Add a possibility to fetch gas price from multiple sources (#420)

CONFIGURATION.md

@@ -12,7 +12,7 @@ COMMON_HOME_GAS_PRICE_SUPPLIER_URL | The URL used to get a JSON response from th
 COMMON_HOME_GAS_PRICE_SPEED_TYPE | Assuming the gas price oracle responds with the following JSON structure: `{"fast": 20.0, "block_time": 12.834, "health": true, "standard": 6.0, "block_number": 6470469, "instant": 71.0, "slow": 1.889}`, this parameter specifies the desirable transaction speed. The speed type can be omitted when `COMMON_HOME_GAS_PRICE_SUPPLIER_URL` is not used. | `instant` / `fast` / `standard` / `slow`
 COMMON_HOME_GAS_PRICE_FALLBACK | The gas price (in Wei) that is used if both the oracle and the fall back gas price specified in the Home Bridge contract are not available. | integer
 COMMON_HOME_GAS_PRICE_FACTOR | A value that will multiply the gas price of the oracle to convert it to gwei. If the oracle API returns gas prices in gwei then this can be set to `1`. Also, it could be used to intentionally pay more gas than suggested by the oracle to guarantee the transaction verification. E.g. `1.25` or `1.5`. | integer
-COMMON_FOREIGN_GAS_PRICE_SUPPLIER_URL | The URL used to get a JSON response from the gas price prediction oracle for the Foreign network. The provided gas price is used to send the validator's transactions to the RPC node. If the Foreign network is Ethereum Foundation mainnet, the oracle URL can be: https://gasprice.poa.network. Otherwise this parameter can be omitted. | URL
+COMMON_FOREIGN_GAS_PRICE_SUPPLIER_URL | The URL used to get a JSON response from the gas price prediction oracle for the Foreign network. The provided gas price is used to send the validator's transactions to the RPC node. If the Foreign network is Ethereum Foundation mainnet, the oracle URL can be: https://gasprice.poa.network. Otherwise this parameter can be omitted. Set to `gas-price-oracle` if you want to use npm `gas-price-oracle` package for retrieving gas price from multiple sources. | URL
 COMMON_FOREIGN_GAS_PRICE_SPEED_TYPE | Assuming the gas price oracle responds with the following JSON structure: `{"fast": 20.0, "block_time": 12.834, "health": true, "standard": 6.0, "block_number": 6470469, "instant": 71.0, "slow": 1.889}`, this parameter specifies the desirable transaction speed. The speed type can be omitted when `COMMON_FOREIGN_GAS_PRICE_SUPPLIER_URL`is not used. | `instant` / `fast` / `standard` / `slow`
 COMMON_FOREIGN_GAS_PRICE_FALLBACK | The gas price (in Wei) used if both the oracle and fall back gas price specified in the Foreign Bridge contract are not available. | integer
 COMMON_FOREIGN_GAS_PRICE_FACTOR | A value that will multiply the gas price of the oracle to convert it to gwei. If the oracle API returns gas prices in gwei then this can be set to `1`. Also, it could be used to intentionally pay more gas than suggested by the oracle to guarantee the transaction verification. E.g. `1.25` or `1.5`. | integer

commons/package.json

@@ -8,6 +8,7 @@
     "test": "NODE_ENV=test mocha"
   },
   "dependencies": {
+    "gas-price-oracle": "^0.1.5",
     "web3-utils": "1.0.0-beta.34"
   },
   "devDependencies": {

commons/utils.js

@@ -1,7 +1,10 @@
 const { toWei, toBN } = require('web3-utils')
+const { GasPriceOracle } = require('gas-price-oracle')
 const { BRIDGE_MODES, FEE_MANAGER_MODE, ERC_TYPES } = require('./constants')
 const { REWARDABLE_VALIDATORS_ABI } = require('./abis')
 
+const gasPriceOracle = new GasPriceOracle()
+
 function decodeBridgeMode(bridgeModeHash) {
   switch (bridgeModeHash) {
     case '0x92a8d7fe':
@@ -235,8 +238,13 @@ const normalizeGasPrice = (oracleGasPrice, factor, limits = null) => {
 // we use built-in 'fetch' on browser side, and `node-fetch` package in Node.
 const gasPriceFromSupplier = async (fetchFn, options = {}) => {
   try {
-    const response = await fetchFn()
+    let json
-    const json = await response.json()
+    if (fetchFn) {
+      const response = await fetchFn()
+      json = await response.json()
+    } else {
+      json = await gasPriceOracle.fetchGasPricesOffChain()
+    }
     const oracleGasPrice = json[options.speedType]
 
     if (!oracleGasPrice) {

monitor/docker-compose-build.yml

@@ -3,4 +3,6 @@ version: '2.4'
 services:
   monitor:
     image: poanetwork/tokenbridge-monitor
-    build: .
+    build:
+      context: ..
+      dockerfile: ./monitor/Dockerfile

