WIP: distr simulation accum invariance

PENDING.md

@@ -45,6 +45,7 @@ BREAKING CHANGES
     * [simulation] \#2162 Added back correct supply invariants
     * [x/slashing] \#2430 Simulate more slashes, check if validator is jailed before jailing
     * [x/stake] \#2393 Removed `CompleteUnbonding` and `CompleteRedelegation` Msg types, and instead added unbonding/redelegation queues to endblocker
+    * [x/mock/simulation] \#2501 Simulate transactions & invariants for fee distribution
     * [x/stake] \#1673 Validators are no longer deleted until they can no longer possibly be slashed
     * [\#1890](https://github.com/cosmos/cosmos-sdk/issues/1890) Start chain with initial state + sequence of transactions
       * [cli] Rename `gaiad init gentx` to `gaiad gentx`.

cmd/gaia/app/app.go

@@ -3,6 +3,10 @@ package app
 import (
 	"encoding/json"
 	"fmt"
+	"io"
+	"os"
+	"sort"
+
 	bam "github.com/cosmos/cosmos-sdk/baseapp"
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -19,9 +23,6 @@ import (
 	dbm "github.com/tendermint/tendermint/libs/db"
 	"github.com/tendermint/tendermint/libs/log"
 	tmtypes "github.com/tendermint/tendermint/types"
-	"io"
-	"os"
-	"sort"
 )
 
 const (
@@ -334,17 +335,18 @@ var _ sdk.StakingHooks = Hooks{}
 func (h Hooks) OnValidatorCreated(ctx sdk.Context, addr sdk.ValAddress) {
 	h.dh.OnValidatorCreated(ctx, addr)
 }
-func (h Hooks) OnValidatorCommissionChange(ctx sdk.Context, addr sdk.ValAddress) {
-	h.dh.OnValidatorCommissionChange(ctx, addr)
+func (h Hooks) OnValidatorModified(ctx sdk.Context, addr sdk.ValAddress) {
+	h.dh.OnValidatorModified(ctx, addr)
 }
 func (h Hooks) OnValidatorRemoved(ctx sdk.Context, addr sdk.ValAddress) {
 	h.dh.OnValidatorRemoved(ctx, addr)
 }
 func (h Hooks) OnValidatorBonded(ctx sdk.Context, addr sdk.ConsAddress) {
 	h.sh.OnValidatorBonded(ctx, addr)
 }
-func (h Hooks) OnValidatorBeginUnbonding(ctx sdk.Context, addr sdk.ConsAddress) {
-	h.sh.OnValidatorBeginUnbonding(ctx, addr)
+func (h Hooks) OnValidatorBeginUnbonding(ctx sdk.Context, addr sdk.ConsAddress, operator sdk.ValAddress) {
+	h.dh.OnValidatorBeginUnbonding(ctx, addr, operator)
+	h.sh.OnValidatorBeginUnbonding(ctx, addr, operator)
 }
 func (h Hooks) OnDelegationCreated(ctx sdk.Context, delAddr sdk.AccAddress, valAddr sdk.ValAddress) {
 	h.dh.OnDelegationCreated(ctx, delAddr, valAddr)

cmd/gaia/app/sim_test.go

@@ -14,8 +14,10 @@ import (
 	"github.com/tendermint/tendermint/libs/log"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	authsim "github.com/cosmos/cosmos-sdk/x/auth/simulation"
 	banksim "github.com/cosmos/cosmos-sdk/x/bank/simulation"
 	distr "github.com/cosmos/cosmos-sdk/x/distribution"
+	distributionsim "github.com/cosmos/cosmos-sdk/x/distribution/simulation"
 	"github.com/cosmos/cosmos-sdk/x/gov"
 	govsim "github.com/cosmos/cosmos-sdk/x/gov/simulation"
 	"github.com/cosmos/cosmos-sdk/x/mint"
@@ -49,7 +51,7 @@ func appStateFn(r *rand.Rand, accs []simulation.Account) json.RawMessage {
 
