Grcov report - inflation

1

// Copyright (C) Moondance Labs Ltd.

2

// This file is part of Tanssi.

3

4

// Tanssi is free software: you can redistribute it and/or modify

5

// it under the terms of the GNU General Public License as published by

6

// the Free Software Foundation, either version 3 of the License, or

7

// (at your option) any later version.

8

9

// Tanssi is distributed in the hope that it will be useful,

10

// but WITHOUT ANY WARRANTY; without even the implied warranty of

11

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

12

// GNU General Public License for more details.

13

14

// You should have received a copy of the GNU General Public License

15

// along with Tanssi.  If not, see <http://www.gnu.org/licenses/>

16

17

use crate::{

18

    tests::common::ExtBuilder, Balances, CollatorsInflationRatePerBlock, EpochDurationInBlocks,

19

    Perbill, Runtime, SessionsPerEra, ValidatorsInflationRatePerEra, DAYS,

20

};

21

22

#[derive(Debug)]

23

struct InflationRates {

24

    era_inflation: f64,

25

    collators_block_inflation: f64,

26

    validators_era_inflation: f64,

27

28

29

/// Computes the following inflation rates:

30

/// - Collators inflation rate (per block)

31

/// - Validators inflation rate (per era)

32

/// Era inflation is split between collators and validators using collators_fraction

33

3

fn compute_inflation_rates(

34

3

    annual_inflation: f64,

35

3

    collators_fraction: f64,

36

3

    eras_per_year: u32,

37

3

    blocks_per_era: u32,

38

3

) -> InflationRates {

39

3

    assert!(

40

3

        collators_fraction >= 0.0 && collators_fraction <= 1.0,

41

        "collators_fraction must be between 0 and 1"

42

);

43

3

    assert!(

44

3

        annual_inflation >= 0.0 && annual_inflation <= 1.0,

45

        "annual_inflation is a % and should be between 0 (0%) and 1 (100%)"

46

);

47

48

    // Compute era inflation based on annual inflation

49

3

    let era_inflation = (1.0 + annual_inflation).powf(1.0 / (eras_per_year as f64)) - 1.0;

50

3

51

3

    // Compute collators and validators era inflation

52

3

    let collators_era_inflation = (1.0 + era_inflation).powf(collators_fraction) - 1.0;

53

3

    let validators_era_inflation = (1.0 + era_inflation).powf(1.0 - collators_fraction) - 1.0;

54

3

55

3

    // Compute collator block inflation

56

3

    let collators_block_inflation =

57

3

        (1.0 + collators_era_inflation).powf(1.0 / (blocks_per_era as f64)) - 1.0;

58

3

59

3

    InflationRates {

60

3

        era_inflation,

61

3

        collators_block_inflation,

62

3

        validators_era_inflation,

63

3

64

3

65

66

#[test]

67

1

fn formula_is_sound() {

68

1

    let eras_per_year = 100;

69

1

    let blocks_per_era = 100;

70

1

    let annual_inflation = 0.1; // 10%

71

1

72

1

    let rates = compute_inflation_rates(annual_inflation, 0.6, eras_per_year, blocks_per_era);

73

1

74

1

    println!("Rates: {rates:?}");

75

1

76

1

    let col_inf = Perbill::from_float(rates.collators_block_inflation);

77

1

    let val_inf = Perbill::from_float(rates.validators_era_inflation);

78

1

79

1

    // "big" supply to reduce rounding errors

80

1

    let initial_supply = 100_000_000_000_000_000u128;

81

1

    let mut supply = initial_supply;

82

83

100

    for era in 0..eras_per_year {

84

100

        let era_start_supply = supply;

85

86

10000

        for _block in 0..blocks_per_era {

87

10000

            supply += col_inf * supply;

88

10000

89

90

100

        supply += val_inf * supply;

91

100

92

100

        let actual_era_inflation = supply as f64 / era_start_supply as f64 - 1.0;

93

100

94

100

        println!("Era {era}: Supply {supply}, Actual inf: {actual_era_inflation}");

95

100

        assert!((actual_era_inflation - rates.era_inflation).abs() < 0.00001);

96

97

98

1

    let actual_annual_inflation = supply as f64 / initial_supply as f64 - 1.0;

99

1

    println!("Initial supply: {initial_supply}");

100

1

    println!("Final supply:   {supply}");

101

1

    println!("Actual annual inflation: {actual_annual_inflation}");

102

1

    assert!((actual_annual_inflation - annual_inflation).abs() < 0.00001);

103

1

104

105

2

fn runtime_inflations_values_are_correct_prod_or_fast(prod: bool) {

106

2

    ExtBuilder::default().build().execute_with(|| {

107

2

        let sessions_per_era = SessionsPerEra::prod_if(prod);

108

2

        let blocks_per_session = EpochDurationInBlocks::prod_if(prod);

109

2

        let blocks_per_era = blocks_per_session * sessions_per_era;

110

2

        let eras_per_year = (365 * DAYS) / blocks_per_era;

111

2

112

2

        let annual_inflation = 0.1; // 10%

113

2

        let collators_fraction = 0.5; // 50% of era inflation goes to collators.

114

2

115

2

        let rates = compute_inflation_rates(

116

2

            annual_inflation,

117

2

            collators_fraction,

118

2

            eras_per_year,

119

2

            blocks_per_era,

120

2

);

121

2

        println!("{rates:?}");

122

2

123

2

        let col_inf = Perbill::from_float(rates.collators_block_inflation);

124

2

        let val_inf = Perbill::from_float(rates.validators_era_inflation);

125

2

126

2

        assert_eq!(

127

2

            CollatorsInflationRatePerBlock::prod_if(prod),

128

            col_inf,

129

            "Collators inflation didn't match"

130

);

131

2

        assert_eq!(

132

2

            ValidatorsInflationRatePerEra::prod_if(prod),

133

            val_inf,

134

            "Validators inflation didn't match"

135

);

136

137

2

        assert!(

138

2

            CollatorsInflationRatePerBlock::prod_if(prod)

139

2

                < ValidatorsInflationRatePerEra::prod_if(prod),

140

            "block inflation should be less than era inflation, are they swapped?"

141

);

142

143

        // CollatorsInflationRatePerBlock must be used in the pallet that rewards

144

        // container chains collators.

145

2

        assert_eq!(

146

2

            <Runtime as pallet_inflation_rewards::Config>::InflationRate::get(),

147

2

            CollatorsInflationRatePerBlock::get(),

148

2

);

149

150

        // ValidatorsInflationRatePerEra must be used in the pallet that rewards

151

        // external validators. In this pallet the getter directly provides the inflated

152

        // amount.

153

2

        assert_eq!(

154

2

            <Runtime as pallet_external_validators_rewards::Config>::EraInflationProvider::get(),

155

2

            ValidatorsInflationRatePerEra::get() * Balances::total_issuance(),

156

2

);

157

2

})

158

2

159

160

#[test]

161

1

fn runtime_inflations_values_are_correct_in_prod() {

162

1

    runtime_inflations_values_are_correct_prod_or_fast(true)

163

1

164

165

#[test]

166

1

fn runtime_inflations_values_are_correct_in_fast() {

167

1

    runtime_inflations_values_are_correct_prod_or_fast(false)

168

1