mirror of
https://github.com/0glabs/0g-chain.git
synced 2024-12-25 07:45:18 +00:00
* Optimize Pricefeed EndBlocker (#1851) * optimize pricefeed endblocker to iterate all markets only once to remove overhead of opening and closing iterator for each market individually. In addition, extend tests to cover 100% of abci and price updating behavior. * use test cases that can't be confused with mean to ensure median is always used * update kvtool to master branch * update changelog --------- Co-authored-by: Nick DeLuca <nickdeluca08@gmail.com>
This commit is contained in:
parent
77e63c421e
commit
af611ca8e1
@ -1,2 +1,2 @@
|
||||
golang 1.21
|
||||
golang 1.21.9
|
||||
nodejs 18.16.0
|
||||
|
@ -36,6 +36,9 @@ Ref: https://keepachangelog.com/en/1.0.0/
|
||||
|
||||
## [Unreleased]
|
||||
|
||||
### Improvements
|
||||
- (pricefeed) [#1851] optimize EndBlocker to iterate all markets only once
|
||||
|
||||
## [v0.26.0]
|
||||
|
||||
### Features
|
||||
@ -330,6 +333,7 @@ the [changelog](https://github.com/cosmos/cosmos-sdk/blob/v0.38.4/CHANGELOG.md).
|
||||
- [#257](https://github.com/Kava-Labs/kava/pulls/257) Include scripts to run
|
||||
large-scale simulations remotely using aws-batch
|
||||
|
||||
[#1851]: https://github.com/Kava-Labs/kava/pull/1851
|
||||
[#1846]: https://github.com/Kava-Labs/kava/pull/1846
|
||||
[#1848]: https://github.com/Kava-Labs/kava/pull/1848
|
||||
[#1839]: https://github.com/Kava-Labs/kava/pull/1839
|
||||
|
@ -1 +1 @@
|
||||
Subproject commit 79bb25f47d20c10e70f0539c519240fba82b3302
|
||||
Subproject commit 567dfb80905be7d83ba2d33cc5dba9daf0af789c
|
@ -1,7 +1,6 @@
|
||||
package pricefeed
|
||||
|
||||
import (
|
||||
"errors"
|
||||
"time"
|
||||
|
||||
"github.com/cosmos/cosmos-sdk/telemetry"
|
||||
@ -14,15 +13,5 @@ import (
|
||||
func EndBlocker(ctx sdk.Context, k keeper.Keeper) {
|
||||
defer telemetry.ModuleMeasureSince(types.ModuleName, time.Now(), telemetry.MetricKeyEndBlocker)
|
||||
|
||||
// Update the current price of each asset.
|
||||
for _, market := range k.GetMarkets(ctx) {
|
||||
if !market.Active {
|
||||
continue
|
||||
}
|
||||
|
||||
err := k.SetCurrentPrices(ctx, market.MarketID)
|
||||
if err != nil && !errors.Is(err, types.ErrNoValidPrice) {
|
||||
panic(err)
|
||||
}
|
||||
}
|
||||
k.SetCurrentPricesForAllMarkets(ctx)
|
||||
}
|
||||
|
20
x/pricefeed/abci_test.go
Normal file
20
x/pricefeed/abci_test.go
Normal file
@ -0,0 +1,20 @@
|
||||
package pricefeed_test
|
||||
|
||||
import (
|
||||
"testing"
|
||||
|
||||
sdk "github.com/cosmos/cosmos-sdk/types"
|
||||
"github.com/kava-labs/kava/x/pricefeed"
|
||||
"github.com/kava-labs/kava/x/pricefeed/keeper"
|
||||
"github.com/kava-labs/kava/x/pricefeed/testutil"
|
||||
)
|
||||
|
||||
func TestEndBlocker_UpdatesMultipleMarkets(t *testing.T) {
|
||||
testutil.SetCurrentPrices_PriceCalculations(t, func(ctx sdk.Context, keeper keeper.Keeper) {
|
||||
pricefeed.EndBlocker(ctx, keeper)
|
||||
})
|
||||
|
||||
testutil.SetCurrentPrices_EventEmission(t, func(ctx sdk.Context, keeper keeper.Keeper) {
|
||||
pricefeed.EndBlocker(ctx, keeper)
|
||||
})
|
||||
}
|
@ -131,6 +131,74 @@ func (k Keeper) SetCurrentPrices(ctx sdk.Context, marketID string) error {
|
||||
return nil
|
||||
}
|
||||
|
||||
// SetCurrentPricesForAllMarkets updates the price of an asset to the median of all valid oracle inputs
|
||||
func (k Keeper) SetCurrentPricesForAllMarkets(ctx sdk.Context) {
|
||||
orderedMarkets := []string{}
|
||||
marketPricesByID := make(map[string]types.CurrentPrices)
|
||||
|
||||
for _, market := range k.GetMarkets(ctx) {
|
||||
if market.Active {
|
||||
orderedMarkets = append(orderedMarkets, market.MarketID)
|
||||
marketPricesByID[market.MarketID] = types.CurrentPrices{}
|
||||
}
|
||||
}
|
||||
|
||||
