0g-chain/x/pricefeed/keeper/keeper.go

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package keeper
import (
"fmt"
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"sort"
"time"
"github.com/tendermint/tendermint/libs/log"
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"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"
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"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
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// Codec for binary encoding/decoding
cdc *codec.Codec
// The reference to the Paramstore to get and set pricefeed specific params
paramSubspace subspace.Subspace
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}
// NewKeeper returns a new keeper for the pricefeed module.
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func NewKeeper(
cdc *codec.Codec, key sdk.StoreKey, paramstore subspace.Subspace,
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) Keeper {
if !paramstore.HasKeyTable() {
paramstore = paramstore.WithKeyTable(types.ParamKeyTable())
}
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return Keeper{
cdc: cdc,
key: key,
paramSubspace: paramstore,
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}
}
// Logger returns a module-specific logger.
func (k Keeper) Logger(ctx sdk.Context) log.Logger {
return ctx.Logger().With("module", fmt.Sprintf("x/%s", types.ModuleName))
}
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// SetPrice updates the posted price for a specific oracle
func (k Keeper) SetPrice(
ctx sdk.Context,
oracle sdk.AccAddress,
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marketID string,
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price sdk.Dec,
expiry time.Time) (types.PostedPrice, error) {
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// 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
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}
}
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// 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
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}
// 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
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}
// 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 {
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_, ok := k.GetMarket(ctx, marketID)
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if !ok {
return sdkerrors.Wrap(types.ErrInvalidMarket, marketID)
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}
// store current price
validPrevPrice := true
prevPrice, err := k.GetCurrentPrice(ctx, marketID)
if err != nil {
validPrevPrice = false
}
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prices, err := k.GetRawPrices(ctx, marketID)
if err != nil {
return err
}
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var notExpiredPrices types.CurrentPrices
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// filter out expired prices
for _, v := range prices {
if v.Expiry.After(ctx.BlockTime()) {
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notExpiredPrices = append(notExpiredPrices, types.NewCurrentPrice(v.MarketID, v.Price))
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}
}
if len(notExpiredPrices) == 0 {
// NOTE: The current price stored will continue storing the most recent (expired)
// price if this is not set.
// This zero's out the current price stored value for that market and ensures
// that CDP methods that GetCurrentPrice will return error.
k.setCurrentPrice(ctx, marketID, types.CurrentPrice{})
return types.ErrNoValidPrice
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}
medianPrice := k.CalculateMedianPrice(ctx, notExpiredPrices)
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// check case that market price was not set in genesis
if validPrevPrice && !medianPrice.Equal(prevPrice.Price) {
// only emit event if price has changed
ctx.EventManager().EmitEvent(
sdk.NewEvent(
types.EventTypeMarketPriceUpdated,
sdk.NewAttribute(types.AttributeMarketID, marketID),
sdk.NewAttribute(types.AttributeMarketPrice, medianPrice.String()),
),
)
}
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currentPrice := types.NewCurrentPrice(marketID, medianPrice)
k.setCurrentPrice(ctx, marketID, currentPrice)
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return nil
}
func (k Keeper) setCurrentPrice(ctx sdk.Context, marketID string, currentPrice types.CurrentPrice) {
store := ctx.KVStore(k.key)
store.Set(types.CurrentPriceKey(marketID), k.cdc.MustMarshalBinaryBare(currentPrice))
}
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// CalculateMedianPrice calculates the median prices for the input prices.
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func (k Keeper) CalculateMedianPrice(ctx sdk.Context, prices types.CurrentPrices) sdk.Dec {
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l := len(prices)
if l == 1 {
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// 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
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}
// for odd numbers of prices, return the middle element
return prices[l/2].Price
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}
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func (k Keeper) calculateMeanPrice(ctx sdk.Context, prices types.CurrentPrices) sdk.Dec {
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sum := prices[0].Price.Add(prices[1].Price)
mean := sum.Quo(sdk.NewDec(2))
return mean
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}
// 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)
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bz := store.Get(types.CurrentPriceKey(marketID))
if bz == nil {
return types.CurrentPrice{}, types.ErrNoValidPrice
}
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var price types.CurrentPrice
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err := k.cdc.UnmarshalBinaryBare(bz, &price)
if err != nil {
return types.CurrentPrice{}, err
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}
if price.Price.Equal(sdk.ZeroDec()) {
return types.CurrentPrice{}, types.ErrNoValidPrice
}
return price, nil
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}
// 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)
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bz := store.Get(types.RawPriceKey(marketID))
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if bz == nil {
return types.PostedPrices{}, nil
}
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var prices types.PostedPrices
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err := k.cdc.UnmarshalBinaryBare(bz, &prices)
if err != nil {
return types.PostedPrices{}, err
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}
return prices, nil
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}