text: #
  # Copyright (c) 2019, Neptune Labs Sp. z o.o.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  #
  
  import os
  import re
  
  
  class CGroupFilesystemReader(object):
      def __init__(self):
          cgroup_memory_dir = self.__cgroup_mount_dir(subsystem='memory')
          self.__memory_usage_file = os.path.join(cgroup_memory_dir, 'memory.usage_in_bytes')
          self.__memory_limit_file = os.path.join(cgroup_memory_dir, 'memory.limit_in_bytes')
  
          cgroup_cpu_dir = self.__cgroup_mount_dir(subsystem='cpu')
          self.__cpu_period_file = os.path.join(cgroup_cpu_dir, 'cpu.cfs_period_us')
          self.__cpu_quota_file = os.path.join(cgroup_cpu_dir, 'cpu.cfs_quota_us')
  
          cgroup_cpuacct_dir = self.__cgroup_mount_dir(subsystem='cpuacct')
          self.__cpuacct_usage_file = os.path.join(cgroup_cpuacct_dir, 'cpuacct.usage')
  
      def get_memory_usage_in_bytes(self):
          return self.__read_int_file(self.__memory_usage_file)
  
      def get_memory_limit_in_bytes(self):
          return self.__read_int_file(self.__memory_limit_file)
  
      def get_cpu_quota_micros(self):
          return self.__read_int_file(self.__cpu_quota_file)
  
      def get_cpu_period_micros(self):
          return self.__read_int_file(self.__cpu_period_file)
  
      def get_cpuacct_usage_nanos(self):
          return self.__read_int_file(self.__cpuacct_usage_file)
  
      def __read_int_file(self, filename):
          with open(filename) as f:
              return int(f.read())
  
      def __cgroup_mount_dir(self, subsystem):
          """
          :param subsystem: cgroup subsystem like memory, cpu
          :return: directory where given subsystem is mounted
          """
          with open('/proc/mounts', 'r') as f:
              for l in f.readlines():
                  split_line = re.split(r'\s+', l)
                  mount_dir = split_line[1]
  
                  if 'cgroup' in mount_dir:
                      dirname = mount_dir.split('/')[-1]
                      subsystems = dirname.split(',')
                      if subsystem in subsystems:
                          return mount_dir
  
          assert False, 'Mount directory for "{}" subsystem not found'.format(subsystem)
  