Add MinCommissionRate param

docs/core/proto-docs.md

@@ -6393,6 +6393,7 @@ Params defines the parameters for the staking module.
 | `historical_entries` | [uint32](#uint32) |  | historical_entries is the number of historical entries to persist. |
 | `bond_denom` | [string](#string) |  | bond_denom defines the bondable coin denomination. |
 | `power_reduction` | [string](#string) |  | power_reduction is the amount of staking tokens required for 1 unit of consensus-engine power |
+| `min_commission_rate` | [string](#string) |  |  |
 
 
 

proto/cosmos/staking/v1beta1/staking.proto

@@ -288,6 +288,12 @@ message Params {
     (gogoproto.customtype) = "github.com/cosmos/cosmos-sdk/types.Int",
     (gogoproto.nullable)   = false
   ];
+  // min_commission_rate is the chain-wide minimum commission rate that a validator can charge their delegators
+  string min_commission_rate = 7 [
+    (gogoproto.moretags)   = "yaml:\"min_commission_rate\"",
+    (gogoproto.customtype) = "github.com/cosmos/cosmos-sdk/types.Dec",
+    (gogoproto.nullable)   = false
+  ];
 }
 
 // DelegationResponse is equivalent to Delegation except that it contains a

x/staking/client/testutil/suite.go

@@ -230,7 +230,7 @@ func (s *IntegrationTestSuite) TestGetCmdQueryValidator() {
 		},
 		{
 			"happy case",
-			[]string{fmt.Sprintf("%s", val.ValAddress), fmt.Sprintf("--%s=json", tmcli.OutputFlag)},
+			[]string{val.ValAddress.String(), fmt.Sprintf("--%s=json", tmcli.OutputFlag)},
 			false,
 		},
 	}
@@ -867,13 +867,14 @@ func (s *IntegrationTestSuite) TestGetCmdQueryParams() {
 historical_entries: 10000
 max_entries: 7
 max_validators: 100
+min_commission_rate: "0.000000000000000000"
 power_reduction: "1000000"
 unbonding_time: 1814400s`,
 		},
 		{
 			"with json output",
 			[]string{fmt.Sprintf("--%s=json", tmcli.OutputFlag)},
-			`{"unbonding_time":"1814400s","max_validators":100,"max_entries":7,"historical_entries":10000,"bond_denom":"stake","power_reduction":"1000000"}`,
+			`{"unbonding_time":"1814400s","max_validators":100,"max_entries":7,"historical_entries":10000,"bond_denom":"stake","power_reduction":"1000000","min_commission_rate":"0.000000000000000000"}`,
 		},
 	}
 	for _, tc := range testCases {

x/staking/keeper/params.go

@@ -46,7 +46,13 @@ func (k Keeper) PowerReduction(ctx sdk.Context) (res sdk.Int) {
 	return
 }
 
-// Get all parameteras as types.Params
+// MinCommissionRate - Minimum validator commission rate
+func (k Keeper) MinCommissionRate(ctx sdk.Context) (res sdk.Dec) {
+	k.paramstore.Get(ctx, types.KeyMinCommissionRate, &res)
+	return
+}
+
+// Get all parameters as types.Params
 func (k Keeper) GetParams(ctx sdk.Context) types.Params {
 	return types.NewParams(
 		k.UnbondingTime(ctx),
@@ -55,6 +61,7 @@ func (k Keeper) GetParams(ctx sdk.Context) types.Params {
 		k.HistoricalEntries(ctx),
 		k.BondDenom(ctx),
 		k.PowerReduction(ctx),
+		k.MinCommissionRate(ctx),
 	)
 }
 

x/staking/keeper/validator.go

@@ -138,6 +138,10 @@ func (k Keeper) UpdateValidatorCommission(ctx sdk.Context,
 		return commission, err
 	}
 
+	if newRate.LT(k.MinCommissionRate(ctx)) {
+		return commission, fmt.Errorf("cannot set validator commission to less than minimum rate of %s", k.MinCommissionRate(ctx))
+	}
+
 	commission.Rate = newRate
 	commission.UpdateTime = blockTime
 

x/staking/keeper/validator_test.go

@@ -1041,6 +1041,11 @@ func TestUpdateValidatorCommission(t *testing.T) {
 	app, ctx, _, addrVals := bootstrapValidatorTest(t, 1000, 20)
 	ctx = ctx.WithBlockHeader(tmproto.Header{Time: time.Now().UTC()})
 
