ed
5a85653654
Lightweight, in-memory profiler for AppController init phases. Used by
the startup_speedup_20260606 track to measure where the time goes
during boot (config hydration, hook server start, subsystem init, etc.).
The profiler is exposed via /api/startup_profile (Phase 8 work) and
the Diagnostics panel so the user can see the exact per-phase cost.
Public API:
StartupProfiler() - create
.phase(name) - context manager
.snapshot() - {phases: {name: {start_ts, duration_ms}}, total_ms, count}
.reset() - clear recorded phases
.enable() / .disable() - toggle recording
Implementation:
- dataclass with list of _Phase(name, start_ts, end_ts)
- @contextmanager records wall-clock via time.perf_counter
- records duration even if the body raises (try/finally)
- snapshot is a copy, so consumers can't mutate the live state
TDD: 5 tests in tests/test_startup_profiler.py cover: basic
recording, total math, snapshot isolation, exception safety, empty
state.
71 lines
1.8 KiB
Python
71 lines
1.8 KiB
Python
"""Tests for src/startup_profiler.py.
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TDD Red phase: this file should fail before src/startup_profiler.py exists,
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pass after it's implemented.
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"""
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import time
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from pathlib import Path
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import sys
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ROOT = Path(__file__).resolve().parent.parent
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sys.path.insert(0, str(ROOT))
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from src.startup_profiler import StartupProfiler # noqa: E402
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def test_startup_profiler_records_phase_duration() -> None:
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prof = StartupProfiler()
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with prof.phase("init_config"):
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time.sleep(0.01)
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snap = prof.snapshot()
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assert "phases" in snap
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assert "init_config" in snap["phases"]
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entry = snap["phases"]["init_config"]
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assert entry["duration_ms"] >= 8.0
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assert entry["duration_ms"] < 500.0
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assert entry["start_ts"] > 0
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def test_startup_profiler_total_reflects_sum() -> None:
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prof = StartupProfiler()
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with prof.phase("a"):
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time.sleep(0.005)
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with prof.phase("b"):
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time.sleep(0.005)
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snap = prof.snapshot()
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assert snap["total_ms"] >= 10.0
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assert abs(snap["total_ms"] - (snap["phases"]["a"]["duration_ms"] + snap["phases"]["b"]["duration_ms"])) < 0.5
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def test_startup_profiler_snapshot_is_independent_copy() -> None:
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prof = StartupProfiler()
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with prof.phase("x"):
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pass
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snap1 = prof.snapshot()
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with prof.phase("y"):
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pass
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snap2 = prof.snapshot()
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assert "x" in snap1["phases"]
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assert "y" not in snap1["phases"]
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assert "y" in snap2["phases"]
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def test_startup_profiler_phase_records_on_exception() -> None:
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prof = StartupProfiler()
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try:
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with prof.phase("will_fail"):
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raise RuntimeError("boom")
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except RuntimeError:
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pass
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snap = prof.snapshot()
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assert "will_fail" in snap["phases"]
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assert snap["phases"]["will_fail"]["duration_ms"] >= 0
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def test_startup_profiler_empty_snapshot() -> None:
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prof = StartupProfiler()
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snap = prof.snapshot()
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assert snap["phases"] == {}
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assert snap["total_ms"] == 0.0
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