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TroveManager.sol
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TroveManager.sol
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// SPDX-License-Identifier: MIT
pragma solidity 0.6.11;
import "./Interfaces/ITroveManager.sol";
import "./Interfaces/IStabilityPool.sol";
import "./Interfaces/ICollSurplusPool.sol";
import "./Interfaces/ILUSDToken.sol";
import "./Interfaces/ISortedTroves.sol";
import "./Interfaces/ILQTYToken.sol";
import "./Interfaces/ILQTYStaking.sol";
import "./Dependencies/LiquityBase.sol";
import "./Dependencies/OwnableUpgradeable.sol";
import "./Dependencies/CheckContract.sol";
import "./Dependencies/console.sol";
contract TroveManager is LiquityBase, OwnableUpgradeable, CheckContract, ITroveManager {
string constant public NAME = "TroveManager";
// --- Connected contract declarations ---
address public borrowerOperationsAddress;
IStabilityPool public override stabilityPool;
address gasPoolAddress;
ICollSurplusPool collSurplusPool;
ILUSDToken public override lusdToken;
ILQTYToken public override lqtyToken;
ILQTYStaking public override lqtyStaking;
// A doubly linked list of Troves, sorted by their sorted by their collateral ratios
ISortedTroves public sortedTroves;
// --- Data structures ---
uint constant public SECONDS_IN_ONE_MINUTE = 60;
/*
* Half-life of 12h. 12h = 720 min
* (1/2) = d^720 => d = (1/2)^(1/720)
*/
uint constant public MINUTE_DECAY_FACTOR = 999037758833783000;
uint constant public REDEMPTION_FEE_FLOOR = DECIMAL_PRECISION / 1000 * 5; // 0.5%
uint constant public MAX_BORROWING_FEE = DECIMAL_PRECISION / 100 * 5; // 5%
// During bootsrap period redemptions are not allowed
uint constant public BOOTSTRAP_PERIOD = 14 days;
/*
* BETA: 18 digit decimal. Parameter by which to divide the redeemed fraction, in order to calc the new base rate from a redemption.
* Corresponds to (1 / ALPHA) in the white paper.
*/
uint constant public BETA = 2;
uint public baseRate;
// The timestamp of the latest fee operation (redemption or new LUSD issuance)
uint public lastFeeOperationTime;
enum Status {
nonExistent,
active,
closedByOwner,
closedByLiquidation,
closedByRedemption
}
// Store the necessary data for a trove
struct Trove {
uint debt;
uint coll;
uint stake;
Status status;
uint128 arrayIndex;
}
mapping (address => Trove) public Troves;
uint public totalStakes;
// Snapshot of the value of totalStakes, taken immediately after the latest liquidation
uint public totalStakesSnapshot;
// Snapshot of the total collateral across the ActivePool and DefaultPool, immediately after the latest liquidation.
uint public totalCollateralSnapshot;
/*
* L_ETH and L_LUSDDebt track the sums of accumulated liquidation rewards per unit staked. During its lifetime, each stake earns:
*
* An ETH gain of ( stake * [L_ETH - L_ETH(0)] )
* A LUSDDebt increase of ( stake * [L_LUSDDebt - L_LUSDDebt(0)] )
*
* Where L_ETH(0) and L_LUSDDebt(0) are snapshots of L_ETH and L_LUSDDebt for the active Trove taken at the instant the stake was made
*/
uint public L_ETH;
uint public L_LUSDDebt;
// Map addresses with active troves to their RewardSnapshot
mapping (address => RewardSnapshot) public rewardSnapshots;
// Object containing the ETH and LUSD snapshots for a given active trove
struct RewardSnapshot { uint ETH; uint LUSDDebt;}
// Array of all active trove addresses - used to to compute an approximate hint off-chain, for the sorted list insertion
address[] public TroveOwners;
// Error trackers for the trove redistribution calculation
uint public lastETHError_Redistribution;
uint public lastLUSDDebtError_Redistribution;
/*
* --- Variable container structs for liquidations ---
*
* These structs are used to hold, return and assign variables inside the liquidation functions,
* in order to avoid the error: "CompilerError: Stack too deep".
