✅Gas Saving Technique 19: Early Validation before external call

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Introduction

Optimizing gas costs is crucial when developing smart contracts. An effective approach is implementing early validation checks before external calls are made. By ensuring the validity of function parameters or states beforehand, you can avoid unnecessary gas expenditure, especially if the function is likely to fail due to invalid inputs or states. This tutorial will elaborate on this gas-saving technique.

Impact & Details

Importance of Early Validation

• Avoiding Unnecessary Gas Costs: Early validations help prevent executing costly external calls that are destined to fail, saving gas.

• Enhanced Code Readability and Maintenance: This approach fosters a coding style that’s not only gas-efficient but also clear and maintainable.

Example: Implementing Early Validation

Below is a structured example to illustrate the importance of early validation:

Before Optimization:

solidityCopy code// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract ExampleContract {
    function withdrawAll() external returns (uint256) {
        ILendingPool lp = getLp();  // External call placed before the validation check
        if (balanceOf() == 0) {
            return 0;  // Function would fail here if balance is zero
        }
        // ... rest of the function ...
    }
}

After Optimization:

solidityCopy code// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract ExampleContract {
    function withdrawAll() external returns (uint256) {
        if (balanceOf() == 0) {
            return 0;  // Early validation prevents the external call if balance is zero, saving gas
        }
        ILendingPool lp = getLp();  // External call is made after validation
        // ... rest of the function ...
    }
}

Recommended Mitigation Steps

1. Early Validation Implementation: Review the smart contract, identify and implement validation checks before making external calls.

2. Rearrange Code Sequence: If necessary, rearrange the code to ensure validations are made as early as possible to avoid futile gas consumption in the case of function failure.

3. Test: After rearranging and implementing early checks, rigorously test the smart contract to ensure its functionality while observing the gas savings.

Conclusion

Implementing early validation checks before external calls is a practical and effective technique to optimize gas usage, especially in scenarios where functions might fail. This practice not only economizes gas but also results in cleaner, more understandable, and maintainable code. Always ensure thorough testing after making these optimizations to confirm improved gas efficiency without compromising the contract's functionality.