monitor/validators.js

@@ -100,8 +100,13 @@ async function main(bridgeMode) {
 
   if (MONITOR_VALIDATOR_FOREIGN_TX_LIMIT) {
     logger.debug('calling foreign getGasPrices')
+    const fetchFn =
+      COMMON_FOREIGN_GAS_PRICE_SUPPLIER_URL === 'gas-price-oracle'
+        ? null
+        : () => fetch(COMMON_FOREIGN_GAS_PRICE_SUPPLIER_URL)
+
     foreignGasPrice =
-      (await gasPriceFromSupplier(() => fetch(COMMON_FOREIGN_GAS_PRICE_SUPPLIER_URL), foreignGasPriceSupplierOpts)) ||
+      (await gasPriceFromSupplier(fetchFn, foreignGasPriceSupplierOpts)) ||
       Web3Utils.toBN(COMMON_FOREIGN_GAS_PRICE_FALLBACK)
     foreignGasPriceGwei = Web3Utils.fromWei(foreignGasPrice.toString(), 'gwei')
     foreignTxCost = foreignGasPrice.mul(Web3Utils.toBN(MONITOR_VALIDATOR_FOREIGN_TX_LIMIT))

oracle/docker-compose-build.yml

@@ -3,4 +3,6 @@ version: '2.4'
 services:
   oracle:
     image: poanetwork/tokenbridge-oracle
-    build: .
+    build:
+      context: ..
+      dockerfile: ./oracle/Dockerfile

oracle/src/services/gasPrice.js

@@ -73,13 +73,14 @@ async function start(chainId, fetchOnce) {
     throw new Error(`Unrecognized chainId '${chainId}'`)
   }
 
+  const fetchFn = gasPriceSupplierUrl === 'gas-price-oracle' ? null : () => fetch(gasPriceSupplierUrl)
   if (fetchOnce) {
-    await fetchGasPrice(speedType, factor, bridgeContract, () => fetch(gasPriceSupplierUrl))
+    await fetchGasPrice(speedType, factor, bridgeContract, fetchFn)
     return getPrice()
   }
 
   fetchGasPriceInterval = setIntervalAndRun(
-    () => fetchGasPrice(speedType, factor, bridgeContract, () => fetch(gasPriceSupplierUrl)),
+    () => fetchGasPrice(speedType, factor, bridgeContract, fetchFn),
     updateInterval
   )
   return null

ui/src/stores/GasPriceStore.js

@@ -53,7 +53,8 @@ class GasPriceStore {
     }
 
     const oracleOptions = { speedType: this.speedType, factor: this.factor, logger: console }
-    this.gasPrice = (await gasPriceFromSupplier(() => fetch(this.gasPriceSupplierUrl), oracleOptions)) || this.gasPrice
+    const fetchFn = this.gasPriceSupplierUrl === 'gas-price-oracle' ? null : () => fetch(this.gasPriceSupplierUrl)
+    this.gasPrice = (await gasPriceFromSupplier(fetchFn, oracleOptions)) || this.gasPrice
 
     setTimeout(() => this.updateGasPrice(), this.updateInterval)
   }

yarn.lock

@@ -4209,6 +4209,13 @@ axios@0.19.0:
     follow-redirects "1.5.10"
     is-buffer "^2.0.2"
 
+axios@^0.19.2:
+  version "0.19.2"
+  resolved "https://registry.yarnpkg.com/axios/-/axios-0.19.2.tgz#3ea36c5d8818d0d5f8a8a97a6d36b86cdc00cb27"
+  integrity sha512-fjgm5MvRHLhx+osE2xoekY70AhARk3a6hkN+3Io1jc00jtquGvxYlKlsFUhmUET0V5te6CcZI7lcv2Ym61mjHA==
+  dependencies:
+    follow-redirects "1.5.10"
+
 axobject-query@^2.0.2:
   version "2.0.2"
   resolved "https://registry.yarnpkg.com/axobject-query/-/axobject-query-2.0.2.tgz#ea187abe5b9002b377f925d8bf7d1c561adf38f9"
@@ -9822,6 +9829,14 @@ ganache-core@^2.6.0:
     ethereumjs-wallet "0.6.3"
     web3 "1.2.4"
 
+gas-price-oracle@^0.1.5:
+  version "0.1.5"
+  resolved "https://registry.yarnpkg.com/gas-price-oracle/-/gas-price-oracle-0.1.5.tgz#09dd0d9806465c2f5e63b682e6742f96f6eb525c"
+  integrity sha512-fkaTXnxJcSVco/tMPEcN5gieoUNs8O6JYMXflGLN2+3YeGZAucUI0fgCliazM3nRVAk//bBEm9819/Zb83xhrw==
+  dependencies:
+    axios "^0.19.2"
+    bignumber.js "^9.0.0"
+
 gauge@~2.7.3:
   version "2.7.4"
   resolved "https://registry.yarnpkg.com/gauge/-/gauge-2.7.4.tgz#2c03405c7538c39d7eb37b317022e325fb018bf7"