Add shared managed lock broker
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@@ -0,0 +1,263 @@
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import fcntl
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import os
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import stat
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import subprocess
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import sys
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import tempfile
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import time
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import unittest
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from pathlib import Path
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from unittest.mock import patch
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from harness.lib.managed_lock import (
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LockOrderError,
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LockTimeoutError,
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LockValidationError,
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ManagedLock,
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ManagedLockSet,
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probe_free,
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validate_held_flock,
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)
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class ManagedLockTests(unittest.TestCase):
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def test_lock_is_created_securely_and_held_for_context(self):
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with tempfile.TemporaryDirectory() as d:
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path = Path(d) / "repository.lock"
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with ManagedLock(path) as lock:
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self.assertIsNotNone(lock.fd)
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st = path.stat()
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self.assertEqual(stat.S_IMODE(st.st_mode), 0o600)
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self.assertEqual(st.st_nlink, 1)
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self.assertEqual(st.st_uid, os.getuid())
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self.assertTrue(validate_held_flock(lock.fd, path))
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self.assertTrue(probe_free(path))
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def test_lock_timeout_is_bounded_and_does_not_steal_lock(self):
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with tempfile.TemporaryDirectory() as d:
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path = Path(d) / "issue.lock"
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with ManagedLock(path):
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start = time.monotonic()
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with self.assertRaises(LockTimeoutError):
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with ManagedLock(path, timeout=0.05, poll_interval=0.005):
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pass
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self.assertLess(time.monotonic() - start, 1)
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self.assertTrue(probe_free(path))
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def test_existing_unsafe_lock_file_is_rejected_without_repair(self):
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with tempfile.TemporaryDirectory() as d:
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path = Path(d) / "bad.lock"
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path.write_text("x")
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os.chmod(path, 0o644)
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with self.assertRaises(LockValidationError):
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ManagedLock(path).acquire()
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self.assertEqual(stat.S_IMODE(path.stat().st_mode), 0o644)
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self.assertEqual(path.read_text(), "x")
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def test_literal_dotdot_component_is_rejected_before_normalization(self):
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with tempfile.TemporaryDirectory() as d:
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path = Path(d) / "a" / ".." / "b.lock"
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with self.assertRaises(LockValidationError):
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ManagedLock(path)
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def test_symlink_lock_is_rejected(self):
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with tempfile.TemporaryDirectory() as d:
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root = Path(d)
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target = root / "target"
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target.write_text("do not touch")
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path = root / "link.lock"
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path.symlink_to(target)
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with self.assertRaises(LockValidationError):
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ManagedLock(path).acquire()
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self.assertEqual(target.read_text(), "do not touch")
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def test_symlink_to_safe_lock_is_rejected(self):
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with tempfile.TemporaryDirectory() as d:
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root = Path(d)
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target = root / "safe-target.lock"
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target.touch(mode=0o600)
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path = root / "safe-link.lock"
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path.symlink_to(target)
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with self.assertRaises(LockValidationError):
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ManagedLock(path)
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def test_lock_path_through_symlinked_parent_is_rejected(self):
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with tempfile.TemporaryDirectory() as d:
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root = Path(d)
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target = root / "real"
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target.mkdir()
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parent = root / "linked"
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parent.symlink_to(target, target_is_directory=True)
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with self.assertRaises(LockValidationError):
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ManagedLock(parent / "issue.lock").acquire()
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self.assertFalse((target / "issue.lock").exists())
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def test_ancestor_swap_after_parent_open_cannot_redirect_lock(self):
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"""The final open stays relative to the already pinned parent inode."""
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with tempfile.TemporaryDirectory() as d:
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root = Path(d)
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parent = root / "locks"
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parent.mkdir()
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diverted = root / "diverted"
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diverted.mkdir()
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module = __import__("harness.lib.managed_lock", fromlist=["_open_parent"])
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original_open_parent = module._open_parent
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def swap_after_open(path, *, create_parent):
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fd, name = original_open_parent(path, create_parent=create_parent)
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parent.rename(root / "original-locks")
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parent.symlink_to(diverted, target_is_directory=True)
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return fd, name
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lock = ManagedLock(parent / "issue.lock")
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with patch("harness.lib.managed_lock._open_parent", side_effect=swap_after_open):
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with self.assertRaises(LockValidationError):
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lock.acquire()
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self.assertTrue((root / "original-locks" / "issue.lock").exists())
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self.assertFalse((diverted / "issue.lock").exists())
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self.assertFalse(lock.held)
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def test_hardlink_lock_is_rejected(self):
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with tempfile.TemporaryDirectory() as d:
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root = Path(d)
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path = root / "lock"
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alias = root / "alias"
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path.touch(mode=0o600)
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os.link(path, alias)
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with self.assertRaises(LockValidationError):
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ManagedLock(path).acquire()
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def test_for_issue_builds_canonical_paths(self):
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with tempfile.TemporaryDirectory() as d:
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root = Path(d).absolute()
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issue, repository = ManagedLockSet.paths_for_issue(root, "alice", "ledger", 7)
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self.assertEqual(issue, root / "repositories/alice/ledger/locks/issue-7.lock")
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self.assertEqual(repository, root / "repositories/alice/ledger/locks/repository.lock")
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locks = ManagedLockSet.for_issue(root, "alice", "ledger", 7)