iterator := sdk.KVStorePrefixIterator(ctx.KVStore(k.key), types.RawPriceFeedPrefix)
|
||||
for ; iterator.Valid(); iterator.Next() {
|
||||
var postedPrice types.PostedPrice
|
||||
k.cdc.MustUnmarshal(iterator.Value(), &postedPrice)
|
||||
|
||||
prices, found := marketPricesByID[postedPrice.MarketID]
|
||||
if !found {
|
||||
continue
|
||||
}
|
||||
|
||||
// filter out expired prices
|
||||
if postedPrice.Expiry.After(ctx.BlockTime()) {
|
||||
marketPricesByID[postedPrice.MarketID] = append(prices, types.NewCurrentPrice(postedPrice.MarketID, postedPrice.Price))
|
||||
}
|
||||
}
|
||||
iterator.Close()
|
||||
|
||||
for _, marketID := range orderedMarkets {
|
||||
// store current price
|
||||
validPrevPrice := true
|
||||
prevPrice, err := k.GetCurrentPrice(ctx, marketID)
|
||||
if err != nil {
|
||||
validPrevPrice = false
|
||||
}
|
||||
|
||||
notExpiredPrices, _ := marketPricesByID[marketID]
|
||||
|
||||
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{})
|
||||
continue
|
||||
}
|
||||
|
||||
medianPrice := k.CalculateMedianPrice(notExpiredPrices)
|
||||
|
||||
// check case that market price was not set in genesis
|
||||
//if validPrevPrice && !medianPrice.Equal(prevPrice.Price) {
|
||||
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()),
|
||||
),
|
||||
)
|
||||
}
|
||||
|
||||
currentPrice := types.NewCurrentPrice(marketID, medianPrice)
|
||||
k.setCurrentPrice(ctx, marketID, currentPrice)
|
||||
}
|
||||
}
|
||||
|
||||
func (k Keeper) setCurrentPrice(ctx sdk.Context, marketID string, currentPrice types.CurrentPrice) {
|
||||
store := ctx.KVStore(k.key)
|
||||
store.Set(types.CurrentPriceKey(marketID), k.cdc.MustMarshal(¤tPrice))
|
||||
|
@ -1,6 +1,7 @@
|
||||
package keeper_test
|
||||
|
||||
import (
|
||||
"errors"
|
||||
"testing"
|
||||
"time"
|
||||
|
||||
@ -11,6 +12,8 @@ import (
|
||||
tmprototypes "github.com/cometbft/cometbft/proto/tendermint/types"
|
||||
|
||||
"github.com/kava-labs/kava/app"
|
||||
"github.com/kava-labs/kava/x/pricefeed/keeper"
|
||||
"github.com/kava-labs/kava/x/pricefeed/testutil"
|
||||
"github.com/kava-labs/kava/x/pricefeed/types"
|
||||
)
|
||||
|
||||
@ -236,3 +239,33 @@ func TestKeeper_ExpiredSetCurrentPrices(t *testing.T) {
|
||||
_, err = keeper.GetCurrentPrice(ctx, "tstusd")
|
||||
require.ErrorIs(t, types.ErrNoValidPrice, err, "current prices should be invalid")
|
||||
}
|
||||
|
||||
func TestKeeper_SetCurrentPricesForAllMarkets_PriceUpdate(t *testing.T) {
|
||||
testutil.SetCurrentPrices_PriceCalculations(t, func(ctx sdk.Context, keeper keeper.Keeper) {
|
||||
keeper.SetCurrentPricesForAllMarkets(ctx)
|
||||
})
|
||||
}
|
||||
|
||||
func TestKeeper_SetCurrentPricesForAllMarkets_EventEmission(t *testing.T) {
|
||||
testutil.SetCurrentPrices_EventEmission(t, func(ctx sdk.Context, keeper keeper.Keeper) {
|
||||
keeper.SetCurrentPricesForAllMarkets(ctx)
|
||||
})
|
||||
}
|
||||
|
||||
func TestKeeper_SetCurrentPrices_MatchesAllMarketsBehavior(t *testing.T) {
|
||||
testFunc := func(ctx sdk.Context, k keeper.Keeper) {
|
||||
for _, market := range k.GetMarkets(ctx) {
|
||||
if !market.Active {
|
||||
continue
|
||||
}
|
||||
|
||||
err := k.SetCurrentPrices(ctx, market.MarketID)
|
||||
if err != nil && !errors.Is(err, types.ErrNoValidPrice) {
|
||||
panic(err)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
testutil.SetCurrentPrices_PriceCalculations(t, testFunc)
|
||||
testutil.SetCurrentPrices_EventEmission(t, testFunc)
|
||||
}
|
||||
|
236
x/pricefeed/testutil/helpers.go
Normal file
236
x/pricefeed/testutil/helpers.go
Normal file
@ -0,0 +1,236 @@
|
||||
package testutil
|
||||
|
||||
import (
|
||||
"testing"
|
||||
"time"
|
||||
|
||||
tmprototypes "github.com/cometbft/cometbft/proto/tendermint/types"
|
||||
sdk "github.com/cosmos/cosmos-sdk/types"
|
||||
