Keep the total supply constant. (#258)

Mint validator slashing burned tokens and move to community pool.

app/app.go

@@ -171,6 +171,7 @@ var (
 		registertypes.MetaNodeNotBondedPool:     {authtypes.Minter},
 		registertypes.TotalUnissuedPrepay:       {authtypes.Minter},
 
+		pottypes.ModuleName:        {authtypes.Minter},
 		pottypes.FoundationAccount: {authtypes.Minter, authtypes.Burner},
 		pottypes.TotalRewardPool:   nil,
 		//pottypes.TotalMinedTokens: {authtypes.Minter, authtypes.Burner},
@@ -509,7 +510,6 @@ func NewInitApp(
 		govtypes.ModuleName,
 		stakingtypes.ModuleName,
 		registertypes.ModuleName,
-		pottypes.ModuleName,
 		sdstypes.ModuleName,
 		evmtypes.ModuleName,
 		// no-op modules
@@ -525,6 +525,7 @@ func NewInitApp(
 		evidencetypes.ModuleName,
 		authz.ModuleName,
 		feegrant.ModuleName,
+		pottypes.ModuleName,
 		paramstypes.ModuleName,
 		upgradetypes.ModuleName,
 		vestingtypes.ModuleName,

proto/stratos/pot/v1/pot.proto

@@ -31,6 +31,11 @@ message Params {
     (gogoproto.moretags) = "yaml:\"community_tax\"",
     (gogoproto.customtype) = "github.com/cosmos/cosmos-sdk/types.Dec"
   ];
+  cosmos.base.v1beta1.Coin    initial_total_supply = 6 [
+    (gogoproto.nullable) = false,
+    (gogoproto.jsontag) = "initial_total_supply",
+    (gogoproto.moretags) = "yaml:\"initial_total_supply\""
+  ];
 }
 
 message MiningRewardParam {

x/pot/abci.go

@@ -4,6 +4,7 @@ import (
 	abci "github.com/tendermint/tendermint/abci/types"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
 
 	"github.com/stratosnet/stratos-chain/x/pot/keeper"
 	"github.com/stratosnet/stratos-chain/x/pot/types"
@@ -53,5 +54,15 @@ func EndBlocker(ctx sdk.Context, req abci.RequestEndBlock, k keeper.Keeper) []ab
 		logger.Error("An error occurred while distributing the reward. ", "ErrMsg", err.Error())
 	}
 
+	// reset total supply to 100M stos
+	minter, amount := k.RestoreTotalSupply(ctx)
+	if minter.Empty() || amount.Empty() {
+		return []abci.ValidatorUpdate{}
+	}
+
+	ctx.EventManager().EmitEvent(
+		banktypes.NewCoinMintEvent(minter, amount),
+	)
+
 	return []abci.ValidatorUpdate{}
 }

x/pot/keeper/keeper.go

@@ -1,13 +1,15 @@
 package keeper
 
 import (
+	"bytes"
 	"fmt"
 	"math"
 
 	"github.com/tendermint/tendermint/libs/log"
 
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
 	paramstypes "github.com/cosmos/cosmos-sdk/x/params/types"
 
 	stratos "github.com/stratosnet/stratos-chain/types"
@@ -87,3 +89,60 @@ func (k Keeper) FoundationDeposit(ctx sdk.Context, amount sdk.Coins, from sdk.Ac
 	}
 	return nil
 }
+
+// Restore total supply to 100M stos
+func (k Keeper) RestoreTotalSupply(ctx sdk.Context) (minter sdk.AccAddress, mintCoins sdk.Coins) {
+	// reset total supply to 100M stos
+	events := ctx.EventManager().Events()
+	attrKeyAmtBytes := []byte(sdk.AttributeKeyAmount)
+
+	totalBurnedCoins := sdk.Coins{}
+	for _, event := range events {
+		if event.Type == banktypes.EventTypeCoinBurn {
+			attributes := event.Attributes
+			for _, attr := range attributes {
+				if bytes.Equal(attr.Key, attrKeyAmtBytes) {
+					amount, err := sdk.ParseCoinsNormalized(string(attr.Value))
+					if err != nil {
+						ctx.Logger().Error("An error occurred while parsing burned amount. ", "ErrMsg", err.Error())
+						break
+					}
+					totalBurnedCoins = totalBurnedCoins.Add(amount...)
+				}
+			}
+		}
+	}
+
+	totalBurned := totalBurnedCoins.AmountOf(k.BondDenom(ctx))
+	if totalBurned.IsZero() {
+		return sdk.AccAddress{}, sdk.Coins{}
+	}
+
+	InitialTotalSupply := k.InitialTotalSupply(ctx).Amount
+	currentTotalSupply := k.bankKeeper.GetSupply(ctx, k.BondDenom(ctx)).Amount
+
+	if totalBurned.Add(currentTotalSupply).GT(InitialTotalSupply) {
+		mintCoins = sdk.NewCoins(
+			sdk.NewCoin(k.BondDenom(ctx), InitialTotalSupply.Sub(currentTotalSupply)),
+		)
+	} else {
+		mintCoins = totalBurnedCoins
+	}
+
+	// mint coins
+	err := k.bankKeeper.MintCoins(ctx, types.ModuleName, mintCoins)
+	if err != nil {
+		ctx.Logger().Error("Restore total supply failed:", err.Error())
+		return sdk.AccAddress{}, sdk.Coins{}
+	}
+
+	// send new mint coins to community pool
+	senderAddr := k.accountKeeper.GetModuleAddress(types.ModuleName)
+	err = k.distrKeeper.FundCommunityPool(ctx, mintCoins, senderAddr)
+	if err != nil {
+		ctx.Logger().Error("Restore total supply failed:", err.Error())
+		return sdk.AccAddress{}, sdk.Coins{}
+	}
+
+	return
+}

