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rust-bitcoin-unsafe-fast
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Make fee functions const 

We temporarily removed `const` in the `fee` module to make patching and
reviewing easier. Now add it back in.
This commit is contained in:
Tobin C. Harding 2025-05-26 15:23:44 +10:00
parent 9b2fc021b2
commit b65860067f
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GPG Key ID: 0AEF0A899E41F7DD
1 changed files with 30 additions and 16 deletions
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44
units/src/fee.rs
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@ -56,16 +56,21 @@ impl Amount {
/// # Ok::<_, amount::OutOfRangeError>(()) /// # Ok::<_, amount::OutOfRangeError>(())
/// ``` /// ```
#[must_use] #[must_use]
pub fn checked_div_by_weight_ceil(self, weight: Weight) -> Option<FeeRate> { pub const fn checked_div_by_weight_ceil(self, weight: Weight) -> Option<FeeRate> {
let wu = weight.to_wu(); let wu = weight.to_wu();
if wu == 0 { if wu == 0 {
return None; return None;
} }
let sats = self.to_sat() * 1_000; // Because we use per/kwu. // Mul by 1,000 because we use per/kwu.
let fee_rate = (sats + wu - 1) / wu; if let Some(sats) = self.to_sat().checked_mul(1_000) {
// No need to used checked arithmetic because wu is non-zero.
FeeRate::from_sat_per_kwu(fee_rate) if let Some(bump) = sats.checked_add(wu - 1) {
let fee_rate = bump / wu;
return FeeRate::from_sat_per_kwu(fee_rate);
}
}
None
} }
/// Checked fee rate floor division. /// Checked fee rate floor division.
@ -76,7 +81,7 @@ impl Amount {
/// ///
/// Returns [`None`] if overflow occurred or if `fee_rate` is zero. /// Returns [`None`] if overflow occurred or if `fee_rate` is zero.
#[must_use] #[must_use]
pub fn checked_div_by_fee_rate_floor(self, fee_rate: FeeRate) -> Option<Weight> { pub const fn checked_div_by_fee_rate_floor(self, fee_rate: FeeRate) -> Option<Weight> {
match self.to_sat().checked_mul(1000) { match self.to_sat().checked_mul(1000) {
Some(amount_msats) => match amount_msats.checked_div(fee_rate.to_sat_per_kwu_ceil()) { Some(amount_msats) => match amount_msats.checked_div(fee_rate.to_sat_per_kwu_ceil()) {
Some(wu) => Some(Weight::from_wu(wu)), Some(wu) => Some(Weight::from_wu(wu)),
@ -93,7 +98,7 @@ impl Amount {
/// ///
/// Returns [`None`] if overflow occurred or if `fee_rate` is zero. /// Returns [`None`] if overflow occurred or if `fee_rate` is zero.
#[must_use] #[must_use]
pub fn checked_div_by_fee_rate_ceil(self, fee_rate: FeeRate) -> Option<Weight> { pub const fn checked_div_by_fee_rate_ceil(self, fee_rate: FeeRate) -> Option<Weight> {
// Use ceil because result is used as the divisor. // Use ceil because result is used as the divisor.
let rate = fee_rate.to_sat_per_kwu_ceil(); let rate = fee_rate.to_sat_per_kwu_ceil();
match self.to_sat().checked_mul(1000) { match self.to_sat().checked_mul(1000) {
@ -122,8 +127,12 @@ impl FeeRate {
/// If the calculation would overflow we saturate to [`Amount::MAX`]. Since such a fee can never /// If the calculation would overflow we saturate to [`Amount::MAX`]. Since such a fee can never
/// be paid this is meaningful as an error case while still removing the possibility of silently /// be paid this is meaningful as an error case while still removing the possibility of silently
/// wrapping. /// wrapping.
pub fn to_fee(self, weight: Weight) -> Amount { pub const fn to_fee(self, weight: Weight) -> Amount {
self.checked_mul_by_weight(weight).unwrap_or(Amount::MAX) // No `unwrap_or()` in const context.
match self.checked_mul_by_weight(weight) {
Some(fee) => fee,
None => Amount::MAX,
}
} }
/// Calculates the fee by multiplying this fee rate by weight, in weight units, returning [`None`] /// Calculates the fee by multiplying this fee rate by weight, in weight units, returning [`None`]
@ -150,13 +159,18 @@ impl FeeRate {
/// enough instead of falling short if rounded down. /// enough instead of falling short if rounded down.
/// ///
/// Returns [`None`] if overflow occurred. /// Returns [`None`] if overflow occurred.
pub fn checked_mul_by_weight(self, weight: Weight) -> Option<Amount> { pub const fn checked_mul_by_weight(self, weight: Weight) -> Option<Amount> {
let wu = weight.to_wu(); let wu = weight.to_wu();
let fee_kwu = self.to_sat_per_kwu_floor().checked_mul(wu)?; if let Some(fee_kwu) = self.to_sat_per_kwu_floor().checked_mul(wu) {
let bump = fee_kwu.checked_add(999)?; // We do ceil division. // Bump by 999 to do ceil division using kwu.
if let Some(bump) = fee_kwu.checked_add(999) {
let fee = bump / 1_000; let fee = bump / 1_000;
if let Ok(fee_amount) = Amount::from_sat(fee) {
Amount::from_sat(fee).ok() return Some(fee_amount);
}
}
}
None
} }
} }
@ -332,7 +346,7 @@ impl Weight {
/// enough instead of falling short if rounded down. /// enough instead of falling short if rounded down.
/// ///
/// Returns [`None`] if overflow occurred. /// Returns [`None`] if overflow occurred.
pub fn checked_mul_by_fee_rate(self, fee_rate: FeeRate) -> Option<Amount> { pub const fn checked_mul_by_fee_rate(self, fee_rate: FeeRate) -> Option<Amount> {
fee_rate.checked_mul_by_weight(self) fee_rate.checked_mul_by_weight(self)
} }
} }