diet-guard/diet_guard/_gatelock_lockfile.py
Krzysztof kuhy Rudnicki e8f0ecaae1 Split the six Python gate files; guard the fake-tk patch set
Sixth batch of the 250-line sweep. All six gate sources named for this batch
are now under cap, plus _gate_layout_probe.py, which this batch's import
rewiring pulled into the changeset (over-cap count 38 -> 31).

  _gatelock_ui.py       477 -> 174  (palette/leaf-helper hub)
  _gate_layout_probe.py 346 -> 196
  _gatelock_groups.py   308 -> 137
  _gatelock_calendar_ui 295 ->  77
  _gatelock_calendar.py 286 -> 210
  _gatelock.py          263 -> 238
  _gatelock_mealflow.py 259 -> 207

New siblings: _gatelock_fields (input widgets), _gatelock_layout (assembly),
_gatelock_widgetgroups (per-widget mirroring), _gatelock_calendar_types
(bundles/palette), _gatelock_calendar_widgets (History builders),
_gatelock_dashboard and _gatelock_budgetedit (mixins), _gatelock_lockfile
(the stdlib-only flock), _gate_focus_probe and _gate_measurement.

The load-bearing part is the test seam, not the line counts.
`_gate_fixtures._GATE_TK_MODULES` patches `tk` on a hand-listed tuple, and
that list fails OPEN: a widget builder split into a new sibling that nobody
adds to it builds *real* Tk widgets against fake parents. Neither existing
detector sees that -- check_patch_targets.py only validates paths that still
resolve, and the ~8s runtime only catches network calls. It bit twice during
this split (real StringVars from make_calendar_vars returned MagicMocks
instead of the asserted text), so test_gate_tk_modules.py now asserts the
invariant directly: every module binding `tk` is in the patch set or named in
_NO_WIDGETS with a reason. It caught a pre-existing gap too --
_gatelock_support was never in the set.

Same fail-open shape drove two other choices: `escape_tab_trap` is a call-time
indirection so the keyboard test's patch of `_escape_text_tab_trap` still
bites, and the flock pair moved with its conftest patch target updated in the
same edit (that one fails closed). build_layout is imported from
_gatelock_layout directly rather than re-exported lazily, which avoids both a
cycle and an import-outside-toplevel suppression.

Verified: 703 Python tests / 100% branch coverage, the 5 layout-fits tests
under xvfb, 555 Flutter tests (unchanged), flutter analyze clean,
check_patch_targets 0, `sync` 0 (403 entries), pre-commit clean, and
`gate --demo` renders both tabs with live dashboard data.
~/.local/share/diet_guard byte-identical across the batch (gate timer paused,
restored after).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RA9ynjqXPnexRQnR5oAuCC
2026-08-15 20:08:03 +02:00

50 lines
1.4 KiB
Python

"""Single-instance ``flock`` for the meal gate.
Split out of :mod:`._gatelock` to keep every gate module under the repo's
250-line limit. Deliberately the *stdlib-only* half of the gate: no ``tkinter``
import, so this module never needs to appear in the test suite's
``_GATE_TK_MODULES`` fake-tk patch set.
"""
from __future__ import annotations
import contextlib
import fcntl
from typing import TYPE_CHECKING
from diet_guard._constants import GATE_LOCK_FILE
if TYPE_CHECKING:
from typing import TextIO
__all__ = [
"GATE_LOCK_FILE",
"acquire_gate_lock",
"release_gate_lock",
]
def acquire_gate_lock() -> TextIO | None:
"""Acquire the gate's single-instance ``flock``.
Returns:
An open file handle that must be kept alive for the gate's lifetime
(closing it releases the lock), or None if another gate already holds
it -- in which case the caller must not open a second window.
"""
GATE_LOCK_FILE.parent.mkdir(parents=True, exist_ok=True)
handle = GATE_LOCK_FILE.open("w", encoding="utf-8")
try:
fcntl.flock(handle.fileno(), fcntl.LOCK_EX | fcntl.LOCK_NB)
except OSError:
handle.close()
return None
return handle
def release_gate_lock(handle: TextIO) -> None:
"""Release the single-instance lock and close its handle."""
with contextlib.suppress(OSError):
fcntl.flock(handle.fileno(), fcntl.LOCK_UN)
handle.close()