 	// Randomly generate some genesis accounts
 	for _, acc := range accs {
-		coins := sdk.Coins{sdk.Coin{"steak", sdk.NewInt(100)}}
+		coins := sdk.Coins{sdk.Coin{"steak", sdk.NewInt(10000)}}
 		genesisAccounts = append(genesisAccounts, GenesisAccount{
 			Address: acc.Address,
 			Coins:   coins,
@@ -71,20 +73,16 @@ func appStateFn(r *rand.Rand, accs []simulation.Account) json.RawMessage {
 		valAddrs[i] = valAddr
 
 		validator := stake.NewValidator(valAddr, accs[i].PubKey, stake.Description{})
-		validator.Tokens = sdk.NewDec(100)
-		validator.DelegatorShares = sdk.NewDec(100)
-		delegation := stake.Delegation{accs[i].Address, valAddr, sdk.NewDec(100), 0}
+		validator.Tokens = sdk.NewDec(10000)
+		validator.DelegatorShares = sdk.NewDec(10000)
+		delegation := stake.Delegation{accs[i].Address, valAddr, sdk.NewDec(10000), 0}
 		validators = append(validators, validator)
 		delegations = append(delegations, delegation)
 	}
-	stakeGenesis.Pool.LooseTokens = sdk.NewDec(int64(100*250) + (numInitiallyBonded * 100))
+	stakeGenesis.Pool.LooseTokens = sdk.NewDec(int64(10000*250) + (numInitiallyBonded * 10000))
 	stakeGenesis.Validators = validators
 	stakeGenesis.Bonds = delegations
-
-	// No inflation, for now
 	mintGenesis := mint.DefaultGenesisState()
-	mintGenesis.Params.InflationMax = sdk.NewDec(0)
-	mintGenesis.Params.InflationMin = sdk.NewDec(0)
 
 	genesis := GenesisState{
 		Accounts:     genesisAccounts,
@@ -106,7 +104,12 @@ func appStateFn(r *rand.Rand, accs []simulation.Account) json.RawMessage {
 
 func testAndRunTxs(app *GaiaApp) []simulation.WeightedOperation {
 	return []simulation.WeightedOperation{
+		{5, authsim.SimulateDeductFee(app.accountMapper, app.feeCollectionKeeper)},
 		{100, banksim.SingleInputSendMsg(app.accountMapper, app.bankKeeper)},
+		{50, distributionsim.SimulateMsgSetWithdrawAddress(app.accountMapper, app.distrKeeper)},
+		{50, distributionsim.SimulateMsgWithdrawDelegatorRewardsAll(app.accountMapper, app.distrKeeper)},
+		{50, distributionsim.SimulateMsgWithdrawDelegatorReward(app.accountMapper, app.distrKeeper)},
+		{50, distributionsim.SimulateMsgWithdrawValidatorRewardsAll(app.accountMapper, app.distrKeeper)},
 		{5, govsim.SimulateSubmittingVotingAndSlashingForProposal(app.govKeeper, app.stakeKeeper)},
 		{100, govsim.SimulateMsgDeposit(app.govKeeper, app.stakeKeeper)},
 		{100, stakesim.SimulateMsgCreateValidator(app.accountMapper, app.stakeKeeper)},
@@ -121,8 +124,9 @@ func testAndRunTxs(app *GaiaApp) []simulation.WeightedOperation {
 func invariants(app *GaiaApp) []simulation.Invariant {
 	return []simulation.Invariant{
 		banksim.NonnegativeBalanceInvariant(app.accountMapper),
+		distributionsim.AllInvariants(app.bankKeeper, app.distrKeeper, app.accountMapper),
 		govsim.AllInvariants(),
-		stakesim.AllInvariants(app.bankKeeper, app.stakeKeeper, app.accountMapper),
+		stakesim.AllInvariants(app.bankKeeper, app.stakeKeeper, app.feeCollectionKeeper, app.distrKeeper, app.accountMapper),
 		slashingsim.AllInvariants(),
 	}
 }

