How to send signed transactions concurrently via Infura?

Question

I'm using web3js and web3js-raw as follows to change state of my smart contract on ethereum,

let initiateAddLoyaltyTransaction = function (fromWallet, toWallet, companyName, amount, callback) {
let functionName = 'transferWithAddLoyalty';
amount = web3.utils.toWei(amount.toString(), 'ether');
let params = [fromWallet, toWallet, amount, companyName];
W3JSR.prepareSignSend(config.ethereum[ethereumNetwork].ABI_DEFINITION, config.ethereum[ethereumNetwork].CONTRACT_ADDRESS, functionName,
    config.ethereum[ethereumNetwork].WALLET_ADDRESS, privateKey, params, 10000000000).then((result, error) => {
    callback(result, error);
});

};

It works fine when I call this function and wait for the transaction to mined by miners. But the problem is when I send another transaction before first one completes( because my use case needs to do several transactions in a short period of time) it gives an error saying

message: Error: Returned error: known transaction: 5abe27f97e23fb660b514c87c4d7db150dbd23bcf54632eef09fad6ec64427fe

I can see that the nonce is same for both transactions. Could someone please explain me how to deal with nonce while using Infura. Do I need to maintain nonce localy? And how to retry if one transaction fails

Answer 1

Indeed, your issue is that all the transactions are sent with the same nonce.

Unfortunately the prepareSignSend function doesn't give you the possibility to overwrite the nonce.

Fortunately, you have options:

• start using the underlying ethereumjs-tx directly - you'll have to rewrite some parts of your codebase, but you'll get full flexibility

• make your local copy of web3js-raw, rewrite the prepareSignSend(...) to accept nonce as an optional last parameter and if set, use it instead of the auto-filled one. The new function could look like this:

  this.prepareSignSend = async function(abi,contractAddress,functionName,senderAddress,privateKey, params, gasLimit, customNonce){
      try{
          var txnData = this.encodeFunctionParams(abi, functionName,  params);
          var _gasLimit = await this.ContractInstance.methods[functionName](...params).estimateGas({'from': senderAddress, 'gas': gasLimit});
          var txnRawData = await this.getDefaultTxnAttributes('',senderAddress,contractAddress,'0',txnData,_gasLimit,'')
  
          if ( typeof customNonce !== 'undefined')
              txnRawData.nonce = customNonce;
  
      if (txnRawData) {
          var dataToSend = this.getSignedTransaction(txnRawData, privateKey);
          var txHash = await web3.eth.sendSignedTransaction(dataToSend);
          return Promise.resolve({"status":1,"functionName":functionName,"message":txHash});
      }
      else{
          return Promise.reject({"status":0,"functionName":functionName,"message":"Error in setting Default Txn Attributes"});
      }
  }
  catch (err){
      return Promise.reject({"status":0,"functionName":functionName,"message":err});
    }
  }