x/pot/keeper/params.go

@@ -2,6 +2,7 @@ package keeper
 
 import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
+
 	"github.com/stratosnet/stratos-chain/x/pot/types"
 )
 
@@ -51,3 +52,8 @@ func (k Keeper) GetCommunityTax(ctx sdk.Context) (res sdk.Dec) {
 	k.paramSpace.Get(ctx, types.KeyCommunityTax, &res)
 	return
 }
+
+func (k Keeper) InitialTotalSupply(ctx sdk.Context) (res sdk.Coin) {
+	k.paramSpace.Get(ctx, types.KeyInitialTotalSupply, &res)
+	return
+}

x/pot/types/errors.go

@@ -13,6 +13,9 @@ const (
 	codeErrMissingTargetAddress
 	codeErrInsufficientMatureTotal
 	codeErrMatureEpoch
+	codeErrMiningRewardParams
+	codeErrCommunityTax
+	codeErrInitialTotalSupply
 	codeErrEmptyFromAddr
 	codeErrEmptyReporterAddr
 	codeErrEmptyWalletVolumes
@@ -50,6 +53,9 @@ var (
 	ErrMissingTargetAddress           = sdkerrors.Register(ModuleName, codeErrMissingTargetAddress, "missing target address")
 	ErrInsufficientMatureTotal        = sdkerrors.Register(ModuleName, codeErrInsufficientMatureTotal, "insufficient mature total")
 	ErrMatureEpoch                    = sdkerrors.Register(ModuleName, codeErrMatureEpoch, "the value of epoch must be positive and greater than its previous one")
+	ErrMiningRewardParams             = sdkerrors.Register(ModuleName, codeErrMiningRewardParams, "invalid mining reward param")
+	ErrCommunityTax                   = sdkerrors.Register(ModuleName, codeErrCommunityTax, "invalid community tax param")
+	ErrInitialTotalSupply             = sdkerrors.Register(ModuleName, codeErrInitialTotalSupply, "invalid initial total supply param")
 	ErrEmptyFromAddr                  = sdkerrors.Register(ModuleName, codeErrEmptyFromAddr, "missing from address")
 	ErrEmptyReporterAddr              = sdkerrors.Register(ModuleName, codeErrEmptyReporterAddr, "missing reporter address")
 	ErrEmptyWalletVolumes             = sdkerrors.Register(ModuleName, codeErrEmptyWalletVolumes, "wallet volumes list empty")

x/pot/types/expected_keepers.go

@@ -20,6 +20,8 @@ type BankKeeper interface {
 	SendCoinsFromAccountToModule(ctx sdk.Context, senderAddr sdk.AccAddress, recipientModule string, amt sdk.Coins) error
 	SendCoinsFromModuleToAccount(ctx sdk.Context, senderModule string, recipientAddr sdk.AccAddress, amt sdk.Coins) error
 	SendCoinsFromModuleToModule(ctx sdk.Context, senderPool, recipientPool string, amt sdk.Coins) error
+	GetSupply(ctx sdk.Context, denom string) sdk.Coin
+	MintCoins(ctx sdk.Context, moduleName string, amounts sdk.Coins) error
 }
 
 type RegisterKeeper interface {

x/pot/types/params.go

@@ -26,8 +26,12 @@ var (
 	KeyMatureEpoch        = []byte("MatureEpoch")
 	KeyMiningRewardParams = []byte("MiningRewardParams")
 	KeyCommunityTax       = []byte("CommunityTax")
+	KeyInitialTotalSupply = []byte("InitialTotalSupply")
 
-	DefaultCommunityTax = sdk.NewDecWithPrec(2, 2) // 2%
+	DefaultCommunityTax       = sdk.NewDecWithPrec(2, 2) // 2%
+	DefaultInitialTotalSupply = sdk.NewCoin(DefaultBondDenom,
+		sdk.NewInt(1e8).Mul(sdk.NewInt(stratos.StosToWei)),
+	) //100,000,000 stos
 )
 
