_tx_gas_params()

Get gas params as they are applied to ContractFunction.build_transaction()

Return type: dict

pformat()

Pretty format for logging.

Return type: str

__init__(method, legacy_gas_price=None, base_fee=None, max_priority_fee_per_gas=None, max_fee_per_gas=None)

Parameters

method (eth_defi.gas.GasPriceMethod) –
legacy_gas_price (Optional[int]) –
base_fee (Optional[int]) –
max_priority_fee_per_gas (Optional[int]) –
max_fee_per_gas (Optional[int]) –

Return type

None

estimate_gas_price(web3, method=None, gas_price_buffer_multiplier=1.12)

Get a good gas price for a transaction.

Applies a safety buffer to maxFeePerGas to absorb base fee fluctuations between estimation and transaction submission. See GAS_PRICE_BUFFER_MULTIPLIER for details.

Parameters

web3 (web3.main.Web3) – Web3 instance connected to a node.
method – Force a specific gas pricing method. If None, auto-detect based on whether the chain supports EIP-1559.
gas_price_buffer_multiplier (float) – Multiplier applied to maxFeePerGas to absorb base fee fluctuations. Defaults to GAS_PRICE_BUFFER_MULTIPLIER (1.12 = 12% buffer). Set to 1.0 to disable the buffer.

Return type

eth_defi.gas.GasPriceSuggestion

estimate_gas_fees(web3, method=None, gas_price_buffer_multiplier=1.12)

Get a good gas price for a transaction.

Applies a safety buffer to maxFeePerGas to absorb base fee fluctuations between estimation and transaction submission. See GAS_PRICE_BUFFER_MULTIPLIER for details.

Parameters

web3 (web3.main.Web3) – Web3 instance connected to a node.
method – Force a specific gas pricing method. If None, auto-detect based on whether the chain supports EIP-1559.
gas_price_buffer_multiplier (float) – Multiplier applied to maxFeePerGas to absorb base fee fluctuations. Defaults to GAS_PRICE_BUFFER_MULTIPLIER (1.12 = 12% buffer). Set to 1.0 to disable the buffer.

Return type

eth_defi.gas.GasPriceSuggestion

apply_gas(tx, suggestion)

Apply gas fees to a raw transaction dict.

Example:

from web3 import Web3
from web3._utils.transactions import fill_nonce
from eth_account.signers.local import LocalAccount

web3: Web3
hot_wallet: LocalAccount

# Move 10 tokens from deployer to user1
tx = token.functions.transfer(hot_wallet.address, 10 * 10**18).build_transaction({
    "from": hot_wallet.address,
    'chainId': web3.eth.chain_id,
    "gas": 150_000,  # 150k gas should be more than enough for ERC20.transfer()
})

tx = fill_nonce(web3, tx)
gas_fees = estimate_gas_fees(web3)
apply_gas(tx, gas_fees)

signed = hot_wallet.sign_transaction(tx)
raw_bytes = get_tx_broadcast_data(signed)
tx_hash = web3.eth.send_raw_transaction(raw_bytes)
receipt = web3.eth.get_transaction_receipt(tx_hash)

Returns

Mutated dict

Parameters

tx (dict) –
suggestion (eth_defi.gas.GasPriceSuggestion) –

Return type

dict

node_default_gas_price_strategy(web3, transaction_params)

Gas price strategy for blockchains not supporting dynamic gas fees.

This gas price strategy will query the JSON-RPC for the suggested flat fee. It works on chains that do not support EIP-1559 London hardfork style base fee + max fee dynamic pricing.

These include

BNB Chain

Example:

from eth_defi.gas import node_default_gas_price_strategy
web3.eth.set_gas_price_strategy(node_default_gas_price_strategy)

For more information see

Parameters

web3 (web3.main.Web3) –
transaction_params (dict) –

Return type

int