Estimate_gas return issues

[boundless-forest]

If OutOfFund happened, should return right now instead of continuing with the estimating process.

[boundless-forest]

@sorpaas This pr is ready for review. Should I update the crate version?

[sorpaas]

Should I update the crate version?

Yeah. But I don't quiet understand the PR. With or without this condition it always returns. The difference is the error value the parent gets. Can you explain more about the PR?

[boundless-forest]

Can you explain more about the PR?

Sure, let me explain more details about this. Firstly, we have a pre-compile contract in which the transfer operation is performed.
Here and the transfer value comes from the input value.

So, when somebody estimates the gas used of calling this precompile contract, if the balance is not sufficient, an OutOfFund error will return. However, the estimate gas used logic here will misinterpret this as a result of insufficient gas and use more gas to estimate again util to the max. This is not the case in fact. The error occurs due to insufficient balance in the execution process instead of out of gas.

[cla-bot-2021]

User @AsceticBear, please sign the CLA here.

[boundless-forest]

There is an estimate_gas bug when the calculate_gas_used(test_request) return error due to OutOfGas.

match calculate_gas_used(test_request) {
	// if Ok -- try to reduce the gas used
	Ok(used_gas) => {
		old_best = best;
		best = used_gas;
		change_pct = (U256::from(100) * (old_best - best)) / old_best;
		upper = mid;
		mid = (lower + upper + 1) / 2;
                log::debug!("bear: --- [Ok]: upper {:?}, mid {:?}", upper, mid);
	}

	Err(err) => {
                log::debug!("bear: --- the calculate gas used err! {:?}", err);
		// if Err == OutofGas or OutofFund, we need more gas
		if err.code == ErrorCode::ServerError(0) {
	             lower = mid;
		    mid = (lower + upper + 1) / 2;
		    log::debug!("bear: --- [err]: lower {:?}, mid {:?}", lower, mid);
		    if mid == lower {
			 break;
		    }
		}
	        // Other errors, return directly
	       return Err(err);
	}
}

debug info:

2021-05-08 15:16:01.710 DEBUG        http.worker10 dc_rpc::eth: bear: --- the calculate gas used err! Error { code: ServerError(0), message: "out of gas or fund", data: None }
2021-05-08 15:16:01.710 DEBUG        http.worker10 dc_rpc::eth: bear: --- [err]: lower 500010500, mid 750005250
2021-05-08 15:16:01.710 DEBUG        http.worker10 dc_rpc::eth: bear: --- change_pct 37, threshold_pct 10
2021-05-08 15:16:01.803 DEBUG        http.worker10 dc_rpc::eth: bear: --- [Ok]: upper 750005250, mid 625007875
2021-05-08 15:16:01.803 DEBUG        http.worker10 dc_rpc::eth: bear: --- change_pct 0, threshold_pct 10

As we can see above, The estimate process return error when calculate_gas_used result error code is ServerError(0) & mid != lower. That's incorrect behavior. @sorpaas Please take a review later.

[sorpaas]

Please modify the comment in L824. It's outdated!