Merge rust-bitcoin/rust-bitcoin#4613: Inline `fee` functions back into their respective modules

20c84ce444 units: Make fee module public (Tobin C. Harding)
251e6a85da Inline checked mul function back into weight module (Tobin C. Harding)
a8610a937b Inline checked mul / to fee back into fee_rate module (Tobin C. Harding)
e17c391a3c Inline checked div functions back into unsigned module (Tobin C. Harding)

Pull request description:

  Move all the `fee` functions back onto the respective impl blocks for the associated type.

  Finally, make the `fee` module public so users get the docs. If this is not like we can drop the last patch.

  Close: #4609

ACKs for top commit:
  apoelstra:
    ACK 20c84ce444fe68577bf14842ebaffd796572d91f; successfully ran local tests

Tree-SHA512: e4c9701245fcd0c7881baaf01a7f9d0be1ed80bc3fa848a289fbc6104375d8db5a2a092e9f1aa0b556dcc45349d053418cff8d1c281dda3cefc1e38c6ac2ba85
This commit is contained in:
merge-script 2025-06-13 17:12:17 +00:00
commit 1e4f018838
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5 changed files with 184 additions and 177 deletions

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@ -15,6 +15,7 @@ use super::{
parse_signed_to_satoshi, split_amount_and_denomination, Denomination, Display, DisplayStyle,
OutOfRangeError, ParseAmountError, ParseError, SignedAmount,
};
use crate::{FeeRate, Weight};
mod encapsulate {
use super::OutOfRangeError;
@ -402,6 +403,106 @@ impl Amount {
SignedAmount::from_sat(self.to_sat() as i64) // Cast ok, signed amount and amount share positive range.
.expect("range of Amount is within range of SignedAmount")
}
/// Checked weight floor division.
///
/// Be aware that integer division loses the remainder if no exact division
/// can be made. See also [`Self::checked_div_by_weight_ceil`].
///
/// Returns [`None`] if overflow occurred.
#[must_use]
pub const fn checked_div_by_weight_floor(self, weight: Weight) -> Option<FeeRate> {
let wu = weight.to_wu();
if wu == 0 {
return None;
}
// Mul by 1,000 because we use per/kwu.
match self.to_sat().checked_mul(1_000) {
Some(sats) => {
let fee_rate = sats / wu;
FeeRate::from_sat_per_kwu(fee_rate)
}
None => None,
}
}
/// Checked weight ceiling division.
///
/// Be aware that integer division loses the remainder if no exact division
/// can be made. This method rounds up ensuring the transaction fee rate is
/// sufficient. See also [`Self::checked_div_by_weight_floor`].
///
/// Returns [`None`] if overflow occurred.
///
/// # Examples
///
/// ```
/// # use bitcoin_units::{amount, Amount, FeeRate, Weight};
/// let amount = Amount::from_sat(10)?;
/// let weight = Weight::from_wu(300);
/// let fee_rate = amount.checked_div_by_weight_ceil(weight);
/// assert_eq!(fee_rate, FeeRate::from_sat_per_kwu(34));
/// # Ok::<_, amount::OutOfRangeError>(())
/// ```
#[must_use]
pub const fn checked_div_by_weight_ceil(self, weight: Weight) -> Option<FeeRate> {
let wu = weight.to_wu();
if wu == 0 {
return None;
}
// Mul by 1,000 because we use per/kwu.
if let Some(sats) = self.to_sat().checked_mul(1_000) {
// No need to used checked arithmetic because wu is non-zero.
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.
///
/// Computes the maximum weight that would result in a fee less than or equal to this amount
/// at the given `fee_rate`. Uses floor division to ensure the resulting weight doesn't cause
/// the fee to exceed the amount.
///
/// Returns [`None`] if overflow occurred or if `fee_rate` is zero.
#[must_use]
pub const fn checked_div_by_fee_rate_floor(self, fee_rate: FeeRate) -> Option<Weight> {
if let Some(msats) = self.to_sat().checked_mul(1000) {
if let Some(wu) = msats.checked_div(fee_rate.to_sat_per_kwu_ceil()) {
return Some(Weight::from_wu(wu));
}
}
None
}
/// Checked fee rate ceiling division.
///
/// Computes the minimum weight that would result in a fee greater than or equal to this amount
/// at the given `fee_rate`. Uses ceiling division to ensure the resulting weight is sufficient.
///
/// Returns [`None`] if overflow occurred or if `fee_rate` is zero.
#[must_use]
pub const fn checked_div_by_fee_rate_ceil(self, fee_rate: FeeRate) -> Option<Weight> {
// Use ceil because result is used as the divisor.
let rate = fee_rate.to_sat_per_kwu_ceil();
if rate == 0 {
return None;
}
if let Some(msats) = self.to_sat().checked_mul(1000) {
// No need to used checked arithmetic because rate is non-zero.
if let Some(bump) = msats.checked_add(rate - 1) {
let wu = bump / rate;
return Some(Weight::from_wu(wu));
}
}
None
}
}
impl default::Default for Amount {

