Function TVMFFIPyConvertPyCallback

python/tvm_ffi/cython/tvm_ffi_python_helpers.h:973–997

! * \brief Create an FFI function handle from a Python callable + optional DLPack exchange API. * * Allocates a TVMFFIPyCallbackClosure on the heap, IncRefs the callable, and * registers it with the FFI function-creation API using TVMFFIPyCallback as the * safe-call entry point and TVMFFIPyCallbackClosure::Deleter as the deleter. * * Returns the raw FFI return code (TLS FFI error set on fai

 * \return The return code from TVMFFIFunctionCreate (0 on success).
 */
TVM_FFI_INLINE int TVMFFIPyConvertPyCallback(PyObject* callable,
                                             const DLPackExchangeAPI* dlpack_api,
                                             TVMFFIObjectHandle* out_handle) noexcept {
  // Use nothrow new: plain `new` can throw std::bad_alloc, which in this
  // noexcept function would trigger std::terminate. On allocation failure,
  // set PyErr and return -1 so the Cython caller's CHECK_CALL surfaces it.
  auto* raw = new (std::nothrow) TVMFFIPyCallbackClosure{callable, dlpack_api};
  if (raw == nullptr) {
    PyErr_NoMemory();
    return -1;
  }
  // The callable's +1 is owned by the closure; TVMFFIPyCallbackClosure::Deleter
  // is responsible for Py_DecRef on destruction. By wiring the same Deleter as
  // the unique_ptr deleter, the failure path below (unique_ptr unwind) runs
  // the same cleanup as the success path (invoked by the FFI runtime).
  Py_IncRef(callable);
  std::unique_ptr<TVMFFIPyCallbackClosure, void (*)(void*)> closure(
      raw, &TVMFFIPyCallbackClosure::Deleter);
  int rc = TVMFFIFunctionCreate(closure.get(), &TVMFFIPyCallback, &TVMFFIPyCallbackClosure::Deleter,
                                out_handle);
  // On success, transfer ownership to the FFI function; on failure, let
  // unique_ptr unwind via Deleter (decrefs the callable, frees the closure).
  if (rc == 0) closure.release();
  return rc;
}

/*!
 * \brief Push a temporary FFI object to the call context that will be recycled after the call