R4R: limit unbonding delegation / redelegations

PENDING.md

@@ -89,6 +89,7 @@ FEATURES
   * [\#3179](https://github.com/cosmos/cosmos-sdk/pull/3179) New CodeNoSignatures error code.
   * \#3319 [x/distribution] Queriers for all distribution state worth querying; distribution query commands
   * [\#3356](https://github.com/cosmos/cosmos-sdk/issues/3356) [x/auth] bech32-ify accounts address in error message.
+  * \#3270 [x/staking] limit number of ongoing unbonding delegations /redelegations per pair/trio
 
 * Tendermint
 

docs/spec/staking/messages.md

@@ -101,6 +101,8 @@ This message is expected to fail if:
  - the delegation doesn't exist
  - the validator doesn't exist
  - the delegation has less shares than `SharesAmount`
+ - existing `UnbondingDelegation` has maximum entries as defined by
+   params.MaxEntries
 
 When this message is processed the following actions occur:
  - validator's `DelegatorShares` and the delegation's `Shares` are both reduced
@@ -143,6 +145,8 @@ This message is expected to fail if:
  - the delegation has less shares than `SharesAmount`
  - the source validator has a receiving redelegation which
    is not matured (aka. the redelegation may be transitive) 
+ - existing `Redelegation` has maximum entries as defined by
+   params.MaxEntries
 
 When this message is processed the following actions occur:
  - the source validator's `DelegatorShares` and the delegations `Shares` are