"github.com/stretchr/testify/assert"
|
||||
"github.com/stretchr/testify/require"
|
||||
|
||||
"github.com/kava-labs/kava/app"
|
||||
"github.com/kava-labs/kava/x/pricefeed/keeper"
|
||||
"github.com/kava-labs/kava/x/pricefeed/types"
|
||||
)
|
||||
|
||||
func SetCurrentPrices_PriceCalculations(t *testing.T, f func(ctx sdk.Context, keeper keeper.Keeper)) {
|
||||
_, addrs := app.GeneratePrivKeyAddressPairs(5)
|
||||
tApp := app.NewTestApp()
|
||||
ctx := tApp.NewContext(true, tmprototypes.Header{}).
|
||||
WithBlockTime(time.Now().UTC())
|
||||
keeper := tApp.GetPriceFeedKeeper()
|
||||
|
||||
params := types.Params{
|
||||
Markets: []types.Market{
|
||||
// valid previous price, expired prices, price change, and active
|
||||
{MarketID: "asset1:usd", BaseAsset: "asset1", QuoteAsset: "usd", Oracles: addrs, Active: true},
|
||||
// same data as asset1, but not active and should be ignored
|
||||
{MarketID: "asset2:usd", BaseAsset: "asset2", QuoteAsset: "usd", Oracles: addrs, Active: false},
|
||||
// same data as asset1 except no valid previous price
|
||||
{MarketID: "asset3:usd", BaseAsset: "asset3", QuoteAsset: "usd", Oracles: addrs, Active: true},
|
||||
// previous price set, but no valid prices
|
||||
{MarketID: "asset4:usd", BaseAsset: "asset4", QuoteAsset: "usd", Oracles: addrs, Active: true},
|
||||
// same as market one except different prices
|
||||
{MarketID: "asset5:usd", BaseAsset: "asset5", QuoteAsset: "usd", Oracles: addrs, Active: true},
|
||||
},
|
||||
}
|
||||
keeper.SetParams(ctx, params)
|
||||
|
||||
// need price equal to block time and after block time
|
||||
blockTime := time.Now()
|
||||
initialPriceExpiry := blockTime.Add(1 * time.Hour)
|
||||
|
||||
_, err := keeper.SetPrice(ctx, addrs[0], "asset1:usd", sdk.MustNewDecFromStr("1"), initialPriceExpiry)
|
||||
require.NoError(t, err)
|
||||
_, err = keeper.SetPrice(ctx, addrs[0], "asset2:usd", sdk.MustNewDecFromStr("1"), initialPriceExpiry)
|
||||
require.NoError(t, err)
|
||||
_, err = keeper.SetPrice(ctx, addrs[0], "asset4:usd", sdk.MustNewDecFromStr("1"), initialPriceExpiry)
|
||||
require.NoError(t, err)
|
||||
_, err = keeper.SetPrice(ctx, addrs[0], "asset5:usd", sdk.MustNewDecFromStr("10"), initialPriceExpiry)
|
||||
require.NoError(t, err)
|
||||
|
||||
ctx = ctx.WithBlockTime(blockTime)
|
||||
f(ctx, keeper)
|
||||
|
||||
// price should be set
|
||||
price, err := keeper.GetCurrentPrice(ctx, "asset1:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.OneDec(), price.Price)
|
||||
// not an active market, so price is not set
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset2:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
// no price posted
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset3:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
// price set initially
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset4:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.OneDec(), price.Price)
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset5:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.MustNewDecFromStr("10.0"), price.Price)
|
||||
|
||||
_, err = keeper.SetPrice(ctx, addrs[1], "asset1:usd", sdk.MustNewDecFromStr("2"), initialPriceExpiry.Add(1*time.Hour))
|
||||
require.NoError(t, err)
|
||||
_, err = keeper.SetPrice(ctx, addrs[1], "asset2:usd", sdk.MustNewDecFromStr("2"), initialPriceExpiry.Add(1*time.Hour))
|
||||
require.NoError(t, err)
|
||||
_, err = keeper.SetPrice(ctx, addrs[1], "asset5:usd", sdk.MustNewDecFromStr("20"), initialPriceExpiry.Add(1*time.Hour))
|
||||
require.NoError(t, err)
|
||||
|
||||
blockTime = blockTime.Add(30 * time.Minute)
|
||||
ctx = ctx.WithBlockTime(blockTime)
|
||||
f(ctx, keeper)
|
||||
|
||||
// price should be set
