40 lines
1.0 KiB
Python
40 lines
1.0 KiB
Python
"""ASN provider factory — mirror of :mod:`decnet.geoip.factory`.
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Dispatch key: ``DECNET_ASN_PROVIDER`` (default ``iptoasn``). Lazy
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singleton.
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"""
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from __future__ import annotations
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import os
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from typing import Optional
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from decnet.asn.base import Provider
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_cached: Optional[Provider] = None
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_cached_key: Optional[str] = None
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def get_provider() -> Provider:
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"""Return the configured :class:`Provider` singleton."""
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global _cached, _cached_key
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key = os.environ.get("DECNET_ASN_PROVIDER", "iptoasn").lower()
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if _cached is not None and _cached_key == key:
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return _cached
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if key == "iptoasn":
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from decnet.asn.iptoasn.provider import IptoasnProvider
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provider: Provider = IptoasnProvider()
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else:
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raise ValueError(f"Unsupported ASN provider: {key!r}")
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_cached = provider
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_cached_key = key
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return provider
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def reset_cache() -> None:
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"""Forget the singleton — tests swap providers via the env var."""
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global _cached, _cached_key
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_cached = None
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_cached_key = None
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