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@ -10,6 +10,18 @@
//!
//! We provide `fee.checked_div_by_weight_ceil(weight)` to calculate a minimum threshold fee rate
//! required to pay at least `fee` for transaction with `weight`.
//!
//! We support various `core::ops` traits all of which return [`NumOpResult<T>`].
//!
//! For specific methods see:
//!
//! * [`Amount::checked_div_by_weight_floor`]
//! * [`Amount::checked_div_by_weight_ceil`]
//! * [`Amount::checked_div_by_fee_rate_floor`]
//! * [`Amount::checked_div_by_fee_rate_ceil`]
//! * [`Weight::checked_mul_by_fee_rate`]
//! * [`FeeRate::checked_mul_by_weight`]
//! * [`FeeRate::to_fee`]
use core::ops;
@ -17,166 +29,6 @@ use NumOpResult as R;
use crate::{Amount, FeeRate, MathOp, NumOpError as E, NumOpResult, OptionExt, Weight};
impl Amount {
/// Checked weight floor division.
///
/// Be aware that integer division loses the remainder if no exact division
/// can be made. See also [`Self::checked_div_by_weight_ceil`].
///
/// Returns [`None`] if overflow occurred.
#[must_use]
pub const fn checked_div_by_weight_floor(self, weight: Weight) -> Option<FeeRate> {
let wu = weight.to_wu();
if wu == 0 {
return None;
}
// Mul by 1,000 because we use per/kwu.
match self.to_sat().checked_mul(1_000) {
Some(sats) => {
let fee_rate = sats / wu;
FeeRate::from_sat_per_kwu(fee_rate)
}
None => None,
}
}
/// Checked weight ceiling division.
///
/// Be aware that integer division loses the remainder if no exact division
/// can be made. This method rounds up ensuring the transaction fee rate is
/// sufficient. See also [`Self::checked_div_by_weight_floor`].
///
/// Returns [`None`] if overflow occurred.
///
/// # Examples
///
/// ```
/// # use bitcoin_units::{amount, Amount, FeeRate, Weight};
/// let amount = Amount::from_sat(10)?;
/// let weight = Weight::from_wu(300);
/// let fee_rate = amount.checked_div_by_weight_ceil(weight);
/// assert_eq!(fee_rate, FeeRate::from_sat_per_kwu(34));
/// # Ok::<_, amount::OutOfRangeError>(())
/// ```
#[must_use]
pub const fn checked_div_by_weight_ceil(self, weight: Weight) -> Option<FeeRate> {
let wu = weight.to_wu();
if wu == 0 {
return None;
}
// Mul by 1,000 because we use per/kwu.
if let Some(sats) = self.to_sat().checked_mul(1_000) {
// No need to used checked arithmetic because wu is non-zero.
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.
///
/// Computes the maximum weight that would result in a fee less than or equal to this amount
/// at the given `fee_rate`. Uses floor division to ensure the resulting weight doesn't cause
/// the fee to exceed the amount.
///
/// Returns [`None`] if overflow occurred or if `fee_rate` is zero.
#[must_use]
pub const fn checked_div_by_fee_rate_floor(self, fee_rate: FeeRate) -> Option<Weight> {
if let Some(msats) = self.to_sat().checked_mul(1000) {
if let Some(wu) = msats.checked_div(fee_rate.to_sat_per_kwu_ceil()) {
return Some(Weight::from_wu(wu));
}
}
None
}
/// Checked fee rate ceiling division.
///
/// Computes the minimum weight that would result in a fee greater than or equal to this amount
/// at the given `fee_rate`. Uses ceiling division to ensure the resulting weight is sufficient.
///
/// Returns [`None`] if overflow occurred or if `fee_rate` is zero.
#[must_use]
pub const fn checked_div_by_fee_rate_ceil(self, fee_rate: FeeRate) -> Option<Weight> {
// Use ceil because result is used as the divisor.
let rate = fee_rate.to_sat_per_kwu_ceil();
if rate == 0 {
return None;
}
if let Some(msats) = self.to_sat().checked_mul(1000) {
// No need to used checked arithmetic because rate is non-zero.
if let Some(bump) = msats.checked_add(rate - 1) {
let wu = bump / rate;
return Some(Weight::from_wu(wu));
}
}
None
}
}
impl FeeRate {
/// Calculates the fee by multiplying this fee rate by weight.
///
/// Computes the absolute fee amount for a given [`Weight`] at this fee rate. When the resulting
/// fee is a non-integer amount, the amount is rounded up, ensuring that the transaction fee is
/// enough instead of falling short if rounded down.
///
/// 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
/// wrapping.
pub const fn to_fee(self, weight: Weight) -> Amount {
// 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`]
/// if an overflow occurred.
///
/// This is equivalent to `Self::checked_mul_by_weight()`.
#[must_use]
#[deprecated(since = "TBD", note = "use `to_fee()` instead")]
pub fn fee_wu(self, weight: Weight) -> Option<Amount> { self.checked_mul_by_weight(weight) }
/// Calculates the fee by multiplying this fee rate by weight, in virtual bytes, returning [`None`]
/// if an overflow occurred.
///
/// This is equivalent to converting `vb` to [`Weight`] using [`Weight::from_vb`] and then calling
/// `Self::fee_wu(weight)`.
#[must_use]
#[deprecated(since = "TBD", note = "use Weight::from_vb and then `to_fee()` instead")]
pub fn fee_vb(self, vb: u64) -> Option<Amount> { Weight::from_vb(vb).map(|w| self.to_fee(w)) }
/// Checked weight multiplication.
///
/// Computes the absolute fee amount for a given [`Weight`] at this fee rate. When the resulting
/// fee is a non-integer amount, the amount is rounded up, ensuring that the transaction fee is
/// enough instead of falling short if rounded down.
///
/// Returns [`None`] if overflow occurred.
#[must_use]
pub const fn checked_mul_by_weight(self, weight: Weight) -> Option<Amount> {
let wu = weight.to_wu();
if let Some(fee_kwu) = self.to_sat_per_kwu_floor().checked_mul(wu) {
// Bump by 999 to do ceil division using kwu.
if let Some(bump) = fee_kwu.checked_add(999) {
let fee = bump / 1_000;
if let Ok(fee_amount) = Amount::from_sat(fee) {
return Some(fee_amount);
}
}
}
None
}
}
crate::internal_macros::impl_op_for_references! {
impl ops::Mul<FeeRate> for Weight {
type Output = NumOpResult<Amount>;
@ -341,20 +193,6 @@ crate::internal_macros::impl_op_for_references! {
}
}
impl Weight {
/// Checked fee rate multiplication.
///
/// Computes the absolute fee amount for a given [`FeeRate`] at this weight. When the resulting
/// fee is a non-integer amount, the amount is rounded up, ensuring that the transaction fee is
/// enough instead of falling short if rounded down.
///
/// Returns [`None`] if overflow occurred.
#[must_use]
pub const fn checked_mul_by_fee_rate(self, fee_rate: FeeRate) -> Option<Amount> {
fee_rate.checked_mul_by_weight(self)
}
}
#[cfg(test)]
mod tests {
use super::*;

