update

README.md

@@ -1,6 +1,16 @@
 # Gas Price Oracle library for Ethereum dApps
+A library that has a collection of onchain and offchain gas price oracle URLs
 
-## Instalation
+Current offchain list:  
+- https://ethgasstation.info/json/ethgasAPI.json  
+- https://gas-oracle.zoltu.io/  
+- https://www.etherchain.org/api/gasPriceOracle  
+- https://gasprice.poa.network/  
+
+Current onchain list:  
+- [chainlink](https://etherscan.io/address/0xA417221ef64b1549575C977764E651c9FAB50141)  
+
+## Installation
 `npm i gas-price-oracle`
 
 ## Import
@@ -9,11 +19,19 @@ const { GasPriceOracle } = require('gas-price-oracle');
 ```
 ## Usage
 ### Basic
-```js
-const oracle = new GasPriceOracle();
 
-oracle.gasPrices().then((gas) => {
+```js
-    console.log(gas)
+
+const options = {
+    defaultRpc: 'https://api.mycryptoapi.com/eth'
+}
+const oracle = new GasPriceOracle(options);
+// optional fallbackGasPrices
+const fallbackGasPrices = {
+    instant: 70, fast: 31, standard: 20, low: 7
+}
+oracle.gasPrices(fallbackGasPrices).then((gasPrices) => {
+    console.log(gasPrices) // { instant: 50, fast: 21, standard: 10, low: 3 }
 });
 ```
 
@@ -21,28 +39,17 @@ oracle.gasPrices().then((gas) => {
 ```js
 const oracle = new GasPriceOracle();
 
-oracle.fetchGasPricesOffChain().then((gas) => {
+oracle.fetchGasPricesOffChain().then((gasPrices) => {
-    console.log(gas)
+    console.log(gasPrices) // { instant: 50, fast: 21, standard: 10, low: 3 }
 });
 ```
 
 ### Custom RPC URL for onchain oracles
 ```js
-const customRpc = 'https://mainnet.infura.io/v3/<API_KEY>'
+const defaultRpc = 'https://mainnet.infura.io/v3/<API_KEY>'
-const oracle = new GasPriceOracle(customRpc);
+const oracle = new GasPriceOracle({ defaultRpc });
 
-oracle.fetchGasPricesOnChain().then((gas) => {
+oracle.fetchGasPricesOnChain().then((gasPrices) => {
-    console.log(gas)
+    console.log(gasPrices) // 21
-});
-```
-
-### Don't throw an error if oracles are down
-```js
-oracle.fetchGasPricesOnChain(false).then((gas) => {
-    console.log(gas)
-});
-
-oracle.fetchGasPricesOffChain(false).then((gas) => {
-    console.log(gas)
 });
 ```

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "gas-price-oracle",
-  "version": "1.0.0",
+  "version": "0.1.1",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {

package.json

@@ -1,8 +1,13 @@
 {
   "name": "gas-price-oracle",
-  "version": "0.1.1",
+  "version": "0.1.2",
   "description": "Gas Price Oracle library for Ethereum dApps.",
   "main": "lib/index.js",
+  "homepage": "https://github.com/peppersec/gas-price-oracle",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/peppersec/gas-price-oracle.git"
+  },
   "types": "lib/index.d.ts",
   "prepare": "npm run build",
   "prepublishOnly": "npm test && npm run lint",
@@ -12,7 +17,12 @@
     "lint": "tslint -p tsconfig.json"
   },
   "author": "Alexey Pertsev <alexey@peppersec.com> (https://peppersec.com)",
-  "keywords": ["Gas", "Gas price", "Ethereum", "Oracle"],
+  "keywords": [
+    "Gas",
+    "Gas price",
+    "Ethereum",
+    "Oracle"
+  ],
   "license": "MIT",
   "devDependencies": {
     "@types/chai": "^4.2.11",

src/index.ts

@@ -1,26 +1,21 @@
 import fetch from 'node-fetch';
 import config from './config';
-import { GasPrice, OffChainOracle, OnChainOracle } from './types';
+import { GasPrice, OffChainOracle, OnChainOracle, ConstructorArgs } from './types';
 import BigNumber from 'bignumber.js';
 
 export class GasPriceOracle {
-  lastGasPrice: GasPrice = {
+  lastGasPrice: GasPrice;
-    instant: 40,
-    fast: 21,
-    standard: 10,
-    low: 1
-  };
   defaultRpc = 'https://api.mycryptoapi.com/eth';
   offChainOracles = { ...config.offChainOracles };
   onChainOracles = { ...config.onChainOracles };
 
-  constructor(defaultRpc?: string) {
+  constructor(options: ConstructorArgs) {
-    if (defaultRpc) {
+    if (options && options.defaultRpc) {
-      this.defaultRpc = defaultRpc;
+      this.defaultRpc = options.defaultRpc;
     }
   }
 
