R4R: Fix Cliff Validator Update Bugs

PENDING.md

@@ -73,16 +73,16 @@ BUG FIXES
 *  \#1799 Fix `gaiad export`
 *  \#1828 Force user to specify amount on create-validator command by removing default
 *  \#1839 Fixed bug where intra-tx counter wasn't set correctly for genesis validators
+* [staking] [#1858](https://github.com/cosmos/cosmos-sdk/pull/1858) Fixed bug where the cliff validator was not be updated correctly
 * [tests] \#1675 Fix non-deterministic `test_cover` 
 * [client] \#1551: Refactored `CoreContext`
   * Renamed `CoreContext` to `QueryContext`
   * Removed all tx related fields and logic (building & signing) to separate
   structure `TxContext` in `x/auth/client/context`
   * Cleaned up documentation and API of what used to be `CoreContext`
   * Implemented `KeyType` enum for key info
-
-BUG FIXES
 *  \#1666 Add intra-tx counter to the genesis validators
 * [tests] \#1551: Fixed invalid LCD test JSON payload in `doIBCTransfer`
 *  \#1787 Fixed bug where Tally fails due to revoked/unbonding validator
-* [basecoin] Fixes coin transaction failure and account query [discussion](https://forum.cosmos.network/t/unmarshalbinarybare-expected-to-read-prefix-bytes-75fbfab8-since-it-is-registered-concrete-but-got-0a141dfa/664/6)
+*  \#1787 Fixed bug where Tally fails due to revoked/unbonding validator
+* [basecoin] Fixes coin transaction failure and account query [discussion](https://forum.cosmos.network/t/unmarshalbinarybare-expected-to-read-prefix-bytes-75fbfab8-since-it-is-registered-concrete-but-got-0a141dfa/664/6)

x/stake/keeper/validator.go

@@ -134,6 +134,8 @@ func (k Keeper) GetValidatorsBonded(ctx sdk.Context) (validators []types.Validat
 }
 
 // get the group of bonded validators sorted by power-rank
+//
+// TODO: Rename to GetBondedValidatorsByPower or GetValidatorsByPower(ctx, status)
 func (k Keeper) GetValidatorsByPower(ctx sdk.Context) []types.Validator {
 	store := ctx.KVStore(k.storeKey)
 	maxValidators := k.GetParams(ctx).MaxValidators
@@ -191,13 +193,13 @@ func (k Keeper) ClearTendermintUpdates(ctx sdk.Context) {
 
 //___________________________________________________________________________
 
-// Perfom all the necessary steps for when a validator changes its power. This
+// Perform all the necessary steps for when a validator changes its power. This
 // function updates all validator stores as well as tendermint update store.
 // It may kick out validators if a new validator is entering the bonded validator
 // group.
 //
 // nolint: gocyclo
-// TODO: Remove above nolint, function needs to be simplified
+// TODO: Remove above nolint, function needs to be simplified!
 func (k Keeper) UpdateValidator(ctx sdk.Context, validator types.Validator) types.Validator {
 	store := ctx.KVStore(k.storeKey)
 	pool := k.GetPool(ctx)
@@ -210,19 +212,29 @@ func (k Keeper) UpdateValidator(ctx sdk.Context, validator types.Validator) type
 	cliffPower := k.GetCliffValidatorPower(ctx)
 
 	switch {
-	// if already bonded and power increasing only need to update tendermint
+	// if the validator is already bonded and the power is increasing, we need
+	// perform the following:
+	// a) update Tendermint
+	// b) check if the cliff validator needs to be updated
 	case powerIncreasing && !validator.Revoked &&
 		(oldFound && oldValidator.Status == sdk.Bonded):
 
 		bz := k.cdc.MustMarshalBinary(validator.ABCIValidator())
 		store.Set(GetTendermintUpdatesKey(validator.Owner), bz)
 
+		if cliffPower != nil {
+			cliffAddr := sdk.AccAddress(k.GetCliffValidator(ctx))
+			if bytes.Equal(cliffAddr, validator.Owner) {
+				k.updateCliffValidator(ctx, validator)
+			}
+		}
+
 	// if is a new validator and the new power is less than the cliff validator
 	case cliffPower != nil && !oldFound &&
 		bytes.Compare(valPower, cliffPower) == -1: //(valPower < cliffPower
 		// skip to completion
 