docs/spec/staking/state.md

@@ -28,6 +28,7 @@ and defines overall functioning of the staking module.
 type Params struct {
     UnbondingTime time.Duration // time duration of unbonding
     MaxValidators uint16        // maximum number of validators
+    MaxEntries    uint16        // max entries for either unbonding delegation or redelegation (per pair/trio)
     BondDenom     string        // bondable coin denomination
 }
 ```

x/staking/keeper/delegation.go

@@ -154,6 +154,20 @@ func (k Keeper) IterateUnbondingDelegations(ctx sdk.Context, fn func(index int64
 	}
 }
 
+// HasMaxUnbondingDelegationEntries - unbonding delegation has maximum number of entries
+func (k Keeper) HasMaxUnbondingDelegationEntries(ctx sdk.Context,
+	delegatorAddr sdk.AccAddress, validatorAddr sdk.ValAddress) bool {
+
+	ubd, found := k.GetUnbondingDelegation(ctx, delegatorAddr, validatorAddr)
+	if !found {
+		return false
+	}
+	if len(ubd.Entries) >= int(k.MaxEntries(ctx)) {
+		return true
+	}
+	return false
+}
+
 // set the unbonding delegation and associated index
 func (k Keeper) SetUnbondingDelegation(ctx sdk.Context, ubd types.UnbondingDelegation) {
 	store := ctx.KVStore(k.storeKey)
@@ -314,6 +328,21 @@ func (k Keeper) HasReceivingRedelegation(ctx sdk.Context,
 	return false
 }
 
+// HasMaxRedelegationEntries - redelegation has maximum number of entries
+func (k Keeper) HasMaxRedelegationEntries(ctx sdk.Context,
+	delegatorAddr sdk.AccAddress, validatorSrcAddr,
+	validatorDstAddr sdk.ValAddress) bool {
+
+	red, found := k.GetRedelegation(ctx, delegatorAddr, validatorSrcAddr, validatorDstAddr)
+	if !found {
+		return false
+	}
+	if len(red.Entries) >= int(k.MaxEntries(ctx)) {
+		return true
+	}
+	return false
+}
+
 // set a redelegation and associated index
 func (k Keeper) SetRedelegation(ctx sdk.Context, red types.Redelegation) {
 	store := ctx.KVStore(k.storeKey)
@@ -576,6 +605,10 @@ func (k Keeper) Undelegate(ctx sdk.Context, delAddr sdk.AccAddress,
 		return completionTime, nil
 	}
 
+	if k.HasMaxUnbondingDelegationEntries(ctx, delAddr, valAddr) {
+		return time.Time{}, types.ErrMaxUnbondingDelegationEntries(k.Codespace())
+	}
+
 	ubd := k.SetUnbondingDelegationEntry(ctx, delAddr,
 		valAddr, height, completionTime, balance)
 
@@ -633,6 +666,10 @@ func (k Keeper) BeginRedelegation(ctx sdk.Context, delAddr sdk.AccAddress,
 		return time.Time{}, types.ErrTransitiveRedelegation(k.Codespace())
 	}
 
+	if k.HasMaxRedelegationEntries(ctx, delAddr, valSrcAddr, valDstAddr) {
+		return time.Time{}, types.ErrMaxRedelegationEntries(k.Codespace())
+	}
+
 	returnAmount, err := k.unbond(ctx, delAddr, valSrcAddr, sharesAmount)
 	if err != nil {
 		return time.Time{}, err

x/staking/keeper/delegation_test.go

@@ -198,7 +198,7 @@ func TestUnbondDelegation(t *testing.T) {
 
 	amount, err := keeper.unbond(ctx, addrDels[0], addrVals[0], sdk.NewDec(6))
 	require.NoError(t, err)
-	require.Equal(t, int64(6), amount.Int64()) // shares to be added to an unbonding delegation / redelegation
+	require.Equal(t, int64(6), amount.Int64()) // shares to be added to an unbonding delegation
 
 	delegation, found := keeper.GetDelegation(ctx, addrDels[0], addrVals[0])
 	require.True(t, found)
@@ -212,6 +212,53 @@ func TestUnbondDelegation(t *testing.T) {
 	require.Equal(t, int64(4), pool.BondedTokens.Int64())
 }
 
+func TestUnbondingDelegationsMaxEntries(t *testing.T) {
+	ctx, _, keeper := CreateTestInput(t, false, 0)
+	pool := keeper.GetPool(ctx)
+	pool.NotBondedTokens = sdk.NewInt(10)
+
+	//create a validator and a delegator to that validator
+	validator := types.NewValidator(addrVals[0], PKs[0], types.Description{})
+	validator, pool, issuedShares := validator.AddTokensFromDel(pool, sdk.NewInt(10))
+	require.Equal(t, int64(10), issuedShares.RoundInt64())
+	keeper.SetPool(ctx, pool)
+	validator = TestingUpdateValidator(keeper, ctx, validator, true)
+
+	pool = keeper.GetPool(ctx)
