Token Upgrade System

The token upgrade system is used to implement secure smart contract upgrades, allowing contract logic to be updated while maintaining state and balances. This tutorial will explain how to implement an upgradeable token system.

Features

Transparent proxy pattern
UUPS proxy pattern
State-preserving upgrades
Permission control mechanism
Security check mechanism

Contract Implementation

solidity

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

import "@openzeppelin/contracts-upgradeable/token/ERC20/ERC20Upgradeable.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "@openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import "@openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";

/**
 * @title UpgradeableToken
 * @dev Upgradeable token contract implementation (UUPS pattern)
 */
contract UpgradeableToken is 
    Initializable,
    ERC20Upgradeable,
    OwnableUpgradeable,
    UUPSUpgradeable
{
    // Version number
    uint256 public version;
    
    // Minter permission mapping
    mapping(address => bool) public minters;
    
    // Blacklist mapping
    mapping(address => bool) public blacklist;
    
    // Events
    event MinterAdded(address indexed account);
    event MinterRemoved(address indexed account);
    event Blacklisted(address indexed account);
    event UnBlacklisted(address indexed account);
    event TokensRecovered(address indexed token, uint256 amount);

    /// @custom:oz-upgrades-unsafe-allow constructor
    constructor() {
        _disableInitializers();
    }

    /**
     * @dev Initialization function (replaces constructor)
     */
    function initialize(
        string memory name,
        string memory symbol,
        uint256 initialSupply
    ) public initializer {
        __ERC20_init(name, symbol);
        __Ownable_init();
        __UUPSUpgradeable_init();
        
        version = 1;
        _mint(msg.sender, initialSupply);
    }

    /**
     * @dev Mint tokens (minters only)
     */
    function mint(address to, uint256 amount) external {
        require(minters[msg.sender], "Not a minter");
        _mint(to, amount);
    }

    /**
     * @dev Burn tokens
     */
    function burn(uint256 amount) external {
        _burn(msg.sender, amount);
    }

    /**
     * @dev Add minter (owner only)
     */
    function addMinter(address account) external onlyOwner {
        require(account != address(0), "Invalid address");
        require(!minters[account], "Already a minter");
        minters[account] = true;
        emit MinterAdded(account);
    }

    /**
     * @dev Remove minter (owner only)
     */
    function removeMinter(address account) external onlyOwner {
        require(minters[account], "Not a minter");
        minters[account] = false;
        emit MinterRemoved(account);
    }

    /**
     * @dev Add to blacklist (owner only)
     */
    function blacklistAddress(address account) external onlyOwner {
        require(account != address(0), "Invalid address");
        require(!blacklist[account], "Already blacklisted");
        blacklist[account] = true;
        emit Blacklisted(account);
    }

    /**
     * @dev Remove from blacklist (owner only)
     */
    function unBlacklistAddress(address account) external onlyOwner {
        require(blacklist[account], "Not blacklisted");
        blacklist[account] = false;
        emit UnBlacklisted(account);
    }

    /**
     * @dev Check blacklist before transfer
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual override {
        super._beforeTokenTransfer(from, to, amount);
        require(!blacklist[from] && !blacklist[to], "Address blacklisted");
    }

    /**
     * @dev Authorize upgrade (owner only)
     */
    function _authorizeUpgrade(address newImplementation) internal override onlyOwner {
        // Additional upgrade check logic can be added here
    }

    /**
     * @dev Get current version
     */
    function getVersion() external view returns (uint256) {
        return version;
    }

    /**
     * @dev Recover accidentally transferred tokens (owner only)
     */
    function recoverToken(
        address token,
        uint256 amount
    ) external onlyOwner {
        require(token != address(this), "Cannot recover native token");
        IERC20Upgradeable(token).transfer(owner(), amount);
        emit TokensRecovered(token, amount);
    }
}

