Source code for eth_defi.gas

"""Gas price strategies.

`Web3.py no longer support gas price strategies post London hard work <https://web3py.readthedocs.io/en/stable/gas_price.html>`_.
"""
import enum
from dataclasses import dataclass
from typing import Optional

from web3 import Web3
from web3.gas_strategies.rpc import rpc_gas_price_strategy


[docs]class GasPriceMethod(enum.Enum): """What method we did use for setting the gas price.""" #: Legacy chains legacy = "legacy" #: Post London hard work london = "london"
[docs]@dataclass class GasPriceSuggestion: """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 """ #: How the gas price was determined method: GasPriceMethod #: Non London hard fork chains legacy_gas_price: Optional[int] = None #: 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 def __repr__(self): return f"<Gas pricing method:{self.method.name} base:{self.base_fee} priority:{self.max_priority_fee_per_gas} max:{self.max_fee_per_gas} legacy:{self.legacy_gas_price}>"
[docs]def estimate_gas_fees(web3: Web3) -> GasPriceSuggestion: """Get a good gas price for a transaction. TODO: This is non-optimal, first draft implementation. """ last_block = web3.eth.get_block("latest") base_fee = last_block.get("baseFeePerGas") if base_fee is not None: # London gas strategy # see https://github.com/ethereum/web3.py/blob/c70f7fbe1cfa98b1ce8597a08c99e05759a9667b/web3/_utils/transactions.py#L57 # see https://github.com/ethereum/web3.py/blob/36adb16c68f570c343d01ecc8d0096cbac814172/web3/middleware/gas_price_strategy.py#L57 base_fee = base_fee max_fee_per_gas = web3.eth.max_priority_fee + (2 * base_fee) max_priority_fee_per_gas = web3.eth.max_priority_fee return GasPriceSuggestion(method=GasPriceMethod.london, base_fee=base_fee, max_priority_fee_per_gas=max_priority_fee_per_gas, max_fee_per_gas=max_fee_per_gas) else: # Legacy gas strategy return GasPriceSuggestion(method=GasPriceMethod.legacy, legacy_gas_price=web3.eth.generate_gas_price())
[docs]def apply_gas(tx: dict, suggestion: GasPriceSuggestion): """Apply gas fees to a raw transaction dict. Example: .. code-block:: 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) tx_hash = web3.eth.send_raw_transaction(signed.rawTransaction) receipt = web3.eth.get_transaction_receipt(tx_hash) """ if suggestion.method == GasPriceMethod.london: tx["maxFeePerGas"] = suggestion.max_fee_per_gas tx["maxPriorityFeePerGas"] = suggestion.max_priority_fee_per_gas else: tx["gasPrice"] = suggestion.legacy_gas_price
[docs]def node_default_gas_price_strategy(web3: Web3, transaction_params: dict) -> int: """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: .. code-block:: 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 - https://web3py.readthedocs.io/en/stable/gas_price.html - https://www.blockchain-council.org/ethereum/eip-1559/ """ node_default_price = rpc_gas_price_strategy(web3) return node_default_price