**/
struct LocalVariables_OuterLiquidationFunction {
uint price;
uint LUSDInStabPool;
bool recoveryModeAtStart;
uint liquidatedDebt;
uint liquidatedColl;
}
struct LocalVariables_InnerSingleLiquidateFunction {
uint collToLiquidate;
uint pendingDebtReward;
uint pendingCollReward;
}
struct LocalVariables_LiquidationSequence {
uint remainingLUSDInStabPool;
uint i;
uint ICR;
address user;
bool backToNormalMode;
uint entireSystemDebt;
uint entireSystemColl;
}
struct LiquidationValues {
uint entireTroveDebt;
uint entireTroveColl;
uint collGasCompensation;
uint LUSDGasCompensation;
uint debtToOffset;
uint collToSendToSP;
uint debtToRedistribute;
uint collToRedistribute;
uint collSurplus;
}
struct LiquidationTotals {
uint totalCollInSequence;
uint totalDebtInSequence;
uint totalCollGasCompensation;
uint totalLUSDGasCompensation;
uint totalDebtToOffset;
uint totalCollToSendToSP;
uint totalDebtToRedistribute;
uint totalCollToRedistribute;
uint totalCollSurplus;
}
struct ContractsCache {
IActivePool activePool;
IDefaultPool defaultPool;
ILUSDToken lusdToken;
ILQTYStaking lqtyStaking;
ISortedTroves sortedTroves;
ICollSurplusPool collSurplusPool;
address gasPoolAddress;
}
// --- Variable container structs for redemptions ---
struct RedemptionTotals {
uint remainingLUSD;
uint totalLUSDToRedeem;
uint totalETHDrawn;
uint ETHFee;
uint ETHToSendToRedeemer;
uint decayedBaseRate;
uint price;
uint totalLUSDSupplyAtStart;
}
struct SingleRedemptionValues {
uint LUSDLot;
uint ETHLot;
bool cancelledPartial;
}
// --- Events ---
event BorrowerOperationsAddressChanged(address _newBorrowerOperationsAddress);
event PriceFeedAddressChanged(address _newPriceFeedAddress);
event LUSDTokenAddressChanged(address _newLUSDTokenAddress);
event ActivePoolAddressChanged(address _activePoolAddress);
event DefaultPoolAddressChanged(address _defaultPoolAddress);
event StabilityPoolAddressChanged(address _stabilityPoolAddress);
event GasPoolAddressChanged(address _gasPoolAddress);
event CollSurplusPoolAddressChanged(address _collSurplusPoolAddress);
event SortedTrovesAddressChanged(address _sortedTrovesAddress);
event LQTYTokenAddressChanged(address _lqtyTokenAddress);
event LQTYStakingAddressChanged(address _lqtyStakingAddress);
event Liquidation(uint _liquidatedDebt, uint _liquidatedColl, uint _collGasCompensation, uint _LUSDGasCompensation);
event Redemption(uint _attemptedLUSDAmount, uint _actualLUSDAmount, uint _ETHSent, uint _ETHFee);
event TroveUpdated(address indexed _borrower, uint _debt, uint _coll, uint _stake, TroveManagerOperation _operation);
event TroveLiquidated(address indexed _borrower, uint _debt, uint _coll, TroveManagerOperation _operation);
event BaseRateUpdated(uint _baseRate);
event LastFeeOpTimeUpdated(uint _lastFeeOpTime);
event TotalStakesUpdated(uint _newTotalStakes);
event SystemSnapshotsUpdated(uint _totalStakesSnapshot, uint _totalCollateralSnapshot);
event LTermsUpdated(uint _L_ETH, uint _L_LUSDDebt);
event TroveSnapshotsUpdated(uint _L_ETH, uint _L_LUSDDebt);
event TroveIndexUpdated(address _borrower, uint _newIndex);
enum TroveManagerOperation {
applyPendingRewards,
liquidateInNormalMode,
liquidateInRecoveryMode,
redeemCollateral
}
// --- Dependency setter ---
function initialize() public initializer {
__Ownable_init();
}
function setAddresses(
address _borrowerOperationsAddress,
address _activePoolAddress,
address _defaultPoolAddress,
address _stabilityPoolAddress,
address _gasPoolAddress,
address _collSurplusPoolAddress,
address _priceFeedAddress,
address _lusdTokenAddress,
address _sortedTrovesAddress,
address _lqtyTokenAddress,
address _lqtyStakingAddress
)
external
override
onlyOwner
{
checkContract(_borrowerOperationsAddress);
checkContract(_activePoolAddress);
checkContract(_defaultPoolAddress);
checkContract(_stabilityPoolAddress);
checkContract(_gasPoolAddress);
checkContract(_collSurplusPoolAddress);
checkContract(_priceFeedAddress);
checkContract(_lusdTokenAddress);
checkContract(_sortedTrovesAddress);
checkContract(_lqtyTokenAddress);
checkContract(_lqtyStakingAddress);
borrowerOperationsAddress = _borrowerOperationsAddress;
activePool = IActivePool(_activePoolAddress);
defaultPool = IDefaultPool(_defaultPoolAddress);
stabilityPool = IStabilityPool(_stabilityPoolAddress);
gasPoolAddress = _gasPoolAddress;
collSurplusPool = ICollSurplusPool(_collSurplusPoolAddress);
priceFeed = IPriceFeed(_priceFeedAddress);
lusdToken = ILUSDToken(_lusdTokenAddress);
sortedTroves = ISortedTroves(_sortedTrovesAddress);
lqtyToken = ILQTYToken(_lqtyTokenAddress);
lqtyStaking = ILQTYStaking(_lqtyStakingAddress);
emit BorrowerOperationsAddressChanged(_borrowerOperationsAddress);
emit ActivePoolAddressChanged(_activePoolAddress);
emit DefaultPoolAddressChanged(_defaultPoolAddress);
emit StabilityPoolAddressChanged(_stabilityPoolAddress);
emit GasPoolAddressChanged(_gasPoolAddress);
emit CollSurplusPoolAddressChanged(_collSurplusPoolAddress);
emit PriceFeedAddressChanged(_priceFeedAddress);
emit LUSDTokenAddressChanged(_lusdTokenAddress);
emit SortedTrovesAddressChanged(_sortedTrovesAddress);
emit LQTYTokenAddressChanged(_lqtyTokenAddress);
emit LQTYStakingAddressChanged(_lqtyStakingAddress);
renounceOwnership();
}
// --- Getters ---
function getTroveOwnersCount() external view override returns (uint) {
return TroveOwners.length;
}
function getTroveFromTroveOwnersArray(uint _index) external view override returns (address) {
return TroveOwners[_index];
}
// --- Trove Liquidation functions ---
// Single liquidation function. Closes the trove if its ICR is lower than the minimum collateral ratio.