/**
 * @title UpgradeableTokenV2
 * @dev Example of upgradeable token contract V2 version
 */
contract UpgradeableTokenV2 is UpgradeableToken {
    // New state variables
    uint256 public maxSupply;
    mapping(address => bool) public vips;
    
    // New events
    event VipAdded(address indexed account);
    event VipRemoved(address indexed account);
    
    /**
     * @dev Initialize V2 version
     */
    function initializeV2(uint256 _maxSupply) external reinitializer(2) {
        maxSupply = _maxSupply;
        version = 2;
    }
    
    /**
     * @dev Add VIP (owner only)
     */
    function addVip(address account) external onlyOwner {
        require(account != address(0), "Invalid address");
        require(!vips[account], "Already a VIP");
        vips[account] = true;
        emit VipAdded(account);
    }
    
    /**
     * @dev Remove VIP (owner only)
     */
    function removeVip(address account) external onlyOwner {
        require(vips[account], "Not a VIP");
        vips[account] = false;
        emit VipRemoved(account);
    }
    
    /**
     * @dev Override mint function, add max supply check
     */
    function mint(address to, uint256 amount) external override {
        require(minters[msg.sender], "Not a minter");
        require(totalSupply() + amount <= maxSupply, "Exceeds max supply");
        _mint(to, amount);
    }
    
    /**
     * @dev VIP users get fee-free transfers
     */
    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal virtual override {
        super._beforeTokenTransfer(from, to, amount);
        // VIP users can bypass some restrictions
        if (vips[from] || vips[to]) {
            return;
        }
        // Restrictions for regular users can be added here
    }
}

Key Concepts

Proxy Pattern

The upgrade system supports:

UUPS proxy pattern
Transparent proxy pattern
State variable layout
Initialization mechanism

Version Management

Version control includes:

Version number tracking
Reinitialization
State migration
Compatibility check

Permission Control

Permission mechanism includes:

Owner permission
Mint permission
Upgrade authorization
Blacklist management

Security Considerations

Upgrade Security
- State layout check
- Initialization protection
- Permission verification
- Logic verification
Permission Management
- Role separation
- Permission check
- Operation restriction
- Event recording
State Protection
- Variable layout
- Storage conflict
- Data migration
- Rollback mechanism
Business Security
- Blacklist mechanism
- Transfer restriction
- Mint control
- Error handling

Best Practices

Upgrade Process
- Thorough testing
- Gradual upgrade
- State verification
- Rollback预案
Contract Design
- Modular structure
- Clear interface
- Complete event
- Detailed comments
Test Verification
- Unit test
- Integration test
- Upgrade test
- Security audit
Operation and Maintenance
- Monitoring system
- Log analysis
- Emergency response
- Regular inspection

Extended Features

Multi-signature upgrade
Time-lock upgrade
Automated testing
State migration tool
Version rollback

Application Scenarios

Function upgrade
- Add new features
- Fix vulnerabilities
- Optimize performance
- Update rules
Governance upgrade
- Parameter adjustment
- Rule change
- Permission update
- Mechanism improvement
Compatibility upgrade
- Protocol adaptation
- Standard update
- Interface change
- Ecological integration

Summary

The token upgrade system is an important tool for maintaining smart contracts. Through this tutorial, you can:

Implement secure contract upgrades
Manage versions and states
Control upgrade permissions
Ensure system stability

Frequently Asked Questions (FAQ)

1. Basic Concepts

Q: What is token upgrade? A: Token upgrade is a contract update mechanism, with the main features including:

Function update
Data migration
Version control
Compatibility handling
Smooth transition

Q: What types of upgrade systems are there? A: The main types include:

Proxy upgrade
Migration upgrade
Data upgrade
Function upgrade
Emergency upgrade

Q: How to design upgrade strategies? A: Design points:

solidity

function upgrade(
    address newImplementation
) public onlyAdmin {
    // 1. Verify new implementation
    require(newImplementation != address(0), "Invalid implementation");
    require(newImplementation != implementation(), "Same implementation");
    
