Class LimitedSet

celery/utils/collections.py:441–662

Kind-of Set (or priority queue) with limitations. Good for when you need to test for membership (`a in set`), but the set should not grow unbounded. ``maxlen`` is enforced at all times, so if the limit is reached we'll also remove non-expired items. You can also configure ``mi

class LimitedSet:
    """Kind-of Set (or priority queue) with limitations.

    Good for when you need to test for membership (`a in set`),
    but the set should not grow unbounded.

    ``maxlen`` is enforced at all times, so if the limit is reached
    we'll also remove non-expired items.

    You can also configure ``minlen``: this is the minimal residual size
    of the set.

    All arguments are optional, and no limits are enabled by default.

    Arguments:
        maxlen (int): Optional max number of items.
            Adding more items than ``maxlen`` will result in immediate
            removal of items sorted by oldest insertion time.

        expires (float): TTL for all items.
            Expired items are purged as keys are inserted.

        minlen (int): Minimal residual size of this set.
            .. versionadded:: 4.0

            Value must be less than ``maxlen`` if both are configured.

            Older expired items will be deleted, only after the set
            exceeds ``minlen`` number of items.

        data (Sequence): Initial data to initialize set with.
            Can be an iterable of ``(key, value)`` pairs,
            a dict (``{key: insertion_time}``), or another instance
            of :class:`LimitedSet`.

    Example:
        >>> s = LimitedSet(maxlen=50000, expires=3600, minlen=4000)
        >>> for i in range(60000):
        ...     s.add(i)
        ...     s.add(str(i))
        ...
        >>> 57000 in s  # last 50k inserted values are kept
        True
        >>> '10' in s  # '10' did expire and was purged from set.
        False
        >>> len(s)  # maxlen is reached
        50000
        >>> s.purge(now=time.monotonic() + 7200)  # clock + 2 hours
        >>> len(s)  # now only minlen items are cached
        4000
        >>>> 57000 in s  # even this item is gone now
        False
    """

    max_heap_percent_overload = 15

    def __init__(self, maxlen=0, expires=0, data=None, minlen=0):
        # type: (int, float, Mapping, int) -> None