Non-Zero Balances

Initializing a storage variable from zero to a non-zero value is one of the most gas-intensive operations a contract can perform. It requires a total of 22,100 gas, including 20,000 gas for changing the value from zero to non-zero and 2,100 gas for cold storage access.

This is why the OpenZeppelin reentrancy guard marks functions as active or inactive using 1 and 2 instead of 0 and 1. Changing a storage variable from one non-zero value to another only costs 5,000 gas.

In practical applications of ERC20, you should avoid having ERC20 token balances drop to zero. Always keep a small amount in the balance. This approach can help achieve a similar effect. If an address frequently empties and reloads its account balance, it will lead to many zero-to-one writes, which are costly in terms of gas.

Difference Between Conflux Core Space and eSpace

Conflux provides two different environments for smart contracts: Core Space and eSpace. Core Space is optimized for high throughput and low latency, while eSpace is compatible with Ethereum, allowing for easy porting of Ethereum-based contracts.

In Core Space, the gas cost for storage operations is generally lower due to its unique consensus mechanism. eSpace, being Ethereum-compatible, follows a similar gas cost structure to Ethereum, but there are subtle differences due to the underlying Conflux blockchain architecture. Specific gas costs for the SSTORE opcode in eSpace might differ slightly from Ethereum's due to these optimizations.

For instance, while Ethereum charges 20,000 gas for a zero-to-non-zero storage write, eSpace might have slight variations based on the latest protocol updates.

Improved Contract Implementation

Below, we provide an improved contract implementation to manage balance updates efficiently:

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.13;

contract BalanceManagement {
    mapping(address => uint256) public balances;

    // Initialize with non-zero to avoid expensive zero to one write
    constructor() {
        balances[msg.sender] = 1; // Starts with 1 instead of 0
    }

    // Increment balance safely
    function incrementBalance(uint256 amount) external {
        require(amount > 0, "Amount must be positive");
        balances[msg.sender] += amount;
    }

    // Decrement balance, avoiding going to zero
    function decrementBalance(uint256 amount) external {
        require(balances[msg.sender] > amount, "Insufficient funds to decrement");
        balances[msg.sender] -= amount;
        if (balances[msg.sender] == 0) {
            balances[msg.sender] = 1; // Reset to 1 to avoid zero balance
        }
    }
}

Recommendations for Gas Optimization

🌟1. Use Non-Zero Balances: Ensure that token balances do not drop to zero. Implement logic to reset the balance to a small positive value if it ever reaches zero.

🌟2. Optimize Storage Initialization: Start storage variables at a non-zero value to avoid costly initializations and manage subsequent updates carefully to keep modifications within non-zero values.