docs/spec/staking/hooks.md

@@ -5,12 +5,12 @@ The staking module allow for the following hooks to be registered with staking e
 ``` golang
 // event hooks for staking validator object
 type StakingHooks interface {
-	OnValidatorCreated(ctx Context, address ValAddress)          // called when a validator is created
-	OnValidatorCommissionChange(ctx Context, address ValAddress) // called when a validator's commission is modified
-	OnValidatorRemoved(ctx Context, address ValAddress)          // called when a validator is deleted
+	OnValidatorCreated(ctx Context, address ValAddress)  // Must be called when a validator is created
+	OnValidatorModified(ctx Context, address ValAddress) // Must be called when a validator's state changes
+	OnValidatorRemoved(ctx Context, address ValAddress)  // Must be called when a validator is deleted
 
 	OnValidatorBonded(ctx Context, address ConsAddress)         // called when a validator is bonded
-	OnValidatorBeginUnbonding(ctx Context, address ConsAddress) // called when a validator begins unbonding
+	OnValidatorBeginUnbonding(ctx Context, address ConsAddress, operator ValAddress) // called when a validator begins unbonding
 
 	OnDelegationCreated(ctx Context, delAddr AccAddress, valAddr ValAddress)        // called when a delegation is created
 	OnDelegationSharesModified(ctx Context, delAddr AccAddress, valAddr ValAddress) // called when a delegation's shares are modified

types/decimal.go

@@ -247,6 +247,11 @@ func (d Dec) QuoInt(i Int) Dec {
 	return Dec{mul}
 }
 
+// is integer, e.g. decimals are zero.
+func (d Dec) IsInteger() bool {
+	return new(big.Int).Rem(d.Int, precisionReuse).Sign() == 0
+}
+
 func (d Dec) String() string {
 	str := d.ToLeftPaddedWithDecimals(Precision)
 	placement := len(str) - Precision

types/stake.go

@@ -85,9 +85,9 @@ type ValidatorSet interface {
 
 // delegation bond for a delegated proof of stake system
 type Delegation interface {
-	GetDelegator() AccAddress // delegator AccAddress for the bond
-	GetValidator() ValAddress // validator operator address
-	GetShares() Dec           // amount of validator's shares held in this delegation
+	GetDelegatorAddr() AccAddress // delegator AccAddress for the bond
+	GetValidatorAddr() ValAddress // validator operator address
+	GetShares() Dec               // amount of validator's shares held in this delegation
 }
 
 // properties for the set of all delegations for a particular
@@ -111,12 +111,12 @@ type DelegationSet interface {
 
 // event hooks for staking validator object
 type StakingHooks interface {
-	OnValidatorCreated(ctx Context, address ValAddress)          // Must be called when a validator is created
-	OnValidatorCommissionChange(ctx Context, address ValAddress) // Must be called when a validator's commission is modified
-	OnValidatorRemoved(ctx Context, address ValAddress)          // Must be called when a validator is deleted
+	OnValidatorCreated(ctx Context, address ValAddress)  // Must be called when a validator is created
+	OnValidatorModified(ctx Context, address ValAddress) // Must be called when a validator's state changes
+	OnValidatorRemoved(ctx Context, address ValAddress)  // Must be called when a validator is deleted
 