+	// Set MinCommissionRate to 0.05
+	params := app.StakingKeeper.GetParams(ctx)
+	params.MinCommissionRate = sdk.NewDecWithPrec(5, 2)
+	app.StakingKeeper.SetParams(ctx, params)
+
 	commission1 := types.NewCommissionWithTime(
 		sdk.NewDecWithPrec(1, 1), sdk.NewDecWithPrec(3, 1),
 		sdk.NewDecWithPrec(1, 1), time.Now().UTC().Add(time.Duration(-1)*time.Hour),
@@ -1065,6 +1070,7 @@ func TestUpdateValidatorCommission(t *testing.T) {
 		{val2, sdk.NewDecWithPrec(-1, 1), true},
 		{val2, sdk.NewDecWithPrec(4, 1), true},
 		{val2, sdk.NewDecWithPrec(3, 1), true},
+		{val2, sdk.NewDecWithPrec(1, 2), true},
 		{val2, sdk.NewDecWithPrec(2, 1), false},
 	}
 

x/staking/legacy/v043/json.go

@@ -31,6 +31,7 @@ func migrateParams(oldParams v040staking.Params) v043staking.Params {
 		oldParams.HistoricalEntries,
 		oldParams.BondDenom,
 		sdk.DefaultPowerReduction,
+		v043staking.DefaultMinCommissionRate,
 	)
 }
 

x/staking/legacy/v043/json_test.go

@@ -53,6 +53,7 @@ func TestMigrateJSON(t *testing.T) {
 		"historical_entries": 10000,
 		"max_entries": 7,
 		"max_validators": 100,
+		"min_commission_rate": "0.000000000000000000",
 		"power_reduction": "1000000",
 		"unbonding_time": "1814400s"
 	},

x/staking/legacy/v043/store.go

@@ -58,12 +58,14 @@ func migrateValidatorsByPowerIndexKey(store sdk.KVStore) {
 func migrateParamsStore(ctx sdk.Context, paramstore paramtypes.Subspace) {
 	paramstore.WithKeyTable(types.ParamKeyTable())
 	paramstore.Set(ctx, types.KeyPowerReduction, sdk.DefaultPowerReduction)
+	paramstore.Set(ctx, types.KeyMinCommissionRate, types.DefaultMinCommissionRate)
 }
 
 // MigrateStore performs in-place store migrations from v0.40 to v0.43. The
 // migration includes:
 //
 // - Setting the Power Reduction param in the paramstore
+// - Setting the MinCommissionRate param in the paramstore
 func MigrateStore(ctx sdk.Context, storeKey sdk.StoreKey, paramstore paramtypes.Subspace) error {
 	store := ctx.KVStore(storeKey)
 

x/staking/legacy/v043/store_test.go

@@ -141,7 +141,13 @@ func TestStoreMigration(t *testing.T) {
 		})
 	}
 
+	// Make sure that power reduction param is set to default
 	powerReduction := sdk.NewInt(0)
 	paramSubspace.Get(ctx, types.KeyPowerReduction, &powerReduction)
 	require.True(t, powerReduction.Equal(sdk.DefaultPowerReduction))
+
+	// Make sure that min commission rate param is set to default
+	minCommissionRate := sdk.NewDec(1)
+	paramSubspace.Get(ctx, types.KeyMinCommissionRate, &minCommissionRate)
+	require.True(t, minCommissionRate.Equal(types.DefaultMinCommissionRate))
 }

x/staking/simulation/genesis.go

@@ -40,9 +40,10 @@ func GetHistEntries(r *rand.Rand) uint32 {
 func RandomizedGenState(simState *module.SimulationState) {
 	// params
 	var (
-		unbondTime  time.Duration
-		maxVals     uint32
-		histEntries uint32
+		unbondTime        time.Duration
+		maxVals           uint32
+		histEntries       uint32
+		minCommissionRate sdk.Dec
 	)
 
 	simState.AppParams.GetOrGenerate(
@@ -63,7 +64,7 @@ func RandomizedGenState(simState *module.SimulationState) {
 	// NOTE: the slashing module need to be defined after the staking module on the
 	// NewSimulationManager constructor for this to work
 	simState.UnbondTime = unbondTime
-	params := types.NewParams(simState.UnbondTime, maxVals, 7, histEntries, sdk.DefaultBondDenom, sdk.DefaultPowerReduction)
+	params := types.NewParams(simState.UnbondTime, maxVals, 7, histEntries, sdk.DefaultBondDenom, sdk.DefaultPowerReduction, minCommissionRate)
 
