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Tweak the constants a bit

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This commit is contained in:
Stjepan Glavina 2017-03-18 20:24:44 +01:00
parent 942173b38f
commit c4454a5507
2 changed files with 7 additions and 7 deletions
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4
src/libcollections/slice.rs
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@ -1668,9 +1668,9 @@ fn merge_sort<T, F>(v: &mut [T], mut is_less: F)
where F: FnMut(&T, &T) -> bool where F: FnMut(&T, &T) -> bool
{ {
// Slices of up to this length get sorted using insertion sort. // Slices of up to this length get sorted using insertion sort.
const MAX_INSERTION: usize = 16; const MAX_INSERTION: usize = 20;
// Very short runs are extended using insertion sort to span at least this many elements. // Very short runs are extended using insertion sort to span at least this many elements.
const MIN_RUN: usize = 8; const MIN_RUN: usize = 10;
// Sorting has no meaningful behavior on zero-sized types. // Sorting has no meaningful behavior on zero-sized types.
if size_of::<T>() == 0 { if size_of::<T>() == 0 {

10
src/libcore/slice/sort.rs
View File

@ -355,7 +355,7 @@ fn partition<T, F>(v: &mut [T], pivot: usize, is_less: &mut F) -> (usize, bool)
l += 1; l += 1;
} }
// Find the last element lesser that the pivot. // Find the last element smaller that the pivot.
while l < r && !is_less(v.get_unchecked(r - 1), pivot) { while l < r && !is_less(v.get_unchecked(r - 1), pivot) {
r -= 1; r -= 1;
} }
@ -472,7 +472,7 @@ fn choose_pivot<T, F>(v: &mut [T], is_less: &mut F) -> (usize, bool)
{ {
// Minimal length to choose the median-of-medians method. // Minimal length to choose the median-of-medians method.
// Shorter slices use the simple median-of-three method. // Shorter slices use the simple median-of-three method.
const SHORTEST_MEDIAN_OF_MEDIANS: usize = 90; const SHORTEST_MEDIAN_OF_MEDIANS: usize = 80;
// Maximal number of swaps that can be performed in this function. // Maximal number of swaps that can be performed in this function.
const MAX_SWAPS: usize = 4 * 3; const MAX_SWAPS: usize = 4 * 3;
@ -539,7 +539,7 @@ fn recurse<'a, T, F>(mut v: &'a mut [T], is_less: &mut F, mut pred: Option<&'a T
where F: FnMut(&T, &T) -> bool where F: FnMut(&T, &T) -> bool
{ {
// Slices of up to this length get sorted using insertion sort. // Slices of up to this length get sorted using insertion sort.
const MAX_INSERTION: usize = 16; const MAX_INSERTION: usize = 20;
// True if the last partitioning was reasonably balanced. // True if the last partitioning was reasonably balanced.
let mut was_balanced = true; let mut was_balanced = true;
@ -627,8 +627,8 @@ pub fn quicksort<T, F>(v: &mut [T], mut is_less: F)
return; return;
} }
// Limit the number of imbalanced partitions to `floor(log2(len)) + 2`. // Limit the number of imbalanced partitions to `floor(log2(len)) + 1`.
let limit = mem::size_of::<usize>() * 8 - v.len().leading_zeros() as usize + 1; let limit = mem::size_of::<usize>() * 8 - v.len().leading_zeros() as usize;
recurse(v, &mut is_less, None, limit); recurse(v, &mut is_less, None, limit);
} }