Fixed memory leak

Author: ankane

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.3.1 (unreleased)
+
+- Fixed memory leak
+
 ## 0.3.0 (2025-04-03)
 
 - Dropped support for Ruby < 3.2

lib/thundersvm/model.rb

@@ -158,7 +158,7 @@ def create_dataset(x, y = nil)
     end
 
     def str_ptr(arr)
-      ptr = Fiddle::Pointer.malloc(Fiddle::SIZEOF_VOIDP * arr.size)
+      ptr = Fiddle::Pointer.malloc(Fiddle::SIZEOF_VOIDP * arr.size, Fiddle::RUBY_FREE)
       arr.each_with_index do |v, i|
         ptr[i * Fiddle::SIZEOF_VOIDP, Fiddle::SIZEOF_VOIDP] = Fiddle::Pointer["#{v}\x00"].ref
       end