From: Ville Sipola <ville_sipola@...>
Date: 2011-04-27T19:46:33+09:00
Subject: Fast way to move C array to ruby (rb_ary_new4)?

Good day

I have a number of large arrays in a C module, and I'd need to move them
to ruby as quickly as possible.

Currently I use the following type of an approach:

instance_array_in_ruby = rb_iv_get(calling_class, "@x");
double c_array[1000000];

for(i=0;i<1000000;i++)
{
   rb_ary_store(instance_array_in_ruby, i, rb_float_new(c_array[i]));
}

But that's slow, apparently due to the large number of rb_float_new:s.

There is a function called rb_ary_new4 that would seem to fit
the purpose of quickly moving an entire C array to ruby. Only I'm unable
to get it work, as it, too requires VALUE:s.
I've tried many things including mumbo-jumbo like
rb_iv_set(calling_class,"@x",rb_ary_new4(1000000, (VALUE)c_array));, but
I'm only managing to get segfaults or solutions that still need a
million rb_something_new:s.

Would you know an efficient way of moving a large data from C array to
ruby array?

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