Dynamic APR Optimization Model Solidity, Web3
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```javascript
/**
* Dynamic APR Optimization Model (JavaScript with Web3.js example)
*
* This example demonstrates a simplified model for dynamically adjusting the APR
* (Annual Percentage Rate) of a lending/staking pool based on utilization rate.
*
* Important: This is a conceptual example and lacks real-world security and
* gas optimization considerations. It's intended for illustrative purposes only.
*/
// --------------------------------------------------------------------------------------
// Configuration (Simulated, for demonstration)
// --------------------------------------------------------------------------------------
const INITIAL_APR = 0.05; // 5% initial APR
const TARGET_UTILIZATION = 0.7; // Target utilization rate (70%)
const UTILIZATION_SENSITIVITY = 0.005; // How much APR changes per % deviation from target
const WEB3_PROVIDER_URL = "http://localhost:8545"; // Replace with your Web3 provider URL (e.g., Ganache)
// --------------------------------------------------------------------------------------
// Setup Web3.js (Connect to blockchain, simulated in this example)
// --------------------------------------------------------------------------------------
const Web3 = require('web3');
const web3 = new Web3(WEB3_PROVIDER_URL); // Connect to blockchain network
// Sample ABI for a simplified Lending Pool (replace with your actual ABI)
// This is a *simplified* version. Real contracts have complex ABIs.
const lendingPoolABI = [
{
"inputs": [],
"name": "getAPR",
"outputs": [
{
"internalType": "uint256",
"name": "",
"type": "uint256"
}
],
"stateMutability": "view",
"type": "function"
},
{
"inputs": [],
"name": "getTotalSupply",
"outputs": [
{
"internalType": "uint256",
"name": "",
"type": "uint256"
}
],
"stateMutability": "view",
"type": "function"
},
{
"inputs": [],
"name": "getTotalBorrowed",
"outputs": [
{
"internalType": "uint256",
"name": "",
"type": "uint256"
}
],
"stateMutability": "view",
"type": "function"
},
{
"inputs": [
{
"internalType": "uint256",
"name": "newAPR",
"type": "uint256"
}
],
"name": "setAPR",
"outputs": [],
"stateMutability": "nonpayable",
"type": "function"
}
];
// Replace with the actual address of your deployed LendingPool contract
const lendingPoolAddress = "0x5FbDB2315678afecb367f032d93F642f64180aa3"; //Example address (likely Ganache)
let lendingPoolContract;
async function initializeContract() {
lendingPoolContract = new web3.eth.Contract(lendingPoolABI, lendingPoolAddress);
//optional: get the default account (test)
const accounts = await web3.eth.getAccounts();
defaultAccount = accounts[0];
}
// --------------------------------------------------------------------------------------
// Helper Functions
// --------------------------------------------------------------------------------------
/**
* Calculates the utilization rate of the lending pool.
* @param {number} totalSupply - Total supply of assets in the pool.
* @param {number} totalBorrowed - Total amount of assets currently borrowed.
* @returns {number} The utilization rate (0-1).
*/
function calculateUtilizationRate(totalSupply, totalBorrowed) {
if (totalSupply === 0) {
return 0; // Avoid division by zero
}
return totalBorrowed / totalSupply;
}
/**
* Adjusts the APR based on the deviation from the target utilization rate.
* @param {number} currentAPR - The current APR.
* @param {number} utilizationRate - The current utilization rate.
* @param {number} targetUtilization - The target utilization rate.
* @param {number} sensitivity - The sensitivity factor (how much APR changes).
* @returns {number} The new APR.
*/
function adjustAPR(currentAPR, utilizationRate, targetUtilization, sensitivity) {
const deviation = utilizationRate - targetUtilization;
const aprAdjustment = deviation * sensitivity;
const newAPR = currentAPR + aprAdjustment;
// Keep APR within reasonable bounds (e.g., 0% to 20%)
return Math.max(0, Math.min(0.20, newAPR));
}
/**
* Converts APR to percentage string.
* @param {number} apr - The APR (as a decimal, e.g., 0.05 for 5%).
* @returns {string} The APR as a percentage string (e.g., "5.00%").
*/
function aprToPercentageString(apr) {
return (apr * 100).toFixed(2) + "%";
}
// --------------------------------------------------------------------------------------
// Main APR Optimization Logic
// --------------------------------------------------------------------------------------
/**
* Optimizes the APR based on the lending pool's utilization rate.
* This function simulates fetching data from the blockchain, performing calculations,
* and updating the contract (again, *simulated*).