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@ -13,7 +13,7 @@ use arbitrary::{Arbitrary, Unstructured};
use NumOpResult as R;
use crate::{Amount,MathOp, NumOpError as E, NumOpResult};
use crate::{Amount, MathOp, NumOpError as E, NumOpResult, Weight};
mod encapsulate {
/// Fee rate.
@ -184,6 +184,62 @@ impl FeeRate {
None => None,
}
}
/// Calculates the fee by multiplying this fee rate by weight.
///
/// Computes the absolute fee amount for a given [`Weight`] at this fee rate. When the resulting
/// fee is a non-integer amount, the amount is rounded up, ensuring that the transaction fee is
/// enough instead of falling short if rounded down.
///
/// 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
/// wrapping.
pub const fn to_fee(self, weight: Weight) -> Amount {
// 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`]
/// if an overflow occurred.
///
/// This is equivalent to `Self::checked_mul_by_weight()`.
#[must_use]
#[deprecated(since = "TBD", note = "use `to_fee()` instead")]
pub fn fee_wu(self, weight: Weight) -> Option<Amount> { self.checked_mul_by_weight(weight) }
/// Calculates the fee by multiplying this fee rate by weight, in virtual bytes, returning [`None`]
/// if an overflow occurred.
///
/// This is equivalent to converting `vb` to [`Weight`] using [`Weight::from_vb`] and then calling
/// `Self::fee_wu(weight)`.
#[must_use]
#[deprecated(since = "TBD", note = "use Weight::from_vb and then `to_fee()` instead")]
pub fn fee_vb(self, vb: u64) -> Option<Amount> { Weight::from_vb(vb).map(|w| self.to_fee(w)) }
/// Checked weight multiplication.
///
/// Computes the absolute fee amount for a given [`Weight`] at this fee rate. When the resulting
/// fee is a non-integer amount, the amount is rounded up, ensuring that the transaction fee is
/// enough instead of falling short if rounded down.
///
/// Returns [`None`] if overflow occurred.
#[must_use]
pub const fn checked_mul_by_weight(self, weight: Weight) -> Option<Amount> {
let wu = weight.to_wu();
if let Some(fee_kwu) = self.to_sat_per_kwu_floor().checked_mul(wu) {
// Bump by 999 to do ceil division using kwu.
if let Some(bump) = fee_kwu.checked_add(999) {
let fee = bump / 1_000;
if let Ok(fee_amount) = Amount::from_sat(fee) {
return Some(fee_amount);
}
}
}
None
}
}
crate::internal_macros::impl_op_for_references! {

