From def22bce370b8ba43da7d3e05687e155790f909e Mon Sep 17 00:00:00 2001
From: Tal Kol <talkol@gmail.com>
Date: Sun, 26 Jul 2020 13:07:41 +0300
Subject: [PATCH] Added proper support for gas limit, changed Web3 HTTP
 provider to support keepalive

---
 src/helpers.ts                |  6 ++++++
 src/write/ethereum-helpers.ts | 20 +++++++++++++++++---
 src/write/ethereum.test.ts    |  4 ++++
 src/write/ethereum.ts         |  6 +++++-
 4 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/src/helpers.ts b/src/helpers.ts
index 4538886..0a72489 100644
--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -15,6 +15,12 @@ export function getCurrentClockTime() {
   return Math.round(new Date().getTime() / 1000);
 }
 
+export function toNumber(val: number | string) {
+  if (typeof val == 'string') {
+    return parseInt(val);
+  } else return val;
+}
+
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
 export type JsonResponse = any;
 
diff --git a/src/write/ethereum-helpers.ts b/src/write/ethereum-helpers.ts
index d16470d..59606ed 100644
--- a/src/write/ethereum-helpers.ts
+++ b/src/write/ethereum-helpers.ts
@@ -1,6 +1,10 @@
 import * as Logger from '../logger';
 import { State, EthereumTxStatus, GasPriceStrategy } from '../model/state';
-import { getCurrentClockTime, jsonStringifyComplexTypes } from '../helpers';
+import { getCurrentClockTime, jsonStringifyComplexTypes, toNumber } from '../helpers';
+import { TransactionConfig } from 'web3-core';
+
+const GAS_LIMIT_ESTIMATE_EXTRA = 100000;
+const GAS_LIMIT_HARD_LIMIT = 2000000;
 
 export type Type = 'ready-to-sync' | 'ready-for-committee';
 
@@ -50,14 +54,24 @@ export async function signAndSendTransaction(
 
   const nonce = await state.web3.eth.getTransactionCount(senderAddress, 'latest'); // ignore pending pool
 
-  const txObject = {
+  const txObject: TransactionConfig = {
     from: senderAddress,
     to: contractAddress,
     gasPrice: gasPrice,
-    gas: 10000000, // TODO: fix with real value
     data: encodedAbi,
     nonce: nonce,
   };
+
+  let gasLimit = toNumber(await state.web3.eth.estimateGas(txObject));
+  if (gasLimit <= 0) throw new Error(`Cannot estimate gas for tx with data ${encodedAbi}`);
+  gasLimit += GAS_LIMIT_ESTIMATE_EXTRA;
+  if (gasLimit > GAS_LIMIT_HARD_LIMIT) {
+    throw new Error(`Gas limit estimate ${gasLimit} over hard limit ${GAS_LIMIT_HARD_LIMIT}`);
+  }
+  txObject.gas = gasLimit;
+
+  Logger.log(`About to sign and send tx object: ${jsonStringifyComplexTypes(txObject)}.`);
+
   const { rawTransaction, transactionHash } = await state.signer.sign(txObject);
   if (!rawTransaction || !transactionHash) {
     throw new Error(`Could not sign tx object: ${jsonStringifyComplexTypes(txObject)}.`);
diff --git a/src/write/ethereum.test.ts b/src/write/ethereum.test.ts
index 77d8b72..784c9f2 100644
--- a/src/write/ethereum.test.ts
+++ b/src/write/ethereum.test.ts
@@ -31,6 +31,10 @@ function getMockWeb3Client(behavior: 'success' | 'badsend' | 'pending' | 'revert
         if (behavior == 'overmax') return '999000000000';
         return '40000000000';
       },
+      estimateGas: async () => {
+        await sleep(0);
+        return 500000;
+      },
       sendSignedTransaction: async () => {
         await sleep(0);
         if (behavior == 'badsend') throw new Error('send error');
diff --git a/src/write/ethereum.ts b/src/write/ethereum.ts
index 449f508..4967f30 100644
--- a/src/write/ethereum.ts
+++ b/src/write/ethereum.ts
@@ -14,7 +14,11 @@ import { compiledContracts } from '@orbs-network/orbs-ethereum-contracts-v2/rele
 
 export function initWeb3Client(ethereumEndpoint: string, electionsContractAddress: string, state: State) {
   // init web3
-  state.web3 = new Web3(ethereumEndpoint);
+  state.web3 = new Web3(
+    new Web3.providers.HttpProvider(ethereumEndpoint, {
+      keepAlive: true,
+    })
+  );
   // TODO: state.web3.eth.transactionPollingTimeout = 0.01;
   // TODO:  do we need to disable web3 receipt polling explicitly?
   // init contracts