-  async fetchGasPricesOffChain(throwIfFailsToFetch = true): Promise<GasPrice> {
+  async fetchGasPricesOffChain(): Promise<GasPrice> {
     for (let oracle of Object.values(this.offChainOracles)) {
       const { name, url, instantPropertyName, fastPropertyName, standardPropertyName, lowPropertyName, denominator } = oracle;
       try {
@@ -36,8 +31,7 @@ export class GasPriceOracle {
             standard: parseFloat(gas[standardPropertyName]) / denominator,
             low: parseFloat(gas[lowPropertyName]) / denominator
           };
-          this.lastGasPrice = gasPrices;
+          return gasPrices;
-          return this.lastGasPrice;
         } else {
           throw new Error(`Fetch gasPrice from ${name} oracle failed. Trying another one...`);
         }
@@ -45,18 +39,16 @@ export class GasPriceOracle {
         console.error(e.message);
       }
     }
-    if (throwIfFailsToFetch) {
     throw new Error('All oracles are down. Probaly network error.');
   }
-    return this.lastGasPrice;
-  }
 
-  async fetchGasPricesOnChain(throwIfFailsToFetch = true): Promise<GasPrice> {
+  async fetchGasPricesOnChain(): Promise<number> {
     for (let oracle of Object.values(this.onChainOracles)) {
       const { name, callData, contract, denominator } = oracle;
       let { rpc } = oracle;
       rpc = rpc ? rpc : this.defaultRpc;
-      const body = { jsonrpc: '2.0',
+      const body = {
+        jsonrpc: '2.0',
         id: 1337,
         method: 'eth_call',
         params: [{ 'data': callData, 'to': contract }, 'latest']
@@ -76,14 +68,7 @@ export class GasPriceOracle {
             throw new Error(`${name} oracle provides corrupted values`);
           }
           fastGasPrice = fastGasPrice.div(denominator);
-          const gasPrices: GasPrice = {
+          return fastGasPrice.toNumber();
-            instant: fastGasPrice.multipliedBy(1.3).toNumber(),
-            fast: fastGasPrice.toNumber(),
-            standard: fastGasPrice.multipliedBy(0.85).toNumber(),
-            low: fastGasPrice.multipliedBy(0.5).toNumber()
-          };
-          this.lastGasPrice = gasPrices;
-          return this.lastGasPrice;
         } else {
           throw new Error(`Fetch gasPrice from ${name} oracle failed. Trying another one...`);
         }
@@ -91,29 +76,38 @@ export class GasPriceOracle {
         console.error(e.message);
       }
     }
-    if (throwIfFailsToFetch) {
     throw new Error('All oracles are down. Probaly network error.');
   }
-    return this.lastGasPrice;
-  }
 
-  async gasPrices(): Promise<GasPrice> {
+  async gasPrices(fallbackGasPrices?: GasPrice): Promise<GasPrice> {
-    let gas = this.lastGasPrice;
+    const defaultFastGas = 22;
+    const defaultFallbackGasPrices = {
+      instant: defaultFastGas * 1.3,
+      fast: defaultFastGas,
+      standard: defaultFastGas * 0.85,
+      low: defaultFastGas * 0.5
+    };
+    this.lastGasPrice = this.lastGasPrice || fallbackGasPrices || defaultFallbackGasPrices;
     try {
-      gas = await this.fetchGasPricesOffChain();
+      this.lastGasPrice = await this.fetchGasPricesOffChain();
-      return gas;
+      return this.lastGasPrice;
     } catch (e) {
       console.log('Failed to fetch gas prices from offchain oracles. Trying onchain ones...');
     }
 
     try {
-      gas = await this.fetchGasPricesOnChain();
+      const fastGas = await this.fetchGasPricesOnChain();
-      return gas;
+      this.lastGasPrice = {
+        instant: fastGas * 1.3,
+        fast: fastGas,
+        standard: fastGas * 0.85,
+        low: fastGas * 0.5
+      };
+      return this.lastGasPrice;
     } catch (e) {
       console.log('Failed to fetch gas prices from onchain oracles. Last known gas will be returned');
     }
-
+    return this.lastGasPrice;
-    return gas;
   }
 
   addOffChainOracle(oracle: OffChainOracle) {

src/types.ts

@@ -22,3 +22,7 @@ export type GasPrice = {
   standard: number;
   low: number;
 };
+
+export interface ConstructorArgs {
+  defaultRpc?: string;
+}

tests/index.test.ts

@@ -41,46 +41,26 @@ describe('fetchGasPricesOffChain', function () {
     await oracle.fetchGasPricesOffChain().should.be.rejectedWith('All oracles are down. Probaly network error.');
     mockery.disable();
   });
-
-  it('should not throw if throwIfFailsToFetch is false', async function () {
-    mockery.enable({ useCleanCache: true, warnOnUnregistered: false });
-    const { GasPriceOracle } = require('../src/index');
-    oracle = new GasPriceOracle();
-    await oracle.fetchGasPricesOffChain(false);
-    mockery.disable();
-  });
 });
 
 describe('fetchGasPricesOnChain', function () {
   it('should work', async function () {
-    const gas: GasPrice = await oracle.fetchGasPricesOnChain();
+    const gas: number = await oracle.fetchGasPricesOnChain();
 
