refactor(x/inflation): change InflationDecay type to string (#1557)

Allows decay to be set as floating point value Signed-off-by: Artur Troian <[email protected]>
akash-network · Apr 19, 2022 · 9a9a2f9 · 9a9a2f9
1 parent 305639e
commit 9a9a2f9
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Showing 6 changed files with 213 additions and 105 deletions.
diff --git a/proto/akash/inflation/v1beta2/params.proto b/proto/akash/inflation/v1beta2/params.proto
@@ -7,7 +7,9 @@ option go_package = "github.com/ovrclk/akash/x/inflation/types/v1beta2";
 // Params defines the parameters for the x/deployment package
 message Params {
   // InflationDecayFactor is the number of years it takes inflation to halve.
-  uint32 inflation_decay_factor = 1 [
+  string inflation_decay_factor = 1 [
+    (gogoproto.customtype) = "github.com/cosmos/cosmos-sdk/types.Dec",
+    (gogoproto.nullable)   = false,
     (gogoproto.customname) = "InflationDecayFactor",
     (gogoproto.jsontag)    = "inflation_decay_factor",
     (gogoproto.moretags)   = "yaml:\"inflation_decay_factor\""

diff --git a/x/inflation/simulation/genesis.go b/x/inflation/simulation/genesis.go
@@ -3,14 +3,15 @@ package simulation
 import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/types/module"
+
 	types "github.com/ovrclk/akash/x/inflation/types/v1beta2"
 )
 
 // RandomizedGenState generates a random GenesisState for supply
 func RandomizedGenState(simState *module.SimulationState) {
 	deploymentGenesis := &types.GenesisState{
 		Params: types.Params{
-			InflationDecayFactor: 2,
+			InflationDecayFactor: types.DefaultInflationDecayFactor(),
 			InitialInflation:     sdk.NewDec(100),
 			Variance:             sdk.MustNewDecFromStr("0.05"),
 		},

diff --git a/x/inflation/types/v1beta2/inflation_calculator.go b/x/inflation/types/v1beta2/inflation_calculator.go
@@ -1,6 +1,7 @@
 package v1beta2
 
 import (
+	"fmt"
 	"time"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -17,74 +18,84 @@ func GetInflationCalculator(
 		var inflationParams Params
 		inflationParamSubspace.GetParamSet(ctx, &inflationParams)
 
-		// years passed since genesis = seconds passed since genesis / number of seconds per year
-		// can be a fraction, eg: 0.5
-		yearsPassed := decimal.WithPrecision(sdk.Precision).
-			Quo(
-				// seconds since genesis
-				decimal.WithPrecision(sdk.Precision).
-					Sub(
-						decimal.New(ctx.BlockTime().Unix(), 0),
-						decimal.New(genesisTime.Unix(), 0),
-					),
-				// Number of hours in an year = 8766 (averaging the leap year hours)
-				// Number of minutes in an hour = 60
-				// Number of seconds in a minute = 60
-				// => Number of seconds per year = 60 * 60 * 8766 = 31557600
-				decimal.New(31557600, 0),
-			)
-		// 2^(-t/tHalf)
-		pow := decimal.WithPrecision(sdk.Precision)
-		pow = pow.Context.
-			Pow(
-				pow,
-				decimal.New(2, 0),
-				decimal.WithPrecision(sdk.Precision).
-					Mul(
-						decimal.New(-1, 0),
-						decimal.WithPrecision(sdk.Precision).
-							Quo(
-								yearsPassed,
-								decimal.New(int64(inflationParams.InflationDecayFactor), 0),
-							),
-					),
-			)
-		// convert pow to sdk.Dec with a 6 unit precision: sdk.Decimal(big.Int(pow * 10^6)) / 10^6
-		powDec := sdk.NewDecFromBigInt(
+		return inflationCalculator(ctx.BlockTime(), genesisTime, minter, params, inflationParams, bondedRatio)
+	}
+}
+
+// inflationCalculator calculate current inflation value
+// - btime - block time from sdk.Context
+// - gtime - genesis time
+func inflationCalculator(btime, gtime time.Time, minter minttypes.Minter, mparams minttypes.Params, iparams Params, bondedRatio sdk.Dec) sdk.Dec {
+	inflationDecayFactor := new(decimal.Big)
+	if _, valid := inflationDecayFactor.SetString(iparams.InflationDecayFactor.String()); !valid {
+		panic(fmt.Sprintf("InflationDecayFactor contains invalid value [%s]. expected integer/float", iparams.InflationDecayFactor.String()))
+	}
+
+	// years passed since genesis = seconds passed since genesis / number of seconds per year
+	// can be a fraction, eg: 0.5
+	yearsPassed := decimal.WithPrecision(sdk.Precision).
+		Quo(
+			// seconds since genesis
+			decimal.WithPrecision(sdk.Precision).
+				Sub(
+					decimal.New(btime.Unix(), 0),
+					decimal.New(gtime.Unix(), 0),
+				),
+			// Number of hours in an year = 8766 (averaging the leap year hours)
+			// Number of minutes in an hour = 60
+			// Number of seconds in a minute = 60
+			// => Number of seconds per year = 60 * 60 * 8766 = 31557600
+			decimal.New(31557600, 0),
+		)
+	// 2^(-t/tHalf)
+	inflationCoefDec := decimal.WithPrecision(sdk.Precision)
+	inflationCoefDec = inflationCoefDec.Context.
+		Pow(
+			inflationCoefDec,
+			decimal.New(2, 0),
 			decimal.WithPrecision(sdk.Precision).
-				Mul(pow, decimal.New(1000000, 0)).
-				Int(nil),
-		).QuoInt64(1000000)
+				Mul(
+					decimal.New(-1, 0),
+					decimal.WithPrecision(sdk.Precision).
+						Quo(yearsPassed, inflationDecayFactor),
+				),
+		)
+	// convert inflationCoefDec to sdk.Dec with a 6 unit precision: sdk.Decimal(big.Int(pow * 10^6)) / 10^6
+	inflationCoef := sdk.NewDecFromBigInt(
+		decimal.WithPrecision(sdk.Precision).
+			Mul(inflationCoefDec, decimal.New(1000000, 0)).
+			Int(nil),
+	).QuoInt64(1000000)
 
