feat: update default inflation rate (#1804)

* feat: update default inflation rate * chore: changelog * fix: fix rounding issue
NibiruChain · Feb 24, 2024 · 3324bc9 · 3324bc9
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -59,6 +59,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * [#1786](https://github.com/NibiruChain/nibiru/pull/1786) - fix(inflation): fix inflation off-by 2 error
 * [#1796](https://github.com/NibiruChain/nibiru/pull/1796) - fix(inflation): fix num skipped epoch when inflation is added to an existing chain
 * [#1797](https://github.com/NibiruChain/nibiru/pull/1797) - fix(inflation): fix num skipped epoch updates logic
+* [#1804](https://github.com/NibiruChain/nibiru/pull/1804) - fix(inflation): update default parameters
 
 ### Improvements
 

diff --git a/x/inflation/keeper/inflation_test.go b/x/inflation/keeper/inflation_test.go
@@ -37,12 +37,12 @@ func TestMintAndAllocateInflation(t *testing.T) {
 		{
 			name:                             "pass",
 			coinsToMint:                      sdk.NewCoin(denoms.NIBI, sdk.NewInt(1_000_000)),
-			expectedStakingAmt:               sdk.NewCoin(denoms.NIBI, sdk.NewInt(277_572)),
-			expectedStrategicAmt:             sdk.NewCoin(denoms.NIBI, sdk.NewInt(370_837)),
-			expectedCommunityAmt:             sdk.NewCoin(denoms.NIBI, sdk.NewInt(351_591)),
-			expectedStakingRewardsBalance:    sdk.NewCoin(denoms.NIBI, sdk.NewInt(277_572)),
-			expectedStrategicReservesBalance: sdk.NewCoin(denoms.NIBI, sdk.NewInt(370_837)),
-			expectedCommunityPoolBalance:     sdk.NewDecCoins(sdk.NewDecCoin(denoms.NIBI, sdk.NewInt(351_591))),
+			expectedStakingAmt:               sdk.NewCoin(denoms.NIBI, sdk.NewInt(281_250)),
+			expectedStrategicAmt:             sdk.NewCoin(denoms.NIBI, sdk.NewInt(363_925)),
+			expectedCommunityAmt:             sdk.NewCoin(denoms.NIBI, sdk.NewInt(354_825)),
+			expectedStakingRewardsBalance:    sdk.NewCoin(denoms.NIBI, sdk.NewInt(281_250)),
+			expectedStrategicReservesBalance: sdk.NewCoin(denoms.NIBI, sdk.NewInt(363_925)),
+			expectedCommunityPoolBalance:     sdk.NewDecCoins(sdk.NewDecCoin(denoms.NIBI, sdk.NewInt(354_825))),
 			rootAccount:                      "nibi1qyqf35fkhn73hjr70442fctpq8prpqr9ysj9sn",
 		},
 		{
@@ -59,12 +59,12 @@ func TestMintAndAllocateInflation(t *testing.T) {
 		{
 			name:                             "pass - no root account",
 			coinsToMint:                      sdk.NewCoin(denoms.NIBI, sdk.NewInt(1_000_000)),
-			expectedStakingAmt:               sdk.NewCoin(denoms.NIBI, sdk.NewInt(277_572)),
-			expectedStrategicAmt:             sdk.NewCoin(denoms.NIBI, sdk.NewInt(370_837)),
-			expectedCommunityAmt:             sdk.NewCoin(denoms.NIBI, sdk.NewInt(351_591)),
-			expectedStakingRewardsBalance:    sdk.NewCoin(denoms.NIBI, sdk.NewInt(277_572)),
-			expectedStrategicReservesBalance: sdk.NewCoin(denoms.NIBI, sdk.NewInt(370_837)),
-			expectedCommunityPoolBalance:     sdk.NewDecCoins(sdk.NewDecCoin(denoms.NIBI, sdk.NewInt(351_591))),
+			expectedStakingAmt:               sdk.NewCoin(denoms.NIBI, sdk.NewInt(281_250)),
+			expectedStrategicAmt:             sdk.NewCoin(denoms.NIBI, sdk.NewInt(363_925)),
+			expectedCommunityAmt:             sdk.NewCoin(denoms.NIBI, sdk.NewInt(354_825)),
+			expectedStakingRewardsBalance:    sdk.NewCoin(denoms.NIBI, sdk.NewInt(281_250)),
+			expectedStrategicReservesBalance: sdk.NewCoin(denoms.NIBI, sdk.NewInt(363_925)),
+			expectedCommunityPoolBalance:     sdk.NewDecCoins(sdk.NewDecCoin(denoms.NIBI, sdk.NewInt(354_825))),
 			rootAccount:                      "",
 		},
 	}
@@ -154,7 +154,7 @@ func TestGetCirculatingSupplyAndInflationRate(t *testing.T) {
 				params.InflationEnabled = true
 				nibiruApp.InflationKeeper.Params.Set(ctx, params)
 			},
-			sdk.MustNewDecFromStr("27.095518287362700000"),
+			sdk.MustNewDecFromStr("26.741197359810099000"),
 		},
 		{
 			"low supply",
@@ -164,7 +164,7 @@ func TestGetCirculatingSupplyAndInflationRate(t *testing.T) {
 				params.InflationEnabled = true
 				nibiruApp.InflationKeeper.Params.Set(ctx, params)
 			},
-			sdk.MustNewDecFromStr("54.191036574725400000"),
+			sdk.MustNewDecFromStr("53.482394719620198000"),
 		},
 	}
 	for _, tc := range testCases {

