# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import logging, os

from autotest_lib.client.cros import cros_ui_test
from autotest_lib.client.common_lib import error

CGROUP_DIR = '/sys/fs/cgroup/cpu/chrome_renderers'
FG_CGROUP_DIR = os.path.join(CGROUP_DIR, 'foreground')
BG_CGROUP_DIR = os.path.join(CGROUP_DIR, 'background')

class platform_ChromeCgroups(cros_ui_test.UITest):
    version = 1

    def _get_cgroup_tasks(self, cgroup_dir):
        """
        Returns the set of tasks in a cgroup.

        @param cgroup_dir Directory containing the cgroup.
        """
        task_path = os.path.join(cgroup_dir, 'tasks')
        task_file = open(task_path)
        if not task_file:
            raise error.TestError('failed to open %s' % task_path)
        tasks = set(line.rstrip() for line in task_file.readlines())
        task_file.close()
        logging.info('tasks in cgroup %s: %s' % (cgroup_dir, ','.join(tasks)))
        return tasks

    def run_once(self):
        """
        Check that the chrome_renderers cgroups are created and that tasks
        are placed in them.
        """
        # Make sure the cgroup directories actually exist.
        if not os.path.isdir(CGROUP_DIR):
            raise error.TestFail('chrome_renderers cgroup does not exist')
        if not os.path.isdir(FG_CGROUP_DIR):
            raise error.TestFail('foreground cgroup does not exist')
        if not os.path.isdir(BG_CGROUP_DIR):
            raise error.TestFail('background cgroup does not exist')

        # Open up two tabs in the same window. One should be in the foreground
        # while the other is in the background.
        self.pyauto.NavigateToURL('http://www.google.com')
        self.pyauto.AppendTab('http://www.youtube.com')

        # Make sure the foreground and background cgroups are non-empty.
        if not self._get_cgroup_tasks(FG_CGROUP_DIR):
            raise error.TestFail('no tasks in foreground cgroup')
        if not self._get_cgroup_tasks(BG_CGROUP_DIR):
            raise error.TestFail('no tasks in background cgroup')