-    gas.instant.should.be.a('number');
+    gas.should.be.a('number');
-    gas.fast.should.be.a('number');
+    gas.should.not.be.equal(0);
-    gas.standard.should.be.a('number');
-    gas.low.should.be.a('number');
-
-    gas.instant.should.be.above(gas.fast);
-    gas.fast.should.be.above(gas.standard);
-    gas.standard.should.be.above(gas.low);
-    gas.low.should.not.be.equal(0);
   });
 
   it('should work with custom rpc', async function () {
     const rpc = 'https://ethereum-rpc.trustwalletapp.com';
-    const oracle = new GasPriceOracle(rpc);
+    const oracle = new GasPriceOracle({ defaultRpc: rpc });
     oracle.defaultRpc.should.be.equal(rpc);
-    const gas: GasPrice = await oracle.fetchGasPricesOnChain();
+    const gas: number = await oracle.fetchGasPricesOnChain();
 
-    gas.instant.should.be.a('number');
+    gas.should.be.a('number');
-    gas.fast.should.be.a('number');
-    gas.standard.should.be.a('number');
-    gas.low.should.be.a('number');
 
-    gas.instant.should.be.above(gas.fast);
+    gas.should.be.above(1);
-    gas.fast.should.be.above(gas.standard);
+    gas.should.not.be.equal(0);
-    gas.standard.should.be.above(gas.low);
-    gas.low.should.not.be.equal(0);
   });
 
   it('should remove oracle', async function () {
@@ -95,17 +75,10 @@ describe('fetchGasPricesOnChain', function () {
     oracle.removeOnChainOracle('chainlink');
     await oracle.fetchGasPricesOnChain().should.be.rejectedWith('All oracles are down. Probaly network error.');
     oracle.addOnChainOracle(chainlink);
-    const gas: GasPrice = await oracle.fetchGasPricesOnChain();
+    const gas: number = await oracle.fetchGasPricesOnChain();
 
-    gas.instant.should.be.a('number');
+    gas.should.be.a('number');
-    gas.fast.should.be.a('number');
+    gas.should.not.be.equal(0);
-    gas.standard.should.be.a('number');
-    gas.low.should.be.a('number');
-
-    gas.instant.should.be.above(gas.fast);
-    gas.fast.should.be.above(gas.standard);
-    gas.standard.should.be.above(gas.low);
-    gas.low.should.not.be.equal(0);
   });
 
   it('should throw if all onchain oracles are down', async function () {
@@ -116,13 +89,6 @@ describe('fetchGasPricesOnChain', function () {
     mockery.disable();
   });
 
-  it('should not throw if throwIfFailsToFetch is false', async function () {
-    mockery.enable({ useCleanCache: true, warnOnUnregistered: false });
-    const { GasPriceOracle } = require('../src/index');
-    oracle = new GasPriceOracle();
-    await oracle.fetchGasPricesOnChain(false);
-    mockery.disable();
-  });
 });
 
 describe('gasPrice', function () {
@@ -139,6 +105,31 @@ describe('gasPrice', function () {
     gas.standard.should.be.above(gas.low);
     gas.low.should.not.be.equal(0);
   });
+  it('should fallback', async function () {
+    mockery.enable({ useCleanCache: true, warnOnUnregistered: false });
+    const { GasPriceOracle } = require('../src/index');
+    oracle = new GasPriceOracle();
+    const gas: GasPrice = await oracle.gasPrices();
+
+    gas.instant.should.be.equal(28.6);
+    gas.fast.should.be.equal(22);
+    gas.standard.should.be.equal(18.7);
+    gas.low.should.be.equal(11);
+    mockery.disable();
+  });
+
+  it('should fallback to set values', async function () {
+    mockery.enable({ useCleanCache: true, warnOnUnregistered: false });
+    const { GasPriceOracle } = require('../src/index');
+    oracle = new GasPriceOracle();
+    const gas: GasPrice = await oracle.gasPrices({ instant: 50, fast: 21, standard: 10, low: 3 });
+
+    gas.instant.should.be.equal(50);
+    gas.fast.should.be.equal(21);
+    gas.standard.should.be.equal(10);
+    gas.low.should.be.equal(3);
+    mockery.disable();
+  });
 });
 
 after('after', function () {