Multicall を使って効率的に contract を呼び出す

// 1. Multicall Contract と連携するための Contract Instance を生成
const multicall = new ethers.Contract(
  "address", // multicall contract の address
  ABI, // Application Binary Interface
  ethers.provider // 実際の ethereum network と通信するための Provider
)
// 2. Multicall#aggregate を呼び出すための引数を作成
const inputs = [ ... ]
// 3. Multicall#aggregate を呼び出し、実行結果を受け取る
const result = await multicall.callStatic.aggregate(inputs);
// 4. 3 で取得したデータから指定した function の実行結果を出力
console.log(result[1][N])

const ERC20_ABI = jsonfile.readFileSync("./abis/ERC20.json")

const TOKENS = {
  USDC: {
    address: "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    decimals: 6
  },
  USDT: {
    address: "0xdac17f958d2ee523a2206206994597c13d831ec7",
    decimals: 6
  },
  DAI: {
    address: "0x6b175474e89094c44da98b954eedeac495271d0f",
    decimals: 18
  }
}
const USER = "0xbebc44782c7db0a1a60cb6fe97d0b483032ff1c7" // Curve.fi: DAI/USDC/USDT Pool

task("call:direct", "call:direct").setAction(async ({}, hre: HardhatRuntimeEnvironment) => {
  const { ethers } = hre
  const usdc = new ethers.Contract(
    TOKENS.USDC.address,
    new ethers.utils.Interface(ERC20_ABI),
    ethers.provider
  )
  const usdt = new ethers.Contract(
    TOKENS.USDT.address,
    new ethers.utils.Interface(ERC20_ABI),
    ethers.provider
  )
  const dai = new ethers.Contract(
    TOKENS.DAI.address,
    new ethers.utils.Interface(ERC20_ABI),
    ethers.provider
  )
  const results = await Promise.all([
    usdc.balanceOf(USER), // 1回
    usdt.balanceOf(USER), // 2回
    dai.balanceOf(USER), // 3回
  ])
  console.log(...)
})

import keccak256 from "keccak256"
import { task } from "hardhat/config"
import { HardhatRuntimeEnvironment } from "hardhat/types"
import jsonfile from "jsonfile"
import { BigNumber } from "ethers"
import { ERC20__factory, Multicall__factory } from "../../libs/contracts/__generated__"

const multicall_abi = jsonfile.readFileSync("./abis/Multicall.json") // Multicall の Contract のABI (etherscan などで取得可能です)
const MULTICALL_ADDRESS = "0xeefba1e63905ef1d7acba5a8513c70307c1ce441" // Multicall Contract の address

// 今回利用する token (USDC/USDT/DAI) の address, decimals
const TOKENS = {
  USDC: {
    address: "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48",
    decimals: 6
  },
  USDT: {
    address: "0xdac17f958d2ee523a2206206994597c13d831ec7",
    decimals: 6
  },
  DAI: {
    address: "0x6b175474e89094c44da98b954eedeac495271d0f",
    decimals: 18
  }
}

// Curve.fi: DAI/USDC/USDT Pool の address
const ADDRESS = "0xbebc44782c7db0a1a60cb6fe97d0b483032ff1c7"

/**
 * use multicall by only ethersjs
 * - support only mainnet
 */
task("multicall", "multicall").setAction(async ({}, hre: HardhatRuntimeEnvironment) => {
  const { ethers } = hre

  const multicall = new ethers.Contract(
    MULTICALL_ADDRESS,
    new ethers.utils.Interface(multicall_abi),
    ethers.provider
  )

  // Multicall#aggregate に渡す callData の作成
  const selector = keccak256("balanceOf(address)").toString('hex').substr(0, 8) // #balanceOf(address) の method id 作成
  const param = ADDRESS.substring(2).padStart(64, "0") // 呼び出す function の引数生成: input を zero padding し 32byte のデータに加工する

  const inputs = [
    {
      target: TOKENS.USDC.address, // USDC
      callData: `0x${selector}${param}`
    },
    {
      target: TOKENS.USDT.address, // USDT
      callData: `0x${selector}${param}`
    },
    {
      target: TOKENS.DAI.address, // DAI
      callData: `0x${selector}${param}`
    },
  ]
  const result = await multicall.callStatic.aggregate(inputs);
  for (const [index, key] of Object.keys(TOKENS).entries()) {
    const balanceOf = ethers.utils.formatUnits( // 表示向けに、token の decimals 分 shift させる
      BigNumber.from(result[1][index]), // Multicall#aggregate 実行結果から、arguments order を考慮して、該当するデータを取得する
      TOKENS[key as keyof typeof TOKENS].decimals
    )
    console.log(`${key} ... ${balanceOf}`)
  }
})

$ npx hardhat multicall --network mainnet
USDC ... 1085091186.161086
USDT ... 822667786.055421
DAI ... 1252359115.58683885475104325