function liquidate(address _borrower) external override {
_requireTroveIsActive(_borrower);
address[] memory borrowers = new address[](1);
borrowers[0] = _borrower;
batchLiquidateTroves(borrowers);
}
// --- Inner single liquidation functions ---
// Liquidate one trove, in Normal Mode.
function _liquidateNormalMode(
IActivePool _activePool,
IDefaultPool _defaultPool,
address _borrower,
uint _LUSDInStabPool
)
internal
returns (LiquidationValues memory singleLiquidation)
{
LocalVariables_InnerSingleLiquidateFunction memory vars;
(singleLiquidation.entireTroveDebt,
singleLiquidation.entireTroveColl,
vars.pendingDebtReward,
vars.pendingCollReward) = getEntireDebtAndColl(_borrower);
_movePendingTroveRewardsToActivePool(_activePool, _defaultPool, vars.pendingDebtReward, vars.pendingCollReward);
_removeStake(_borrower);
singleLiquidation.collGasCompensation = _getCollGasCompensation(singleLiquidation.entireTroveColl);
singleLiquidation.LUSDGasCompensation = LUSD_GAS_COMPENSATION;
uint collToLiquidate = singleLiquidation.entireTroveColl.sub(singleLiquidation.collGasCompensation);
(singleLiquidation.debtToOffset,
singleLiquidation.collToSendToSP,
singleLiquidation.debtToRedistribute,
singleLiquidation.collToRedistribute) = _getOffsetAndRedistributionVals(singleLiquidation.entireTroveDebt, collToLiquidate, _LUSDInStabPool);
_closeTrove(_borrower, Status.closedByLiquidation);
emit TroveLiquidated(_borrower, singleLiquidation.entireTroveDebt, singleLiquidation.entireTroveColl, TroveManagerOperation.liquidateInNormalMode);
emit TroveUpdated(_borrower, 0, 0, 0, TroveManagerOperation.liquidateInNormalMode);
return singleLiquidation;
}
// Liquidate one trove, in Recovery Mode.
function _liquidateRecoveryMode(
IActivePool _activePool,
IDefaultPool _defaultPool,
address _borrower,
uint _ICR,
uint _LUSDInStabPool,
uint _TCR,
uint _price
)
internal
returns (LiquidationValues memory singleLiquidation)
{
LocalVariables_InnerSingleLiquidateFunction memory vars;
if (TroveOwners.length <= 1) {return singleLiquidation;} // don't liquidate if last trove
(singleLiquidation.entireTroveDebt,
singleLiquidation.entireTroveColl,
vars.pendingDebtReward,
vars.pendingCollReward) = getEntireDebtAndColl(_borrower);
singleLiquidation.collGasCompensation = _getCollGasCompensation(singleLiquidation.entireTroveColl);
singleLiquidation.LUSDGasCompensation = LUSD_GAS_COMPENSATION;
vars.collToLiquidate = singleLiquidation.entireTroveColl.sub(singleLiquidation.collGasCompensation);
// If ICR <= 100%, purely redistribute the Trove across all active Troves
if (_ICR <= _100pct) {
_movePendingTroveRewardsToActivePool(_activePool, _defaultPool, vars.pendingDebtReward, vars.pendingCollReward);
_removeStake(_borrower);
singleLiquidation.debtToOffset = 0;
singleLiquidation.collToSendToSP = 0;
singleLiquidation.debtToRedistribute = singleLiquidation.entireTroveDebt;
singleLiquidation.collToRedistribute = vars.collToLiquidate;
_closeTrove(_borrower, Status.closedByLiquidation);
emit TroveLiquidated(_borrower, singleLiquidation.entireTroveDebt, singleLiquidation.entireTroveColl, TroveManagerOperation.liquidateInRecoveryMode);
emit TroveUpdated(_borrower, 0, 0, 0, TroveManagerOperation.liquidateInRecoveryMode);
// If 100% < ICR < MCR, offset as much as possible, and redistribute the remainder
} else if ((_ICR > _100pct) && (_ICR < MCR)) {
_movePendingTroveRewardsToActivePool(_activePool, _defaultPool, vars.pendingDebtReward, vars.pendingCollReward);
_removeStake(_borrower);
(singleLiquidation.debtToOffset,
singleLiquidation.collToSendToSP,
singleLiquidation.debtToRedistribute,
singleLiquidation.collToRedistribute) = _getOffsetAndRedistributionVals(singleLiquidation.entireTroveDebt, vars.collToLiquidate, _LUSDInStabPool);
_closeTrove(_borrower, Status.closedByLiquidation);
emit TroveLiquidated(_borrower, singleLiquidation.entireTroveDebt, singleLiquidation.entireTroveColl, TroveManagerOperation.liquidateInRecoveryMode);
emit TroveUpdated(_borrower, 0, 0, 0, TroveManagerOperation.liquidateInRecoveryMode);
/*
* If 110% <= ICR < current TCR (accounting for the preceding liquidations in the current sequence)
* and there is LUSD in the Stability Pool, only offset, with no redistribution,
* but at a capped rate of 1.1 and only if the whole debt can be liquidated.
* The remainder due to the capped rate will be claimable as collateral surplus.
