code: def __init__(self, fname, offset_start, page_size):
      self.fname = fname
      self.offset = align_to_page(offset_start, page_size)
      self.next_page_allocated = Value(ctypes.c_uint64, 0)
      self.next_page_written = Value(ctypes.c_uint64, 0)
  
      self.page_size = page_size
      self.page_offset = 0
      self.my_page = -1
  
      self.page_data = np.zeros(self.page_size, "<u1")
      self.allocations = []
      self.current_sample_id = None
  
file_path: ffcv/ffcv/memory_allocator.py
imports: import numpy
  from time import sleep
  from os import SEEK_END
  from multiprocessing import Value
  from .utils import align_to_page
  import ctypes
label_desc: Use image node_id 1 to create a new MemoryAllocator object  with example: obj = MemoryAllocator(fname, offset_start, page_size)