package keeper import ( "sort" "time" "github.com/cosmos/cosmos-sdk/codec" sdk "github.com/cosmos/cosmos-sdk/types" sdkerrors "github.com/cosmos/cosmos-sdk/types/errors" "github.com/cosmos/cosmos-sdk/x/params/subspace" "github.com/kava-labs/kava/x/pricefeed/types" ) // Keeper struct for pricefeed module type Keeper struct { // key used to access the stores from Context key sdk.StoreKey // Codec for binary encoding/decoding cdc *codec.Codec // The reference to the Paramstore to get and set pricefeed specific params paramSubspace subspace.Subspace } // NewKeeper returns a new keeper for the pricefeed module. func NewKeeper( cdc *codec.Codec, key sdk.StoreKey, paramstore subspace.Subspace, ) Keeper { if !paramstore.HasKeyTable() { paramstore = paramstore.WithKeyTable(types.ParamKeyTable()) } return Keeper{ cdc: cdc, key: key, paramSubspace: paramstore, } } // SetPrice updates the posted price for a specific oracle func (k Keeper) SetPrice( ctx sdk.Context, oracle sdk.AccAddress, marketID string, price sdk.Dec, expiry time.Time) (types.PostedPrice, error) { // If the expiry is less than or equal to the current blockheight, we consider the price valid if !expiry.After(ctx.BlockTime()) { return types.PostedPrice{}, types.ErrExpired } store := ctx.KVStore(k.key) prices, err := k.GetRawPrices(ctx, marketID) if err != nil { return types.PostedPrice{}, err } var index int found := false for i := range prices { if prices[i].OracleAddress.Equals(oracle) { index = i found = true break } } // set the price for that particular oracle if found { prices[index] = types.NewPostedPrice(marketID, oracle, price, expiry) } else { prices = append(prices, types.NewPostedPrice(marketID, oracle, price, expiry)) index = len(prices) - 1 } // Emit an event containing the oracle's new price ctx.EventManager().EmitEvent( sdk.NewEvent( types.EventTypeOracleUpdatedPrice, sdk.NewAttribute(types.AttributeMarketID, marketID), sdk.NewAttribute(types.AttributeOracle, oracle.String()), sdk.NewAttribute(types.AttributeMarketPrice, price.String()), sdk.NewAttribute(types.AttributeExpiry, expiry.UTC().String()), ), ) store.Set(types.RawPriceKey(marketID), k.cdc.MustMarshalBinaryBare(prices)) return prices[index], nil } // SetCurrentPrices updates the price of an asset to the median of all valid oracle inputs func (k Keeper) SetCurrentPrices(ctx sdk.Context, marketID string) error { _, ok := k.GetMarket(ctx, marketID) if !ok { return sdkerrors.Wrap(types.ErrInvalidMarket, marketID) } // store current price validPrevPrice := true prevPrice, err := k.GetCurrentPrice(ctx, marketID) if err != nil { validPrevPrice = false } prices, err := k.GetRawPrices(ctx, marketID) if err != nil { return err } var notExpiredPrices types.CurrentPrices // filter out expired prices for _, v := range prices { if v.Expiry.After(ctx.BlockTime()) { notExpiredPrices = append(notExpiredPrices, types.NewCurrentPrice(v.MarketID, v.Price)) } } if len(notExpiredPrices) == 0 { store := ctx.KVStore(k.key) store.Set( types.CurrentPriceKey(marketID), k.cdc.MustMarshalBinaryBare(types.CurrentPrice{}), ) return types.ErrNoValidPrice } medianPrice := k.CalculateMedianPrice(ctx, notExpiredPrices) // check case that market price was not set in genesis if validPrevPrice { // only emit event if price has changed if !medianPrice.Equal(prevPrice.Price) { ctx.EventManager().EmitEvent( sdk.NewEvent( types.EventTypeMarketPriceUpdated, sdk.NewAttribute(types.AttributeMarketID, marketID), sdk.NewAttribute(types.AttributeMarketPrice, medianPrice.String()), ), ) } } store := ctx.KVStore(k.key) currentPrice := types.NewCurrentPrice(marketID, medianPrice) store.Set( types.CurrentPriceKey(marketID), k.cdc.MustMarshalBinaryBare(currentPrice), ) return nil } // CalculateMedianPrice calculates the median prices for the input prices. func (k Keeper) CalculateMedianPrice(ctx sdk.Context, prices types.CurrentPrices) sdk.Dec { l := len(prices) if l == 1 { // Return immediately if there's only one price return prices[0].Price } // sort the prices sort.Slice(prices, func(i, j int) bool { return prices[i].Price.LT(prices[j].Price) }) // for even numbers of prices, the median is calculated as the mean of the two middle prices if l%2 == 0 { median := k.calculateMeanPrice(ctx, prices[l/2-1:l/2+1]) return median } // for odd numbers of prices, return the middle element return prices[l/2].Price } func (k Keeper) calculateMeanPrice(ctx sdk.Context, prices types.CurrentPrices) sdk.Dec { sum := prices[0].Price.Add(prices[1].Price) mean := sum.Quo(sdk.NewDec(2)) return mean } // GetCurrentPrice fetches the current median price of all oracles for a specific market func (k Keeper) GetCurrentPrice(ctx sdk.Context, marketID string) (types.CurrentPrice, error) { store := ctx.KVStore(k.key) bz := store.Get(types.CurrentPriceKey(marketID)) if bz == nil { return types.CurrentPrice{}, types.ErrNoValidPrice } var price types.CurrentPrice err := k.cdc.UnmarshalBinaryBare(bz, &price) if err != nil { return types.CurrentPrice{}, err } if price.Price.Equal(sdk.ZeroDec()) { return types.CurrentPrice{}, types.ErrNoValidPrice } return price, nil } // GetRawPrices fetches the set of all prices posted by oracles for an asset func (k Keeper) GetRawPrices(ctx sdk.Context, marketID string) (types.PostedPrices, error) { store := ctx.KVStore(k.key) bz := store.Get(types.RawPriceKey(marketID)) if bz == nil { return types.PostedPrices{}, nil } var prices types.PostedPrices err := k.cdc.UnmarshalBinaryBare(bz, &prices) if err != nil { return types.PostedPrices{}, err } return prices, nil }