-		idealInflation := inflationParams.InitialInflation.Mul(powDec)
+	idealInflation := iparams.InitialInflation.Mul(inflationCoef)
 
-		// (1 - bondedRatio/GoalBonded) * InflationRateChange
-		inflationRateChangePerYear := sdk.OneDec().
-			Sub(bondedRatio.Quo(params.GoalBonded)).
-			Mul(params.InflationRateChange)
-		inflationRateChange := inflationRateChangePerYear.Quo(sdk.NewDec(int64(params.BlocksPerYear)))
+	// (1 - bondedRatio/GoalBonded) * InflationRateChange
+	inflationRateChangePerYear := sdk.OneDec().
+		Sub(bondedRatio.Quo(mparams.GoalBonded)).
+		Mul(mparams.InflationRateChange)
 
-		// note inflationRateChange may be negative
-		currentInflation := minter.Inflation.Add(inflationRateChange)
+	inflationRateChange := inflationRateChangePerYear.Quo(sdk.NewDecFromInt(sdk.NewIntFromUint64(mparams.BlocksPerYear)))
 
-		// min, max currentInflation based on a defined range parameter 'r'
-		// currentInflation range = [I(t) - I(t) * R, I(t) + I(t) * R]
-		r := inflationParams.Variance
-		minInflation := idealInflation.Sub(idealInflation.Mul(r))
-		maxInflation := idealInflation.Add(idealInflation.Mul(r))
+	sdk.NewDecFromInt(sdk.NewIntFromUint64(mparams.BlocksPerYear))
 
-		// minInflation >= minimumMinInflation
-		minimumMinInflation := sdk.ZeroDec() // 0 for now
-		if minInflation.LT(minimumMinInflation) {
-			minInflation = minimumMinInflation
-		}
+	// note inflationRateChange may be negative
+	currentInflation := minter.Inflation.Add(inflationRateChange)
 
-		if currentInflation.LT(minInflation) {
-			currentInflation = minInflation
-		} else if currentInflation.GT(maxInflation) {
-			currentInflation = maxInflation
-		}
+	// min, max currentInflation based on a defined range parameter 'r'
+	// currentInflation range = [I(t) - I(t) * R, I(t) + I(t) * R]
+	// R is from iparams.Variance
+	minInflation := idealInflation.Sub(idealInflation.Mul(iparams.Variance))
+	maxInflation := idealInflation.Add(idealInflation.Mul(iparams.Variance))
 
