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Optimized debt tokens

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This commit is contained in:
The3D 2020-08-22 19:33:55 +02:00
parent 4d054dd56d
commit 5b7a2f2a55
3 changed files with 48 additions and 48 deletions
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55
contracts/tokenization/StableDebtToken.sol
View File

@ -11,27 +11,17 @@ import {IStableDebtToken} from './interfaces/IStableDebtToken.sol';
/**
* @title contract StableDebtToken
*
* @notice defines the interface for the stable debt token
*
* @dev it does not inherit from IERC20 to save in code size
*
* @notice Implements a stable debt token to track the user positions
* @author Aave
*
**/
contract StableDebtToken is IStableDebtToken, DebtTokenBase {
using SafeMath for uint256;
using WadRayMath for uint256;
uint256 public constant DEBT_TOKEN_REVISION = 0x1;
struct UserData {
uint256 currentRate;
uint40 lastUpdateTimestamp;
}
uint256 private avgStableRate;
mapping(address => UserData) private _usersData;
uint256 private _avgStableRate;
mapping(address => uint40) _timestamps;
constructor(
address pool,
@ -53,7 +43,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
* @return the average stable rate
**/
function getAverageStableRate() external virtual override view returns (uint256) {
return avgStableRate;
return _avgStableRate;
}
/**
@ -61,7 +51,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
* @return the last update timestamp
**/
function getUserLastUpdated(address user) external virtual override view returns (uint40) {
return _usersData[user].lastUpdateTimestamp;
return _timestamps[user];
}
/**
@ -70,7 +60,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
* @return the stable rate of user
**/
function getUserStableRate(address user) external virtual override view returns (uint256) {
return _usersData[user].currentRate;
return _usersData[user].dataField;
}
/**
@ -78,16 +68,14 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
* @return the accumulated debt of the user
**/
function balanceOf(address account) public virtual override view returns (uint256) {
uint256 accountBalance = _balances[account];
uint256 accountBalance = _usersData[account].balance;
uint256 stableRate = _usersData[account].dataField;
if (accountBalance == 0) {
return 0;
}
UserData storage userData = _usersData[account];
uint256 cumulatedInterest = MathUtils.calculateCompoundedInterest(
userData.currentRate,
userData.lastUpdateTimestamp
stableRate,
_timestamps[account]
);
return accountBalance.wadToRay().rayMul(cumulatedInterest).rayToWad();
}
@ -126,19 +114,20 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
vars.amountInRay = amount.wadToRay();
//calculates the new stable rate for the user
vars.newStableRate = _usersData[user]
.currentRate
vars.newStableRate = uint256(_usersData[user]
.dataField)
.rayMul(currentBalance.wadToRay())
.add(vars.amountInRay.rayMul(rate))
.rayDiv(currentBalance.add(amount).wadToRay());
_usersData[user].currentRate = vars.newStableRate;
require(vars.newStableRate < (1 << 128), "Debt token: stable rate overflow");
_usersData[user].dataField = uint128(vars.newStableRate);
//solium-disable-next-line
_usersData[user].lastUpdateTimestamp = uint40(block.timestamp);
_timestamps[user] = uint40(block.timestamp);
//calculates the updated average stable rate
avgStableRate = avgStableRate
_avgStableRate = _avgStableRate
.rayMul(vars.supplyBeforeMint.wadToRay())
.add(rate.rayMul(vars.amountInRay))
.rayDiv(vars.supplyAfterMint.wadToRay());
@ -171,20 +160,20 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
uint256 supplyAfterBurn = supplyBeforeBurn.sub(amount);
if (supplyAfterBurn == 0) {
avgStableRate = 0;
_avgStableRate = 0;
} else {
avgStableRate = avgStableRate
_avgStableRate = _avgStableRate
.rayMul(supplyBeforeBurn.wadToRay())
.sub(_usersData[user].currentRate.rayMul(amount.wadToRay()))
.sub(uint256(_usersData[user].dataField).rayMul(amount.wadToRay()))
.rayDiv(supplyAfterBurn.wadToRay());
}
if (amount == currentBalance) {
_usersData[user].currentRate = 0;
_usersData[user].lastUpdateTimestamp = 0;
_usersData[user].dataField = 0;
_timestamps[user] = 0;
} else {
//solium-disable-next-line
_usersData[user].lastUpdateTimestamp = uint40(block.timestamp);
_timestamps[user] = uint40(block.timestamp);
}
if (balanceIncrease > amount) {