 	// validators & delegations
 	var (

x/staking/types/params.go

@@ -32,13 +32,19 @@ const (
 	DefaultHistoricalEntries uint32 = 10000
 )
 
+var (
+	// DefaultMinCommissionRate is set to 0%
+	DefaultMinCommissionRate = sdk.ZeroDec()
+)
+
 var (
 	KeyUnbondingTime     = []byte("UnbondingTime")
 	KeyMaxValidators     = []byte("MaxValidators")
 	KeyMaxEntries        = []byte("MaxEntries")
 	KeyBondDenom         = []byte("BondDenom")
 	KeyHistoricalEntries = []byte("HistoricalEntries")
 	KeyPowerReduction    = []byte("PowerReduction")
+	KeyMinCommissionRate = []byte("MinCommissionRate")
 )
 
 var _ paramtypes.ParamSet = (*Params)(nil)
@@ -49,14 +55,15 @@ func ParamKeyTable() paramtypes.KeyTable {
 }
 
 // NewParams creates a new Params instance
-func NewParams(unbondingTime time.Duration, maxValidators, maxEntries, historicalEntries uint32, bondDenom string, powerReduction sdk.Int) Params {
+func NewParams(unbondingTime time.Duration, maxValidators, maxEntries, historicalEntries uint32, bondDenom string, powerReduction sdk.Int, minCommissionRate sdk.Dec) Params {
 	return Params{
 		UnbondingTime:     unbondingTime,
 		MaxValidators:     maxValidators,
 		MaxEntries:        maxEntries,
 		HistoricalEntries: historicalEntries,
 		BondDenom:         bondDenom,
 		PowerReduction:    powerReduction,
+		MinCommissionRate: minCommissionRate,
 	}
 }
 
@@ -69,6 +76,7 @@ func (p *Params) ParamSetPairs() paramtypes.ParamSetPairs {
 		paramtypes.NewParamSetPair(KeyHistoricalEntries, &p.HistoricalEntries, validateHistoricalEntries),
 		paramtypes.NewParamSetPair(KeyBondDenom, &p.BondDenom, validateBondDenom),
 		paramtypes.NewParamSetPair(KeyPowerReduction, &p.PowerReduction, ValidatePowerReduction),
+		paramtypes.NewParamSetPair(KeyMinCommissionRate, &p.MinCommissionRate, validateMinCommissionRate),
 	}
 }
 
@@ -81,6 +89,7 @@ func DefaultParams() Params {
 		DefaultHistoricalEntries,
 		sdk.DefaultBondDenom,
 		sdk.DefaultPowerReduction,
+		DefaultMinCommissionRate,
 	)
 }
 
@@ -128,6 +137,14 @@ func (p Params) Validate() error {
 		return err
 	}
 
+	if err := ValidatePowerReduction(p.PowerReduction); err != nil {
+		return err
+	}
+
+	if err := validateMinCommissionRate(p.MinCommissionRate); err != nil {
+		return err
+	}
+
 	return nil
 }
 
@@ -208,3 +225,19 @@ func ValidatePowerReduction(i interface{}) error {
 
 	return nil
 }
+
+func validateMinCommissionRate(i interface{}) error {
+	v, ok := i.(sdk.Dec)
+	if !ok {
+		return fmt.Errorf("invalid parameter type: %T", i)
+	}
+
+	if v.IsNegative() {
+		return fmt.Errorf("minimum commission rate cannot be negative: %s", v)
+	}
+	if v.GT(sdk.OneDec()) {
+		return fmt.Errorf("minimum commission rate cannot be greater than 100%%: %s", v)
+	}
+
+	return nil
+}