Parse transaction log for EIP-3009 TransferWithAuthorization

[innerop]

Suggestion

Hi,

I'm executing a meta transaction using EIP-3009 with an ERC20 smart contract.

I'm doing this:

        const tx = await provider.waitForTransaction(transaction.hash)

        const gasUsed = parseInt(tx.gasUsed, 16) 

        console.log(tx)

and the transaction is succeeding and I get this:

{
  to: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48',
  from: '0xa...',
  contractAddress: null,
  transactionIndex: 50,
  gasUsed: BigNumber { _hex: '0x013df7', _isBigNumber: true },
  logsBloom: '0x00000000000000008000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100000200000000000000000000000008000008080000000000000000000000000000000000000000000000000080000000000000000000000000000000000008000010000000000000000000000000000000000000000000000000010000004000000008000000000000000000200000000000000000000004000000000000000000000000000000000402000000000000000000000000400000000000000000000000000000000000000000000000000000000000000000000000000000002000000000000000',
  blockHash: '0x7a3cf3bb1860d14e0f8dbbd7cb00abd04b3429e7a6710b070400493f8429f6c7',
  transactionHash: '0x6ffcc5812522537c90935cb1bfac72fd8ee7389356498c6cf1356af61f947fb6',
  logs: [
    {
      transactionIndex: 50,
      blockNumber: 16523565,
      transactionHash: '0x6ffcc5812522537c90935cb1bfac72fd8ee7389356498c6cf1356af61f947fb6',
      address: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48',
      topics: [Array],
      data: '0x',
      logIndex: 86,
      blockHash: '0x7a3cf3bb1860d14e0f8dbbd7cb00abd04b3429e7a6710b070400493f8429f6c7'
    },
    {
      transactionIndex: 50,
      blockNumber: 16523565,
      transactionHash: '0x6ffcc5812522537c90935cb1bfac72fd8ee7389356498c6cf1356af61f947fb6',
      address: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48',
      topics: [Array],
      data: '0x00000000000000000000000000000000000000000000000000000000000f4240',
      logIndex: 87,
      blockHash: '0x7a3cf3bb1860d14e0f8dbbd7cb00abd04b3429e7a6710b070400493f8429f6c7'
    }
  ],
  blockNumber: 16523565,
  confirmations: 1,
  cumulativeGasUsed: BigNumber { _hex: '0x2f2864', _isBigNumber: true },
  effectiveGasPrice: BigNumber { _hex: '0x0474d09023', _isBigNumber: true },
  status: 1,
  type: 2,
  byzantium: true
} 

When I convert gasUsed to decimal it makes no sense. I can see my ETH balance in the delegated wallet go down by just over $2 after the above transaction but the gasUsed number does not match that when I divided it by 10e18 and then multiple it by the price of ETH in USD. Maybe gas is not measured in ETH? I'm confused. How do I calcualte gasUsed in USD value?

Please help! Thank you!

[ricmoo]

The gasUsed is just how many units of gas were consumed. If you are trying to compute the fee, you need to multiply that by the effectiveGasPrice, which is the Wei-per-gas. It's like gas in your car: if you use 5 litres and pay $1.50 per litre, the fee for gas is $7.50 (5 * 1.50). That is in Wei, so if you want ether, you would then use the formatEther utility function for its display logic.

So, utils.formatEther(receipt.gasUsed.mul(receipt.effectiveGasPrice)).

Make sense? :)

[innerop]

Yes! It makes perfect sense! Thank you!!! :) :)

waitForTransaction works great but it is returning after only 1 confirmation, which does the job as far as getting the transaction info

do I need to be concerned that there maybe a fork or some such thing in the network and that the transaction may be reverted? In other words, do I need to wait for 14 confirmations to be sure (this is part of an accounting system so users will get impacted if the system assumes the transaction has finality whereas in reality it may revert.

is there a way using this gem of a library (ethers) to wait for N conformations given the tx hash? I know how it's done in web3js but I'm trying to stick to ethers...

Thank you so much!

[ricmoo]

You can just pass in a number of confirmations into tx.wait(14) or into provider.waitForTransaction(hash, 14), but that is more of a PoW concept for security.

It depends on the risk associated with the transaction. Generally, it should be safe to wait for a single transaction for many user UX purposes, and waiting for additional blocks increases the cost to attack, but if economic finality is more important, you can wait until there next finalized block.

This is something that I’ll be adding to v6.1, the ability to wait on "finalized". I believe it is around 30 minutes (but don’t quite me in that ;)), but after economic finality it should be 100% (minus epsilon) safe to assume the blockchain cannot be undone.

Hope that helps. But I haven’t researched how finality works that thoroughly, I just know the gist. :)