+	require.Equal(t, int64(10), pool.BondedTokens.Int64())
+	require.Equal(t, int64(10), validator.BondedTokens().Int64())
+
+	delegation := types.Delegation{
+		DelegatorAddr: addrDels[0],
+		ValidatorAddr: addrVals[0],
+		Shares:        issuedShares,
+	}
+	keeper.SetDelegation(ctx, delegation)
+
+	maxEntries := keeper.MaxEntries(ctx)
+
+	// should all pass
+	var completionTime time.Time
+	for i := uint16(0); i < maxEntries; i++ {
+		var err error
+		completionTime, err = keeper.Undelegate(ctx, addrDels[0], addrVals[0], sdk.NewDec(1))
+		require.NoError(t, err)
+	}
+
+	// an additional unbond should fail due to max entries
+	_, err := keeper.Undelegate(ctx, addrDels[0], addrVals[0], sdk.NewDec(1))
+	require.Error(t, err)
+
+	// mature unbonding delegations
+	ctx = ctx.WithBlockTime(completionTime)
+	err = keeper.CompleteUnbonding(ctx, addrDels[0], addrVals[0])
+	require.NoError(t, err)
+
+	// unbonding  should work again
+	_, err = keeper.Undelegate(ctx, addrDels[0], addrVals[0], sdk.NewDec(1))
+	require.NoError(t, err)
+}
+
 // test removing all self delegation from a validator which should
 // shift it from the bonded to unbonded state
 func TestUndelegateSelfDelegation(t *testing.T) {
@@ -593,6 +640,59 @@ func TestRedelegateToSameValidator(t *testing.T) {
 
 }
 
+func TestRedelegationMaxEntries(t *testing.T) {
+	ctx, _, keeper := CreateTestInput(t, false, 0)
+	pool := keeper.GetPool(ctx)
+	pool.NotBondedTokens = sdk.NewInt(20)
+
+	//create a validator with a self-delegation
+	validator := types.NewValidator(addrVals[0], PKs[0], types.Description{})
+	validator, pool, issuedShares := validator.AddTokensFromDel(pool, sdk.NewInt(10))
+	require.Equal(t, int64(10), issuedShares.RoundInt64())
+	keeper.SetPool(ctx, pool)
+	validator = TestingUpdateValidator(keeper, ctx, validator, true)
+	pool = keeper.GetPool(ctx)
+	val0AccAddr := sdk.AccAddress(addrVals[0].Bytes())
+	selfDelegation := types.Delegation{
+		DelegatorAddr: val0AccAddr,
+		ValidatorAddr: addrVals[0],
+		Shares:        issuedShares,
+	}
+	keeper.SetDelegation(ctx, selfDelegation)
+
+	// create a second validator
+	validator2 := types.NewValidator(addrVals[1], PKs[1], types.Description{})
+	validator2, pool, issuedShares = validator2.AddTokensFromDel(pool, sdk.NewInt(10))
+	require.Equal(t, int64(10), issuedShares.RoundInt64())
+	pool.BondedTokens = pool.BondedTokens.Add(sdk.NewInt(10))
+	keeper.SetPool(ctx, pool)
+	validator2 = TestingUpdateValidator(keeper, ctx, validator2, true)
+	require.Equal(t, sdk.Bonded, validator2.Status)
+
+	maxEntries := keeper.MaxEntries(ctx)
+
+	// redelegations should pass
+	var completionTime time.Time
+	for i := uint16(0); i < maxEntries; i++ {
+		var err error
+		completionTime, err = keeper.BeginRedelegation(ctx, val0AccAddr, addrVals[0], addrVals[1], sdk.NewDec(1))
+		require.NoError(t, err)
+	}
+
+	// an additional redelegation should fail due to max entries
+	_, err := keeper.BeginRedelegation(ctx, val0AccAddr, addrVals[0], addrVals[1], sdk.NewDec(1))
+	require.Error(t, err)
+
+	// mature redelegations
+	ctx = ctx.WithBlockTime(completionTime)
+	err = keeper.CompleteRedelegation(ctx, val0AccAddr, addrVals[0], addrVals[1])
+	require.NoError(t, err)
+
+	// redelegation should work again
+	_, err = keeper.BeginRedelegation(ctx, val0AccAddr, addrVals[0], addrVals[1], sdk.NewDec(1))
+	require.NoError(t, err)
+}
+
 func TestRedelegateSelfDelegation(t *testing.T) {
 	ctx, _, keeper := CreateTestInput(t, false, 0)
 	pool := keeper.GetPool(ctx)

x/staking/keeper/params.go

@@ -30,18 +30,27 @@ func (k Keeper) MaxValidators(ctx sdk.Context) (res uint16) {
 	return
 }
 
+// MaxEntries - Maximum number of simultaneous unbonding
+// delegations or redelegations (per pair/trio)
+func (k Keeper) MaxEntries(ctx sdk.Context) (res uint16) {
+	k.paramstore.Get(ctx, types.KeyMaxEntries, &res)
+	return
+}
+
 // BondDenom - Bondable coin denomination
 func (k Keeper) BondDenom(ctx sdk.Context) (res string) {
