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Sharing arrays with ary_dup() #6577

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4 changes: 3 additions & 1 deletion src/array.c
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Original file line number Diff line number Diff line change
Expand Up @@ -934,7 +934,9 @@ mrb_ary_set(mrb_state *mrb, mrb_value ary, mrb_int n, mrb_value val)
static struct RArray*
ary_dup(mrb_state *mrb, struct RArray *a)
{
return ary_new_from_values(mrb, ARY_LEN(a), ARY_PTR(a));
struct RArray *dup = ary_new_capa(mrb, 0);
ary_replace(mrb, dup, a);
return dup;
Comment on lines +937 to +939
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@gemini-code-assist gemini-code-assist bot Jul 18, 2025

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medium

The current implementation uses ary_replace to duplicate the array, which might introduce a slight performance overhead due to the additional function call and potential re-allocation. Consider directly allocating and copying the array contents for better performance in the duplication scenario. A more explicit check for sharing conditions upfront could improve both clarity and performance.

For example:

mrb_int len = ARY_LEN(a);
struct RArray *dup = ary_new_capa(mrb, len);
if (ARY_SHARED_P(a)) {
  ary_replace(mrb, dup, a);
} else {
  array_copy(ARY_PTR(dup), ARY_PTR(a), len);
  ARY_SET_LEN(dup, len);
}
return dup;
mrb_int len = ARY_LEN(a);
struct RArray *dup = ary_new_capa(mrb, len);
if (ARY_SHARED_P(a)) {
  ary_replace(mrb, dup, a);
} else {
  array_copy(ARY_PTR(dup), ARY_PTR(a), len);
  ARY_SET_LEN(dup, len);
}
return dup;

}

MRB_API mrb_value
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