-	OnValidatorBonded(ctx Context, address ConsAddress)         // Must be called when a validator is bonded
-	OnValidatorBeginUnbonding(ctx Context, address ConsAddress) // Must be called when a validator begins unbonding
+	OnValidatorBonded(ctx Context, address ConsAddress)                              // Must be called when a validator is bonded
+	OnValidatorBeginUnbonding(ctx Context, address ConsAddress, operator ValAddress) // Must be called when a validator begins unbonding
 
 	OnDelegationCreated(ctx Context, delAddr AccAddress, valAddr ValAddress)        // Must be called when a delegation is created
 	OnDelegationSharesModified(ctx Context, delAddr AccAddress, valAddr ValAddress) // Must be called when a delegation's shares are modified

x/auth/simulation/fake.go

@@ -0,0 +1,62 @@
+package simulation
+
+import (
+	"errors"
+	"fmt"
+	"math/big"
+	"math/rand"
+
+	"github.com/cosmos/cosmos-sdk/baseapp"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/auth"
+	"github.com/cosmos/cosmos-sdk/x/mock/simulation"
+)
+
+// SimulateDeductFee
+func SimulateDeductFee(m auth.AccountMapper, f auth.FeeCollectionKeeper) simulation.Operation {
+	return func(r *rand.Rand, app *baseapp.BaseApp, ctx sdk.Context,
+		accs []simulation.Account, event func(string)) (
+		action string, fOp []simulation.FutureOperation, err error) {
+
+		account := simulation.RandomAcc(r, accs)
+		stored := m.GetAccount(ctx, account.Address)
+		initCoins := stored.GetCoins()
+
+		if len(initCoins) == 0 {
+			event(fmt.Sprintf("auth/SimulateDeductFee/false"))
+			return action, nil, nil
+		}
+
+		denomIndex := r.Intn(len(initCoins))
+		amt, err := randPositiveInt(r, initCoins[denomIndex].Amount)
+		if err != nil {
+			event(fmt.Sprintf("auth/SimulateDeductFee/false"))
+			return action, nil, nil
+		}
+
+		coins := sdk.Coins{sdk.NewCoin(initCoins[denomIndex].Denom, amt)}
+		err = stored.SetCoins(initCoins.Minus(coins))
+		if err != nil {
+			panic(err)
+		}
+		m.SetAccount(ctx, stored)
+		if !coins.IsNotNegative() {
+			panic("setting negative fees")
+		}
+
+		f.AddCollectedFees(ctx, coins)
+
+		event(fmt.Sprintf("auth/SimulateDeductFee/true"))
+
+		action = "TestDeductFee"
+		return action, nil, nil
+	}
+}
+
+func randPositiveInt(r *rand.Rand, max sdk.Int) (sdk.Int, error) {
+	if !max.GT(sdk.OneInt()) {
+		return sdk.Int{}, errors.New("max too small")
+	}
+	max = max.Sub(sdk.OneInt())
+	return sdk.NewIntFromBigInt(new(big.Int).Rand(r, max.BigInt())).Add(sdk.OneInt()), nil
+}

x/distribution/alias.go

@@ -49,7 +49,7 @@ var (
 
 	NewMsgSetWithdrawAddress          = types.NewMsgSetWithdrawAddress
 	NewMsgWithdrawDelegatorRewardsAll = types.NewMsgWithdrawDelegatorRewardsAll
-	NewMsgWithdrawDelegationReward    = types.NewMsgWithdrawDelegatorReward
+	NewMsgWithdrawDelegatorReward     = types.NewMsgWithdrawDelegatorReward
 	NewMsgWithdrawValidatorRewardsAll = types.NewMsgWithdrawValidatorRewardsAll
 )
 

x/distribution/handler.go

@@ -58,7 +58,10 @@ func handleMsgWithdrawDelegatorRewardsAll(ctx sdk.Context, msg types.MsgWithdraw
 
 func handleMsgWithdrawDelegatorReward(ctx sdk.Context, msg types.MsgWithdrawDelegatorReward, k keeper.Keeper) sdk.Result {
 