 	k.paramstore.Get(ctx, types.KeyBondDenom, &res)
 	return
 }
 
 // Get all parameteras as types.Params
-func (k Keeper) GetParams(ctx sdk.Context) (res types.Params) {
-	res.UnbondingTime = k.UnbondingTime(ctx)
-	res.MaxValidators = k.MaxValidators(ctx)
-	res.BondDenom = k.BondDenom(ctx)
-	return
+func (k Keeper) GetParams(ctx sdk.Context) types.Params {
+	return types.NewParams(
+		k.UnbondingTime(ctx),
+		k.MaxValidators(ctx),
+		k.MaxEntries(ctx),
+		k.BondDenom(ctx),
+	)
 }
 
 // set the params

x/staking/types/errors.go

@@ -149,8 +149,9 @@ func ErrNoUnbondingDelegation(codespace sdk.CodespaceType) sdk.Error {
 	return sdk.NewError(codespace, CodeInvalidDelegation, "no unbonding delegation found")
 }
 
-func ErrExistingUnbondingDelegation(codespace sdk.CodespaceType) sdk.Error {
-	return sdk.NewError(codespace, CodeInvalidDelegation, "existing unbonding delegation found")
+func ErrMaxUnbondingDelegationEntries(codespace sdk.CodespaceType) sdk.Error {
+	return sdk.NewError(codespace, CodeInvalidDelegation,
+		"to many unbonding delegation entries in this delegator/validator duo, please wait for some entries to mature")
 }
 
 func ErrBadRedelegationAddr(codespace sdk.CodespaceType) sdk.Error {
@@ -178,6 +179,11 @@ func ErrTransitiveRedelegation(codespace sdk.CodespaceType) sdk.Error {
 		"redelegation to this validator already in progress, first redelegation to this validator must complete before next redelegation")
 }
 
+func ErrMaxRedelegationEntries(codespace sdk.CodespaceType) sdk.Error {
+	return sdk.NewError(codespace, CodeInvalidDelegation,
+		"to many redelegation entries in this delegator/src-validator/dst-validator trio, please wait for some entries to mature")
+}
+
 func ErrDelegatorShareExRateInvalid(codespace sdk.CodespaceType) sdk.Error {
 	return sdk.NewError(codespace, CodeInvalidDelegation,
 		"cannot delegate to validators with invalid (zero) ex-rate")

x/staking/types/params.go

@@ -28,6 +28,7 @@ const (
 var (
 	KeyUnbondingTime = []byte("UnbondingTime")
 	KeyMaxValidators = []byte("MaxValidators")
+	KeyMaxEntries    = []byte("KeyMaxEntries")
 	KeyBondDenom     = []byte("BondDenom")
 )
 
@@ -37,14 +38,27 @@ var _ params.ParamSet = (*Params)(nil)
 type Params struct {
 	UnbondingTime time.Duration `json:"unbonding_time"` // time duration of unbonding
 	MaxValidators uint16        `json:"max_validators"` // maximum number of validators
+	MaxEntries    uint16        `json:"max_entries"`    // max entries for either unbonding delegation or redelegation (per pair/trio)
 	BondDenom     string        `json:"bond_denom"`     // bondable coin denomination
 }
 
+func NewParams(unbondingTime time.Duration, maxValidators, maxEntries uint16,
+	bondDenom string) Params {
+
+	return Params{
+		UnbondingTime: unbondingTime,
+		MaxValidators: maxValidators,
+		MaxEntries:    maxEntries,
+		BondDenom:     bondDenom,
+	}
+}
+
 // Implements params.ParamSet
 func (p *Params) KeyValuePairs() params.KeyValuePairs {
 	return params.KeyValuePairs{
 		{KeyUnbondingTime, &p.UnbondingTime},
 		{KeyMaxValidators, &p.MaxValidators},
+		{KeyMaxEntries, &p.MaxEntries},
 		{KeyBondDenom, &p.BondDenom},
 	}
 }
@@ -58,20 +72,17 @@ func (p Params) Equal(p2 Params) bool {
 
 // DefaultParams returns a default set of parameters.
 func DefaultParams() Params {
-	return Params{
-		UnbondingTime: defaultUnbondingTime,
-		MaxValidators: 100,
-		BondDenom:     DefaultBondDenom,
-	}
+	return NewParams(defaultUnbondingTime, 100, 7, DefaultBondDenom)
 }
 
 // String returns a human readable string representation of the parameters.
 func (p Params) String() string {
 	return fmt.Sprintf(`Params:
   Unbonding Time: %s)
   Max Validators: %d)
+  Max Entries: %d)
   Bonded Coin Denomination: %s`, p.UnbondingTime,
-		p.MaxValidators, p.BondDenom)
+		p.MaxValidators, p.MaxEntries, p.BondDenom)
 }
 
 // unmarshal the current staking params value from store key or panic