diff options
Diffstat (limited to 'packages/instant/src/util/gas_price_estimator.ts')
-rw-r--r-- | packages/instant/src/util/gas_price_estimator.ts | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/packages/instant/src/util/gas_price_estimator.ts b/packages/instant/src/util/gas_price_estimator.ts new file mode 100644 index 000000000..6b15809a3 --- /dev/null +++ b/packages/instant/src/util/gas_price_estimator.ts @@ -0,0 +1,62 @@ +import { BigNumber, fetchAsync } from '@0x/utils'; + +import { + DEFAULT_ESTIMATED_TRANSACTION_TIME_MS, + DEFAULT_GAS_PRICE, + ETH_GAS_STATION_API_BASE_URL, + GWEI_IN_WEI, +} from '../constants'; + +interface EthGasStationResult { + average: number; + fastestWait: number; + fastWait: number; + fast: number; + safeLowWait: number; + blockNum: number; + avgWait: number; + block_time: number; + speed: number; + fastest: number; + safeLow: number; +} + +interface GasInfo { + gasPriceInWei: BigNumber; + estimatedTimeMs: number; +} + +const fetchFastAmountInWeiAsync = async (): Promise<GasInfo> => { + const res = await fetchAsync(`${ETH_GAS_STATION_API_BASE_URL}/json/ethgasAPI.json`); + const gasInfo = (await res.json()) as EthGasStationResult; + // Eth Gas Station result is gwei * 10 + const gasPriceInGwei = new BigNumber(gasInfo.fast / 10); + // Time is in minutes + const estimatedTimeMs = gasInfo.fastWait * 60 * 1000; // Minutes to MS + return { gasPriceInWei: gasPriceInGwei.mul(GWEI_IN_WEI), estimatedTimeMs }; +}; + +export class GasPriceEstimator { + private _lastFetched?: GasInfo; + public async getGasInfoAsync(): Promise<GasInfo> { + let fetchedAmount: GasInfo | undefined; + try { + fetchedAmount = await fetchFastAmountInWeiAsync(); + } catch { + fetchedAmount = undefined; + } + + if (fetchedAmount) { + this._lastFetched = fetchedAmount; + } + + return ( + fetchedAmount || + this._lastFetched || { + gasPriceInWei: DEFAULT_GAS_PRICE, + estimatedTimeMs: DEFAULT_ESTIMATED_TRANSACTION_TIME_MS, + } + ); + } +} +export const gasPriceEstimator = new GasPriceEstimator(); |