-	k.WithdrawDelegationReward(ctx, msg.DelegatorAddr, msg.ValidatorAddr)
+	err := k.WithdrawDelegationReward(ctx, msg.DelegatorAddr, msg.ValidatorAddr)
+	if err != nil {
+		return err.Result()
+	}
 
 	tags := sdk.NewTags(
 		tags.Action, tags.ActionWithdrawDelegatorReward,
@@ -72,7 +75,10 @@ func handleMsgWithdrawDelegatorReward(ctx sdk.Context, msg types.MsgWithdrawDele
 
 func handleMsgWithdrawValidatorRewardsAll(ctx sdk.Context, msg types.MsgWithdrawValidatorRewardsAll, k keeper.Keeper) sdk.Result {
 
-	k.WithdrawValidatorRewardsAll(ctx, msg.ValidatorAddr)
+	err := k.WithdrawValidatorRewardsAll(ctx, msg.ValidatorAddr)
+	if err != nil {
+		return err.Result()
+	}
 
 	tags := sdk.NewTags(
 		tags.Action, tags.ActionWithdrawValidatorRewardsAll,

x/distribution/keeper/delegation.go

@@ -5,6 +5,13 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/distribution/types"
 )
 
+// check whether a delegator distribution info exists
+func (k Keeper) HasDelegationDistInfo(ctx sdk.Context, delAddr sdk.AccAddress,
+	valOperatorAddr sdk.ValAddress) (has bool) {
+	store := ctx.KVStore(k.storeKey)
+	return store.Has(GetDelegationDistInfoKey(delAddr, valOperatorAddr))
+}
+
 // get the delegator distribution info
 func (k Keeper) GetDelegationDistInfo(ctx sdk.Context, delAddr sdk.AccAddress,
 	valOperatorAddr sdk.ValAddress) (ddi types.DelegationDistInfo) {
@@ -62,29 +69,40 @@ func (k Keeper) RemoveDelegatorWithdrawAddr(ctx sdk.Context, delAddr, withdrawAd
 
 //___________________________________________________________________________________________
 
-// withdraw all the rewards for a single delegation
+// Withdraw all the rewards for a single delegation.
+// NOTE: This gets called "onDelegationSharesModified",
+// meaning any changes to bonded coins.
 func (k Keeper) WithdrawDelegationReward(ctx sdk.Context, delegatorAddr sdk.AccAddress,
-	validatorAddr sdk.ValAddress) {
+	valAddr sdk.ValAddress) sdk.Error {
 
+	if !k.HasDelegationDistInfo(ctx, delegatorAddr, valAddr) {
+		return types.ErrNoDelegationDistInfo(k.codespace)
+	}
+
+	// TODO: Reconcile with duplicate code in getDelegatorRewardsAll.
 	height := ctx.BlockHeight()
-	bondedTokens := k.stakeKeeper.TotalPower(ctx)
+	lastTotalPower := k.stakeKeeper.GetLastTotalPower(ctx)
+	lastValPower := k.stakeKeeper.GetLastValidatorPower(ctx, valAddr)
 	feePool := k.GetFeePool(ctx)
-	delInfo := k.GetDelegationDistInfo(ctx, delegatorAddr, validatorAddr)
-	valInfo := k.GetValidatorDistInfo(ctx, validatorAddr)
-	validator := k.stakeKeeper.Validator(ctx, validatorAddr)
-	delegation := k.stakeKeeper.Delegation(ctx, delegatorAddr, validatorAddr)
+	delInfo := k.GetDelegationDistInfo(ctx, delegatorAddr, valAddr)
+	valInfo := k.GetValidatorDistInfo(ctx, valAddr)
+	validator := k.stakeKeeper.Validator(ctx, valAddr)
+	delegation := k.stakeKeeper.Delegation(ctx, delegatorAddr, valAddr)
 
-	delInfo, valInfo, feePool, withdraw := delInfo.WithdrawRewards(feePool, valInfo, height, bondedTokens,
-		validator.GetTokens(), validator.GetDelegatorShares(), delegation.GetShares(), validator.GetCommission())
+	delInfo, valInfo, feePool, withdraw := delInfo.WithdrawRewards(feePool, valInfo, height, lastTotalPower,
