4 # Copyright (C) 2009, 2010, 2011 Google Inc.
6 # This program is free software; you can redistribute it and/or modify
7 # it under the terms of the GNU General Public License as published by
8 # the Free Software Foundation; either version 2 of the License, or
9 # (at your option) any later version.
11 # This program is distributed in the hope that it will be useful, but
12 # WITHOUT ANY WARRANTY; without even the implied warranty of
13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 # General Public License for more details.
16 # You should have received a copy of the GNU General Public License
17 # along with this program; if not, write to the Free Software
18 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 """Wrapper around mlockall(2).
28 from ganeti import errors
31 # pylint: disable=F0401
37 # Flags for mlockall(2) (from bits/mman.h)
42 def Mlockall(_ctypes=ctypes):
43 """Lock current process' virtual address space into RAM.
45 This is equivalent to the C call C{mlockall(MCL_CURRENT | MCL_FUTURE)}. See
46 mlockall(2) for more details. This function requires the C{ctypes} module.
48 @raises errors.NoCtypesError: If the C{ctypes} module is not found
52 raise errors.NoCtypesError()
55 libc = _ctypes.cdll.LoadLibrary("libc.so.6")
56 except EnvironmentError, err:
57 logging.error("Failure trying to load libc: %s", err)
60 logging.error("Cannot set memory lock, ctypes cannot load libc")
63 # The ctypes module before Python 2.6 does not have built-in functionality to
64 # access the global errno global (which, depending on the libc and build
65 # options, is per thread), where function error codes are stored. Use GNU
66 # libc's way to retrieve errno(3) instead, which is to use the pointer named
67 # "__errno_location" (see errno.h and bits/errno.h).
68 # pylint: disable=W0212
69 libc.__errno_location.restype = _ctypes.POINTER(_ctypes.c_int)
71 if libc.mlockall(_MCL_CURRENT | _MCL_FUTURE):
72 # pylint: disable=W0212
73 logging.error("Cannot set memory lock: %s",
74 os.strerror(libc.__errno_location().contents.value))
77 logging.debug("Memory lock set")