-		return currentInflation
+	// the lowest possible value of minInflation is set for 0
+	// tho it can be set to higher value in the future
+	minInflation = sdk.MaxDec(sdk.ZeroDec(), minInflation)
+
+	if currentInflation.LT(minInflation) {
+		currentInflation = minInflation
+	} else if currentInflation.GT(maxInflation) {
+		currentInflation = maxInflation
 	}
+
+	return currentInflation
 }
diff --git a/x/inflation/types/v1beta2/inflation_calculator_test.go b/x/inflation/types/v1beta2/inflation_calculator_test.go
@@ -0,0 +1,82 @@
+package v1beta2
+
+import (
+	"testing"
+	"time"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	minttypes "github.com/cosmos/cosmos-sdk/x/mint/types"
+	"github.com/stretchr/testify/suite"
+)
+
+const (
+	blocksPerYear = 5256000
+)
+
+type InflationCalculatorTestSuite struct {
+	suite.Suite
+	params      Params
+	genesistime time.Time
+}
+
+func (s *InflationCalculatorTestSuite) SetupSuite() {
+	var err error
+	s.genesistime, err = time.Parse(time.RFC3339, "2021-03-08T15:00:00Z")
+	s.Require().NoError(err)
+
+	s.params.InflationDecayFactor, err = sdk.NewDecFromStr("2.10306569")
+	s.Require().NoError(err)
+
+	s.params.InitialInflation, err = sdk.NewDecFromStr("48.546257")
+	s.Require().NoError(err)
+
+	s.params.Variance, err = sdk.NewDecFromStr("0.05")
+	s.Require().NoError(err)
+}
+
+func TestIntegrationTestSuite(t *testing.T) {
+	suite.Run(t, new(InflationCalculatorTestSuite))
+}
+
+func (s *InflationCalculatorTestSuite) TestInflationCalculatorInvalidDecayFactor() {
+	testFn := func() {
+		inflationCalculator(
+			time.Time{},
+			time.Time{},
+			minttypes.Minter{},
+			minttypes.Params{},
+			Params{},
+			sdk.Dec{})
+	}
+
+	s.Panics(testFn)
+}
+
+func (s *InflationCalculatorTestSuite) TestInflationCalculator1() {
+	goalBonded, err := sdk.NewDecFromStr("0.67")
+	s.Require().NoError(err)
+
+	currBonded, err := sdk.NewDecFromStr("0.7324")
+	s.Require().NoError(err)
+
+	currInflation, err := sdk.NewDecFromStr("0.230326319830867266")
+	s.Require().NoError(err)
+
+	blockTime, _ := time.Parse(time.RFC3339, "2022-04-18T18:28:26+00:00")
+
+	res := inflationCalculator(
+		blockTime,
+		s.genesistime,
+		minttypes.Minter{
+			Inflation: currInflation,
+		},
+		minttypes.Params{
+			BlocksPerYear:       blocksPerYear,
+			GoalBonded:          goalBonded,
+			InflationRateChange: s.params.Variance,
+		},
+		s.params,
+		currBonded)
+
+	s.Require().Equal("31.967899564902300000", res.String())
+}
diff --git a/x/inflation/types/v1beta2/params.go b/x/inflation/types/v1beta2/params.go
@@ -10,13 +10,13 @@ import (
 var _ paramtypes.ParamSet = (*Params)(nil)
 
 const (
-	DefaultInflationDecayFactor uint32 = 2 // years
-
 	keyInflationDecayFactor = "InflationDecayFactor"
 	keyInitialInflation     = "InitialInflation"
 	keyVariance             = "Variance"
 )
 
+func DefaultInflationDecayFactor() sdk.Dec { return sdk.NewDec(2) } // years
+
 func DefaultInitialInflation() sdk.Dec { return sdk.NewDec(100) }
 func DefaultVarince() sdk.Dec          { return sdk.MustNewDecFromStr("0.05") }
 
@@ -40,7 +40,7 @@ func (p *Params) ParamSetPairs() paramtypes.ParamSetPairs {
 
 func DefaultParams() Params {
 	return Params{
-		InflationDecayFactor: DefaultInflationDecayFactor,
+		InflationDecayFactor: DefaultInflationDecayFactor(),
 		InitialInflation:     DefaultInitialInflation(),
 		Variance:             DefaultVarince(),
 	}
@@ -61,8 +61,8 @@ func (p Params) Validate() error {
 }
 
 func validateInflationDecayFactor(i interface{}) error {
-	v, ok := i.(uint32)
-	if !ok || v < 1 {
+	v, ok := i.(sdk.Dec)
+	if !ok || v.LT(sdk.NewDec(1)) {
 		return errors.Wrapf(ErrInvalidParam, "%T", i)
 	}