Teknium
41 lines
1.6 KiB
Python
41 lines
1.6 KiB
Python
"""Best-effort accessors for the single-writer stream fence.
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The fence lives on ``AIAgent`` (``_claim_stream_writer`` / ``_stream_writer_is_current``)
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but is used from other streaming modules. Calling it directly would turn an
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*additive* safety net into a fatal AttributeError on a partially-updated checkout,
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hot-reloaded gateway, duck-typed agent, or test double (a cron job died this way).
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The fence may only drop a *provably* superseded stream, never the sole writer, so
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when it is unavailable or raises the correct degradation is "no fence": keep streaming.
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"""
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from __future__ import annotations
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import logging
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from typing import Any
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logger = logging.getLogger(__name__)
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def claim_stream_writer(agent: Any) -> int:
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"""Claim the delta sink for this stream attempt; ``0`` (never fenced) when the agent lacks the fence or the claim raised."""
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claim = getattr(agent, "_claim_stream_writer", None)
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if callable(claim):
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try:
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return int(claim())
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except Exception:
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logger.debug("stream single-writer: claim failed; proceeding unfenced", exc_info=True)
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return 0
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def stream_writer_is_current(agent: Any, token: int) -> bool:
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"""True when ``token`` is still the active writer; a falsy token or a fence-less agent cannot prove supersession, so True."""
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if not token:
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return True
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is_current = getattr(agent, "_stream_writer_is_current", None)
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if callable(is_current):
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try:
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return bool(is_current(token))
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except Exception:
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logger.debug("stream single-writer: is_current check failed; treating as current", exc_info=True)
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return True
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