admin/mruby-mruby
1
0
Fork 0
mirror of https://github.com/mruby/mruby synced 2026-06-08 16:11:16 +00:00
Code Issues Packages Projects Releases Wiki Activity

array.c: replace recursive heapify with iterative implementation

Browse Source 
Eliminates stack overflow risk on memory-constrained devices by reducing
stack usage from O(log n) to O(1) during heap sort operations.

Co-authored-by: Atlassian Rovo Dev
This commit is contained in:
Yukihiro "Matz" Matsumoto
2025-06-30 14:41:04 +09:00
parent 05ad26f92a
commit 6d8c673efb
1 changed files with 22 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/array.c
+22 -11
View File
@@ -1844,20 +1844,31 @@ sort_cmp(mrb_state *mrb, mrb_value ary, mrb_value *p, mrb_int a, mrb_int b, mrb_
static void
heapify(mrb_state *mrb, mrb_value ary, mrb_value *a, mrb_int index, mrb_int size, mrb_value blk)
{
mrb_int max = index;
mrb_int left_index = 2 * index + 1;
mrb_int right_index = left_index + 1;
if (left_index < size && sort_cmp(mrb, ary, a, left_index, max, blk)) {
max = left_index;
}
if (right_index < size && sort_cmp(mrb, ary, a, right_index, max, blk)) {
max = right_index;
}
if (max != index) {
/* Iterative heapify to avoid stack overflow on memory-constrained devices */
while (1) {
mrb_int max = index;
mrb_int left_index = 2 * index + 1;
mrb_int right_index = left_index + 1;
if (left_index < size && sort_cmp(mrb, ary, a, left_index, max, blk)) {
max = left_index;
}
if (right_index < size && sort_cmp(mrb, ary, a, right_index, max, blk)) {
max = right_index;
}
if (max == index) {
/* Heap property satisfied, no more swaps needed */
break;
}
/* Swap elements and continue heapifying down the affected subtree */
mrb_value tmp = a[max];
a[max] = a[index];
a[index] = tmp;
heapify(mrb, ary, a, max, size, blk);
/* Continue with the affected child subtree */
index = max;
}
}