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self.assertEqual(locks.issue.path, issue)
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self.assertEqual(locks.repository.path, repository)
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def test_for_issue_rejects_unsafe_identity_issue_and_root(self):
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with tempfile.TemporaryDirectory() as d:
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root = Path(d).absolute()
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for owner, repo in [("../alice", "ledger"), ("alice/x", "ledger"), ("alice", ".."), ("alice", "")]:
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with self.subTest(owner=owner, repo=repo), self.assertRaises(ValueError):
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ManagedLockSet.for_issue(root, owner, repo, 1)
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for issue in (0, -1, True, "1"):
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with self.subTest(issue=issue), self.assertRaises(ValueError):
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ManagedLockSet.for_issue(root, "alice", "ledger", issue)
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with self.assertRaises(ValueError):
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ManagedLockSet.for_issue(Path("relative"), "alice", "ledger", 1)
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with self.assertRaises(ValueError):
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ManagedLockSet.for_issue(root / ".." / root.name, "alice", "ledger", 1)
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def test_managed_lock_set_holds_issue_then_repository_scope_only(self):
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with tempfile.TemporaryDirectory() as d:
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root = Path(d)
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issue, repo = root / "issue", root / "repo"
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events = []
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locks = ManagedLockSet(issue, repo, event_sink=events.append)
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with locks:
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self.assertTrue(validate_held_flock(locks.issue.fd, issue))
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self.assertFalse(locks.repository.held)
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with locks.repository_scope():
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self.assertTrue(validate_held_flock(locks.repository.fd, repo))
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self.assertFalse(locks.repository.held)
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self.assertEqual(events, ["acquire:issue", "acquire:repository", "release:repository", "release:issue"])
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def test_release_issue_rejects_while_repository_held(self):
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with tempfile.TemporaryDirectory() as d:
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locks = ManagedLockSet(Path(d) / "issue", Path(d) / "repo")
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with locks:
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with locks.repository_scope():
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with self.assertRaises(LockOrderError):
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locks.release_issue()
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locks.release_issue()
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self.assertFalse(locks.issue.held)
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def test_context_exception_cleans_up_issue_and_repository(self):
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with tempfile.TemporaryDirectory() as d:
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locks = ManagedLockSet(Path(d) / "issue", Path(d) / "repo")
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with self.assertRaises(RuntimeError):
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with locks:
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with locks.repository_scope():
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raise RuntimeError("boom")
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self.assertFalse(locks.issue.held)
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self.assertFalse(locks.repository.held)
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self.assertTrue(probe_free(locks.issue.path))
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self.assertTrue(probe_free(locks.repository.path))
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def test_repository_scope_requires_issue_and_cleans_up_acquire_exception(self):
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with tempfile.TemporaryDirectory() as d:
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locks = ManagedLockSet(Path(d) / "issue", Path(d) / "repo")
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with self.assertRaises(LockOrderError):
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with locks.repository_scope():
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pass
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with ManagedLock(locks.repository.path):
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with locks:
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with self.assertRaises(LockTimeoutError):
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with locks.repository_scope():
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pass
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self.assertTrue(locks.issue.held)
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locks.release_issue()
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def test_repository_scope_event_exception_releases_repository_and_issue_context(self):
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with tempfile.TemporaryDirectory() as d:
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def fail_on_repository(event):
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if event == "acquire:repository":
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raise RuntimeError("event failure")
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locks = ManagedLockSet(Path(d) / "issue", Path(d) / "repo", event_sink=fail_on_repository)
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locks.issue.acquire()
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with self.assertRaises(RuntimeError):
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with locks.repository_scope():
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pass
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self.assertTrue(locks.issue.held)
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self.assertFalse(locks.repository.held)
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locks.release_issue()
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self.assertTrue(probe_free(locks.issue.path))
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self.assertTrue(probe_free(locks.repository.path))
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def test_write_metadata_replaces_bytes_exactly_on_repeated_writes(self):
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with tempfile.TemporaryDirectory() as d:
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path = Path(d) / "metadata.lock"
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with ManagedLock(path) as lock:
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lock.write_metadata({"long": "x" * 100})
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lock.write_metadata({"x": 1})
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self.assertEqual(path.read_bytes(), b'{"x":1}\n')
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def test_metadata_requires_held_lock(self):
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with tempfile.TemporaryDirectory() as d:
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lock = ManagedLock(Path(d) / "metadata.lock")
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with self.assertRaises(RuntimeError):
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lock.write_metadata({"state": "held"})
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def test_probe_free_does_not_delete_or_modify_lock(self):
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with tempfile.TemporaryDirectory() as d:
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path = Path(d) / "probe.lock"
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with ManagedLock(path):
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pass
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before = path.stat()
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self.assertTrue(probe_free(path))
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after = path.stat()
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self.assertEqual((before.st_ino, before.st_size, before.st_mode), (after.st_ino, after.st_size, after.st_mode))
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def test_other_process_cannot_acquire_while_context_alive(self):
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with tempfile.TemporaryDirectory() as d:
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path = Path(d) / "process.lock"
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script = """
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import sys
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sys.path.insert(0, sys.argv[2])
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from harness.lib.managed_lock import ManagedLock, LockTimeoutError
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try:
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with ManagedLock(sys.argv[1], timeout=0.03, poll_interval=0.005):
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print('acquired')
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except LockTimeoutError:
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print('blocked')
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"""
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with ManagedLock(path):
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result = subprocess.run([sys.executable, "-c", script, str(path), str(Path.cwd())], text=True, capture_output=True, check=True)
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self.assertEqual(result.stdout.strip(), "blocked")
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if __name__ == "__main__":
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unittest.main()
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