memory.md

Memory Allocation

There are three methods to customize memory allocation in mruby.

1. Provide your own realloc()/free()
2. Redefine mrb_default_allocf()
3. Specify a function with mrb_open_allocf()

Provide your own realloc()/free()

On some platforms, especially on microcontrollers, the standard library may not provide malloc(), realloc(), and free(). In such cases, it may be necessary to define memory allocation functions for the specific platform. mruby uses realloc() and free() from the standard C library for memory management. By defining these two functions of your own, you can make mruby work. However, note the following two points:

First, realloc(NULL, size) behaves the same as malloc(size). Second, free(NULL) exits without doing anything.

Redefine mrb_default_allocf()

The only function in mruby that uses the standard C library's memory allocation functions is mrb_default_allocf(), defined in alloc.c. By defining this function within your application, you can customize the memory management of your application.

Specify a function with mrb_open_allocf()

If you want to perform different memory management for each mrb_state within your application, you can use the mrb_open_allocf() function to create the mrb_state structure. This allows you to specify a memory allocation function (which is compatible with mrb_default_allocf) for each mrb_state. Although this scheme is not recommended. It may become obsolete in the future, since I have never seen per mrb_state memory management use-case.