{"record":{"id":"9c62656ab4763ffe","repo":"nautechsystems/nautilus_trader","slug":"failed-converting-gas-limit-to-u64","errorCode":null,"errorMessage":"Failed converting gas limit to u64","messagePattern":"Failed converting gas limit to u64","errorType":"exception","errorClass":"anyhow::Error","httpStatus":null,"severity":"error","filePath":"crates/adapters/dydx/src/grpc/builder.rs","lineNumber":96,"sourceCode":"        if let Some(gas) = gas_used {\n            self.calculate_fee_from_gas(gas)\n        } else {\n            Ok(Self::default_fee())\n        }\n    }\n\n    /// Calculate fee from gas usage.\n    fn calculate_fee_from_gas(&self, gas_used: u64) -> Result<Fee, anyhow::Error> {\n        let gas_multiplier = Decimal::try_from(GAS_MULTIPLIER)?;\n        let gas_limit = Decimal::from(gas_used) * gas_multiplier;\n\n        // Gas price for dYdX (typically 0.025 adydx per gas)\n        let gas_price = Decimal::new(25, 3); // 0.025\n        let amount = (gas_price * gas_limit).ceil();\n\n        let gas_limit_u64 = gas_limit\n            .to_u64()\n            .ok_or_else(|| anyhow::anyhow!(\"Failed converting gas limit to u64\"))?;\n\n        let amount_u128 = amount\n            .to_u128()\n            .ok_or_else(|| anyhow::anyhow!(\"Failed converting gas cost to u128\"))?;\n\n        Ok(Fee::from_amount_and_gas(\n            Coin {\n                amount: amount_u128,\n                denom: self\n                    .fee_denom\n                    .parse()\n                    .map_err(|e| anyhow::anyhow!(\"Invalid fee denom: {e}\"))?,\n            },\n            gas_limit_u64,\n        ))\n    }\n\n    /// Get default fee (zero fee).","sourceCodeStart":78,"sourceCodeEnd":114,"githubUrl":"https://github.com/nautechsystems/nautilus_trader/blob/18893faf8b356be3320add8de2f861b0b647cf06/crates/adapters/dydx/src/grpc/builder.rs#L78-L114","documentation":"calculate_fee_from_gas computes the fee as gas_price * gas_limit using Decimal arithmetic, then converts the gas limit back to u64 for the cosmrs Fee. If the Decimal gas limit cannot be represented as u64 (e.g. it is negative, fractional, or exceeds u64::MAX), the conversion fails and this error is returned.","triggerScenarios":"Calling calculate_fee (-> calculate_fee_from_gas) with a gas_limit Decimal that is negative, non-integer, or greater than 2^64-1.","commonSituations":"A misconfigured or corrupted gas estimate (e.g. gas limit parsed from an API response with unexpected units); passing a fractional Decimal like 0.5; an upstream simulation returning an absurdly large gas figure.","solutions":["Ensure the gas limit passed to calculate_fee is a non-negative whole number Decimal within u64 range (practically <= ~1.8e19, real txs use far less).","Sanity-clamp the gas estimate before calling: if gas_limit <= 0 or > a sane ceiling, fix the estimation source.","Check where the gas value originates (simulation response vs hardcoded default) and correct unit conversion there.","If a fractional gas value comes from averaging estimates, round it (e.g. .ceil()/.round()) before calling."],"exampleFix":"// before\nlet gas_limit = Decimal::new(-5, 0); // negative -> conversion fails\n// after\nlet gas_limit = Decimal::from(2_000_000u64); // valid whole-number gas limit","handlingStrategy":"validation","validationCode":"fn valid_gas_limit(g: Decimal) -> bool {\n    g.is_sign_positive() && g.fract().is_zero() && g <= Decimal::from(u64::MAX)\n}","typeGuard":null,"tryCatchPattern":"let fee = client.calculate_fee(instrument_id, gas_limit)\n    .map_err(|e| {\n        if e.to_string().contains(\"gas limit to u64\") {\n            // clamp/fix gas estimate at the source\n        }\n        e\n    })?;","preventionTips":["Clamp gas estimates to a sane ceiling (e.g. 50_000_000) before fee calculation","Round fractional gas values before passing Decimals","Validate upstream simulation responses for unit errors"],"tags":["dydx","fee","decimal-conversion","gas"],"backgroundTag":"value-out-of-range","analyzedSha":"18893faf8b356be3320add8de2f861b0b647cf06","analyzedAt":"2026-09-08T20:49:34.690Z","contentChangedAt":"2026-09-08T20:49:34.690Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}