lib/cros_update_progress.py

# Copyright 2016 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.

"""A progress class for tracking CrOS auto-update process.

This class is mainly designed for:
  1. Set the pattern for generating the filenames of
     track_status_file/execute_log_file.
     track_status_file: Used for record the current step of CrOS auto-update
                        process. Only has one line.
     execute_log_file: Used for record the whole logging info of the CrOS
                       auto-update process, including any debug information.
  2. Write current auto-update process into the track_status_file.
  3. Read current auto-update process from the track_status_file.

This file also offers external functions that are related to add/check/delete
the progress of the CrOS auto-update process.
"""

import datetime
import glob
import os
import re

from chromite.lib.xbuddy import cherrypy_log_util


# Module-local log function.
def _Log(message, *args):
  return cherrypy_log_util.LogWithTag('CROS_UPDATE_PROGRESS', message, *args)

# Path for status tracking log.
_TRACK_LOG_FILE_PATH = '/tmp/auto-update/tracking_log/%s_%s.log'

# Pattern for status tracking log filename.
_TRACK_LOG_FILE_NAME_PATTERN = r'([^_]+)_([^_]+).log'

# The gap hour used in checking AU processes' count.
AU_PROCESS_HOUR_GAP = 3


def IsProcessAlive(pid):
  """Detect whether a process is alive.

  Args:
    pid: The process id.

  Returns:
    True if the process is still alive. False otherwise.
  """
  path = '/proc/%s/stat' % pid
  if not os.path.exists(path):
    return False

  with open(path, 'r') as fp:
    stat = fp.readline().rstrip('\n')

  return stat.split()[2] != 'Z'


def GetAllTrackStatusFileByTime():
  """Return all track status files existing in TRACK_LOG_FILE_PATH.

  Returns:
    A track status file list ordered by created time reversely.
  """
  return sorted(glob.glob(_TRACK_LOG_FILE_PATH % ('*', '*')),
                key=os.path.getctime, reverse=True)


def ParsePidFromTrackLogFileName(track_log_filename):
  """Parse pid from a given track log file's name.

  The track log file's name for auto-update is fixed:
      hostname_pid.log

  This func is used to parse pid from a given track log file.

  Args:
    track_log_filename: the filename of the track log to be parsed.

  Returns:
    the parsed pid (int).
  """
  match = re.match(_TRACK_LOG_FILE_NAME_PATTERN, track_log_filename)
  try:
    return int(match.groups()[1])
  except (AttributeError, IndexError, ValueError) as e:
    _Log('Cannot parse pid from track log file %s: %s', track_log_filename, e)
    return None


def GetAllRunningAUProcess():
  """Get all the ongoing AU processes' pids from tracking logs.

  This func only checks the tracking logs generated in latest several hours,
  which is for avoiding the case that 'there's a running process whose id is
  as the same as a previous AU process'.

  Returns:
    A list of background AU processes' pids.
  """
  pids = []
  now = datetime.datetime.now()
  track_log_list = GetAllTrackStatusFileByTime()
  # Only check log file created in 3 hours.
  for track_log in track_log_list:
    try:
      created_time = datetime.datetime.fromtimestamp(
          os.path.getctime(track_log))
      if now - created_time >= datetime.timedelta(hours=AU_PROCESS_HOUR_GAP):
        break

      pid = ParsePidFromTrackLogFileName(os.path.basename(track_log))
      if pid and IsProcessAlive(pid):
        pids.append(pid)
    except (ValueError, OSError) as e:
      _Log('Error happened in getting pid from %s: %s', track_log, e)

  return pids