Files
pezkuwi-subxt/substrate/frame/staking/src/inflation.rs
T
Bastian Köcher bd5758932b Make all PerThing types implement all trait methods on the type (#5422)
This removes the requirement to import `PerThing` to use a type that
implements the trait.
2020-03-27 11:21:14 +01:00

104 lines
4.2 KiB
Rust

// Copyright 2019-2020 Parity Technologies (UK) Ltd.
// This file is part of Substrate.
// Substrate is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Substrate is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Substrate. If not, see <http://www.gnu.org/licenses/>.
//! This module expose one function `P_NPoS` (Payout NPoS) or `compute_total_payout` which returns
//! the total payout for the era given the era duration and the staking rate in NPoS.
//! The staking rate in NPoS is the total amount of tokens staked by nominators and validators,
//! divided by the total token supply.
use sp_runtime::{Perbill, traits::AtLeast32Bit, curve::PiecewiseLinear};
/// The total payout to all validators (and their nominators) per era.
///
/// Defined as such:
/// `payout = yearly_inflation(npos_token_staked / total_tokens) * total_tokens / era_per_year`
///
/// `era_duration` is expressed in millisecond.
pub fn compute_total_payout<N>(
yearly_inflation: &PiecewiseLinear<'static>,
npos_token_staked: N,
total_tokens: N,
era_duration: u64
) -> (N, N) where N: AtLeast32Bit + Clone {
// Milliseconds per year for the Julian year (365.25 days).
const MILLISECONDS_PER_YEAR: u64 = 1000 * 3600 * 24 * 36525 / 100;
let portion = Perbill::from_rational_approximation(era_duration as u64, MILLISECONDS_PER_YEAR);
let payout = portion * yearly_inflation.calculate_for_fraction_times_denominator(
npos_token_staked,
total_tokens.clone(),
);
let maximum = portion * (yearly_inflation.maximum * total_tokens);
(payout, maximum)
}
#[cfg(test)]
mod test {
use sp_runtime::curve::PiecewiseLinear;
pallet_staking_reward_curve::build! {
const I_NPOS: PiecewiseLinear<'static> = curve!(
min_inflation: 0_025_000,
max_inflation: 0_100_000,
ideal_stake: 0_500_000,
falloff: 0_050_000,
max_piece_count: 40,
test_precision: 0_005_000,
);
}
#[test]
fn npos_curve_is_sensible() {
const YEAR: u64 = 365 * 24 * 60 * 60 * 1000;
// check maximum inflation.
// not 10_000 due to rounding error.
assert_eq!(super::compute_total_payout(&I_NPOS, 0, 100_000u64, YEAR).1, 9_993);
//super::I_NPOS.calculate_for_fraction_times_denominator(25, 100)
assert_eq!(super::compute_total_payout(&I_NPOS, 0, 100_000u64, YEAR).0, 2_498);
assert_eq!(super::compute_total_payout(&I_NPOS, 5_000, 100_000u64, YEAR).0, 3_248);
assert_eq!(super::compute_total_payout(&I_NPOS, 25_000, 100_000u64, YEAR).0, 6_246);
assert_eq!(super::compute_total_payout(&I_NPOS, 40_000, 100_000u64, YEAR).0, 8_494);
assert_eq!(super::compute_total_payout(&I_NPOS, 50_000, 100_000u64, YEAR).0, 9_993);
assert_eq!(super::compute_total_payout(&I_NPOS, 60_000, 100_000u64, YEAR).0, 4_379);
assert_eq!(super::compute_total_payout(&I_NPOS, 75_000, 100_000u64, YEAR).0, 2_733);
assert_eq!(super::compute_total_payout(&I_NPOS, 95_000, 100_000u64, YEAR).0, 2_513);
assert_eq!(super::compute_total_payout(&I_NPOS, 100_000, 100_000u64, YEAR).0, 2_505);
const DAY: u64 = 24 * 60 * 60 * 1000;
assert_eq!(super::compute_total_payout(&I_NPOS, 25_000, 100_000u64, DAY).0, 17);
assert_eq!(super::compute_total_payout(&I_NPOS, 50_000, 100_000u64, DAY).0, 27);
assert_eq!(super::compute_total_payout(&I_NPOS, 75_000, 100_000u64, DAY).0, 7);
const SIX_HOURS: u64 = 6 * 60 * 60 * 1000;
assert_eq!(super::compute_total_payout(&I_NPOS, 25_000, 100_000u64, SIX_HOURS).0, 4);
assert_eq!(super::compute_total_payout(&I_NPOS, 50_000, 100_000u64, SIX_HOURS).0, 7);
assert_eq!(super::compute_total_payout(&I_NPOS, 75_000, 100_000u64, SIX_HOURS).0, 2);
const HOUR: u64 = 60 * 60 * 1000;
assert_eq!(
super::compute_total_payout(
&I_NPOS,
2_500_000_000_000_000_000_000_000_000u128,
5_000_000_000_000_000_000_000_000_000u128,
HOUR
).0,
57_038_500_000_000_000_000_000
);
}
}