*/
} else if ((_ICR >= MCR) && (_ICR < _TCR) && (singleLiquidation.entireTroveDebt <= _LUSDInStabPool)) {
_movePendingTroveRewardsToActivePool(_activePool, _defaultPool, vars.pendingDebtReward, vars.pendingCollReward);
assert(_LUSDInStabPool != 0);
_removeStake(_borrower);
singleLiquidation = _getCappedOffsetVals(singleLiquidation.entireTroveDebt, singleLiquidation.entireTroveColl, _price);
_closeTrove(_borrower, Status.closedByLiquidation);
if (singleLiquidation.collSurplus > 0) {
collSurplusPool.accountSurplus(_borrower, singleLiquidation.collSurplus);
}
emit TroveLiquidated(_borrower, singleLiquidation.entireTroveDebt, singleLiquidation.collToSendToSP, TroveManagerOperation.liquidateInRecoveryMode);
emit TroveUpdated(_borrower, 0, 0, 0, TroveManagerOperation.liquidateInRecoveryMode);
} else { // if (_ICR >= MCR && ( _ICR >= _TCR || singleLiquidation.entireTroveDebt > _LUSDInStabPool))
LiquidationValues memory zeroVals;
return zeroVals;
}
return singleLiquidation;
}
/* In a full liquidation, returns the values for a trove's coll and debt to be offset, and coll and debt to be
* redistributed to active troves.
*/
function _getOffsetAndRedistributionVals
(
uint _debt,
uint _coll,
uint _LUSDInStabPool
)
internal
pure
returns (uint debtToOffset, uint collToSendToSP, uint debtToRedistribute, uint collToRedistribute)
{
if (_LUSDInStabPool > 0) {
/*
* Offset as much debt & collateral as possible against the Stability Pool, and redistribute the remainder
* between all active troves.
*
* If the trove's debt is larger than the deposited LUSD in the Stability Pool:
*
* - Offset an amount of the trove's debt equal to the LUSD in the Stability Pool
* - Send a fraction of the trove's collateral to the Stability Pool, equal to the fraction of its offset debt
*
*/
debtToOffset = LiquityMath._min(_debt, _LUSDInStabPool);
collToSendToSP = _coll.mul(debtToOffset).div(_debt);
debtToRedistribute = _debt.sub(debtToOffset);
collToRedistribute = _coll.sub(collToSendToSP);
} else {
debtToOffset = 0;
collToSendToSP = 0;
debtToRedistribute = _debt;
collToRedistribute = _coll;
}
}
/*
* Get its offset coll/debt and ETH gas comp, and close the trove.
*/
function _getCappedOffsetVals
(
uint _entireTroveDebt,
uint _entireTroveColl,
uint _price
)
internal
pure
returns (LiquidationValues memory singleLiquidation)
{
singleLiquidation.entireTroveDebt = _entireTroveDebt;
singleLiquidation.entireTroveColl = _entireTroveColl;
uint collToOffset = _entireTroveDebt.mul(MCR).div(_price);
singleLiquidation.collGasCompensation = _getCollGasCompensation(collToOffset);
singleLiquidation.LUSDGasCompensation = LUSD_GAS_COMPENSATION;
singleLiquidation.debtToOffset = _entireTroveDebt;
singleLiquidation.collToSendToSP = collToOffset.sub(singleLiquidation.collGasCompensation);
singleLiquidation.collSurplus = _entireTroveColl.sub(collToOffset);
singleLiquidation.debtToRedistribute = 0;
singleLiquidation.collToRedistribute = 0;
}
/*
* Liquidate a sequence of troves. Closes a maximum number of n under-collateralized Troves,
* starting from the one with the lowest collateral ratio in the system, and moving upwards
*/
function liquidateTroves(uint _n) external override {
ContractsCache memory contractsCache = ContractsCache(
activePool,
defaultPool,
ILUSDToken(address(0)),
ILQTYStaking(address(0)),
sortedTroves,
ICollSurplusPool(address(0)),
address(0)
);
IStabilityPool stabilityPoolCached = stabilityPool;
LocalVariables_OuterLiquidationFunction memory vars;
LiquidationTotals memory totals;
vars.price = priceFeed.fetchPrice();
vars.LUSDInStabPool = stabilityPoolCached.getTotalLUSDDeposits();
vars.recoveryModeAtStart = _checkRecoveryMode(vars.price);
// Perform the appropriate liquidation sequence - tally the values, and obtain their totals
if (vars.recoveryModeAtStart) {
totals = _getTotalsFromLiquidateTrovesSequence_RecoveryMode(contractsCache, vars.price, vars.LUSDInStabPool, _n);
} else { // if !vars.recoveryModeAtStart
totals = _getTotalsFromLiquidateTrovesSequence_NormalMode(contractsCache.activePool, contractsCache.defaultPool, vars.price, vars.LUSDInStabPool, _n);
}
require(totals.totalDebtInSequence > 0, "TroveManager: nothing to liquidate");
// Move liquidated ETH and LUSD to the appropriate pools
stabilityPoolCached.offset(totals.totalDebtToOffset, totals.totalCollToSendToSP);
_redistributeDebtAndColl(contractsCache.activePool, contractsCache.defaultPool, totals.totalDebtToRedistribute, totals.totalCollToRedistribute);
if (totals.totalCollSurplus > 0) {
contractsCache.activePool.sendETH(address(collSurplusPool), totals.totalCollSurplus);
}
// Update system snapshots
_updateSystemSnapshots_excludeCollRemainder(contractsCache.activePool, totals.totalCollGasCompensation);
