Reserve Mac replay ownership before showcase preparation

roadscore/prototype/mac_replay_ownership.py

@@ -0,0 +1,45 @@
+"""Exclusive Mac showcase ownership while the compiled camera port is global."""
+from contextlib import contextmanager
+import errno
+import fcntl
+import os
+from pathlib import Path
+import socket
+
+
+class ReplayBusy(RuntimeError):
+  pass
+
+
+def check_camera_port():
+  """Check the existing IPv4 ZMQ publisher bind without connecting or sending."""
+  try:
+    with socket.socket(socket.AF_INET,socket.SOCK_STREAM) as probe:
+      # Match a normal listening socket's restart behavior after TIME_WAIT.
+      probe.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
+      probe.bind(('0.0.0.0',9000))
+  except OSError as error:
+    if error.errno==errno.EADDRINUSE:
+      raise ReplayBusy('Mac replay camera port 9000 is already in use. Close the existing Mac replay before starting another.') from None
+    raise ReplayBusy('Cannot verify Mac replay camera port 9000: '+str(error)) from error
+
+
+@contextmanager
+def mac_replay_lease(root, *, port_check=None):
+  """Hold this descriptor until parent cleanup ends; children never inherit it."""
+  path=Path(root)/'generated/mac_showcase.lock'
+  path.parent.mkdir(parents=True,exist_ok=True)
+  with path.open('a+') as lease:
+    os.set_inheritable(lease.fileno(),False)
+    try:fcntl.flock(lease,fcntl.LOCK_EX|fcntl.LOCK_NB)
+    except BlockingIOError:
+      raise ReplayBusy('A Mac RoadScore replay is already running. Close its existing demo before starting another.') from None
+    try:
+      (check_camera_port if port_check is None else port_check)()
+      yield lease
+    finally:fcntl.flock(lease,fcntl.LOCK_UN)
+
+
+def preflight(root):
+  """Advisory check before paired launch; the Mac parent later holds its lease."""
+  with mac_replay_lease(root):pass

roadscore/prototype/mac_showcase.py

@@ -411,6 +411,14 @@ def main():
     return audio_worker(a)
   if a.no_control_server:raise SystemExit('--no-control-server is an internal prepared audio-worker option')
   if sys.platform!='darwin' or Path('/TICI').exists():raise SystemExit('Prepared Mac showcase runs only on the Mac')
+  if a.check:return parent_main(a)
+  from mac_replay_ownership import ReplayBusy, mac_replay_lease
+  try:
+    with mac_replay_lease(a.project_root.resolve()/'roadscore'):return parent_main(a)
+  except ReplayBusy as error:raise SystemExit(str(error)) from None
+
+
+def parent_main(a):
   launch_started=time.monotonic()
   project=a.project_root.resolve();rt=a.runtime or project/'.host_runtime/darwin/worktree'
   py=rt.parent/'venv/bin/python'

roadscore/prototype/test_mac_replay_ownership.py

@@ -0,0 +1,69 @@
+import errno
+import os
+from pathlib import Path
+import tempfile
+import unittest
+from unittest.mock import MagicMock, patch
+
+import mac_showcase
+from mac_replay_ownership import ReplayBusy, check_camera_port, mac_replay_lease, preflight
+
+
+class MacReplayOwnershipTests(unittest.TestCase):
+  def setUp(self):
+    temporary=tempfile.TemporaryDirectory();self.addCleanup(temporary.cleanup)
+    self.root=Path(temporary.name)
+
+  def test_two_real_descriptors_are_exclusive_and_release_on_exception(self):
+    check=MagicMock()
+    with self.assertRaisesRegex(ValueError,'fixture failure'):
+      with mac_replay_lease(self.root,port_check=check) as held:
+        self.assertFalse(os.get_inheritable(held.fileno()))
+        with self.assertRaises(ReplayBusy):
+          with mac_replay_lease(self.root,port_check=check):self.fail('Second lease acquired')
+        self.assertEqual(check.call_count,1)
+        raise ValueError('fixture failure')
+    with mac_replay_lease(self.root,port_check=check):pass
+    self.assertEqual(check.call_count,2)
+
+  def test_port_failure_releases_lease_and_preflight_does_not_hold_it(self):
+    with patch('mac_replay_ownership.check_camera_port',side_effect=ReplayBusy('busy')):
+      with self.assertRaises(ReplayBusy):preflight(self.root)
+    with patch('mac_replay_ownership.check_camera_port') as check:
+      preflight(self.root)
+      with mac_replay_lease(self.root):pass
+      self.assertEqual(check.call_count,2)
+
+  def test_port_probe_reports_busy_without_connecting_or_sending(self):
+    probe=MagicMock();probe.__enter__.return_value=probe
+    with patch('mac_replay_ownership.socket.socket',return_value=probe):
+      check_camera_port()
+      probe.bind.assert_called_once_with(('0.0.0.0',9000))
+      probe.connect.assert_not_called();probe.send.assert_not_called()
+      probe.bind.side_effect=OSError(errno.EADDRINUSE,'in use')
+      with self.assertRaisesRegex(ReplayBusy,'port 9000'):check_camera_port()
+
+  def test_parent_holds_lease_before_any_preparation(self):
+    args=mac_showcase.parser().parse_args(['--project-root',str(self.root)])
+    def prepared(value):
+      with self.assertRaises(ReplayBusy):
+        with mac_replay_lease(self.root/'roadscore',port_check=lambda:None):pass
+      return 17
+    with (patch('mac_showcase.parser') as parser,patch('mac_showcase.parent_main',side_effect=prepared) as parent,
+          patch('mac_showcase.sys.platform','darwin'),patch('mac_replay_ownership.check_camera_port')):
+      parser.return_value.parse_args.return_value=args
+      self.assertEqual(mac_showcase.main(),17)
+      parent.assert_called_once_with(args)
+    with mac_replay_lease(self.root/'roadscore',port_check=lambda:None):pass
+
+  def test_worker_and_check_never_acquire_parent_lease(self):
+    for flags,target in ((['--audio-worker'],'audio_worker'),(['--check'],'parent_main')):
+      args=mac_showcase.parser().parse_args(flags)
+      with (patch('mac_showcase.parser') as parser,patch('mac_showcase.'+target,return_value=23),
+            patch('mac_showcase.sys.platform','darwin'),patch('mac_replay_ownership.mac_replay_lease') as lease):
+        parser.return_value.parse_args.return_value=args
+        self.assertEqual(mac_showcase.main(),23)
+        lease.assert_not_called()
+
+
+if __name__=='__main__':unittest.main()