hermes-agent/tests/test_hermes_state_compression_locks.py
Teknium fdefb2d38c fix(compression): prefer psutil.pid_exists for lease liveness probe; add same-pid self-reclaim guard
Hardening on top of the salvaged dead-PID lease reclamation from PR #65775
(@the3asic):

- Probe via psutil.pid_exists (hard dependency; CONTRIBUTING.md critical
  rule #1) with the contributor's os.kill(pid, 0) POSIX probe retained
  only as a scaffold-phase fallback when psutil is missing.
- Same-process holders (pid == os.getpid()) are never probed and never
  self-reclaimed — another thread's live lease is owned by the lease
  refresher/release path.
- Any probe doubt (exceptions, permission errors) conservatively keeps
  the lease until normal TTL expiry; Windows stays TTL-only.
- Tests: psutil-first dead-pid reclaim (probe call pinned), os.kill
  fallback path, probe-doubt keeps lease, same-pid no self-reclaim,
  legacy holder + Windows paths assert NO probe via either API.
2026-07-23 16:21:19 -07:00

314 lines
10 KiB
Python

"""Tests for ``SessionDB`` compression-lock primitives.
These cover the atomic per-session lock that prevents two compression
paths from racing on the same ``session_id`` and producing orphan child
sessions (Damien's "parent → two orphan children" repro shape, see
``tests/agent/test_compression_concurrent_fork.py`` for the
behavioural regression test).
Focus here: the lock primitives themselves (acquire, release, TTL,
diagnostic accessor) — not the wiring into compression.
"""
from __future__ import annotations
import os
import threading
import time
from pathlib import Path
from types import SimpleNamespace
import pytest
import hermes_state
from hermes_state import SessionDB
@pytest.fixture
def db(tmp_path: Path) -> SessionDB:
return SessionDB(tmp_path / "state.db")
# ----------------------------------------------------------------------
# Single-holder semantics
# ----------------------------------------------------------------------
def test_acquire_succeeds_when_unlocked(db: SessionDB) -> None:
assert db.try_acquire_compression_lock("sess1", "holder1") is True
assert db.get_compression_lock_holder("sess1") == "holder1"
def test_acquire_blocks_second_holder(db: SessionDB) -> None:
assert db.try_acquire_compression_lock("sess1", "holder1") is True
assert db.try_acquire_compression_lock("sess1", "holder2") is False
# First holder still owns it
assert db.get_compression_lock_holder("sess1") == "holder1"
def test_release_allows_reacquire(db: SessionDB) -> None:
db.try_acquire_compression_lock("sess1", "holder1")
db.release_compression_lock("sess1", "holder1")
assert db.get_compression_lock_holder("sess1") is None
assert db.try_acquire_compression_lock("sess1", "holder2") is True
def test_release_with_wrong_holder_is_noop(db: SessionDB) -> None:
db.try_acquire_compression_lock("sess1", "holder1")
# Late-returning compressor must not release a lock it doesn't own
db.release_compression_lock("sess1", "holder_other")
assert db.get_compression_lock_holder("sess1") == "holder1"
def test_release_when_unlocked_is_noop(db: SessionDB) -> None:
# No exception, no state change
db.release_compression_lock("never_locked", "holder1")
assert db.get_compression_lock_holder("never_locked") is None
# ----------------------------------------------------------------------
# Per-session isolation
# ----------------------------------------------------------------------
def test_locks_are_per_session(db: SessionDB) -> None:
assert db.try_acquire_compression_lock("sess1", "holder1") is True
# Different session: independent lock
assert db.try_acquire_compression_lock("sess2", "holder2") is True
assert db.get_compression_lock_holder("sess1") == "holder1"
assert db.get_compression_lock_holder("sess2") == "holder2"
# ----------------------------------------------------------------------
# TTL / expiry recovery
# ----------------------------------------------------------------------
def test_expired_lock_is_reclaimable(db: SessionDB) -> None:
"""A crashed compressor must not permanently block the session."""