vars.liquidatedDebt = totals.totalDebtInSequence;
vars.liquidatedColl = totals.totalCollInSequence.sub(totals.totalCollGasCompensation).sub(totals.totalCollSurplus);
emit Liquidation(vars.liquidatedDebt, vars.liquidatedColl, totals.totalCollGasCompensation, totals.totalLUSDGasCompensation);
// Send gas compensation to caller
_sendGasCompensation(contractsCache.activePool, msg.sender, totals.totalLUSDGasCompensation, totals.totalCollGasCompensation);
}
/*
* This function is used when the liquidateTroves sequence starts during Recovery Mode. However, it
* handle the case where the system *leaves* Recovery Mode, part way through the liquidation sequence
*/
function _getTotalsFromLiquidateTrovesSequence_RecoveryMode
(
ContractsCache memory _contractsCache,
uint _price,
uint _LUSDInStabPool,
uint _n
)
internal
returns(LiquidationTotals memory totals)
{
LocalVariables_LiquidationSequence memory vars;
LiquidationValues memory singleLiquidation;
vars.remainingLUSDInStabPool = _LUSDInStabPool;
vars.backToNormalMode = false;
vars.entireSystemDebt = getEntireSystemDebt();
vars.entireSystemColl = getEntireSystemColl();
vars.user = _contractsCache.sortedTroves.getLast();
address firstUser = _contractsCache.sortedTroves.getFirst();
for (vars.i = 0; vars.i < _n && vars.user != firstUser; vars.i++) {
// we need to cache it, because current user is likely going to be deleted
address nextUser = _contractsCache.sortedTroves.getPrev(vars.user);
vars.ICR = getCurrentICR(vars.user, _price);
if (!vars.backToNormalMode) {
// Break the loop if ICR is greater than MCR and Stability Pool is empty
if (vars.ICR >= MCR && vars.remainingLUSDInStabPool == 0) { break; }
uint TCR = LiquityMath._computeCR(vars.entireSystemColl, vars.entireSystemDebt, _price);
singleLiquidation = _liquidateRecoveryMode(_contractsCache.activePool, _contractsCache.defaultPool, vars.user, vars.ICR, vars.remainingLUSDInStabPool, TCR, _price);
// Update aggregate trackers
vars.remainingLUSDInStabPool = vars.remainingLUSDInStabPool.sub(singleLiquidation.debtToOffset);
vars.entireSystemDebt = vars.entireSystemDebt.sub(singleLiquidation.debtToOffset);
vars.entireSystemColl = vars.entireSystemColl.sub(singleLiquidation.collToSendToSP).sub(singleLiquidation.collSurplus);
// Add liquidation values to their respective running totals
totals = _addLiquidationValuesToTotals(totals, singleLiquidation);
vars.backToNormalMode = !_checkPotentialRecoveryMode(vars.entireSystemColl, vars.entireSystemDebt, _price);
}
else if (vars.backToNormalMode && vars.ICR < MCR) {
singleLiquidation = _liquidateNormalMode(_contractsCache.activePool, _contractsCache.defaultPool, vars.user, vars.remainingLUSDInStabPool);
vars.remainingLUSDInStabPool = vars.remainingLUSDInStabPool.sub(singleLiquidation.debtToOffset);
// Add liquidation values to their respective running totals
totals = _addLiquidationValuesToTotals(totals, singleLiquidation);
} else break; // break if the loop reaches a Trove with ICR >= MCR
vars.user = nextUser;
}
}
function _getTotalsFromLiquidateTrovesSequence_NormalMode
(
IActivePool _activePool,
IDefaultPool _defaultPool,
uint _price,
uint _LUSDInStabPool,
uint _n
)
internal
returns(LiquidationTotals memory totals)
{
LocalVariables_LiquidationSequence memory vars;
LiquidationValues memory singleLiquidation;
ISortedTroves sortedTrovesCached = sortedTroves;
vars.remainingLUSDInStabPool = _LUSDInStabPool;
for (vars.i = 0; vars.i < _n; vars.i++) {
vars.user = sortedTrovesCached.getLast();
vars.ICR = getCurrentICR(vars.user, _price);
if (vars.ICR < MCR) {
singleLiquidation = _liquidateNormalMode(_activePool, _defaultPool, vars.user, vars.remainingLUSDInStabPool);
vars.remainingLUSDInStabPool = vars.remainingLUSDInStabPool.sub(singleLiquidation.debtToOffset);
// Add liquidation values to their respective running totals
totals = _addLiquidationValuesToTotals(totals, singleLiquidation);
} else break; // break if the loop reaches a Trove with ICR >= MCR
}
}
/*
* Attempt to liquidate a custom list of troves provided by the caller.
*/
function batchLiquidateTroves(address[] memory _troveArray) public override {
require(_troveArray.length != 0, "TroveManager: Calldata address array must not be empty");
IActivePool activePoolCached = activePool;
IDefaultPool defaultPoolCached = defaultPool;
IStabilityPool stabilityPoolCached = stabilityPool;
LocalVariables_OuterLiquidationFunction memory vars;
LiquidationTotals memory totals;
vars.price = priceFeed.fetchPrice();
vars.LUSDInStabPool = stabilityPoolCached.getTotalLUSDDeposits();
vars.recoveryModeAtStart = _checkRecoveryMode(vars.price);
// Perform the appropriate liquidation sequence - tally values and obtain their totals.