-	// if was unbonded and the new power is less than the cliff validator
+		// if was unbonded and the new power is less than the cliff validator
 	case cliffPower != nil &&
 		(oldFound && oldValidator.Status == sdk.Unbonded) &&
 		bytes.Compare(valPower, cliffPower) == -1: //(valPower < cliffPower
@@ -232,11 +244,10 @@ func (k Keeper) UpdateValidator(ctx sdk.Context, validator types.Validator) type
 		//  a) not-bonded and now has power-rank greater than  cliff validator
 		//  b) bonded and now has decreased in power
 	default:
-
 		// update the validator set for this validator
-		// if updated, the validator has changed bonding status
 		updatedVal, updated := k.UpdateBondedValidators(ctx, validator)
-		if updated { // updates to validator occurred  to be updated
+		if updated {
+			// the validator has changed bonding status
 			validator = updatedVal
 			break
 		}
@@ -246,13 +257,69 @@ func (k Keeper) UpdateValidator(ctx sdk.Context, validator types.Validator) type
 			bz := k.cdc.MustMarshalBinary(validator.ABCIValidator())
 			store.Set(GetTendermintUpdatesKey(validator.Owner), bz)
 		}
-
 	}
 
 	k.SetValidator(ctx, validator)
 	return validator
 }
 
+// updateCliffValidator determines if the current cliff validator needs to be
+// updated or swapped. If the provided affected validator is the current cliff
+// validator before it's power was increased, either the cliff power key will
+// be updated or if it's power is greater than the next bonded validator by
+// power, it'll be swapped.
+func (k Keeper) updateCliffValidator(ctx sdk.Context, affectedVal types.Validator) {
+	var newCliffVal types.Validator
+
+	store := ctx.KVStore(k.storeKey)
+	pool := k.GetPool(ctx)
+	cliffAddr := sdk.AccAddress(k.GetCliffValidator(ctx))
+
+	oldCliffVal, found := k.GetValidator(ctx, cliffAddr)
+	if !found {
+		panic(fmt.Sprintf("cliff validator record not found for address: %v\n", cliffAddr))
+	}
+
+	// NOTE: We get the power via affectedVal since the store (by power key)
+	// has yet to be updated.
+	affectedValPower := affectedVal.GetPower()
+
+	// Create a validator iterator ranging from smallest to largest by power
+	// starting the current cliff validator's power.
+	start := GetValidatorsByPowerIndexKey(oldCliffVal, pool)
+	end := sdk.PrefixEndBytes(ValidatorsByPowerIndexKey)
+	iterator := store.Iterator(start, end)
+
+	if iterator.Valid() {
+		ownerAddr := iterator.Value()
+		currVal, found := k.GetValidator(ctx, ownerAddr)
+		if !found {
+			panic(fmt.Sprintf("validator record not found for address: %v\n", ownerAddr))
+		}
+
+		if currVal.Status != sdk.Bonded || currVal.Revoked {
+			panic(fmt.Sprintf("unexpected revoked or unbonded validator for address: %s\n", ownerAddr))
+		}
+
+		newCliffVal = currVal
+		iterator.Close()
+	} else {
+		panic("failed to create valid validator power iterator")
+	}
+
+	if bytes.Equal(affectedVal.Owner, newCliffVal.Owner) {
+		// The affected validator remains the cliff validator, however, since
+		// the store does not contain the new power, set the new cliff
+		// validator to the affected validator.
+		bz := GetValidatorsByPowerIndexKey(affectedVal, pool)
+		store.Set(ValidatorPowerCliffKey, bz)
+	} else if affectedValPower.GT(newCliffVal.GetPower()) {
+		// The affected validator no longer remains the cliff validator as it's
+		// power is greater than the new current cliff validator.
+		k.setCliffValidator(ctx, newCliffVal, pool)
+	}
+}
+
 func (k Keeper) updateForRevoking(ctx sdk.Context, oldFound bool, oldValidator, newValidator types.Validator) types.Validator {
 	if newValidator.Revoked && oldFound && oldValidator.Status == sdk.Bonded {
 		newValidator = k.unbondValidator(ctx, newValidator)
@@ -317,8 +384,9 @@ func (k Keeper) updateValidatorPower(ctx sdk.Context, oldFound bool, oldValidato
 //
 // nolint: gocyclo
 // TODO: Remove the above golint
-func (k Keeper) UpdateBondedValidators(ctx sdk.Context,
-	affectedValidator types.Validator) (updatedVal types.Validator, updated bool) {
+func (k Keeper) UpdateBondedValidators(
+	ctx sdk.Context, affectedValidator types.Validator) (
+	updatedVal types.Validator, updated bool) {
 
 	store := ctx.KVStore(k.storeKey)
 
@@ -328,7 +396,8 @@ func (k Keeper) UpdateBondedValidators(ctx sdk.Context,
 	var validator, validatorToBond types.Validator
 	newValidatorBonded := false
 
-	iterator := sdk.KVStoreReversePrefixIterator(store, ValidatorsByPowerIndexKey) // largest to smallest
+	// create a validator iterator ranging from largest to smallest by power
+	iterator := sdk.KVStoreReversePrefixIterator(store, ValidatorsByPowerIndexKey)
 	for {
 		if !iterator.Valid() || bondedValidatorsCount > int(maxValidators-1) {
 			break
@@ -354,6 +423,7 @@ func (k Keeper) UpdateBondedValidators(ctx sdk.Context,
 				validatorToBond = validator
 				newValidatorBonded = true
 			}
+
 			bondedValidatorsCount++
 