    // 2. Check compatibility
    require(
        IUpgradeable(newImplementation).supportsInterface(type(IToken).interfaceId),
        "Incompatible interface"
    );
    
    // 3. Execute upgrade
    _upgradeTo(newImplementation);
    emit Upgraded(newImplementation);
}

Q: How to manage upgrade processes? A: Management strategies:

Version management
Test verification
Approval process
Backup recovery
Monitoring feedback

Q: What are the risks of upgrade systems? A: The main risks include:

Data loss
Function interruption
Compatibility issues
Permission abuse
Upgrade failure

Q: How to protect upgrade security? A: Security measures include:

Multi-signature
Time locking
Data verification
Rollback mechanism
Emergency预案

Q: How to optimize upgrade mechanisms? A: Optimization strategies:

Storage layout
Gas optimization
Data compression
Batch processing
Incremental update

Q: How to improve system efficiency? A: Improvement solutions:

Parallel processing
Cache optimization
Intelligent scheduling
Automated processing
Resource optimization

5. Implementation details

Q: How to implement data migration? A: Implementation mechanism:

solidity

function migrateData(
    address oldContract,
    address newContract
) internal {
    // 1. Read old data
    OldStorage storage oldStorage = OldStorage(oldContract);
    
    // 2. Convert format
    NewData memory newData = convertData(oldStorage);
    
    // 3. Write to new storage
    NewStorage storage newStorage = NewStorage(newContract);
    newStorage.store(newData);
}

Q: How to handle emergency rollbacks? A: Handling mechanism:

State saving
Quick rollback
Data recovery
Verification check
Log recording

6. Best practices

Q: Upgrade system development suggestions? A: Development suggestions:

Complete testing
Security audit
Documentation improvement
Version management
Monitoring and warning

Q: How to improve system reliability? A: Improvement solutions:

Fault detection
Automatic recovery
State verification
Log recording
Backup mechanism

7. Error handling

Q: Common errors and solutions? A: Error types:

"Invalid implementation": Check address
"Upgrade failed": Retry upgrade
"Data corrupted": Restore data
"Not authorized": Permission check
"System locked": Wait for unlock

Q: How to handle abnormal situations? A: Handling mechanism:

Automatic rollback
Manual recovery
Error reporting
Notification mechanism
Compensation processing

8. Upgrade maintenance

Q: How to manage upgrade versions? A: Upgrade strategies:

Version planning
Compatibility testing
Gray release
Monitoring feedback
Emergency handling

Q: How to monitor system status? A: Monitoring solutions:

Version tracking
Performance monitoring
Error statistics
Usage analysis
Effect evaluation

9. Integration with other systems

Q: How to integrate with governance systems? A: Integration solutions:

Proposal mechanism
Vote control
Execution delay
State synchronization
Permission management

Q: How to implement cross-chain upgrades? A: Implementation strategies:

Coordinated upgrade
State synchronization
Data verification
Consistency guarantee
Exception handling

Token Upgrade System ​

Features ​

Contract Implementation ​

Key Concepts ​

Proxy Pattern ​

Version Management ​

Permission Control ​

Security Considerations ​

Best Practices ​

Extended Features ​

Application Scenarios ​

Summary ​

Frequently Asked Questions (FAQ) ​

1. Basic Concepts ​

2. Function-related ​

3. Security-related ​

4. Optimization-related ​

5. Implementation details ​

6. Best practices ​

7. Error handling ​

8. Upgrade maintenance ​

9. Integration with other systems ​

Token Upgrade System

Features

Contract Implementation

Key Concepts

Proxy Pattern

Version Management

Permission Control

Security Considerations

Best Practices

Extended Features

Application Scenarios

Summary

Frequently Asked Questions (FAQ)

1. Basic Concepts

2. Function-related

3. Security-related

4. Optimization-related

5. Implementation details

6. Best practices

7. Error handling

8. Upgrade maintenance

9. Integration with other systems