pakfire/patches/0005-builder-Use-cgroups-if-the-system-supports-it.patch

   1 From 904c8f1136b683a90a08cd4cf671a26f24e45f03 Mon Sep 17 00:00:00 2001
   2 From: Michael Tremer <michael.tremer@ipfire.org>
   3 Date: Fri, 8 Mar 2013 16:08:16 +0100
   4 Subject: [PATCH 05/19] builder: Use cgroups if the system supports it.
   5
   6 A systemd-based system is required right now.
   7 ---
   8  python/pakfire/builder.py | 12 ++++++--
   9  python/pakfire/cgroup.py  | 73 ++++++++++++++++++++++++++++-------------------
  10  2 files changed, 52 insertions(+), 33 deletions(-)
  11
  12 diff --git a/python/pakfire/builder.py b/python/pakfire/builder.py
  13 index 5cb00aa..7427a8c 100644
  14 --- a/python/pakfire/builder.py
  15 +++ b/python/pakfire/builder.py
  16 @@ -309,10 +309,16 @@ class BuildEnviron(object):
  17                         self.cgroup = None
  18                         return
  19
  20 -               self.cgroup = cgroup.CGroup("pakfire/builder/%s" % self.build_id)
  21 +               # Search for the cgroup this process is currently running in.
  22 +               parent_cgroup = cgroup.find_by_pid(os.getpid())
  23 +               if not parent_cgroup:
  24 +                       return
  25 +
  26 +               # Create our own cgroup inside the parent cgroup.
  27 +               self.cgroup = parent_cgroup.create_child_cgroup("pakfire/builder/%s" % self.build_id)
  28
  29 -               # Attach the pakfire-builder process to the parent group.
  30 -               self.cgroup.parent.attach()
  31 +               # Attach the pakfire-builder process to the group.
  32 +               self.cgroup.attach()
  33
  34         def init_logging(self, logfile):
  35                 if logfile:
  36 diff --git a/python/pakfire/cgroup.py b/python/pakfire/cgroup.py
  37 index f372a6c..6c85937 100644
  38 --- a/python/pakfire/cgroup.py
  39 +++ b/python/pakfire/cgroup.py
  40 @@ -8,40 +8,14 @@ import time
  41  import logging
  42  log = logging.getLogger("pakfire.cgroups")
  43
  44 -CGROUP_PATH_CANDIDATES = (
  45 -       "/sys/fs/cgroup",
  46 -)
  47 -
  48 -def find_cgroup_path():
  49 -       """
  50 -               This function tries to find the right place
  51 -               where to put the cgroups.
  52 -       """
  53 -       for path in CGROUP_PATH_CANDIDATES:
  54 -               check_path = os.path.join(path, "tasks")
  55 -               if not os.path.exists(check_path):
  56 -                       continue
  57 -
  58 -               return path
  59 -
  60 -CGROUP_PATH = find_cgroup_path()
  61 -
  62 -def supported():
  63 -       """
  64 -               Returns True or False depending on
  65 -               whether cgroups are supported or not.
  66 -       """
  67 -       if CGROUP_PATH is None:
  68 -               return False
  69 -
  70 -       return True
  71 +CGROUP_MOUNTPOINT = "/sys/fs/cgroup/systemd"
  72
  73  class CGroup(object):
  74         def __init__(self, name):
  75                 assert supported(), "cgroups are not supported by this kernel"
  76
  77                 self.name = name
  78 -               self.path = os.path.join(CGROUP_PATH, name)
  79 +               self.path = os.path.join(CGROUP_MOUNTPOINT, name)
  80                 self.path = os.path.abspath(self.path)
  81
  82                 # The parent cgroup.
  83 @@ -58,6 +32,31 @@ class CGroup(object):
  84         def __cmp__(self, other):
  85                 return cmp(self.path, other.path)
  86
  87 +       @classmethod
  88 +       def find_by_pid(cls, pid):
  89 +               """
  90 +                       Returns the cgroup of the process with the given PID.
  91 +
  92 +                       If no cgroup can be found, None is returned.
  93 +               """
  94 +               if not cls.supported:
  95 +                       return
  96 +
  97 +               for d, subdirs, files in os.walk(CGROUP_MOUNTPOINT):
  98 +                       if not "tasks" in files:
  99 +                               continue
 100 +
 101 +                       cgroup = cls(d)
 102 +                       if pid in cgroup.tasks:
 103 +                               return cgroup
 104 +
 105 +       @staticmethod
 106 +       def supported():
 107 +               """
 108 +                       Returns true, if this hosts supports cgroups.
 109 +               """
 110 +               return os.path.ismount(CGROUP_MOUNTPOINT)
 111 +
 112         def create(self):
 113                 """
 114                         Creates the filesystem structure for
 115 @@ -69,6 +68,13 @@ class CGroup(object):
 116                 log.debug("cgroup '%s' has been created." % self.name)
 117                 os.makedirs(self.path)
 118
 119 +       def create_child_cgroup(self, name):
 120 +               """
 121 +                       Create a child cgroup with name relative to the
 122 +                       parent cgroup.
 123 +               """
 124 +               return self.__class__(os.path.join(self.name, name))
 125 +
 126         def attach(self):
 127                 """
 128                         Attaches this task to the cgroup.
 129 @@ -152,8 +158,8 @@ class CGroup(object):
 130
 131         @property
 132         def parent(self):
 133 -               # Cannot go above CGROUP_PATH.
 134 -               if self.path == CGROUP_PATH:
 135 +               # Cannot go above CGROUP_MOUNTPOINT.
 136 +               if self.path == CGROUP_MOUNTPOINT:
 137                         return
 138
 139                 if self._parent is None:
 140 @@ -317,3 +323,10 @@ class CGroup(object):
 141                         time.sleep(0.2)
 142
 143                 return self.is_empty()
 144 +
 145 +
 146 +# Alias for simple access to check if this host supports cgroups.
 147 +supported = CGroup.supported
 148 +
 149 +# Alias for simple access to find the cgroup of a certain process.
 150 +find_by_pid = CGroup.find_by_pid
 151 --
 152 1.8.1.4
 153