web3mc - multicall library for web3py

Based on makerdao's multicall contractand brownie implementation with batching and asynchronous support. Works directly with web3py contract functions and parameters

Installation

pip install web3mc

Quickstart

Basic usage

(this is default value if empty - set by web3py)

export WEB3_HTTP_PROVIDER_URI=http://localhost:8545

from web3.auto import w3
from web3mc.auto import multicall

abi = [{"constant": True, "inputs": [], "name": "name", "outputs": [{"name": "", "type": "string"}], "payable": False,
        "stateMutability": "view", "type": "function", },
       {"constant": True, "inputs": [], "name": "symbol", "outputs": [{"name": "", "type": "string"}], "payable": False,
        "stateMutability": "view", "type": "function", },
       {"constant": True, "inputs": [{"name": "", "type": "address"}], "name": "balanceOf",
        "outputs": [{"name": "", "type": "uint256"}], "payable": False, "stateMutability": "view", "type": "function"}]

weth_erc20 = w3.eth.contract("0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2", abi=abi)

calls = [weth_erc20.functions.name(), weth_erc20.functions.symbol(), weth_erc20.functions.balanceOf("vitalik.eth")]

result = multicall.aggregate(calls)
print(result)  # ['Wrapped Ether', 'WETH', 26992040046283229929]

Call multiple contracts with same abi (implementation)

...
weth_erc20 = w3.eth.contract("0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2", abi=abi)

calls = [weth_erc20.functions.name(),weth_erc20.functions.symbol(),weth_erc20.functions.balanceOf("vitalik.eth")] * 2
# WBTC, USDC
addresses = ["0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2"] * 3 + ["0x2260FAC5E5542a773Aa44fBCfeDf7C193bc2C599"] * 3

result = multicall.aggregate(calls, use_try=True, addresses=addresses)  # tryAggregate()
print(result)  # ['Wrapped BTC', 'WBTC', 0, 'USD Coin', 'USDC', 396267093705]

Parameters

Environment variable

• WEB3_HTTP_PROVIDER_URI - can be overwritten directly (from web3py)

Custom parameters

from web3mc import Multicall

multicall = Multicall(
    provider_url="<your custom provider url>",  # Overrides env parameter
    batch=100,  # can lead to overflow
    max_retries=3,  # retries without use_try (aggregate function in contract)
    gas_limit=50_000_000,  # gas limit for calls
    _semaphore=1000,  # max concurrent coroutines, change carefully!
)

Testing

Install dependencies, make sure you set WEB3_HTTP_PROVIDER_URI environment variable

pytest tests