BSON_MEM_SET_VTABLE(3)

💖 BSON_MEM_SET_VTABLE ✨

okay bestie, so this is a libbson page — that's the C library situation — and today's main character is bson_mem_set_vtable(3), the function that lets you decide how libbson gets its memory. yes, that's a lot of power. yes, you're gonna be normal about it (you're gonna be normal about it, right? 🫶).

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🌸 SYNOPSIS 🌸

Here's the whole vtable struct — every field, exactly as-is, no edits, no vibes-based refactoring 🎀:

typedef struct _bson_mem_vtable_t {
   void *(*malloc) (size_t num_bytes);
   void *(*calloc) (size_t n_members, size_t num_bytes);
   void *(*realloc) (void *mem, size_t num_bytes);
   void (*free) (void *mem);
   void *(*aligned_alloc) (size_t alignment, size_t num_bytes);
   void *padding[3];
} bson_mem_vtable_t;

and then the actual function call, iconic and tiny 💅:

void
bson_mem_set_vtable (const bson_mem_vtable_t *vtable);

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🦋 PARAMETERS 🦋

• vtable — a bson_mem_vtable_t where every non-padding field is set. all of them. not most of them. the whole little squad, filled in ✅.

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⭐ DESCRIPTION ⭐

so what does this bad boy do? it shall install a new memory allocator to be used by Libbson 🧚. that's it. that's the whole assignment. you hand it a vtable and boom — libbson is now allocating through your functions instead of whatever it was doing before. main character energy for your allocator, honestly 👑.

For backwards compatibility, if vtable->aligned_alloc is not set, calls to vtable->aligned_alloc will use vtable->malloc instead. lowkey a nice little fallback, no cap 🌈.

⚠️ WARNING: This function MUST be called at the beginning of the process. Failure to do so will result in memory being freed by the wrong allocator. 💀 like, actually genuinely bad — mismatched allocator/free is the kind of bug that makes you stare at the ceiling at 3am. call it first. first thing. periodt 🔥.

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🎀 AUTHOR 🎀

MongoDB, Inc — absolute icons, we stan 💜.

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🌸 COPYRIGHT 🌸

2009-present, MongoDB, Inc. 🫶

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and that's the page, bestie ✨ — brought to you by libbson version 2.5.6, dated Oct 09, 2026. go forth and set your vtable at the beginning of the process, i'm literally begging 🙈💖.