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Update CompactTarget::from_next_work_required to take timespan as i64 

Bitcoin Core's consensus rules allow this timespan interval to be
negative. This commit also updates Params::pow_target_timespan to be a
u32. This field is almost compared to u64 and i64s, so changing this to
a u32 will allow users to use `.into()` for converstions
This commit is contained in:
Shing Him Ng 2024-11-27 07:34:47 -06:00
parent f27a788288
commit 5e47c4123d
2 changed files with 25 additions and 12 deletions
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4
bitcoin/src/network/params.rs
View File

@ -113,7 +113,7 @@ pub struct Params {
/// Expected amount of time to mine one block. /// Expected amount of time to mine one block.
pub pow_target_spacing: u64, pub pow_target_spacing: u64,
/// Difficulty recalculation interval. /// Difficulty recalculation interval.
pub pow_target_timespan: u64, pub pow_target_timespan: u32,
/// Determines whether minimal difficulty may be used for blocks or not. /// Determines whether minimal difficulty may be used for blocks or not.
pub allow_min_difficulty_blocks: bool, pub allow_min_difficulty_blocks: bool,
/// Determines whether retargeting is disabled for this network or not. /// Determines whether retargeting is disabled for this network or not.
@ -261,7 +261,7 @@ impl Params {
/// Calculates the number of blocks between difficulty adjustments. /// Calculates the number of blocks between difficulty adjustments.
pub fn difficulty_adjustment_interval(&self) -> u64 { pub fn difficulty_adjustment_interval(&self) -> u64 {
self.pow_target_timespan / self.pow_target_spacing u64::from(self.pow_target_timespan) / self.pow_target_spacing
} }
} }