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset1:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.MustNewDecFromStr("1.5"), price.Price)
|
||||
// not an active market, so price is not set
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset2:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
// no price posted
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset3:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
// price set initially
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset4:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.OneDec(), price.Price)
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset5:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.MustNewDecFromStr("15.0"), price.Price)
|
||||
|
||||
_, err = keeper.SetPrice(ctx, addrs[2], "asset1:usd", sdk.MustNewDecFromStr("30"), initialPriceExpiry.Add(1*time.Hour))
|
||||
require.NoError(t, err)
|
||||
_, err = keeper.SetPrice(ctx, addrs[2], "asset2:usd", sdk.MustNewDecFromStr("30"), initialPriceExpiry.Add(1*time.Hour))
|
||||
require.NoError(t, err)
|
||||
_, err = keeper.SetPrice(ctx, addrs[2], "asset5:usd", sdk.MustNewDecFromStr("30"), initialPriceExpiry.Add(1*time.Hour))
|
||||
require.NoError(t, err)
|
||||
|
||||
blockTime = blockTime.Add(15 * time.Minute)
|
||||
ctx = ctx.WithBlockTime(blockTime)
|
||||
f(ctx, keeper)
|
||||
|
||||
// price should be set
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset1:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.MustNewDecFromStr("2.0"), price.Price)
|
||||
// not an active market, so price is not set
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset2:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
// no price posted
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset3:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
// price set initially
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset4:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.OneDec(), price.Price)
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset5:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.MustNewDecFromStr("20.0"), price.Price)
|
||||
|
||||
blockTime = blockTime.Add(15 * time.Minute)
|
||||
ctx = ctx.WithBlockTime(blockTime)
|
||||
f(ctx, keeper)
|
||||
|
||||
// price should be set
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset1:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.MustNewDecFromStr("16"), price.Price)
|
||||
// not an active market, so price is not set
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset2:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
// no price posted
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset3:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
// price set initially, now expired
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset4:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset5:usd")
|
||||
require.NoError(t, err)
|
||||
require.Equal(t, sdk.MustNewDecFromStr("25.0"), price.Price)
|
||||
|
||||
blockTime = blockTime.Add(10 * time.Hour)
|
||||
ctx = ctx.WithBlockTime(blockTime)
|
||||
f(ctx, keeper)
|
||||
|
||||
// all prices expired now
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset1:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset2:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset3:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset4:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
price, err = keeper.GetCurrentPrice(ctx, "asset5:usd")
|
||||
require.Equal(t, types.ErrNoValidPrice, err)
|
||||
}
|
||||
|
||||
func SetCurrentPrices_EventEmission(t *testing.T, f func(ctx sdk.Context, keeper keeper.Keeper)) {
|
||||
_, addrs := app.GeneratePrivKeyAddressPairs(5)
|
||||
tApp := app.NewTestApp()
|
||||
ctx := tApp.NewContext(true, tmprototypes.Header{}).
