0g-chain/x/cdp/keeper/seize.go
Kevin Davis e913dc2ff0
Fix misleading comments from audit (#592)
* fix misleading or incorrect comments

* fix unnecessary variable declaration

* fix punctuation
2020-06-17 14:40:44 -04:00

100 lines
3.6 KiB
Go

package keeper
import (
"fmt"
sdk "github.com/cosmos/cosmos-sdk/types"
"github.com/kava-labs/kava/x/cdp/types"
)
// SeizeCollateral liquidates the collateral in the input cdp.
// the following operations are performed:
// 1. Collateral for all deposits is sent from the cdp module to the liquidator module account
// 2. The liquidation penalty is applied
// 3. Debt coins are sent from the cdp module to the liquidator module account
// 4. The total amount of principal outstanding for that collateral type is decremented
// (this is the equivalent of saying that fees are no longer accumulated by a cdp once it gets liquidated)
func (k Keeper) SeizeCollateral(ctx sdk.Context, cdp types.CDP) error {
// Calculate the previous collateral ratio
oldCollateralToDebtRatio := k.CalculateCollateralToDebtRatio(ctx, cdp.Collateral, cdp.Principal.Add(cdp.AccumulatedFees))
// Move debt coins from cdp to liquidator account
deposits := k.GetDeposits(ctx, cdp.ID)
debt := cdp.Principal.Amount.Add(cdp.AccumulatedFees.Amount)
modAccountDebt := k.getModAccountDebt(ctx, types.ModuleName)
debt = sdk.MinInt(debt, modAccountDebt)
debtCoin := sdk.NewCoin(k.GetDebtDenom(ctx), debt)
err := k.supplyKeeper.SendCoinsFromModuleToModule(ctx, types.ModuleName, types.LiquidatorMacc, sdk.NewCoins(debtCoin))
if err != nil {
return err
}
// liquidate deposits and send collateral from cdp to liquidator
for _, dep := range deposits {
err := k.supplyKeeper.SendCoinsFromModuleToModule(ctx, types.ModuleName, types.LiquidatorMacc, sdk.NewCoins(dep.Amount))
if err != nil {
return err
}
k.DeleteDeposit(ctx, dep.CdpID, dep.Depositor)
ctx.EventManager().EmitEvent(
sdk.NewEvent(
types.EventTypeCdpLiquidation,
sdk.NewAttribute(sdk.AttributeKeyModule, types.AttributeValueCategory),
sdk.NewAttribute(types.AttributeKeyCdpID, fmt.Sprintf("%d", cdp.ID)),
sdk.NewAttribute(types.AttributeKeyDeposit, dep.String()),
),
)
}
err = k.AuctionCollateral(ctx, deposits, debt, cdp.Principal.Denom)
if err != nil {
return err
}
// Decrement total principal for this collateral type
coinsToDecrement := cdp.Principal.Add(cdp.AccumulatedFees)
k.DecrementTotalPrincipal(ctx, cdp.Collateral.Denom, coinsToDecrement)
// Delete CDP from state
k.RemoveCdpOwnerIndex(ctx, cdp)
k.RemoveCdpCollateralRatioIndex(ctx, cdp.Collateral.Denom, cdp.ID, oldCollateralToDebtRatio)
return k.DeleteCDP(ctx, cdp)
}
// LiquidateCdps seizes collateral from all CDPs below the input liquidation ratio
func (k Keeper) LiquidateCdps(ctx sdk.Context, marketID string, denom string, liquidationRatio sdk.Dec) error {
price, err := k.pricefeedKeeper.GetCurrentPrice(ctx, marketID)
if err != nil {
return err
}
priceDivLiqRatio := price.Price.Quo(liquidationRatio)
if priceDivLiqRatio.IsZero() {
priceDivLiqRatio = sdk.SmallestDec()
}
// price = $0.5
// liquidation ratio = 1.5
// normalizedRatio = (1/(0.5/1.5)) = 3
normalizedRatio := sdk.OneDec().Quo(priceDivLiqRatio)
cdpsToLiquidate := k.GetAllCdpsByDenomAndRatio(ctx, denom, normalizedRatio)
for _, c := range cdpsToLiquidate {
err := k.SeizeCollateral(ctx, c)
if err != nil {
return err
}
}
return nil
}
// ApplyLiquidationPenalty multiplies the input debt amount by the liquidation penalty
func (k Keeper) ApplyLiquidationPenalty(ctx sdk.Context, denom string, debt sdk.Int) sdk.Int {
penalty := k.getLiquidationPenalty(ctx, denom)
return sdk.NewDecFromInt(debt).Mul(penalty).RoundInt()
}
func (k Keeper) getModAccountDebt(ctx sdk.Context, accountName string) sdk.Int {
macc := k.supplyKeeper.GetModuleAccount(ctx, accountName)
return macc.GetCoins().AmountOf(k.GetDebtDenom(ctx))
}