73 lines
2.0 KiB
Rust
73 lines
2.0 KiB
Rust
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//! configuration for network rent
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#[derive(Serialize, Deserialize, PartialEq, Clone, Debug)]
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pub struct Rent {
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/// Rental rate
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pub lamports_per_byte_year: u64,
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/// exemption threshold, in years
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pub exemption_threshold: f64,
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}
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/// default rental rate in lamports/byte-year, based on:
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/// 2^^34 lamports per Sol
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/// $1 per Sol
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/// $0.01 per megabyte day
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/// $3.65 per megabyte year
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pub const DEFAULT_LAMPORTS_PER_BYTE_YEAR: u64 = 17_179_869_184 / 100 * 365 / (1024 * 1024);
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/// default amount of time (in years) the balance has to include rent for
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pub const DEFAULT_EXEMPTION_THRESHOLD: f64 = 2.0;
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impl Default for Rent {
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fn default() -> Self {
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Self {
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lamports_per_byte_year: DEFAULT_LAMPORTS_PER_BYTE_YEAR,
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exemption_threshold: DEFAULT_EXEMPTION_THRESHOLD,
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}
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}
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}
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impl Rent {
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/// minimum balance due for a given size Account::data.len()
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pub fn minimum_balance(&self, data_len: usize) -> u64 {
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let bytes = data_len as u64;
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bytes * (self.exemption_threshold * self.lamports_per_byte_year as f64) as u64
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}
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/// whether a given balance and data_len would be exempt
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pub fn is_exempt(&self, balance: u64, data_len: usize) -> bool {
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balance >= self.minimum_balance(data_len)
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}
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/// rent due on account's data_len with balance
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pub fn due(&self, balance: u64, data_len: usize, years_elapsed: f64) -> u64 {
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if self.is_exempt(balance, data_len) {
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0
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} else {
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let bytes = data_len as u64;
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((self.lamports_per_byte_year * bytes) as f64 * years_elapsed) as u64
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn test_due() {
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let rent = Rent::default();
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assert_eq!(rent.due(0, 1, 1.0), DEFAULT_LAMPORTS_PER_BYTE_YEAR);
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assert_eq!(
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rent.due(
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DEFAULT_LAMPORTS_PER_BYTE_YEAR * DEFAULT_EXEMPTION_THRESHOLD as u64,
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1,
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1.0
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),
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0
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);
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}
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}
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