|
||||
WithBlockTime(time.Now().UTC())
|
||||
keeper := tApp.GetPriceFeedKeeper()
|
||||
|
||||
params := types.Params{
|
||||
Markets: []types.Market{
|
||||
{MarketID: "asset1:usd", BaseAsset: "asset1", QuoteAsset: "usd", Oracles: addrs, Active: true},
|
||||
},
|
||||
}
|
||||
keeper.SetParams(ctx, params)
|
||||
|
||||
blockTime := time.Now()
|
||||
initialPriceExpiry := blockTime.Add(1 * time.Hour)
|
||||
|
||||
// post a price
|
||||
_, err := keeper.SetPrice(ctx, addrs[0], "asset1:usd", sdk.MustNewDecFromStr("1"), initialPriceExpiry)
|
||||
require.NoError(t, err)
|
||||
|
||||
// reset context with fresh event manager
|
||||
ctx = ctx.WithBlockTime(blockTime).WithEventManager(sdk.NewEventManager())
|
||||
f(ctx, keeper)
|
||||
|
||||
// no previous price so no event
|
||||
require.Equal(t, 0, len(ctx.EventManager().Events()))
|
||||
|
||||
// post same price from another oracle
|
||||
_, err = keeper.SetPrice(ctx, addrs[1], "asset1:usd", sdk.MustNewDecFromStr("1"), initialPriceExpiry)
|
||||
require.NoError(t, err)
|
||||
|
||||
blockTime = blockTime.Add(10 * time.Second)
|
||||
ctx = ctx.WithBlockTime(blockTime).WithEventManager(sdk.NewEventManager())
|
||||
f(ctx, keeper)
|
||||
|
||||
// no price change so no event
|
||||
require.Equal(t, 0, len(ctx.EventManager().Events()))
|
||||
|
||||
// post price changes
|
||||
_, err = keeper.SetPrice(ctx, addrs[2], "asset1:usd", sdk.MustNewDecFromStr("2"), initialPriceExpiry)
|
||||
require.NoError(t, err)
|
||||
_, err = keeper.SetPrice(ctx, addrs[3], "asset1:usd", sdk.MustNewDecFromStr("10"), initialPriceExpiry)
|
||||
require.NoError(t, err)
|
||||
_, err = keeper.SetPrice(ctx, addrs[4], "asset1:usd", sdk.MustNewDecFromStr("10"), initialPriceExpiry)
|
||||
require.NoError(t, err)
|
||||
|
||||
blockTime = blockTime.Add(10 * time.Second)
|
||||
ctx = ctx.WithBlockTime(blockTime).WithEventManager(sdk.NewEventManager())
|
||||
f(ctx, keeper)
|
||||
|
||||
// price is changes so event should be emitted
|
||||
require.Equal(t, 1, len(ctx.EventManager().Events()))
|
||||
|
||||
event := ctx.EventManager().Events()[0]
|
||||
|
||||
// has correct event type
|
||||
assert.Equal(t, types.EventTypeMarketPriceUpdated, event.Type)
|
||||
// has correct attributes
|
||||
marketID, found := event.GetAttribute(types.AttributeMarketID)
|
||||
require.True(t, found)
|
||||
marketPrice, found := event.GetAttribute(types.AttributeMarketPrice)
|
||||
require.True(t, found)
|
||||
// attributes have correct values
|
||||
assert.Equal(t, "asset1:usd", marketID.Value)
|
||||
assert.Equal(t, sdk.MustNewDecFromStr("2").String(), marketPrice.Value)
|
||||
}
|
Loading…
Reference in New Issue
Block a user