Function dds_stream_extract_key_from_data 

pub unsafe extern "C" fn dds_stream_extract_key_from_data(
    is: *mut dds_istream_t,
    os: *mut dds_ostream_t,
    allocator: *const dds_cdrstream_allocator,
    desc: *const dds_cdrstream_desc,
) -> bool

@brief Extract serialized key fields from serialized sample data. @component cdr_serializer

Reads sample data from @p is and writes the serialized key representation to @p os using native byte order. The generated key uses @ref DDS_CDR_KEY_SERIALIZATION_SAMPLE.

@param is input stream containing serialized sample data @param os output stream for the serialized key @param allocator allocator used for temporary storage and stream growth @param desc CDR stream descriptor for the sample type @returns true on success, false on extraction failure