File-based integer key-value store

store.py

import struct

store_fn = 'store'

#key_bits = 16
#value_bits = 16
#struct_format = 'H'
key_bits = 32
value_bits = 32
struct_format = 'I'

value_bytes = value_bits//8
value_struct = struct.Struct(struct_format)


def make_store():
    with open(store_fn, 'wb') as f:
        for i in range(2**key_bits * value_bytes):
            f.write(b'\x00')

make_store()


store = open(store_fn, 'rb+')

def get(key):
    store.seek(key * value_bytes)
    data = store.read(value_bytes)
    [value] = value_struct.unpack(data)
    return value

def put(key, value):
    store.seek(key * value_bytes)
    data = value_struct.pack(value)
    store.write(data)

put(123, 456)
print(get(65535))
put(65535, 65535)
print(get(123))
print(get(65535))


store.close()