modifier consumes all gas

Question

Given a modifier:

modifier yetNotCalculated() {
    require(calculated == false);
    _;
}

and then using it in my function:

function calculateResult() public yetNotCalculated {
    calculate();
    calculated = true;
}

When the modifier rejects further processing (calculated is set to true), it consumes all my gas :( ! is this a desired behaviour ?

Here I am invoking that function using web3 library, and that what I get as receipt:

    { blockHash: '0xc8219ac506e4020f61e199126d8b578c8d8219222286d684661415593c251495',
  blockNumber: 12476,
  contractAddress: null,
  cumulativeGasUsed: 2100000,
  from: '0xe6cb4d38ae1f3458f5095652a68b304b3aa7f82c',
  gasUsed: 2100000,
  logs: [],
  logsBloom: '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000',
  root: '0x6047a5fe941496e089cf73e0c2cbd7db1608794bac0a73368fcfcd34833a1aef',
  to: '0xf8b8741024621ee0936bafac55ff544421d7924b',
  transactionHash: '0xf8b40eeb956b425fc4cfadec1c1cc2a479addbc635c74fb6000945fedd41696a',
  transactionIndex: 0 }

as you can see 2100000 gas was used which is my gas limit. why is that :) ? Thanks

Answer 1

It's not the modifier, it's the require. require reverts/errors if the condition is false, so, if calculated==true then revert.

This might not be a great application for modifier or require. Have you considered if(!calculated) calculate(); return true;?

Hope it helps

Answer 2

“If you're asking about gas consumption up until the require statement, then the answer is yes. As of the Byzantium release, all gas consumed up to the point of a require statement is consumed, but any remaining gas is returned. Prior to Byzantium, require() and assert() were identical and all gas would be consumed. From the Solidity docs: Internally, Solidity performs a revert operation (instruction 0xfd) for a require-style exception and executes an invalid operation (instruction 0xfe) to throw an assert-style exception. In both cases, this causes the EVM to revert all changes made to the state...Note that assert-style exceptions consume all gas available to the call, while require-style exceptions will not consume any gas starting from the Metropolis release.” (By Adam Kipnis)

As far as I know this is the right answer.