if (vars.recoveryModeAtStart) {
totals = _getTotalFromBatchLiquidate_RecoveryMode(activePoolCached, defaultPoolCached, vars.price, vars.LUSDInStabPool, _troveArray);
} else { // if !vars.recoveryModeAtStart
totals = _getTotalsFromBatchLiquidate_NormalMode(activePoolCached, defaultPoolCached, vars.price, vars.LUSDInStabPool, _troveArray);
}
require(totals.totalDebtInSequence > 0, "TroveManager: nothing to liquidate");
// Move liquidated ETH and LUSD to the appropriate pools
stabilityPoolCached.offset(totals.totalDebtToOffset, totals.totalCollToSendToSP);
_redistributeDebtAndColl(activePoolCached, defaultPoolCached, totals.totalDebtToRedistribute, totals.totalCollToRedistribute);
if (totals.totalCollSurplus > 0) {
activePoolCached.sendETH(address(collSurplusPool), totals.totalCollSurplus);
}
// Update system snapshots
_updateSystemSnapshots_excludeCollRemainder(activePoolCached, totals.totalCollGasCompensation);
vars.liquidatedDebt = totals.totalDebtInSequence;
vars.liquidatedColl = totals.totalCollInSequence.sub(totals.totalCollGasCompensation).sub(totals.totalCollSurplus);
emit Liquidation(vars.liquidatedDebt, vars.liquidatedColl, totals.totalCollGasCompensation, totals.totalLUSDGasCompensation);
// Send gas compensation to caller
_sendGasCompensation(activePoolCached, msg.sender, totals.totalLUSDGasCompensation, totals.totalCollGasCompensation);
}
/*
* This function is used when the batch liquidation sequence starts during Recovery Mode. However, it
* handle the case where the system *leaves* Recovery Mode, part way through the liquidation sequence
*/
function _getTotalFromBatchLiquidate_RecoveryMode
(
IActivePool _activePool,
IDefaultPool _defaultPool,
uint _price,
uint _LUSDInStabPool,
address[] memory _troveArray
)
internal
returns(LiquidationTotals memory totals)
{
LocalVariables_LiquidationSequence memory vars;
LiquidationValues memory singleLiquidation;
vars.remainingLUSDInStabPool = _LUSDInStabPool;
vars.backToNormalMode = false;
vars.entireSystemDebt = getEntireSystemDebt();
vars.entireSystemColl = getEntireSystemColl();
for (vars.i = 0; vars.i < _troveArray.length; vars.i++) {
vars.user = _troveArray[vars.i];
// Skip non-active troves
if (Troves[vars.user].status != Status.active) { continue; }
vars.ICR = getCurrentICR(vars.user, _price);
if (!vars.backToNormalMode) {
// Skip this trove if ICR is greater than MCR and Stability Pool is empty
if (vars.ICR >= MCR && vars.remainingLUSDInStabPool == 0) { continue; }
uint TCR = LiquityMath._computeCR(vars.entireSystemColl, vars.entireSystemDebt, _price);
singleLiquidation = _liquidateRecoveryMode(_activePool, _defaultPool, vars.user, vars.ICR, vars.remainingLUSDInStabPool, TCR, _price);
// Update aggregate trackers
vars.remainingLUSDInStabPool = vars.remainingLUSDInStabPool.sub(singleLiquidation.debtToOffset);
vars.entireSystemDebt = vars.entireSystemDebt.sub(singleLiquidation.debtToOffset);
vars.entireSystemColl = vars.entireSystemColl.sub(singleLiquidation.collToSendToSP).sub(singleLiquidation.collSurplus);
// Add liquidation values to their respective running totals
totals = _addLiquidationValuesToTotals(totals, singleLiquidation);
vars.backToNormalMode = !_checkPotentialRecoveryMode(vars.entireSystemColl, vars.entireSystemDebt, _price);
}
else if (vars.backToNormalMode && vars.ICR < MCR) {
singleLiquidation = _liquidateNormalMode(_activePool, _defaultPool, vars.user, vars.remainingLUSDInStabPool);
vars.remainingLUSDInStabPool = vars.remainingLUSDInStabPool.sub(singleLiquidation.debtToOffset);
// Add liquidation values to their respective running totals
totals = _addLiquidationValuesToTotals(totals, singleLiquidation);
} else continue; // In Normal Mode skip troves with ICR >= MCR
}
}
function _getTotalsFromBatchLiquidate_NormalMode
(
IActivePool _activePool,
IDefaultPool _defaultPool,
uint _price,
uint _LUSDInStabPool,
address[] memory _troveArray
)
internal
returns(LiquidationTotals memory totals)
{
LocalVariables_LiquidationSequence memory vars;
LiquidationValues memory singleLiquidation;
vars.remainingLUSDInStabPool = _LUSDInStabPool;
for (vars.i = 0; vars.i < _troveArray.length; vars.i++) {
vars.user = _troveArray[vars.i];
vars.ICR = getCurrentICR(vars.user, _price);
if (vars.ICR < MCR) {
singleLiquidation = _liquidateNormalMode(_activePool, _defaultPool, vars.user, vars.remainingLUSDInStabPool);
vars.remainingLUSDInStabPool = vars.remainingLUSDInStabPool.sub(singleLiquidation.debtToOffset);
// Add liquidation values to their respective running totals
totals = _addLiquidationValuesToTotals(totals, singleLiquidation);
}
}
}
// --- Liquidation helper functions ---