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@ -34,7 +34,6 @@ extern crate alloc;
#[cfg(feature = "std")]
extern crate std;
mod fee;
mod internal_macros;
mod result;
@ -48,6 +47,7 @@ pub mod _export {
pub mod amount;
pub mod block;
pub mod fee;
pub mod fee_rate;
pub mod locktime;
pub mod parse;

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@ -10,7 +10,7 @@ use arbitrary::{Arbitrary, Unstructured};
#[cfg(feature = "serde")]
use serde::{Deserialize, Deserializer, Serialize, Serializer};
use crate::CheckedSum;
use crate::{Amount, CheckedSum, FeeRate};
/// The factor that non-witness serialization data is multiplied by during weight calculation.
pub const WITNESS_SCALE_FACTOR: usize = 4;
@ -162,6 +162,18 @@ impl Weight {
None => None,
}
}
/// Checked fee rate multiplication.
///
/// Computes the absolute fee amount for a given [`FeeRate`] at this weight. When the resulting
/// fee is a non-integer amount, the amount is rounded up, ensuring that the transaction fee is
/// enough instead of falling short if rounded down.
///
/// Returns [`None`] if overflow occurred.
#[must_use]
pub const fn checked_mul_by_fee_rate(self, fee_rate: FeeRate) -> Option<Amount> {
fee_rate.checked_mul_by_weight(self)
}
}
/// Alternative will display the unit.