# Acquire with a very short TTL
db.try_acquire_compression_lock("sess1", "crashed_holder", ttl_seconds=0.5)
time.sleep(1.0)
# Holder check honours expiry
assert db.get_compression_lock_holder("sess1") is None
# New holder can claim it
assert db.try_acquire_compression_lock("sess1", "fresh_holder") is True
assert db.get_compression_lock_holder("sess1") == "fresh_holder"
def test_non_expired_lock_is_held(db: SessionDB) -> None:
db.try_acquire_compression_lock("sess1", "holder1", ttl_seconds=60)
# Immediately after, still held
assert db.try_acquire_compression_lock("sess1", "holder2") is False
def test_non_expired_lock_from_dead_pid_is_reclaimed(
db: SessionDB, monkeypatch: pytest.MonkeyPatch
) -> None:
dead_holder = "pid=424242:tid=1:agent=abc:nonce=deadbeef"
assert db.try_acquire_compression_lock(
"sess1", dead_holder, ttl_seconds=300
) is True
probed: list[int] = []
def process_is_gone(pid: int) -> bool:
probed.append(pid)
return False
monkeypatch.setattr(
hermes_state, "psutil", SimpleNamespace(pid_exists=process_is_gone)
)
assert db.try_acquire_compression_lock(
"sess1", "pid=525252:tid=2:agent=def:nonce=fresh", ttl_seconds=300
) is True
assert probed == [424242]
def test_dead_pid_reclaim_via_os_kill_fallback_when_psutil_missing(
db: SessionDB, monkeypatch: pytest.MonkeyPatch
) -> None:
"""Scaffold-phase installs (no psutil) fall back to os.kill(pid, 0)."""
dead_holder = "pid=424242:tid=1:agent=abc:nonce=deadbeef"
assert db.try_acquire_compression_lock(
"sess1", dead_holder, ttl_seconds=300
) is True
monkeypatch.setattr(hermes_state, "psutil", None)
def process_is_gone(pid: int, signal: int) -> None:
assert pid == 424242
assert signal == 0
raise ProcessLookupError
monkeypatch.setattr(hermes_state.os, "kill", process_is_gone)
assert db.try_acquire_compression_lock(
"sess1", "pid=525252:tid=2:agent=def:nonce=fresh", ttl_seconds=300
) is True
def test_probe_doubt_keeps_lease_until_ttl(
db: SessionDB, monkeypatch: pytest.MonkeyPatch
) -> None:
"""A probe that errors out is doubt, not proof of death → TTL protects."""
holder = "pid=424242:tid=1:agent=abc:nonce=doubt"
assert db.try_acquire_compression_lock(
"sess1", holder, ttl_seconds=300
) is True
def probe_blows_up(pid: int) -> bool:
raise RuntimeError("transient probe failure")
monkeypatch.setattr(
hermes_state, "psutil", SimpleNamespace(pid_exists=probe_blows_up)
)
assert db.try_acquire_compression_lock(
"sess1", "pid=525252:tid=2:agent=def:nonce=other", ttl_seconds=300
) is False
assert db.get_compression_lock_holder("sess1") == holder
def test_non_expired_lock_from_live_pid_is_not_reclaimed(db: SessionDB) -> None:
live_holder = f"pid={os.getpid()}:tid=1:agent=abc:nonce=live"
assert db.try_acquire_compression_lock(
"sess1", live_holder, ttl_seconds=300
) is True
assert db.try_acquire_compression_lock(
"sess1", "pid=525252:tid=2:agent=def:nonce=other", ttl_seconds=300
) is False
def test_same_process_holder_is_never_self_reclaimed(
db: SessionDB, monkeypatch: pytest.MonkeyPatch
) -> None:
"""A holder from THIS pid is never probed — even a lying probe can't steal it."""
