60 lines
1.9 KiB
Python
60 lines
1.9 KiB
Python
"""Job-type handler dispatch.
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A handler processes one item of a job: ``handler(item_key, ctx)`` and either
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returns (success), raises ``Cancelled`` (cooperative stop, resumable), or raises
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any other exception (item failure). Handlers must be idempotent — at-least-once
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delivery means the same item can run again after an interrupted attempt.
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Domain handlers (safety scoring, analysis, …) register here in later stories; the
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registry ships empty so the worker engine can be built and tested independently.
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"""
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from __future__ import annotations
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from dataclasses import dataclass
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from typing import TYPE_CHECKING, Callable
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if TYPE_CHECKING:
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from photo_pipeline.services.jobs import JobService
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Handler = Callable[[str, "JobContext"], None]
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class Cancelled(Exception):
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"""Raised by a handler that observed cancellation and stopped cleanly."""
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@dataclass
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class JobContext:
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"""What a handler needs from the coordinator: cancellation checks, heartbeats,
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and the session factory to build domain services against."""
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job_id: str
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worker_id: str
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fencing_token: int
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service: "JobService"
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session_factory: object | None = None
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# Handlers that talk to an external tool (uploads) need the typed configuration;
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# the worker passes its own so a test stack is never read from the environment.
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config: object | None = None
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def cancelled(self) -> bool:
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from photo_pipeline.services.jobs import JobState
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snapshot = self.service.get(self.job_id)
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return snapshot is None or snapshot["state"] in (
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JobState.CANCELLING,
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JobState.CANCELLED,
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)
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def heartbeat(self, *, lease_seconds: int = 60) -> bool:
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return self.service.heartbeat(self.job_id, self.worker_id, lease_seconds=lease_seconds)
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# Populated by domain stories via register(); empty for now.
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REGISTRY: dict[str, Handler] = {}
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def register(job_type: str, handler: Handler) -> None:
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REGISTRY[job_type] = handler
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