function _addLiquidationValuesToTotals(LiquidationTotals memory oldTotals, LiquidationValues memory singleLiquidation)
internal pure returns(LiquidationTotals memory newTotals) {
// Tally all the values with their respective running totals
newTotals.totalCollGasCompensation = oldTotals.totalCollGasCompensation.add(singleLiquidation.collGasCompensation);
newTotals.totalLUSDGasCompensation = oldTotals.totalLUSDGasCompensation.add(singleLiquidation.LUSDGasCompensation);
newTotals.totalDebtInSequence = oldTotals.totalDebtInSequence.add(singleLiquidation.entireTroveDebt);
newTotals.totalCollInSequence = oldTotals.totalCollInSequence.add(singleLiquidation.entireTroveColl);
newTotals.totalDebtToOffset = oldTotals.totalDebtToOffset.add(singleLiquidation.debtToOffset);
newTotals.totalCollToSendToSP = oldTotals.totalCollToSendToSP.add(singleLiquidation.collToSendToSP);
newTotals.totalDebtToRedistribute = oldTotals.totalDebtToRedistribute.add(singleLiquidation.debtToRedistribute);
newTotals.totalCollToRedistribute = oldTotals.totalCollToRedistribute.add(singleLiquidation.collToRedistribute);
newTotals.totalCollSurplus = oldTotals.totalCollSurplus.add(singleLiquidation.collSurplus);
return newTotals;
}
function _sendGasCompensation(IActivePool _activePool, address _liquidator, uint _LUSD, uint _ETH) internal {
if (_LUSD > 0) {
lusdToken.returnFromPool(gasPoolAddress, _liquidator, _LUSD);
}
if (_ETH > 0) {
_activePool.sendETH(_liquidator, _ETH);
}
}
// Move a Trove's pending debt and collateral rewards from distributions, from the Default Pool to the Active Pool
function _movePendingTroveRewardsToActivePool(IActivePool _activePool, IDefaultPool _defaultPool, uint _LUSD, uint _ETH) internal {
_defaultPool.decreaseLUSDDebt(_LUSD);
_activePool.increaseLUSDDebt(_LUSD);
_defaultPool.sendETHToActivePool(_ETH);
}
// --- Redemption functions ---
// Redeem as much collateral as possible from _borrower's Trove in exchange for LUSD up to _maxLUSDamount
function _redeemCollateralFromTrove(
ContractsCache memory _contractsCache,
address _borrower,
uint _maxLUSDamount,
uint _price,
address _upperPartialRedemptionHint,
address _lowerPartialRedemptionHint,
uint _partialRedemptionHintNICR
)
internal returns (SingleRedemptionValues memory singleRedemption)
{
// Determine the remaining amount (lot) to be redeemed, capped by the entire debt of the Trove minus the liquidation reserve
singleRedemption.LUSDLot = LiquityMath._min(_maxLUSDamount, Troves[_borrower].debt.sub(LUSD_GAS_COMPENSATION));
// Get the ETHLot of equivalent value in USD
singleRedemption.ETHLot = singleRedemption.LUSDLot.mul(DECIMAL_PRECISION).div(_price);
// Decrease the debt and collateral of the current Trove according to the LUSD lot and corresponding ETH to send
uint newDebt = (Troves[_borrower].debt).sub(singleRedemption.LUSDLot);
uint newColl = (Troves[_borrower].coll).sub(singleRedemption.ETHLot);
if (newDebt == LUSD_GAS_COMPENSATION) {
// No debt left in the Trove (except for the liquidation reserve), therefore the trove gets closed
_removeStake(_borrower);
_closeTrove(_borrower, Status.closedByRedemption);
_redeemCloseTrove(_contractsCache, _borrower, LUSD_GAS_COMPENSATION, newColl);
emit TroveUpdated(_borrower, 0, 0, 0, TroveManagerOperation.redeemCollateral);
} else {
uint newNICR = LiquityMath._computeNominalCR(newColl, newDebt);
/*
* If the provided hint is out of date, we bail since trying to reinsert without a good hint will almost
* certainly result in running out of gas.
*
* If the resultant net debt of the partial is less than the minimum, net debt we bail.
*/
if (newNICR != _partialRedemptionHintNICR || _getNetDebt(newDebt) < MIN_NET_DEBT) {
singleRedemption.cancelledPartial = true;
return singleRedemption;
}
_contractsCache.sortedTroves.reInsert(_borrower, newNICR, _upperPartialRedemptionHint, _lowerPartialRedemptionHint);
Troves[_borrower].debt = newDebt;
Troves[_borrower].coll = newColl;
_updateStakeAndTotalStakes(_borrower);
emit TroveUpdated(
_borrower,
newDebt, newColl,
Troves[_borrower].stake,
TroveManagerOperation.redeemCollateral
);
}
return singleRedemption;
}
/*
* Called when a full redemption occurs, and closes the trove.
* The redeemer swaps (debt - liquidation reserve) LUSD for (debt - liquidation reserve) worth of ETH, so the LUSD liquidation reserve left corresponds to the remaining debt.
* In order to close the trove, the LUSD liquidation reserve is burned, and the corresponding debt is removed from the active pool.
* The debt recorded on the trove's struct is zero'd elswhere, in _closeTrove.
* Any surplus ETH left in the trove, is sent to the Coll surplus pool, and can be later claimed by the borrower.