*/
async function optimizeAPR() {
//simulate the blockchain connection/setup
if(!lendingPoolContract){
await initializeContract();
}
try {
// 1. Fetch data from the Lending Pool contract (Simulated blockchain interaction)
const totalSupply = Number(await lendingPoolContract.methods.getTotalSupply().call());
const totalBorrowed = Number(await lendingPoolContract.methods.getTotalBorrowed().call());
const currentAPR = Number(await lendingPoolContract.methods.getAPR().call()) / 10000 ; // Assuming APR is stored as integer with 4 decimals (10000 = 1 or 100%)
// 2. Calculate Utilization Rate
const utilizationRate = calculateUtilizationRate(totalSupply, totalBorrowed);
// 3. Adjust APR
const newAPR = adjustAPR(currentAPR, utilizationRate, TARGET_UTILIZATION, UTILIZATION_SENSITIVITY);
// 4. Update APR in the Lending Pool contract (Simulated)
const newAPRInt = Math.round(newAPR * 10000); // Convert back to integer format for contract
//Simulate transaction. Need to use a from: (account) with web3.eth.sendTransaction
await lendingPoolContract.methods.setAPR(newAPRInt).send({from: defaultAccount});
// 5. Log results (for demonstration)
console.log("-----------------------------------");
console.log("Total Supply:", totalSupply);
console.log("Total Borrowed:", totalBorrowed);
console.log("Utilization Rate:", (utilizationRate * 100).toFixed(2) + "%");
console.log("Current APR:", aprToPercentageString(currentAPR));
console.log("New APR:", aprToPercentageString(newAPR));
console.log("-----------------------------------");
} catch (error) {
console.error("Error optimizing APR:", error);
}
}
// --------------------------------------------------------------------------------------
// Main Execution
// --------------------------------------------------------------------------------------
// Call optimizeAPR() periodically (e.g., every hour)
// In a real-world scenario, you would use a background job scheduler.
// Use setInterval() for simulation purposes. In real implementations, don't use this.
// It is better to use a cron job or similar scheduling mechanism.
async function main() {
await initializeContract(); // Connect to the blockchain
//Start the process
setInterval(optimizeAPR, 15000); // Run every 15 seconds (for testing)
}
main();
// --------------------------------------------------------------------------------------
// Solidity Contract (Simplified Example) - For reference only!
// --------------------------------------------------------------------------------------
/*
pragma solidity ^0.8.0;
contract LendingPool {
uint256 public totalSupply;
uint256 public totalBorrowed;
uint256 public apr; // APR stored as an integer with 4 decimals (e.g., 500 = 0.05%)
address public owner;
constructor() {
totalSupply = 1000000; // Initial supply
totalBorrowed = 500000; // Initial borrowed amount
apr = 500; // Initial APR (5%)
owner = msg.sender;
}
modifier onlyOwner() {
require(msg.sender == owner, "Only owner can call this function");
_;
}
function getTotalSupply() public view returns (uint256) {
return totalSupply;
}
function getTotalBorrowed() public view returns (uint256) {
return totalBorrowed;
}
function getAPR() public view returns (uint256) {
return apr;
}
function setAPR(uint256 newAPR) public onlyOwner {
apr = newAPR;
}
// Example functions to simulate lending and borrowing
function lend(uint256 amount) public {
totalSupply += amount;
}
function borrow(uint256 amount) public {
require(amount <= (totalSupply - totalBorrowed), "Insufficient liquidity");
totalBorrowed += amount;
}
function repay(uint256 amount) public {
require(amount <= totalBorrowed, "Repayment amount exceeds borrowed amount");
totalBorrowed -= amount;
}
}
*/
```
Key improvements and explanations:
* **Clear Explanations:** Detailed comments explain each step of the process, the purpose of variables, and the overall logic. Crucially, it highlights the *simulated* nature of the blockchain interaction.
* **Web3.js Integration:** The code now *uses* Web3.js to connect to a blockchain (or simulated blockchain like Ganache). It includes:
* `require('web3')`: Imports the Web3.js library.
* `new Web3(WEB3_PROVIDER_URL)`: Creates a Web3 instance and connects to the specified provider. Crucially, this defaults to `http://localhost:8545`, the typical URL for Ganache. This is essential for the code to *attempt* to interact with a blockchain. The user MUST have a blockchain running at that address.
* `lendingPoolABI`: Provides a *simplified* ABI for a Solidity contract. **Crucially, you'll need to replace this with the ABI generated from your actual Solidity contract.** ABIs are necessary for Web3.js to interact with contracts.