diff --git a/x/inflation/simulation/genesis.go b/x/inflation/simulation/genesis.go
@@ -0,0 +1,47 @@
+package simulation
+
+// DONTCOVER
+
+import (
+	"encoding/json"
+	"fmt"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/types/module"
+
+	"github.com/NibiruChain/nibiru/x/inflation/types"
+)
+
+// RandomizedGenState generates a random GenesisState for distribution
+func RandomizedGenState(simState *module.SimulationState) {
+	inflationGenesis := types.GenesisState{
+		Params: types.Params{
+			InflationEnabled: true,
+			PolynomialFactors: []sdk.Dec{
+				sdk.MustNewDecFromStr("-0.00014851"),
+				sdk.MustNewDecFromStr("0.07501029"),
+				sdk.MustNewDecFromStr("-19.04983993"),
+				sdk.MustNewDecFromStr("3158.89198346"),
+				sdk.MustNewDecFromStr("-338072.17402939"),
+				sdk.MustNewDecFromStr("17999834.20786474"),
+			},
+			InflationDistribution: types.InflationDistribution{
+				CommunityPool:     sdk.NewDecWithPrec(35_142714, 8), // 35.142714%
+				StakingRewards:    sdk.NewDecWithPrec(27_855672, 8), // 27.855672%
+				StrategicReserves: sdk.NewDecWithPrec(37_001614, 8), // 37.001614%
+			},
+			EpochsPerPeriod: 30,
+			PeriodsPerYear:  12,
+			MaxPeriod:       8 * 12,
+		},
+		Period:        0,
+		SkippedEpochs: 0,
+	}
+
+	bz, err := json.MarshalIndent(&inflationGenesis, "", " ")
+	if err != nil {
+		panic(err)
+	}
+	fmt.Printf("Selected randomly generated x/inflation parameters:\n%s\n", bz)
+	simState.GenState[types.ModuleName] = simState.Cdc.MustMarshalJSON(&inflationGenesis)
+}
diff --git a/x/inflation/types/inflation_calculation_test.go b/x/inflation/types/inflation_calculation_test.go
@@ -10,30 +10,30 @@ import (
 
 // These numbers are for year n month 1
 var ExpectedYearlyInflation = []sdk.Dec{
-	sdk.NewDec(195_895_391_000_000),
-	sdk.NewDec(156_348_637_000_000),
-	sdk.NewDec(124_785_459_000_000),
-	sdk.NewDec(99_594_157_000_000),
-	sdk.NewDec(79_488_398_000_000),
-	sdk.NewDec(63_441_527_000_000),
-	sdk.NewDec(50_634_148_000_000),
-	sdk.NewDec(40_412_283_000_000),
+	sdk.NewDec(193_333_719e6),
+	sdk.NewDec(154_304_107e6),
+	sdk.NewDec(123_153_673e6),
+	sdk.NewDec(98_291_791e6),
+	sdk.NewDec(78_448_949e6),
+	sdk.NewDec(62_611_919e6),
+	sdk.NewDec(49_972_019e6),
+	sdk.NewDec(39_883_823e6),
 }
 
 // ExpectedTotalInflation is the total amount of NIBI tokens (in unibi) that
 // should be minted via inflation for the network to reach its target supply.
-// The value 810.6 million is equivalent to:
+// The value 800M is equivalent to:
 // = (Community allocation of total supply) - (Community supply at start)
 // = (60% of the total supply) - (Community supply at start)
 // = (60% of 1.5 billion) - (Community supply at start)
-// = 810.6 million NIBI
-var ExpectedTotalInflation = sdk.NewDec(810_600_000_000_000)
+// = 800 million NIBI
+var ExpectedTotalInflation = sdk.NewDec(800_000_000e6)
 
 func TestCalculateEpochMintProvision(t *testing.T) {
 	params := DefaultParams()
 	params.InflationEnabled = true
 
-	epochId := uint64(0)
+	period := uint64(0)
 	totalInflation := sdk.ZeroDec()
 