+		lastValPower, validator.GetDelegatorShares(), delegation.GetShares(), validator.GetCommission())
 
-	k.SetFeePool(ctx, feePool)
 	k.SetValidatorDistInfo(ctx, valInfo)
 	k.SetDelegationDistInfo(ctx, delInfo)
 	withdrawAddr := k.GetDelegatorWithdrawAddr(ctx, delegatorAddr)
-	_, _, err := k.bankKeeper.AddCoins(ctx, withdrawAddr, withdraw.TruncateDecimal())
+	coinsToAdd, change := withdraw.TruncateDecimal()
+	feePool.CommunityPool = feePool.CommunityPool.Plus(change)
+	k.SetFeePool(ctx, feePool)
+	_, _, err := k.bankKeeper.AddCoins(ctx, withdrawAddr, coinsToAdd)
 	if err != nil {
 		panic(err)
 	}
+	return nil
 }
 
 //___________________________________________________________________________________________
@@ -93,8 +111,12 @@ func (k Keeper) WithdrawDelegationReward(ctx sdk.Context, delegatorAddr sdk.AccA
 func (k Keeper) WithdrawDelegationRewardsAll(ctx sdk.Context, delegatorAddr sdk.AccAddress) {
 	height := ctx.BlockHeight()
 	withdraw := k.getDelegatorRewardsAll(ctx, delegatorAddr, height)
+	feePool := k.GetFeePool(ctx)
 	withdrawAddr := k.GetDelegatorWithdrawAddr(ctx, delegatorAddr)
-	_, _, err := k.bankKeeper.AddCoins(ctx, withdrawAddr, withdraw.TruncateDecimal())
+	coinsToAdd, change := withdraw.TruncateDecimal()
+	feePool.CommunityPool = feePool.CommunityPool.Plus(change)
+	k.SetFeePool(ctx, feePool)
+	_, _, err := k.bankKeeper.AddCoins(ctx, withdrawAddr, coinsToAdd)
 	if err != nil {
 		panic(err)
 	}
@@ -104,27 +126,27 @@ func (k Keeper) WithdrawDelegationRewardsAll(ctx sdk.Context, delegatorAddr sdk.
 func (k Keeper) getDelegatorRewardsAll(ctx sdk.Context, delAddr sdk.AccAddress, height int64) types.DecCoins {
 
 	withdraw := types.DecCoins{}
-	bondedTokens := k.stakeKeeper.TotalPower(ctx)
-	feePool := k.GetFeePool(ctx)
+	lastTotalPower := k.stakeKeeper.GetLastTotalPower(ctx)
 
 	// iterate over all the delegations
+	// TODO: Reconcile with duplicate code in WithdrawDelegationReward.
 	operationAtDelegation := func(_ int64, del sdk.Delegation) (stop bool) {
-		valAddr := del.GetValidator()
+		feePool := k.GetFeePool(ctx)
+		valAddr := del.GetValidatorAddr()
+		lastValPower := k.stakeKeeper.GetLastValidatorPower(ctx, valAddr)
 		delInfo := k.GetDelegationDistInfo(ctx, delAddr, valAddr)
 		valInfo := k.GetValidatorDistInfo(ctx, valAddr)
 		validator := k.stakeKeeper.Validator(ctx, valAddr)
 		delegation := k.stakeKeeper.Delegation(ctx, delAddr, valAddr)
 
-		delInfo, valInfo, feePool, diWithdraw := delInfo.WithdrawRewards(feePool, valInfo, height, bondedTokens,
-			validator.GetTokens(), validator.GetDelegatorShares(), delegation.GetShares(), validator.GetCommission())
+		delInfo, valInfo, feePool, diWithdraw := delInfo.WithdrawRewards(feePool, valInfo, height, lastTotalPower,
+			lastValPower, validator.GetDelegatorShares(), delegation.GetShares(), validator.GetCommission())
 		withdraw = withdraw.Plus(diWithdraw)
 		k.SetFeePool(ctx, feePool)
 		k.SetValidatorDistInfo(ctx, valInfo)
 		k.SetDelegationDistInfo(ctx, delInfo)
 		return false
 	}
 	k.stakeKeeper.IterateDelegations(ctx, delAddr, operationAtDelegation)
-
-	k.SetFeePool(ctx, feePool)
 	return withdraw
 }