@nomiclabs/buidler/src/internal/core/providers/gas-providers.ts

Buidler is an extensible developer tool that helps smart contract developers increase productivity by reliably bringing together the tools they want.

import { IEthereumProvider } from "../../../types";

import { numberToRpcQuantity, rpcQuantityToNumber } from "./provider-utils";
import { wrapSend } from "./wrapper";

const DEFAULT_GAS_MULTIPLIER = 1;
export const GANACHE_GAS_MULTIPLIER = 5;

export function createFixedGasProvider(
  provider: IEthereumProvider,
  gasLimit: number
) {
  const rpcGasLimit = numberToRpcQuantity(gasLimit);

  return wrapSend(provider, async (method, params) => {
    if (method === "eth_sendTransaction") {
      const tx = params[0];
      if (tx !== undefined && tx.gas === undefined) {
        tx.gas = rpcGasLimit;
      }
    }

    return provider.send(method, params);
  });
}

export function createFixedGasPriceProvider(
  provider: IEthereumProvider,
  gasPrice: number
) {
  const rpcGasPrice = numberToRpcQuantity(gasPrice);

  return wrapSend(provider, async (method, params) => {
    if (method === "eth_sendTransaction") {
      const tx = params[0];
      if (tx !== undefined && tx.gasPrice === undefined) {
        tx.gasPrice = rpcGasPrice;
      }
    }

    return provider.send(method, params);
  });
}

export function createAutomaticGasProvider(
  provider: IEthereumProvider,
  gasMultiplier: number = DEFAULT_GAS_MULTIPLIER
) {
  const getMultipliedGasEstimation = createMultipliedGasEstimationGetter();

  return wrapSend(provider, async (method, params) => {
    if (method === "eth_sendTransaction") {
      const tx = params[0];
      if (tx !== undefined && tx.gas === undefined) {
        tx.gas = await getMultipliedGasEstimation(
          provider,
          params,
          gasMultiplier
        );
      }
    }

    return provider.send(method, params);
  });
}

export function createAutomaticGasPriceProvider(provider: IEthereumProvider) {
  let gasPrice: string | undefined;

  return wrapSend(provider, async (method, params) => {
    if (method === "eth_sendTransaction") {
      const tx = params[0];
      if (tx !== undefined && tx.gasPrice === undefined) {
        if (gasPrice === undefined) {
          gasPrice = await provider.send("eth_gasPrice");
        }

        tx.gasPrice = gasPrice;
      }
    }

    return provider.send(method, params);
  });
}

/**
 * This provider multiplies whatever gas estimation Ganache gives by [[GANACHE_GAS_MULTIPLIER]]
 *
 * NOTE: This bug was present at least in Ganache 6.4.x.
 * One way to test if the bug is still present is to check if the estimation to
 * run a deployment transaction with this data is high enough:
 *  * 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
 */
export function createGanacheGasMultiplierProvider(
  provider: IEthereumProvider
) {
  let isGanache: boolean | undefined;
  const getMultipliedGasEstimation = createMultipliedGasEstimationGetter();

  return wrapSend(provider, async (method, params) => {
    if (isGanache === undefined) {
      const clientVersion: string = await provider.send("web3_clientVersion");

      isGanache = clientVersion.includes("TestRPC");
    }

    if (method === "eth_estimateGas" && isGanache) {
      return getMultipliedGasEstimation(
        provider,
        params,
        GANACHE_GAS_MULTIPLIER
      );
    }

    return provider.send(method, params);
  });
}

function createMultipliedGasEstimationGetter() {
  // We create this getter this way so this cache is recreated when the BRE
  // is reseted
  let cachedGasLimit: number | undefined;

  async function getBlockGasLimit(
    provider: IEthereumProvider
  ): Promise<number> {
    if (cachedGasLimit === undefined) {
      const latestBlock = await provider.send("eth_getBlockByNumber", [
        "latest",
        false,
      ]);

      const fetchedGasLimit = rpcQuantityToNumber(latestBlock.gasLimit);

      // For future uses, we store a lower value in case the gas limit varies slightly
      cachedGasLimit = Math.floor(fetchedGasLimit * 0.95);

      return fetchedGasLimit;
    }

    return cachedGasLimit;
  }

  return async function getMultipliedGasEstimation(
    provider: IEthereumProvider,
    params: any[],
    gasMultiplier: number
  ): Promise<string> {
    try {
      const realEstimation = await provider.send("eth_estimateGas", params);

      if (gasMultiplier === 1) {
        return realEstimation;
      }

      const normalGas = rpcQuantityToNumber(realEstimation);
      const gasLimit = await getBlockGasLimit(provider);

      const multiplied = Math.floor(normalGas * gasMultiplier);
      const gas = multiplied > gasLimit ? gasLimit - 1 : multiplied;

      return numberToRpcQuantity(gas);
    } catch (error) {
      if (error.message.toLowerCase().includes("execution error")) {
        const blockGasLimit = await getBlockGasLimit(provider);
        return numberToRpcQuantity(blockGasLimit);
      }

      // tslint:disable-next-line only-buidler-error
      throw error;
    }
  };
}