1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110

//! configuration for network inflation

#[derive(Serialize, Deserialize, PartialEq, Clone, Debug, Copy, AbiExample)]
#[serde(rename_all = "camelCase")]
pub struct Inflation {
    /// Initial inflation percentage, from time=0
    pub initial: f64,

    /// Terminal inflation percentage, to time=INF
    pub terminal: f64,

    /// Rate per year, at which inflation is lowered until reaching terminal
    ///  i.e. inflation(year) == MAX(terminal, initial*((1-taper)^year))
    pub taper: f64,

    /// Percentage of total inflation allocated to the foundation
    pub foundation: f64,
    /// Duration of foundation pool inflation, in years
    pub foundation_term: f64,

    /// DEPRECATED, this field is currently unused
    pub storage: f64,
}

const DEFAULT_INITIAL: f64 = 0.15;
const DEFAULT_TERMINAL: f64 = 0.015;
const DEFAULT_TAPER: f64 = 0.15;
const DEFAULT_FOUNDATION: f64 = 0.05;
const DEFAULT_FOUNDATION_TERM: f64 = 7.0;
const DEFAULT_STORAGE: f64 = 0.0;

impl Default for Inflation {
    fn default() -> Self {
        Self {
            initial: DEFAULT_INITIAL,
            terminal: DEFAULT_TERMINAL,
            taper: DEFAULT_TAPER,
            foundation: DEFAULT_FOUNDATION,
            foundation_term: DEFAULT_FOUNDATION_TERM,
            storage: DEFAULT_STORAGE,
        }
    }
}

impl Inflation {
    pub fn new_disabled() -> Self {
        Self {
            initial: 0.0,
            terminal: 0.0,
            taper: 0.0,
            foundation: 0.0,
            foundation_term: 0.0,
            storage: 0.0,
        }
    }
    /// inflation rate at year
    pub fn total(&self, year: f64) -> f64 {
        let tapered = self.initial * ((1.0 - self.taper).powf(year));

        if tapered > self.terminal {
            tapered
        } else {
            self.terminal
        }
    }

    /// portion of total that goes to validators
    pub fn validator(&self, year: f64) -> f64 {
        self.total(year) - self.storage(year) - self.foundation(year)
    }

    /// DEPRECATED
    fn storage(&self, year: f64) -> f64 {
        self.total(year) * self.storage
    }

    /// portion of total that goes to foundation
    pub fn foundation(&self, year: f64) -> f64 {
        if year < self.foundation_term {
            self.total(year) * self.foundation
        } else {
            0.0
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    #[allow(clippy::float_cmp)]
    fn test_inflation_basic() {
        let inflation = Inflation::default();

        let mut last = inflation.total(0.0);

        for year in &[0.1, 0.5, 1.0, DEFAULT_FOUNDATION_TERM, 100.0] {
            let total = inflation.total(*year);
            assert_eq!(
                total,
                inflation.validator(*year) + inflation.storage(*year) + inflation.foundation(*year)
            );
            assert!(total < last);
            assert!(total >= inflation.terminal);
            last = total;
        }
        assert_eq!(last, inflation.terminal);
    }
}