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Commit ec657ced authored by Zhuoyao Zhang's avatar Zhuoyao Zhang
Browse files

Synchronize the setup process of edit monitor 

This cl ensures only one edit monitor instance is in the setup proecess
by requesting exclusive file lock on a setup lock file. If there is
already an edit monitor in setup process, other instances trying to
setup will fail. This prevents race conditions when multiple edit
monitor instance are starting.

Test: atest daemon_manager_test
bug: 382135550
Change-Id: Ia8bd2f35318ae81fc002ccce62e2fde3b8cae26b
parent 96c15d81

tools/edit_monitor/daemon_manager.py

+37 −19
Original line number Diff line number Diff line
@@ -13,6 +13,8 @@ 
# limitations under the License.





import errno

import fcntl

import getpass

import hashlib

import logging
@@ -100,16 +102,32 @@ class DaemonManager: 
      logging.warning("Edit monitor for cog is not supported, exiting...")

      return



    setup_lock_file = pathlib.Path(tempfile.gettempdir()).joinpath(

        self.pid_file_path.name + ".setup"

    )

    logging.info("setup lock file: %s", setup_lock_file)

    with open(setup_lock_file, "w") as f:

      try:

        # Acquire an exclusive lock

        fcntl.flock(f, fcntl.LOCK_EX | fcntl.LOCK_NB)

        self._stop_any_existing_instance()

        self._write_pid_to_pidfile()

        self._start_daemon_process()

      except Exception as e:

        if (

            isinstance(e, IOError) and e.errno == errno.EAGAIN

        ):  # Failed to acquire the file lock.

          logging.warning("Another edit monitor is starting, exitinng...")

          return

        else:

          logging.exception("Failed to start daemon manager with error %s", e)

          self._send_error_event_to_clearcut(

              edit_event_pb2.EditEvent.FAILED_TO_START_EDIT_MONITOR

          )

          raise e

      finally:

        # Release the lock

        fcntl.flock(f, fcntl.LOCK_UN)



  def monitor_daemon(

      self,
@@ -414,18 +432,18 @@ class DaemonManager: 
    pids = []



    try:

      output = subprocess.check_output(

          ["ps", "-ef", "--no-headers"], text=True)

      output = subprocess.check_output(["ps", "-ef", "--no-headers"], text=True)

      for line in output.splitlines():

        parts = line.split()

        process_path = parts[7]

          if pathlib.Path(process_path).name == 'edit_monitor':

        if pathlib.Path(process_path).name == "edit_monitor":

          pid = int(parts[1])

          if pid != self.pid:  # exclude the current process

            pids.append(pid)

    except Exception:

      logging.exception(

          "Failed to get pids of existing edit monitors from ps command.")

          "Failed to get pids of existing edit monitors from ps command."

      )



    return pids

tools/edit_monitor/daemon_manager_test.py

+30 −5
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 


"""Unittests for DaemonManager."""



import fcntl

import logging

import multiprocessing

import os
@@ -82,7 +83,8 @@ class DaemonManagerTest(unittest.TestCase): 
    # tests will be cleaned.

    tempfile.tempdir = self.working_dir.name

    self.patch = mock.patch.dict(

        os.environ, {'ENABLE_ANDROID_EDIT_MONITOR': 'true'})

        os.environ, {'ENABLE_ANDROID_EDIT_MONITOR': 'true'}

    )

    self.patch.start()



  def tearDown(self):
@@ -102,6 +104,7 @@ class DaemonManagerTest(unittest.TestCase): 
    p = self._create_fake_deamon_process()



    self.assert_run_simple_daemon_success()

    self.assert_no_subprocess_running()



  def test_start_success_with_existing_instance_already_dead(self):

    # Create a pidfile with pid that does not exist.
@@ -137,7 +140,9 @@ class DaemonManagerTest(unittest.TestCase): 
    # Verify no daemon process is started.

    self.assertIsNone(dm.daemon_process)



  @mock.patch.dict(os.environ, {'ENABLE_ANDROID_EDIT_MONITOR': 'false'}, clear=True)

  @mock.patch.dict(

      os.environ, {'ENABLE_ANDROID_EDIT_MONITOR': 'false'}, clear=True

  )

  def test_start_return_directly_if_disabled(self):

    dm = daemon_manager.DaemonManager(TEST_BINARY_FILE)

    dm.start()
@@ -154,6 +159,25 @@ class DaemonManagerTest(unittest.TestCase): 
    # Verify no daemon process is started.

    self.assertIsNone(dm.daemon_process)



  def test_start_failed_other_instance_is_starting(self):

    f = open(

        pathlib.Path(self.working_dir.name).joinpath(

            TEST_PID_FILE_PATH + '.setup'

        ),

        'w',

    )

    # Acquire an exclusive lock

    fcntl.flock(f, fcntl.LOCK_EX | fcntl.LOCK_NB)



    dm = daemon_manager.DaemonManager(TEST_BINARY_FILE)

    dm.start()



    # Release the lock

    fcntl.flock(f, fcntl.LOCK_UN)

    f.close()

    # Verify no daemon process is started.

    self.assertIsNone(dm.daemon_process)



  @mock.patch('os.kill')

  def test_start_failed_to_kill_existing_instance(self, mock_kill):

    mock_kill.side_effect = OSError('Unknown OSError')
@@ -177,6 +201,7 @@ class DaemonManagerTest(unittest.TestCase): 
        'edit_monitor'

    )

    pid_file_path_dir.mkdir(parents=True, exist_ok=True)



    # Makes the directory read-only so write pidfile will fail.

    os.chmod(pid_file_path_dir, 0o555)
@@ -452,7 +477,7 @@ class DaemonManagerTest(unittest.TestCase): 
        pass



  def _create_fake_deamon_process(

      self, name: str = ''

      self, name: str = TEST_PID_FILE_PATH

  ) -> multiprocessing.Process:

    # Create a long running subprocess

    p = multiprocessing.Process(target=long_running_daemon)
@@ -463,7 +488,7 @@ class DaemonManagerTest(unittest.TestCase): 
        'edit_monitor'

    )

    pid_file_path_dir.mkdir(parents=True, exist_ok=True)

    with open(pid_file_path_dir.joinpath(name + 'pid.lock'), 'w') as f:

    with open(pid_file_path_dir.joinpath(name), 'w') as f:

      f.write(str(p.pid))

    return p