20
contracts/tokenization/VariableDebtToken.sol
View File

@ -9,10 +9,9 @@ import {WadRayMath} from '../libraries/math/WadRayMath.sol';
import {IVariableDebtToken} from './interfaces/IVariableDebtToken.sol';
/**
* @title interface IVariableDebtToken
* @title contract VariableDebtToken
* @notice Implements a variable debt token to track the user positions
* @author Aave
* @notice defines the basic interface for a variable debt token.
* @dev does not inherit from IERC20 to save in contract size
**/
contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
using SafeMath for uint256;
@ -20,8 +19,6 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
uint256 public constant DEBT_TOKEN_REVISION = 0x1;
mapping(address => uint256) private _userIndexes;
constructor(
address pool,
address underlyingAsset,
@ -42,7 +39,8 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
* @return the debt balance of the user
**/
function balanceOf(address user) public virtual override view returns (uint256) {
uint256 userBalance = _balances[user];
uint256 userBalance = _usersData[user].balance;
uint256 index = _usersData[user].dataField;
if (userBalance == 0) {
return 0;
}
@ -51,7 +49,7 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
userBalance
.wadToRay()
.rayMul(_pool.getReserveNormalizedVariableDebt(_underlyingAssetAddress))
.rayDiv(_userIndexes[user])
.rayDiv(index)
.rayToWad();
}
@ -61,7 +59,7 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
**/
function getUserIndex(address user) external virtual override view returns (uint256) {
return _userIndexes[user];
return _usersData[user].dataField;
}
/**
@ -79,7 +77,8 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
_mint(user, amount.add(balanceIncrease));
uint256 newUserIndex = _pool.getReserveNormalizedVariableDebt(_underlyingAssetAddress);
_userIndexes[user] = newUserIndex;
require(newUserIndex < (1 << 128), "Debt token: Index overflow");
_usersData[user].dataField = uint128(newUserIndex);
emit MintDebt(user, amount, previousBalance, currentBalance, balanceIncrease, newUserIndex);
}
@ -106,8 +105,9 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
//if user not repaid everything
if (currentBalance != amount) {
newUserIndex = _pool.getReserveNormalizedVariableDebt(_underlyingAssetAddress);
require(newUserIndex < (1 << 128), "Debt token: Index overflow");
}
_userIndexes[user] = newUserIndex;
_usersData[user].dataField = uint128(newUserIndex);
emit BurnDebt(user, amount, previousBalance, currentBalance, balanceIncrease, newUserIndex);
}

21
contracts/tokenization/base/DebtTokenBase.sol
View File

@ -27,7 +27,14 @@ abstract contract DebtTokenBase is IERC20Detailed, VersionedInitializable {
address internal immutable _underlyingAssetAddress;
ILendingPool internal immutable _pool;
mapping(address => uint256) internal _balances;
struct UserData{
uint128 balance;
//this field will store the user index for the variable debt token, and the user stable rate for the stable debt token
uint128 dataField;
}
mapping(address => UserData) internal _usersData;
/**
* @dev only lending pool can call functions marked by this modifier
@ -96,7 +103,7 @@ abstract contract DebtTokenBase is IERC20Detailed, VersionedInitializable {
* @return the debt balance of the user since the last burn/mint action
**/
function principalBalanceOf(address user) public view returns (uint256) {
return _balances[user];
return _usersData[user].balance;
}
/**
@ -106,7 +113,9 @@ abstract contract DebtTokenBase is IERC20Detailed, VersionedInitializable {
**/
function _mint(address user, uint256 amount) internal {
_totalSupply = _totalSupply.add(amount);
_balances[user] = _balances[user].add(amount);
uint256 result = amount.add(_usersData[user].balance);
require(result < (1 << 128), "Debt token: balance overflow");
_usersData[user].balance = uint128(result);
}
/**
@ -116,7 +125,9 @@ abstract contract DebtTokenBase is IERC20Detailed, VersionedInitializable {
**/
function _burn(address user, uint256 amount) internal {
_totalSupply = _totalSupply.sub(amount);
_balances[user] = _balances[user].sub(amount);
uint256 result = uint256(_usersData[user].balance).sub(amount);
require(result < (1 << 128), "Debt token: balance overflow");
_usersData[user].balance = uint128(result);
}
/**
@ -176,7 +187,7 @@ abstract contract DebtTokenBase is IERC20Detailed, VersionedInitializable {
uint256
)
{
uint256 previousPrincipalBalance = _balances[user];
uint256 previousPrincipalBalance = _usersData[user].balance;
if (previousPrincipalBalance == 0) {
return (0, 0, 0);