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Small cleanup and perf improvement for peak_sizes_height and peaks (#1526)

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* Small cleanup and perf improvement for  and

* rustfmt

* define a const 'ALL_ONES' for u64::MAX
This commit is contained in:
Gary Yu 2018-09-15 15:28:41 +08:00 committed by Antioch Peverell
parent 26244ef9dd
commit 2c712fefff
2 changed files with 27 additions and 8 deletions
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19
core/src/core/pmmr.rs
View file

@ -47,6 +47,9 @@ use core::BlockHeader;
use ser::{PMMRIndexHashable, PMMRable}; use ser::{PMMRIndexHashable, PMMRable};
use util::LOGGER; use util::LOGGER;
/// 64 bits all ones: 0b11111111...1
const ALL_ONES: u64 = u64::MAX;
/// Storage backend for the MMR, just needs to be indexed by order of insertion. /// Storage backend for the MMR, just needs to be indexed by order of insertion.
/// The PMMR itself does not need the Backend to be accurate on the existence /// The PMMR itself does not need the Backend to be accurate on the existence
/// of an element (i.e. remove could be a no-op) but layers above can /// of an element (i.e. remove could be a no-op) but layers above can
@ -501,10 +504,10 @@ where
/// side of the range, and navigates toward lower siblings toward the right /// side of the range, and navigates toward lower siblings toward the right
/// of the range. /// of the range.
pub fn peaks(num: u64) -> Vec<u64> { pub fn peaks(num: u64) -> Vec<u64> {
let mut peak_size = 1; if num == 0 {
while peak_size < num { return vec![];
peak_size = peak_size << 1 | 1;
} }
let mut peak_size = ALL_ONES >> num.leading_zeros();
let mut num_left = num; let mut num_left = num;
let mut sum_prev_peaks = 0; let mut sum_prev_peaks = 0;
let mut peaks = vec![]; let mut peaks = vec![];
@ -546,10 +549,10 @@ pub fn insertion_to_pmmr_index(mut sz: u64) -> u64 {
/// / \ /// / \
/// 0 1 3 4 /// 0 1 3 4
pub fn peak_sizes_height(size: u64) -> (Vec<u64>, u64) { pub fn peak_sizes_height(size: u64) -> (Vec<u64>, u64) {
let mut peak_size = 1; // start at arbitrary 2-power minus 1 if size == 0 {
while peak_size < size { return (vec![], 0);
peak_size = 2 * peak_size + 1;
} }
let mut peak_size = ALL_ONES >> size.leading_zeros();
let mut sizes = vec![]; let mut sizes = vec![];
let mut size_left = size; let mut size_left = size;
while peak_size != 0 { while peak_size != 0 {
@ -557,7 +560,7 @@ pub fn peak_sizes_height(size: u64) -> (Vec<u64>, u64) {
sizes.push(peak_size); sizes.push(peak_size);
size_left -= peak_size; size_left -= peak_size;
} }
peak_size /= 2; peak_size >>= 1;
} }
(sizes, size_left) (sizes, size_left)
} }
@ -577,7 +580,7 @@ pub fn peak_map_height(mut pos: u64) -> (u64, u64) {
if pos == 0 { if pos == 0 {
return (0, 0); return (0, 0);
} }
let mut peak_size = u64::MAX >> pos.leading_zeros(); let mut peak_size = ALL_ONES >> pos.leading_zeros();
let mut bitmap = 0; let mut bitmap = 0;
while peak_size != 0 { while peak_size != 0 {
bitmap = bitmap << 1; bitmap = bitmap << 1;

16
core/tests/pmmr.rs
View file

@ -60,6 +60,22 @@ fn bench_peak_map() {
} }
} }
#[test]
fn some_peak_size() {
assert_eq!(pmmr::peak_sizes_height(0), (vec![], 0));
assert_eq!(pmmr::peak_sizes_height(1), (vec![1], 0));
assert_eq!(pmmr::peak_sizes_height(2), (vec![1], 1));
assert_eq!(pmmr::peak_sizes_height(3), (vec![3], 0));
assert_eq!(pmmr::peak_sizes_height(4), (vec![3, 1], 0));
assert_eq!(pmmr::peak_sizes_height(5), (vec![3, 1], 1));
assert_eq!(pmmr::peak_sizes_height(6), (vec![3, 1], 2));
assert_eq!(pmmr::peak_sizes_height(7), (vec![7], 0));
assert_eq!(pmmr::peak_sizes_height(u64::MAX), (vec![u64::MAX], 0));
let size_of_peaks = (1..64).map(|i| u64::MAX >> i).collect::<Vec<u64>>();
assert_eq!(pmmr::peak_sizes_height(u64::MAX - 1), (size_of_peaks, 63));
}
#[test] #[test]
#[allow(unused_variables)] #[allow(unused_variables)]
fn first_100_mmr_heights() { fn first_100_mmr_heights() {