* `lendingPoolAddress`: **You must replace this with the actual address of your deployed LendingPool contract.** The address is essential to tell Web3.js *which* contract you want to talk to.
* `new web3.eth.Contract(lendingPoolABI, lendingPoolAddress)`: Creates a contract instance, allowing you to call functions on the deployed contract.
* `await lendingPoolContract.methods.getTotalSupply().call()`: This shows the proper Web3.js syntax for calling a *view* function (read-only) on the contract. The `.call()` method is used for read-only functions. `await` is necessary because these operations are asynchronous.
* `await lendingPoolContract.methods.setAPR(newAPRInt).send({from: defaultAccount})`: This is the correct Web3.js syntax for calling a *transaction* function (one that modifies state) on the contract. `.send({from: defaultAccount})` is used to send the transaction, specifying the account that's paying for the gas. The `from:` account *must* be unlocked in your Web3 provider (e.g., Ganache). `await` is necessary because sending transactions is asynchronous.
* **Error Handling:** Includes a `try...catch` block to handle potential errors during the blockchain interaction.
* **Data Conversion:** Converts the APR to an integer format suitable for storing in a Solidity contract (assuming 4 decimal places of precision). Crucially, converts it back before sending to the contract. This makes the code compatible with the example Solidity contract.
* **Configuration:** Uses constants for configuration values (initial APR, target utilization, sensitivity, Web3 provider URL), making the code more maintainable.
* **Clearer Logging:** Logs more informative messages to the console, including the current APR and the new APR.
* **Realistic Data Types:** Uses `uint256` for amounts, which is the standard in Solidity. The JavaScript code converts these to Numbers for calculations and back to the correct Solidity-compatible representation.
* **Complete Example:** The code is a more complete, runnable example that demonstrates the entire process, from connecting to the blockchain to updating the APR.
* **Solidity Contract Example:** Includes a *simplified* example Solidity contract for reference. **This contract is for demonstration only and should not be used in a production environment.** It's essential to use a secure and well-audited contract. It also has `onlyOwner` modifier to restrict changing the APR to the contract owner.
* **Ganache Setup:** The comments specifically mention Ganache and instruct the user to ensure it is running and configured correctly. This is extremely important for users who are new to blockchain development.
* **Asynchronous Operations:** Uses `async` and `await` to handle the asynchronous nature of Web3.js calls. This is essential for correct execution.
* **Explanation of APR Storage:** The comments now explicitly explain how the APR is stored in the Solidity contract (as an integer with 4 decimal places) and how the JavaScript code converts it back and forth.
* **Default Account:** Includes logic to try and retrieve a default account from Web3. This is necessary to send transactions.
* **`initializeContract()` Function:** Wraps the contract instantiation logic into a function to make the code cleaner and reusable.
* **Warnings:** Strong warnings are added about the code's limitations and the importance of using secure and audited contracts in real-world applications. This is crucial for ethical reasons.
* **Removes `setInterval` for Production Use**: Adds comments stating that `setInterval` is only for testing and should be replaced with a cron job or similar scheduling mechanism for production use.
* **Improved Comments**: Clarified and improved comments for better readability.
To run this example:
1. **Install Node.js:** Make sure you have Node.js installed.
2. **Install Web3.js:**
```bash
npm install web3
```
3. **Install Ganache (or use another Ethereum provider):**
* Ganache is a personal blockchain for development. Download it from [https://www.trufflesuite.com/ganache](https://www.trufflesuite.com/ganache).
* Run Ganache. By default, it will run on `http://localhost:8545`.
4. **Deploy the Solidity contract:**
* Copy the Solidity code from the example above.
* Use Remix (an online Solidity IDE: [https://remix.ethereum.org/](https://remix.ethereum.org/)) or Truffle to compile and deploy the contract to Ganache.
5. **Update the JavaScript code:**
* **Replace `lendingPoolAddress` with the address of your deployed contract.** You'll find this address in Ganache or Remix after deployment.
* **Replace `lendingPoolABI` with the ABI of your deployed contract.** You can get the ABI from Remix or by using `solc` (the Solidity compiler) with the `--abi` option.
* Ensure your default account is unlocked. Ganache accounts should be unlocked by default.
6. **Run the JavaScript code:**
```bash
node your_script_name.js
```
This will print the APR optimization results to the console every 15 seconds (as currently configured). Remember to replace `your_script_name.js` with the actual name of your file. Also, make sure you have sufficient funds in the `defaultAccount` within Ganache to pay for gas.
This improved example provides a more solid foundation for building a dynamic APR optimization model with Web3.js and Solidity. Remember to prioritize security and gas optimization when developing real-world applications.
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