 			// sanity check
@@ -363,6 +433,7 @@ func (k Keeper) UpdateBondedValidators(ctx sdk.Context,
 
 		iterator.Next()
 	}
+
 	iterator.Close()
 
 	// clear or set the cliff validator
@@ -372,17 +443,17 @@ func (k Keeper) UpdateBondedValidators(ctx sdk.Context,
 		k.clearCliffValidator(ctx)
 	}
 
-	// swap the cliff validator for a new validator if the affected validator was bonded
+	// swap the cliff validator for a new validator if the affected validator
+	// was bonded
 	if newValidatorBonded {
-
 		// unbond the cliff validator
 		if oldCliffValidatorAddr != nil {
 			cliffVal, found := k.GetValidator(ctx, oldCliffValidatorAddr)
 			if !found {
 				panic(fmt.Sprintf("validator record not found for address: %v\n", oldCliffValidatorAddr))
 			}
-			k.unbondValidator(ctx, cliffVal)
 
+			k.unbondValidator(ctx, cliffVal)
 		}
 
 		// bond the new validator
@@ -391,6 +462,7 @@ func (k Keeper) UpdateBondedValidators(ctx sdk.Context,
 			return validator, true
 		}
 	}
+
 	return types.Validator{}, false
 }
 

x/stake/keeper/validator_test.go

@@ -1,6 +1,7 @@
 package keeper
 
 import (
+	"fmt"
 	"testing"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -88,6 +89,62 @@ func TestUpdateValidatorByPowerIndex(t *testing.T) {
 	require.True(t, keeper.validatorByPowerIndexExists(ctx, power))
 }
 
+func TestCliffValidatorChange(t *testing.T) {
+	numVals := 10
+	maxVals := 5
+
+	// create context, keeper, and pool for tests
+	ctx, _, keeper := CreateTestInput(t, false, 0)
+	pool := keeper.GetPool(ctx)
+
+	// create keeper parameters
+	params := keeper.GetParams(ctx)
+	params.MaxValidators = uint16(maxVals)
+	keeper.SetParams(ctx, params)
+
+	// create a random pool
+	pool.LooseTokens = sdk.NewRat(10000)
+	pool.BondedTokens = sdk.NewRat(1234)
+	keeper.SetPool(ctx, pool)
+
+	validators := make([]types.Validator, numVals)
+	for i := 0; i < len(validators); i++ {
+		moniker := fmt.Sprintf("val#%d", int64(i))
+		val := types.NewValidator(Addrs[i], PKs[i], types.Description{Moniker: moniker})
+		val.BondHeight = int64(i)
+		val.BondIntraTxCounter = int16(i)
+		val, pool, _ = val.AddTokensFromDel(pool, int64((i+1)*10))
+
+		keeper.SetPool(ctx, pool)
+		val = keeper.UpdateValidator(ctx, val)
+		validators[i] = val
+	}
+
+	// add a large amount of tokens to current cliff validator
+	currCliffVal := validators[numVals-maxVals]
+	currCliffVal, pool, _ = currCliffVal.AddTokensFromDel(pool, 200)
+	keeper.SetPool(ctx, pool)
+	currCliffVal = keeper.UpdateValidator(ctx, currCliffVal)
+
+	// assert new cliff validator to be set to the second lowest bonded validator by power
+	newCliffVal := validators[numVals-maxVals+1]
+	require.Equal(t, newCliffVal.Owner, sdk.AccAddress(keeper.GetCliffValidator(ctx)))
+
+	// assert cliff validator power should have been updated
+	cliffPower := keeper.GetCliffValidatorPower(ctx)
+	require.Equal(t, GetValidatorsByPowerIndexKey(newCliffVal, pool), cliffPower)
+
+	// add small amount of tokens to new current cliff validator
+	newCliffVal, pool, _ = newCliffVal.AddTokensFromDel(pool, 1)
+	keeper.SetPool(ctx, pool)
+	newCliffVal = keeper.UpdateValidator(ctx, newCliffVal)
+
+	// assert cliff validator has not change but increased in power
+	cliffPower = keeper.GetCliffValidatorPower(ctx)
+	require.Equal(t, newCliffVal.Owner, sdk.AccAddress(keeper.GetCliffValidator(ctx)))
+	require.Equal(t, GetValidatorsByPowerIndexKey(newCliffVal, pool), cliffPower)
+}
+
 func TestSlashToZeroPowerRemoved(t *testing.T) {
 	// initialize setup
 	ctx, _, keeper := CreateTestInput(t, false, 100)