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path: root/id_generator.py
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#!/usr/bin/env python3

import itertools
import logging

# This module is commonly used by others in here and should avoid
# taking any unnecessary dependencies back on them.

logger = logging.getLogger(__name__)
generators = {}


def get(name: str, *, start=0) -> int:
    """
    Returns a thread safe monotonically increasing id suitable for use
    as a globally unique identifier.

    >>> import id_generator
    >>> id_generator.get('student_id')
    0
    >>> id_generator.get('student_id')
    1
    >>> id_generator.get('employee_id', start=10000)
    10000
    >>> id_generator.get('employee_id', start=10000)
    10001
    """
    if name not in generators:
        generators[name] = itertools.count(start, 1)
    x = next(generators[name])
    logger.debug(f"Generated next id {x}")
    return x


if __name__ == '__main__':
    import doctest
    doctest.testmod()