33
bitcoin/src/pow.rs
View File

@ -371,12 +371,14 @@ define_extension_trait! {
/// Take the example of the first difficulty adjustment. Block 2016 introduces a new [`CompactTarget`], /// Take the example of the first difficulty adjustment. Block 2016 introduces a new [`CompactTarget`],
/// which takes the net timespan between Block 2015 and Block 0, and recomputes the difficulty. /// which takes the net timespan between Block 2015 and Block 0, and recomputes the difficulty.
/// ///
/// To calculate the timespan, users should first convert their u32 timestamps to i64s before subtracting them
///
/// # Returns /// # Returns
/// ///
/// The expected [`CompactTarget`] recalculation. /// The expected [`CompactTarget`] recalculation.
fn from_next_work_required( fn from_next_work_required(
last: CompactTarget, last: CompactTarget,
timespan: u64, timespan: i64,
params: impl AsRef<Params>, params: impl AsRef<Params>,
) -> CompactTarget { ) -> CompactTarget {
let params = params.as_ref(); let params = params.as_ref();
@ -387,11 +389,11 @@ define_extension_trait! {
// ref: <https://github.com/bitcoin/bitcoin/blob/0503cbea9aab47ec0a87d34611e5453158727169/src/pow.cpp> // ref: <https://github.com/bitcoin/bitcoin/blob/0503cbea9aab47ec0a87d34611e5453158727169/src/pow.cpp>
let min_timespan = params.pow_target_timespan >> 2; // Lines 56/57 let min_timespan = params.pow_target_timespan >> 2; // Lines 56/57
let max_timespan = params.pow_target_timespan << 2; // Lines 58/59 let max_timespan = params.pow_target_timespan << 2; // Lines 58/59
let actual_timespan = timespan.clamp(min_timespan, max_timespan); let actual_timespan = timespan.clamp(min_timespan.into(), max_timespan.into());
let prev_target: Target = last.into(); let prev_target: Target = last.into();
let maximum_retarget = prev_target.max_transition_threshold(params); // bnPowLimit let maximum_retarget = prev_target.max_transition_threshold(params); // bnPowLimit
let retarget = prev_target.0; // bnNew let retarget = prev_target.0; // bnNew
let retarget = retarget.mul(actual_timespan.into()); let retarget = retarget.mul(u128::try_from(actual_timespan).expect("clamped value won't be negative").into());
let retarget = retarget.div(params.pow_target_timespan.into()); let retarget = retarget.div(params.pow_target_timespan.into());
let retarget = Target(retarget); let retarget = Target(retarget);
if retarget.ge(&maximum_retarget) { if retarget.ge(&maximum_retarget) {
@ -1750,8 +1752,8 @@ mod tests {
fn compact_target_from_upwards_difficulty_adjustment() { fn compact_target_from_upwards_difficulty_adjustment() {
let params = Params::new(crate::Network::Signet); let params = Params::new(crate::Network::Signet);
let starting_bits = CompactTarget::from_consensus(503543726); // Genesis compact target on Signet let starting_bits = CompactTarget::from_consensus(503543726); // Genesis compact target on Signet
let start_time: u64 = 1598918400; // Genesis block unix time let start_time: i64 = 1598918400; // Genesis block unix time
let end_time: u64 = 1599332177; // Block 2015 unix time let end_time: i64 = 1599332177; // Block 2015 unix time
let timespan = end_time - start_time; // Faster than expected let timespan = end_time - start_time; // Faster than expected
let adjustment = CompactTarget::from_next_work_required(starting_bits, timespan, &params); let adjustment = CompactTarget::from_next_work_required(starting_bits, timespan, &params);
let adjustment_bits = CompactTarget::from_consensus(503394215); // Block 2016 compact target let adjustment_bits = CompactTarget::from_consensus(503394215); // Block 2016 compact target
@ -1762,8 +1764,8 @@ mod tests {
fn compact_target_from_downwards_difficulty_adjustment() { fn compact_target_from_downwards_difficulty_adjustment() {
let params = Params::new(crate::Network::Signet); let params = Params::new(crate::Network::Signet);
let starting_bits = CompactTarget::from_consensus(503394215); // Block 2016 compact target let starting_bits = CompactTarget::from_consensus(503394215); // Block 2016 compact target
let start_time: u64 = 1599332844; // Block 2016 unix time let start_time: i64 = 1599332844; // Block 2016 unix time
let end_time: u64 = 1600591200; // Block 4031 unix time let end_time: i64 = 1600591200; // Block 4031 unix time
let timespan = end_time - start_time; // Slower than expected let timespan = end_time - start_time; // Slower than expected
let adjustment = CompactTarget::from_next_work_required(starting_bits, timespan, &params); let adjustment = CompactTarget::from_next_work_required(starting_bits, timespan, &params);
let adjustment_bits = CompactTarget::from_consensus(503397348); // Block 4032 compact target let adjustment_bits = CompactTarget::from_consensus(503397348); // Block 4032 compact target
@ -1829,7 +1831,18 @@ mod tests {
fn compact_target_from_maximum_upward_difficulty_adjustment() { fn compact_target_from_maximum_upward_difficulty_adjustment() {
let params = Params::new(crate::Network::Signet); let params = Params::new(crate::Network::Signet);
let starting_bits = CompactTarget::from_consensus(503403001); let starting_bits = CompactTarget::from_consensus(503403001);
let timespan = (0.2 * params.pow_target_timespan as f64) as u64; let timespan = params.pow_target_timespan / 5;
let got = CompactTarget::from_next_work_required(starting_bits, timespan.into(), params);
let want =
Target::from_compact(starting_bits).min_transition_threshold().to_compact_lossy();
assert_eq!(got, want);
}
#[test]
fn compact_target_from_maximum_upward_difficulty_adjustment_with_negative_timespan() {
let params = Params::new(crate::Network::Signet);
let starting_bits = CompactTarget::from_consensus(503403001);
let timespan: i64 = -i64::from(params.pow_target_timespan);
let got = CompactTarget::from_next_work_required(starting_bits, timespan, params); let got = CompactTarget::from_next_work_required(starting_bits, timespan, params);
let want = let want =
Target::from_compact(starting_bits).min_transition_threshold().to_compact_lossy(); Target::from_compact(starting_bits).min_transition_threshold().to_compact_lossy();
@ -1841,7 +1854,7 @@ mod tests {
let params = Params::new(crate::Network::Signet); let params = Params::new(crate::Network::Signet);
let starting_bits = CompactTarget::from_consensus(403403001); // High difficulty for Signet let starting_bits = CompactTarget::from_consensus(403403001); // High difficulty for Signet
let timespan = 5 * params.pow_target_timespan; // Really slow. let timespan = 5 * params.pow_target_timespan; // Really slow.
let got = CompactTarget::from_next_work_required(starting_bits, timespan, &params); let got = CompactTarget::from_next_work_required(starting_bits, timespan.into(), &params);
let want = let want =
Target::from_compact(starting_bits).max_transition_threshold(params).to_compact_lossy(); Target::from_compact(starting_bits).max_transition_threshold(params).to_compact_lossy();
assert_eq!(got, want); assert_eq!(got, want);
@ -1852,7 +1865,7 @@ mod tests {
let params = Params::new(crate::Network::Signet); let params = Params::new(crate::Network::Signet);
let starting_bits = CompactTarget::from_consensus(503543726); // Genesis compact target on Signet let starting_bits = CompactTarget::from_consensus(503543726); // Genesis compact target on Signet
let timespan = 5 * params.pow_target_timespan; // Really slow. let timespan = 5 * params.pow_target_timespan; // Really slow.
let got = CompactTarget::from_next_work_required(starting_bits, timespan, &params); let got = CompactTarget::from_next_work_required(starting_bits, timespan.into(), &params);
let want = params.max_attainable_target.to_compact_lossy(); let want = params.max_attainable_target.to_compact_lossy();
assert_eq!(got, want); assert_eq!(got, want);
} }