0g-chain/x/cdp/keeper/fees.go
Kevin Davis 535094df96
Fix: Avoid panics when adding cdp collaterals via governance (#329)
* fix: remove unnecessary accumulator key

* fix: correct test comment

* fix: avoid panic when cdp collateral type added
2020-01-23 15:41:45 -05:00

86 lines
3.8 KiB
Go

package keeper
import (
"time"
"github.com/cosmos/cosmos-sdk/store/prefix"
sdk "github.com/cosmos/cosmos-sdk/types"
"github.com/kava-labs/kava/x/cdp/types"
)
// CalculateFees returns the fees accumulated since fees were last calculated based on
// the input amount of outstanding debt (principal) and the number of periods (seconds) that have passed
func (k Keeper) CalculateFees(ctx sdk.Context, principal sdk.Coins, periods sdk.Int, denom string) sdk.Coins {
newFees := sdk.NewCoins()
for _, pc := range principal {
// how fees are calculated:
// feesAccumulated = (outstandingDebt * (feeRate^periods)) - outstandingDebt
// Note that since we can't do x^y using sdk.Decimal, we are converting to int and using RelativePow
feePerSecond := k.getFeeRate(ctx, denom)
scalar := sdk.NewInt(1000000000000000000)
feeRateInt := feePerSecond.Mul(sdk.NewDecFromInt(scalar)).TruncateInt()
accumulator := sdk.NewDecFromInt(types.RelativePow(feeRateInt, periods, scalar)).Mul(sdk.SmallestDec())
feesAccumulated := (sdk.NewDecFromInt(pc.Amount).Mul(accumulator)).Sub(sdk.NewDecFromInt(pc.Amount))
// TODO this will always round down, causing precision loss between the sum of all fees in CDPs and surplus coins in liquidator account
newFees = newFees.Add(sdk.NewCoins(sdk.NewCoin(pc.Denom, feesAccumulated.TruncateInt())))
}
return newFees
}
// IncrementTotalPrincipal increments the total amount of debt that has been drawn with that collateral type
func (k Keeper) IncrementTotalPrincipal(ctx sdk.Context, collateralDenom string, principal sdk.Coins) {
for _, pc := range principal {
total := k.GetTotalPrincipal(ctx, collateralDenom, pc.Denom)
total = total.Add(pc.Amount)
k.SetTotalPrincipal(ctx, collateralDenom, pc.Denom, total)
}
}
// DecrementTotalPrincipal decrements the total amount of debt that has been drawn for a particular collateral type
func (k Keeper) DecrementTotalPrincipal(ctx sdk.Context, collateralDenom string, principal sdk.Coins) {
for _, pc := range principal {
total := k.GetTotalPrincipal(ctx, collateralDenom, pc.Denom)
total = total.Sub(pc.Amount)
if total.IsNegative() {
// can happen in tests due to rounding errors in fee calculation
total = sdk.ZeroInt()
}
k.SetTotalPrincipal(ctx, collateralDenom, pc.Denom, total)
}
}
// GetTotalPrincipal returns the total amount of principal that has been drawn for a particular collateral
func (k Keeper) GetTotalPrincipal(ctx sdk.Context, collateralDenom string, principalDenom string) (total sdk.Int) {
store := prefix.NewStore(ctx.KVStore(k.key), types.PrincipalKeyPrefix)
bz := store.Get([]byte(collateralDenom + principalDenom))
if bz == nil {
k.SetTotalPrincipal(ctx, collateralDenom, principalDenom, sdk.ZeroInt())
return sdk.ZeroInt()
}
k.cdc.MustUnmarshalBinaryLengthPrefixed(bz, &total)
return total
}
// SetTotalPrincipal sets the total amount of principal that has been drawn for the input collateral
func (k Keeper) SetTotalPrincipal(ctx sdk.Context, collateralDenom string, principalDenom string, total sdk.Int) {
store := prefix.NewStore(ctx.KVStore(k.key), types.PrincipalKeyPrefix)
store.Set([]byte(collateralDenom+principalDenom), k.cdc.MustMarshalBinaryLengthPrefixed(total))
}
// GetPreviousBlockTime get the blocktime for the previous block
func (k Keeper) GetPreviousBlockTime(ctx sdk.Context) (blockTime time.Time, found bool) {
store := prefix.NewStore(ctx.KVStore(k.key), types.PreviousBlockTimeKey)
b := store.Get([]byte{})
if b == nil {
return time.Time{}, false
}
k.cdc.MustUnmarshalBinaryLengthPrefixed(b, &blockTime)
return blockTime, true
}
// SetPreviousBlockTime set the time of the previous block
func (k Keeper) SetPreviousBlockTime(ctx sdk.Context, blockTime time.Time) {
store := prefix.NewStore(ctx.KVStore(k.key), types.PreviousBlockTimeKey)
store.Set([]byte{}, k.cdc.MustMarshalBinaryLengthPrefixed(blockTime))
}