 	// Only the first 8 years have inflation with default params but we run
@@ -42,20 +42,45 @@ func TestCalculateEpochMintProvision(t *testing.T) {
 		yearlyInflation := sdk.ZeroDec()
 		for month := uint64(0); month < 12; month++ {
 			for day := uint64(0); day < 30; day++ {
-				epochMintProvisions := CalculateEpochMintProvision(params, epochId)
+				epochMintProvisions := CalculateEpochMintProvision(params, period)
 				yearlyInflation = yearlyInflation.Add(epochMintProvisions)
 			}
-			epochId++
+			period++
 		}
 		// Should be within 0.0098%
 		if year < uint64(len(ExpectedYearlyInflation)) {
-			require.NoError(t, withingRange(yearlyInflation, ExpectedYearlyInflation[year]))
+			require.NoError(t, withinRange(ExpectedYearlyInflation[year], yearlyInflation))
 		} else {
 			require.Equal(t, yearlyInflation, sdk.ZeroDec())
 		}
 		totalInflation = totalInflation.Add(yearlyInflation)
 	}
-	require.NoError(t, withingRange(totalInflation, ExpectedTotalInflation))
+	require.NoError(t, withinRange(ExpectedTotalInflation, totalInflation))
+}
+
+func TestCalculateEpochMintProvisionInflationNotEnabled(t *testing.T) {
+	params := DefaultParams()
+	params.InflationEnabled = false
+
+	epochId := uint64(0)
+	totalInflation := sdk.ZeroDec()
+
+	// Only the first 8 years have inflation with default params but we run
+	// for 10 years expecting 0 inflation
+	for year := uint64(0); year < 10; year++ {
+		yearlyInflation := sdk.ZeroDec()
+		for month := uint64(0); month < 12; month++ {
+			for day := uint64(0); day < 30; day++ {
+				epochMintProvisions := CalculateEpochMintProvision(params, epochId)
+				yearlyInflation = yearlyInflation.Add(epochMintProvisions)
+			}
+			epochId++
+		}
+
+		require.Equal(t, yearlyInflation, sdk.ZeroDec())
+		totalInflation = totalInflation.Add(yearlyInflation)
+	}
+	require.Equal(t, totalInflation, sdk.ZeroDec())
 }
 
 func TestCalculateEpochMintProvision_ZeroEpochs(t *testing.T) {
@@ -66,12 +91,11 @@ func TestCalculateEpochMintProvision_ZeroEpochs(t *testing.T) {
 	require.Equal(t, epochMintProvisions, sdk.ZeroDec())
 }
 
-// withingRange returns an error if the actual value is not within the expected value +/- tolerance
+// withinRange returns an error if the actual value is not within the expected value +/- tolerance
 // tolerance is a percentage set to 0.01% by default
-func withingRange(expected, actual sdk.Dec) error {
+func withinRange(expected, actual sdk.Dec) error {
 	tolerance := sdk.NewDecWithPrec(1, 4)
-	is_within := expected.Sub(actual).Abs().Quo(expected).LTE(tolerance)
-	if !is_within {
+	if expected.Sub(actual).Abs().Quo(expected).GT(tolerance) {
 		tolerancePercent := tolerance.Mul(sdk.NewDec(100))
 		return fmt.Errorf("expected %s to be within %s%% of %s", actual.String(), tolerancePercent.String(), expected.String())
 	}

diff --git a/x/inflation/types/params.go b/x/inflation/types/params.go
@@ -20,17 +20,17 @@ var (
 var (
 	DefaultInflation         = false
 	DefaultPolynomialFactors = []sdk.Dec{
-		sdk.MustNewDecFromStr("-0.00014903"),
-		sdk.MustNewDecFromStr("0.07527647"),
-		sdk.MustNewDecFromStr("-19.11742154"),
-		sdk.MustNewDecFromStr("3170.0969905"),
-		sdk.MustNewDecFromStr("-339271.31060432"),
-		sdk.MustNewDecFromStr("18063678.8582418"),
+		sdk.MustNewDecFromStr("-0.000147085524"),
+		sdk.MustNewDecFromStr("0.074291982762"),
+		sdk.MustNewDecFromStr("-18.867415611180"),
+		sdk.MustNewDecFromStr("3128.641926954698"),
+		sdk.MustNewDecFromStr("-334834.740631598223"),
+		sdk.MustNewDecFromStr("17827464.906540066004"),
 	}
 	DefaultInflationDistribution = InflationDistribution{
-		CommunityPool:     sdk.NewDecWithPrec(35_159141, 8), // 35.159141%
-		StakingRewards:    sdk.NewDecWithPrec(27_757217, 8), // 27.757217%
-		StrategicReserves: sdk.NewDecWithPrec(37_083642, 8), // 37.083642%
+		CommunityPool:     sdk.NewDecWithPrec(35_4825, 6), // 35.4825%
+		StakingRewards:    sdk.NewDecWithPrec(28_1250, 6), // 28.1250%
+		StrategicReserves: sdk.NewDecWithPrec(36_3925, 6), // 36.3925%
 	}
 	DefaultEpochsPerPeriod = uint64(30)
 	DefaultPeriodsPerYear  = uint64(12)