Harvey
89 lines
2.7 KiB
Python
89 lines
2.7 KiB
Python
"""Request-scoped degradation context via ``contextvars``.
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A :class:`DegradationContext` is created per HTTP request by the
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:class:`DegradationMiddleware` and can be accessed from *any* layer
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(repository, service, route) without threading extra arguments through
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call signatures.
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"""
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from __future__ import annotations
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import contextvars
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from typing import Literal
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from infrastructure.integration_result import IntegrationResult, IntegrationStatus
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_degradation_ctx_var: contextvars.ContextVar[DegradationContext | None] = (
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contextvars.ContextVar("degradation_ctx", default=None)
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)
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class DegradationContext:
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"""Accumulates per-source integration status within a single request."""
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__slots__ = ("_services",)
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def __init__(self) -> None:
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self._services: dict[str, IntegrationStatus] = {}
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def record(self, result: IntegrationResult) -> None: # type: ignore[type-arg]
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"""Record an integration result, keeping the worst status per source."""
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prev = self._services.get(result.source)
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if prev is None or _severity(result.status) > _severity(prev):
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self._services[result.source] = result.status
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def summary(self) -> dict[str, str]:
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"""Return ``{source: status}`` for all recorded integrations."""
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return dict(self._services)
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def degraded_summary(self) -> dict[str, str]:
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"""Return only sources that are *not* ``ok``."""
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return {k: v for k, v in self._services.items() if v != "ok"}
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def has_degradation(self) -> bool:
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return any(v != "ok" for v in self._services.values())
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def init_degradation_context() -> DegradationContext:
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"""Create a fresh context and install it in the current ``ContextVar``."""
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ctx = DegradationContext()
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_degradation_ctx_var.set(ctx)
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return ctx
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def get_degradation_context() -> DegradationContext:
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"""Return the current request's context.
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Raises :class:`RuntimeError` when called outside a request scope.
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"""
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ctx = _degradation_ctx_var.get()
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if ctx is None:
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raise RuntimeError(
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"get_degradation_context() called outside a request scope"
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)
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return ctx
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def try_get_degradation_context() -> DegradationContext | None:
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"""Return the current context, or ``None`` if none is active.
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Safe for background tasks / startup code where no request is in
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flight.
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"""
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return _degradation_ctx_var.get()
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def clear_degradation_context() -> None:
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"""Remove the current context (end-of-request cleanup)."""
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_degradation_ctx_var.set(None)
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_SEVERITY: dict[IntegrationStatus, int] = {"ok": 0, "degraded": 1, "error": 2}
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def _severity(status: IntegrationStatus) -> int:
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return _SEVERITY[status]
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