c - LuaJIT pointers and Garbage Collection -


i trying understand luajit's garbage collector handle ffi , have manage manually sure no leakage.

reading luajit ffi semantics docs garbage collector following assertions true?:

  1. if array allocated using ffi.new('float[?]',n) gc can track references , collect necessary?
  2. using ffi.malloc(sizeof('float[n]')) must manually handled such ffi.free or provide "finalizer" such local p = ffi.gc(ffi.malloc(sizeof('float[n]')), ffi.free)?

  3. if library loaded ffi.load contained function float * example(void); , library loaded namespace ex in

    local ptr=ex.example()

    ptr storing pointer , when no references ptr exist, gc collect ptr , memory leaked?

  4. ffi.gc(ptr, ffi.free) lets garbage collector know ptr indeed pointer , memory points can reclaimed when ptr has no references?

in saying

memory areas returned c functions (e.g. malloc()) must manually managed, of course (or use ffi.gc()). pointers cdata objects indistinguishable pointers returned c functions (which 1 of reasons why gc cannot follow them).

is meant though namespace c library functions given ffi in knows return value pointer, garbage collection cannot act autonomously performing (4)?

what meant mike pall when says

"but if function [ffi.gc()] compiled ... gc have call finalizer eventually, costly."

is referring function call ffi.free in case? if so, how ffi.new around overhead?


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