*/
function _redeemCloseTrove(ContractsCache memory _contractsCache, address _borrower, uint _LUSD, uint _ETH) internal {
_contractsCache.lusdToken.burn(gasPoolAddress, _LUSD);
// Update Active Pool LUSD, and send ETH to account
_contractsCache.activePool.decreaseLUSDDebt(_LUSD);
// send ETH from Active Pool to CollSurplus Pool
_contractsCache.collSurplusPool.accountSurplus(_borrower, _ETH);
_contractsCache.activePool.sendETH(address(_contractsCache.collSurplusPool), _ETH);
}
function _isValidFirstRedemptionHint(ISortedTroves _sortedTroves, address _firstRedemptionHint, uint _price) internal view returns (bool) {
if (_firstRedemptionHint == address(0) ||
!_sortedTroves.contains(_firstRedemptionHint) ||
getCurrentICR(_firstRedemptionHint, _price) < MCR
) {
return false;
}
address nextTrove = _sortedTroves.getNext(_firstRedemptionHint);
return nextTrove == address(0) || getCurrentICR(nextTrove, _price) < MCR;
}
/* Send _LUSDamount LUSD to the system and redeem the corresponding amount of collateral from as many Troves as are needed to fill the redemption
* request. Applies pending rewards to a Trove before reducing its debt and coll.
*
* Note that if _amount is very large, this function can run out of gas, specially if traversed troves are small. This can be easily avoided by
* splitting the total _amount in appropriate chunks and calling the function multiple times.
*
* Param `_maxIterations` can also be provided, so the loop through Troves is capped (if it’s zero, it will be ignored).This makes it easier to
* avoid OOG for the frontend, as only knowing approximately the average cost of an iteration is enough, without needing to know the “topology”
* of the trove list. It also avoids the need to set the cap in stone in the contract, nor doing gas calculations, as both gas price and opcode
* costs can vary.
*
* All Troves that are redeemed from -- with the likely exception of the last one -- will end up with no debt left, therefore they will be closed.
* If the last Trove does have some remaining debt, it has a finite ICR, and the reinsertion could be anywhere in the list, therefore it requires a hint.
* A frontend should use getRedemptionHints() to calculate what the ICR of this Trove will be after redemption, and pass a hint for its position
* in the sortedTroves list along with the ICR value that the hint was found for.
*
* If another transaction modifies the list between calling getRedemptionHints() and passing the hints to redeemCollateral(), it
* is very likely that the last (partially) redeemed Trove would end up with a different ICR than what the hint is for. In this case the
* redemption will stop after the last completely redeemed Trove and the sender will keep the remaining LUSD amount, which they can attempt
* to redeem later.
*/
function redeemCollateral(
uint _LUSDamount,
address _firstRedemptionHint,
address _upperPartialRedemptionHint,
address _lowerPartialRedemptionHint,
uint _partialRedemptionHintNICR,
uint _maxIterations,
uint _maxFeePercentage
)
external
override
{
ContractsCache memory contractsCache = ContractsCache(
activePool,
defaultPool,
lusdToken,
lqtyStaking,
sortedTroves,
collSurplusPool,
gasPoolAddress
);
RedemptionTotals memory totals;
_requireValidMaxFeePercentage(_maxFeePercentage);
_requireAfterBootstrapPeriod();
totals.price = priceFeed.fetchPrice();
_requireTCRoverMCR(totals.price);
_requireAmountGreaterThanZero(_LUSDamount);
_requireLUSDBalanceCoversRedemption(contractsCache.lusdToken, msg.sender, _LUSDamount);
totals.totalLUSDSupplyAtStart = getEntireSystemDebt();
// Confirm redeemer's balance is less than total LUSD supply
assert(contractsCache.lusdToken.balanceOf(msg.sender) <= totals.totalLUSDSupplyAtStart);
totals.remainingLUSD = _LUSDamount;
address currentBorrower;
if (_isValidFirstRedemptionHint(contractsCache.sortedTroves, _firstRedemptionHint, totals.price)) {
currentBorrower = _firstRedemptionHint;
} else {
currentBorrower = contractsCache.sortedTroves.getLast();
// Find the first trove with ICR >= MCR
while (currentBorrower != address(0) && getCurrentICR(currentBorrower, totals.price) < MCR) {
currentBorrower = contractsCache.sortedTroves.getPrev(currentBorrower);
}
}
// Loop through the Troves starting from the one with lowest collateral ratio until _amount of LUSD is exchanged for collateral
if (_maxIterations == 0) { _maxIterations = uint(-1); }
while (currentBorrower != address(0) && totals.remainingLUSD > 0 && _maxIterations > 0) {
_maxIterations--;
// Save the address of the Trove preceding the current one, before potentially modifying the list
address nextUserToCheck = contractsCache.sortedTroves.getPrev(currentBorrower);
_applyPendingRewards(contractsCache.activePool, contractsCache.defaultPool, currentBorrower);
SingleRedemptionValues memory singleRedemption = _redeemCollateralFromTrove(
contractsCache,
currentBorrower,
totals.remainingLUSD,
totals.price,
_upperPartialRedemptionHint,
_lowerPartialRedemptionHint,
_partialRedemptionHintNICR
);
if (singleRedemption.cancelledPartial) break; // Partial redemption was cancelled (out-of-date hint, or new net debt < minimum), therefore we could not redeem from the last Trove
totals.totalLUSDToRedeem = totals.totalLUSDToRedeem.add(singleRedemption.LUSDLot);
totals.totalETHDrawn = totals.totalETHDrawn.add(singleRedemption.ETHLot);
totals.remainingLUSD = totals.remainingLUSD.sub(singleRedemption.LUSDLot);
currentBorrower = nextUserToCheck;
}
require(totals.totalETHDrawn > 0, "TroveManager: Unable to redeem any amount");
// Decay the baseRate due to time passed, and then increase it according to the size of this redemption.
// Use the saved total LUSD supply value, from before it was reduced by the redemption.