live_holder = f"pid={os.getpid()}:tid=1:agent=abc:nonce=self"
assert db.try_acquire_compression_lock(
"sess1", live_holder, ttl_seconds=300
) is True
# Even if a (broken) probe were to claim our own PID is dead, the
# same-process guard short-circuits before any probe runs.
monkeypatch.setattr(
hermes_state,
"psutil",
SimpleNamespace(
pid_exists=lambda _pid: pytest.fail(
"same-process holder must not be probed"
)
),
)
monkeypatch.setattr(
hermes_state.os,
"kill",
lambda *_args: pytest.fail("same-process holder must not be probed"),
)
assert db.try_acquire_compression_lock(
"sess1", "pid=525252:tid=2:agent=def:nonce=other", ttl_seconds=300
) is False
assert db.get_compression_lock_holder("sess1") == live_holder
def test_unstructured_holder_waits_for_ttl(
db: SessionDB, monkeypatch: pytest.MonkeyPatch
) -> None:
assert db.try_acquire_compression_lock(
"sess1", "legacy_holder", ttl_seconds=300
) is True
monkeypatch.setattr(
hermes_state,
"psutil",
SimpleNamespace(
pid_exists=lambda _pid: pytest.fail(
"unstructured holder must not probe a PID"
)
),
)
monkeypatch.setattr(
hermes_state.os,
"kill",
lambda *_args: pytest.fail("unstructured holder must not probe a PID"),
)
assert db.try_acquire_compression_lock(
"sess1", "pid=525252:tid=2:agent=def:nonce=other", ttl_seconds=300
) is False
def test_windows_uses_ttl_only_without_pid_probe(
db: SessionDB, monkeypatch: pytest.MonkeyPatch
) -> None:
holder = "pid=424242:tid=1:agent=abc:nonce=windows"
assert db.try_acquire_compression_lock(
"sess1", holder, ttl_seconds=300
) is True
monkeypatch.setattr(hermes_state.os, "name", "nt")
monkeypatch.setattr(
hermes_state,
"psutil",
SimpleNamespace(
pid_exists=lambda _pid: pytest.fail(
"Windows must stay TTL-only — no PID probe"
)
),
)
monkeypatch.setattr(
hermes_state.os,
"kill",
lambda *_args: pytest.fail("Windows must not use os.kill as a PID probe"),
)
assert db.try_acquire_compression_lock(
"sess1", "pid=525252:tid=2:agent=def:nonce=other", ttl_seconds=300
) is False
# ----------------------------------------------------------------------
# Empty / invalid input
# ----------------------------------------------------------------------
def test_acquire_empty_session_id_returns_false(db: SessionDB) -> None:
assert db.try_acquire_compression_lock("", "holder1") is False
def test_release_empty_session_id_is_noop(db: SessionDB) -> None:
# No exception
db.release_compression_lock("", "holder1")
def test_holder_empty_session_id_returns_none(db: SessionDB) -> None:
assert db.get_compression_lock_holder("") is None
# ----------------------------------------------------------------------
# Concurrency: real threads racing on the same session_id
# ----------------------------------------------------------------------
def test_concurrent_acquire_only_one_winner(db: SessionDB) -> None:
"""Damien's race shape: N threads call acquire on the same session_id;
exactly one must win, the rest must be cleanly rejected."""
results: list[bool] = []
barrier = threading.Barrier(8)
lock = threading.Lock()
def try_acquire(idx: int) -> None:
holder = f"thread_{idx}"
barrier.wait() # synchronize start
got = db.try_acquire_compression_lock("contended_session", holder)
with lock:
results.append(got)
threads = [threading.Thread(target=try_acquire, args=(i,)) for i in range(8)]
for t in threads:
t.start()
for t in threads:
t.join()
# Exactly one thread acquired
assert sum(1 for r in results if r is True) == 1
assert sum(1 for r in results if r is False) == 7
# The single winner still owns it
assert db.get_compression_lock_holder("contended_session") is not None