0g-chain/x/cdp/keeper/savings.go
2020-04-30 10:13:31 -04:00

98 lines
4.4 KiB
Go

package keeper
import (
"time"
"github.com/cosmos/cosmos-sdk/store/prefix"
sdk "github.com/cosmos/cosmos-sdk/types"
sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
authexported "github.com/cosmos/cosmos-sdk/x/auth/exported"
authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
supplyexported "github.com/cosmos/cosmos-sdk/x/supply/exported"
auctiontypes "github.com/kava-labs/kava/x/auction/types"
"github.com/kava-labs/kava/x/cdp/types"
)
// DistributeSavingsRate distributes surplus that has accumulated in the liquidator account to address holding stable coins according the the savings rate
func (k Keeper) DistributeSavingsRate(ctx sdk.Context, debtDenom string) error {
dp, found := k.GetDebtParam(ctx, debtDenom)
if !found {
return sdkerrors.Wrap(types.ErrDebtNotSupported, debtDenom)
}
savingsRateMacc := k.supplyKeeper.GetModuleAccount(ctx, types.SavingsRateMacc)
surplusToDistribute := savingsRateMacc.GetCoins().AmountOf(dp.Denom)
if surplusToDistribute.IsZero() {
return nil
}
modAccountCoins := k.getModuleAccountCoins(ctx, dp.Denom)
totalSupplyLessModAccounts := k.supplyKeeper.GetSupply(ctx).GetTotal().Sub(modAccountCoins)
surplusDistributed := sdk.ZeroInt()
var iterationErr error
k.accountKeeper.IterateAccounts(ctx, func(acc authexported.Account) (stop bool) {
_, ok := acc.(supplyexported.ModuleAccountI)
if ok {
// don't distribute savings rate to module accounts
return false
}
debtAmount := acc.GetCoins().AmountOf(debtDenom)
if !debtAmount.IsPositive() {
return false
}
// (balance * rewardToDisribute) / totalSupply
// interest is the ratable fraction of savings rate owed to that account, rounded using bankers rounding
interest := (sdk.NewDecFromInt(debtAmount).Mul(sdk.NewDecFromInt(surplusToDistribute))).Quo(sdk.NewDecFromInt(totalSupplyLessModAccounts.AmountOf(debtDenom))).RoundInt()
// sanity check, if we are going to over-distribute due to rounding, distribute only the remaining savings rate that hasn't been distributed.
if interest.GT(surplusToDistribute.Sub(surplusDistributed)) {
interest = surplusToDistribute.Sub(surplusDistributed)
}
// sanity check - don't send saving rate if the rounded amount is zero
if !interest.IsPositive() {
return false
}
interestCoins := sdk.NewCoins(sdk.NewCoin(debtDenom, interest))
err := k.supplyKeeper.SendCoinsFromModuleToAccount(ctx, types.SavingsRateMacc, acc.GetAddress(), interestCoins)
if err != nil {
iterationErr = err
return true
}
surplusDistributed = surplusDistributed.Add(interest)
return false
})
if iterationErr != nil {
return iterationErr
}
return nil
}
// GetPreviousSavingsDistribution get the time of the previous savings rate distribution
func (k Keeper) GetPreviousSavingsDistribution(ctx sdk.Context) (distTime time.Time, found bool) {
store := prefix.NewStore(ctx.KVStore(k.key), types.PreviousDistributionTimeKey)
b := store.Get([]byte{})
if b == nil {
return time.Time{}, false
}
k.cdc.MustUnmarshalBinaryLengthPrefixed(b, &distTime)
return distTime, true
}
// SetPreviousSavingsDistribution set the time of the previous block
func (k Keeper) SetPreviousSavingsDistribution(ctx sdk.Context, distTime time.Time) {
store := prefix.NewStore(ctx.KVStore(k.key), types.PreviousDistributionTimeKey)
store.Set([]byte{}, k.cdc.MustMarshalBinaryLengthPrefixed(distTime))
}
func (k Keeper) getModuleAccountCoins(ctx sdk.Context, denom string) sdk.Coins {
// NOTE: these are the module accounts that could end up holding stable denoms at some point.
// Since there are currently no api methods to 'GetAllModuleAccounts', this function will need to be updated if a
// new module account is added which can hold stable denoms.
savingsRateMaccCoinAmount := k.supplyKeeper.GetModuleAccount(ctx, types.SavingsRateMacc).GetCoins().AmountOf(denom)
cdpMaccCoinAmount := k.supplyKeeper.GetModuleAccount(ctx, types.ModuleName).GetCoins().AmountOf(denom)
auctionMaccCoinAmount := k.supplyKeeper.GetModuleAccount(ctx, auctiontypes.ModuleName).GetCoins().AmountOf(denom)
liquidatorMaccCoinAmount := k.supplyKeeper.GetModuleAccount(ctx, types.LiquidatorMacc).GetCoins().AmountOf(denom)
feeMaccCoinAmount := k.supplyKeeper.GetModuleAccount(ctx, authtypes.FeeCollectorName).GetCoins().AmountOf(denom)
totalModAccountAmount := savingsRateMaccCoinAmount.Add(cdpMaccCoinAmount).Add(auctionMaccCoinAmount).Add(liquidatorMaccCoinAmount).Add(feeMaccCoinAmount)
return sdk.NewCoins(sdk.NewCoin(denom, totalModAccountAmount))
}