Add write barrier protection to RBS Location objects#3022
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Mark the Location TypedData object with RUBY_TYPED_WB_PROTECTED and route every write to the embedded `buffer` VALUE through RB_OBJ_WRITE. Once an object is write-barrier protected, the GC can skip it during minor collections instead of marking it every time, which speeds up GC. All buffer assignments (initialize, initialize_copy, and the three rbs_new_location* constructors) now go through the write barrier so the old-to-young reference from a promoted Location to its Buffer is tracked correctly.
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Summary
This change adds write barrier protection to the RBS Location C extension to ensure proper garbage collection tracking when Location objects hold references to Ruby objects.
Key Changes
RUBY_TYPED_WB_PROTECTEDflag to thelocation_typedata type definition to enable write barrier protectionlocation_initialize,location_initialize_copy,rbs_new_location,rbs_new_location2, andrbs_new_location_from_loc_rangeto useRB_OBJ_WRITEmacroQnil, then useRB_OBJ_WRITEto properly register the object reference with Ruby's garbage collectorImplementation Details
The write barrier protection ensures that when a Location object stores a reference to a buffer (a Ruby object), the garbage collector is properly notified of this reference. This prevents potential issues where the buffer could be prematurely garbage collected if the Location object is stored in an older generation during generational GC.
By using
RB_OBJ_WRITEinstead of direct assignment, we allow Ruby's write barrier mechanism to track inter-generational references correctly, which is essential for the correctness of generational garbage collection.https://claude.ai/code/session_011JK4Acfc1aTzpgpPZxwJLF