 // ParamKeyTable for pot module
@@ -36,13 +40,16 @@ func ParamKeyTable() paramtypes.KeyTable {
 }
 
 // NewParams creates a new Params object
-func NewParams(bondDenom string, rewardDenom string, matureEpoch int64, miningRewardParams []MiningRewardParam, communityTax sdk.Dec) Params {
+func NewParams(bondDenom string, rewardDenom string, matureEpoch int64, miningRewardParams []MiningRewardParam,
+	communityTax sdk.Dec, initialTotalSupply sdk.Coin) Params {
+
 	return Params{
 		BondDenom:          bondDenom,
 		RewardDenom:        rewardDenom,
 		MatureEpoch:        matureEpoch,
 		MiningRewardParams: miningRewardParams,
 		CommunityTax:       communityTax,
+		InitialTotalSupply: initialTotalSupply,
 	}
 }
 
@@ -85,17 +92,26 @@ func DefaultParams() Params {
 		sdk.NewCoin(DefaultRewardDenom, sdk.NewInt(2500000000)),
 		sdk.NewInt(7000), sdk.NewInt(1000), sdk.NewInt(2000)))
 
-	return NewParams(DefaultBondDenom, DefaultRewardDenom, DefaultMatureEpoch, miningRewardParams, DefaultCommunityTax)
+	return NewParams(
+		DefaultBondDenom,
+		DefaultRewardDenom,
+		DefaultMatureEpoch,
+		miningRewardParams,
+		DefaultCommunityTax,
+		DefaultInitialTotalSupply,
+	)
 }
 
 // HrpString implements the stringer interface for Params
 func (p Params) HrpString() string {
 	return fmt.Sprintf(`Params:
-	BondDenom:			%s
-   RewardDenom:	%s
-	MatureEpoch:        %d
- 	MiningRewardParams:	%s`,
-		p.BondDenom, p.RewardDenom, p.MatureEpoch, p.MiningRewardParams)
+    BondDenom:          %s
+    RewardDenom:        %s
+    MatureEpoch:        %d
+    MiningRewardParams: %s
+    CommunitiyTax:      %v
+    InitialTotalSupply: %v`,
+		p.BondDenom, p.RewardDenom, p.MatureEpoch, p.MiningRewardParams, p.CommunityTax, p.InitialTotalSupply)
 }
 
 // ParamSetPairs - Implements params.ParamSet
@@ -106,6 +122,7 @@ func (p *Params) ParamSetPairs() paramtypes.ParamSetPairs {
 		paramtypes.NewParamSetPair(KeyMatureEpoch, &p.MatureEpoch, validateMatureEpoch),
 		paramtypes.NewParamSetPair(KeyMiningRewardParams, &p.MiningRewardParams, validateMiningRewardParams),
 		paramtypes.NewParamSetPair(KeyCommunityTax, &p.CommunityTax, validateCommunityTax),
+		paramtypes.NewParamSetPair(KeyInitialTotalSupply, &p.InitialTotalSupply, validateInitialTotalSupply),
 	}
 }
 
@@ -188,6 +205,20 @@ func validateCommunityTax(i interface{}) error {
 	return nil
 }
 
+func validateInitialTotalSupply(i interface{}) error {
+	v, ok := i.(sdk.Coin)
+	if !ok {
+		return fmt.Errorf("invalid parameter type: %T", i)
+	}
+	if v.IsNil() {
+		return fmt.Errorf("total supply must be not nil")
+	}
+	if v.IsNegative() {
+		return fmt.Errorf("total supply must be positive: %s", v)
+	}
+	return nil
+}
+
 func (p Params) ValidateBasic() error {
 	if err := validateBondDenom(p.BondDenom); err != nil {
 		return sdkerrors.Wrap(ErrInvalidDenom, "failed to validate bond denomination")
@@ -199,10 +230,13 @@ func (p Params) ValidateBasic() error {
 		return sdkerrors.Wrap(ErrMatureEpoch, "failed to validate mature epoch")
 	}
 	if err := validateMiningRewardParams(p.MiningRewardParams); err != nil {
-		return sdkerrors.Wrap(ErrMatureEpoch, "failed to validate mining reward params")
+		return sdkerrors.Wrap(ErrMiningRewardParams, "failed to validate mining reward params")
 	}
 	if err := validateCommunityTax(p.CommunityTax); err != nil {
-		return sdkerrors.Wrap(ErrMatureEpoch, "failed to validate community tax")
+		return sdkerrors.Wrap(ErrCommunityTax, "failed to validate community tax")
+	}
+	if err := validateInitialTotalSupply(p.InitialTotalSupply); err != nil {
+		return sdkerrors.Wrap(ErrInitialTotalSupply, err.Error())
 	}
 	return nil
 }