# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style license that can be
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# found in the LICENSE file.
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import common, logging, os, time
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from autotest_lib.client.common_lib import error
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from autotest_lib.client.common_lib import utils
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from autotest_lib.client.cros import constants
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# Log messages used to signal when we're restarting UI. Used to detect
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# crashes by cros_ui_test.UITest.
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UI_RESTART_ATTEMPT_MSG = 'cros_ui.py: Attempting StopSession...'
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UI_RESTART_COMPLETE_MSG = 'cros_ui.py: StopSession complete.'
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RESTART_UI_TIMEOUT = 90 # longer because we may be crash dumping now.
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def get_chrome_session_ident(host=None):
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"""Return an identifier that changes whenever Chrome restarts.
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This function returns a value that is unique to the most
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recently started Chrome process; the returned value changes
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each time Chrome restarts and displays the login screen. The
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change in the value can be used to detect a successful Chrome
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restart.
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Note that uniqueness is only guaranteed until the host reboots.
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Args:
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host: If not None, a host object on which to test Chrome
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state, rather than running commands on the local host.
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"""
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if host:
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return host.run(constants.LOGIN_PROMPT_STATUS_COMMAND).stdout
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return utils.run(constants.LOGIN_PROMPT_STATUS_COMMAND).stdout
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def wait_for_chrome_ready(old_session, host=None,
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timeout=RESTART_UI_TIMEOUT):
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"""Wait until a new Chrome login prompt is on screen and ready.
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The standard formula to check whether the prompt has appeared yet
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is with a pattern like the following:
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session = get_chrome_session_ident()
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logout()
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wait_for_chrome_ready(session)
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Args:
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old_session: identifier for the login prompt prior to
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restarting Chrome.
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host: If not None, a host object on which to test Chrome
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state, rather than running commands on the local host.
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timeout: float number of seconds to wait
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Raises:
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TimeoutError: Login prompt didn't get up before timeout
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"""
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utils.poll_for_condition(
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condition=lambda: old_session != get_chrome_session_ident(host),
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exception=utils.TimeoutError('Timed out waiting for login prompt'),
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timeout=timeout, sleep_interval=1.0)
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def stop_and_wait_for_chrome_to_exit(timeout_secs=40):
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"""Stops the UI and waits for chrome to exit.
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Stops the UI and waits for all chrome processes to exit or until
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timeout_secs is reached.
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Args:
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timeout_secs: float number of seconds to wait.
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Returns:
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True upon successfully stopping the UI and all chrome processes exiting.
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False otherwise.
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"""
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status = stop(allow_fail=True)
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if status:
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logging.error('stop ui returned non-zero status: %s', status)
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return False
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start_time = time.time()
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while time.time() - start_time < timeout_secs:
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status = utils.system('pgrep chrome', ignore_status=True)
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if status == 1: return True
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time.sleep(1)
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logging.error('stop ui failed to stop chrome within %s seconds',
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timeout_secs)
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return False
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def stop(allow_fail=False):
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return utils.stop_service("ui", ignore_status=allow_fail)
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def start(allow_fail=False, wait_for_login_prompt=True):
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"""Start the login manager and wait for the prompt to show up."""
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session = get_chrome_session_ident()
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result = utils.start_service("ui", ignore_status=allow_fail)
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# If allow_fail is set, the caller might be calling us when the UI job
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# is already running. In that case, the above command fails.
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if result == 0 and wait_for_login_prompt:
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wait_for_chrome_ready(session)
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return result
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def restart(report_stop_failure=False):
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"""Restart the session manager.
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- If the user is logged in, the session will be terminated.
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- If the UI is currently down, just go ahead and bring it up unless the
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caller has requested that a failure to stop be reported.
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- To ensure all processes are up and ready, this function will wait
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for the login prompt to show up and be marked as visible.
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@param report_stop_failure: False by default, set to True if you care about
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the UI being up at the time of call and
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successfully torn down by this call.
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"""
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session = get_chrome_session_ident()
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# Log what we're about to do to /var/log/messages. Used to log crashes later
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# in cleanup by cros_ui_test.UITest.
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utils.system('logger "%s"' % UI_RESTART_ATTEMPT_MSG)
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try:
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if stop(allow_fail=not report_stop_failure) != 0:
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raise error.TestError('Could not stop session')
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start(wait_for_login_prompt=False)
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# Wait for login prompt to appear to indicate that all processes are
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# up and running again.
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wait_for_chrome_ready(session)
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finally:
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utils.system('logger "%s"' % UI_RESTART_COMPLETE_MSG)
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def nuke():
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"""Nuke the login manager, waiting for it to restart."""
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restart(lambda: utils.nuke_process_by_name(constants.SESSION_MANAGER))
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def is_up():
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"""Return True if the UI is up, False if not."""
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return utils.get_service_pid('ui')!=0
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def clear_respawn_state():
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"""Removes bookkeeping related to respawning crashed UI."""
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for filename in [constants.UI_RESPAWN_TIMESTAMPS_FILE,
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constants.UI_TOO_CRASHY_TIMESTAMPS_FILE]:
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try:
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os.unlink(filename)
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except OSError:
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pass # It's already gone.
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