q792602257andClaude Opus 4.6
d00ada67a5
Acquire an exclusive, non-blocking filelock on the identity state directory as the first action of create_application(), before resolve_host_identity() or any enrollment/heartbeat side effect. A second process against the same identity_path exits immediately with InstanceAlreadyRunningError naming the lock path; the lock releases automatically on any process exit (including SIGKILL) via OS-level advisory locking, and explicitly during run_async()'s shutdown finally block. filelock is promoted from transitive to direct dependency (version unchanged at 3.29.7). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
72 lines
2.2 KiB
Python
72 lines
2.2 KiB
Python
"""Per-installation exclusive-execution lock for the Host Agent process.
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Backed by ``filelock.FileLock`` (OS-level advisory file locking) so that
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the lock is released automatically when the holding process exits for
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any reason — clean shutdown, unhandled exception, or ``SIGKILL`` — without
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requiring any stale-lock cleanup step. See
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``openspec/changes/host-agent-single-instance-lock/design.md`` for the
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rationale behind choosing ``filelock`` over hand-rolled ``fcntl``/``msvcrt``
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branching.
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"""
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from __future__ import annotations
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from pathlib import Path
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from filelock import FileLock, Timeout
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_LOCK_FILENAME = "host_agent.lock"
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class InstanceAlreadyRunningError(RuntimeError):
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"""Raised when another live process already holds the instance lock."""
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def __init__(self, lock_path: Path) -> None:
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self.lock_path = lock_path
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super().__init__(
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"another Host Agent instance is already running for this "
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f"identity state directory (lock held at {lock_path}); "
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"stop the other process before starting a new one"
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)
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class InstanceLock:
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"""Exclusive, non-blocking lock scoped to a Host Agent state directory.
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The state directory (typically ``identity_path.parent``) is created on
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construction to match the colocated-file convention already used for
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``host_console_history.sqlite3`` and ``host_governance_policy.json``.
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"""
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def __init__(self, state_dir: Path) -> None:
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state_dir.mkdir(parents=True, exist_ok=True)
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self._lock_path = state_dir / _LOCK_FILENAME
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self._lock = FileLock(str(self._lock_path), timeout=0)
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self._acquired = False
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@property
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def lock_path(self) -> Path:
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return self._lock_path
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def acquire(self) -> None:
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try:
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self._lock.acquire()
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except Timeout as exc:
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raise InstanceAlreadyRunningError(self._lock_path) from exc
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self._acquired = True
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def release(self) -> None:
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if not self._acquired:
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return
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try:
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self._lock.release()
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finally:
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self._acquired = False
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def __enter__(self) -> InstanceLock:
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self.acquire()
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return self
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def __exit__(self, *exc_info: object) -> None:
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self.release()
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