root / lib / utils / cfunc.py @ 6915fe26
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1 | 36a4acd4 | Michael Hanselmann | #
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2 | 36a4acd4 | Michael Hanselmann | #
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3 | 36a4acd4 | Michael Hanselmann | |
4 | 36a4acd4 | Michael Hanselmann | # Copyright (C) 2009, 2010, 2011 Google Inc.
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5 | 36a4acd4 | Michael Hanselmann | #
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6 | 36a4acd4 | Michael Hanselmann | # This program is free software; you can redistribute it and/or modify
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7 | 36a4acd4 | Michael Hanselmann | # it under the terms of the GNU General Public License as published by
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8 | 36a4acd4 | Michael Hanselmann | # the Free Software Foundation; either version 2 of the License, or
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9 | 36a4acd4 | Michael Hanselmann | # (at your option) any later version.
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10 | 36a4acd4 | Michael Hanselmann | #
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11 | 36a4acd4 | Michael Hanselmann | # This program is distributed in the hope that it will be useful, but
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12 | 36a4acd4 | Michael Hanselmann | # WITHOUT ANY WARRANTY; without even the implied warranty of
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13 | 36a4acd4 | Michael Hanselmann | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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14 | 36a4acd4 | Michael Hanselmann | # General Public License for more details.
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15 | 36a4acd4 | Michael Hanselmann | #
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16 | 36a4acd4 | Michael Hanselmann | # You should have received a copy of the GNU General Public License
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17 | 36a4acd4 | Michael Hanselmann | # along with this program; if not, write to the Free Software
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18 | 36a4acd4 | Michael Hanselmann | # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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19 | 36a4acd4 | Michael Hanselmann | # 02110-1301, USA.
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20 | 36a4acd4 | Michael Hanselmann | |
21 | 36a4acd4 | Michael Hanselmann | """Wrapper around mlockall(2).
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22 | 36a4acd4 | Michael Hanselmann |
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23 | 36a4acd4 | Michael Hanselmann | """
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24 | 36a4acd4 | Michael Hanselmann | |
25 | 36a4acd4 | Michael Hanselmann | import os |
26 | 36a4acd4 | Michael Hanselmann | import logging |
27 | 36a4acd4 | Michael Hanselmann | |
28 | 36a4acd4 | Michael Hanselmann | from ganeti import errors |
29 | 36a4acd4 | Michael Hanselmann | |
30 | 36a4acd4 | Michael Hanselmann | try:
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31 | b459a848 | Andrea Spadaccini | # pylint: disable=F0401
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32 | 36a4acd4 | Michael Hanselmann | import ctypes |
33 | 36a4acd4 | Michael Hanselmann | except ImportError: |
34 | 36a4acd4 | Michael Hanselmann | ctypes = None
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35 | 36a4acd4 | Michael Hanselmann | |
36 | 36a4acd4 | Michael Hanselmann | |
37 | 6915fe26 | Michael Hanselmann | # Flags for mlockall(2) (from bits/mman.h)
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38 | 36a4acd4 | Michael Hanselmann | _MCL_CURRENT = 1
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39 | 36a4acd4 | Michael Hanselmann | _MCL_FUTURE = 2
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40 | 36a4acd4 | Michael Hanselmann | |
41 | 36a4acd4 | Michael Hanselmann | |
42 | 6915fe26 | Michael Hanselmann | class _FuncWrapper: |
43 | 6915fe26 | Michael Hanselmann | def __init__(self, ct): |
44 | 6915fe26 | Michael Hanselmann | """Initializes this class.
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45 | 6915fe26 | Michael Hanselmann |
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46 | 6915fe26 | Michael Hanselmann | """
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47 | 6915fe26 | Michael Hanselmann | # Make use of a dlopen(3) feature whereby giving a NULL handle returns the
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48 | 6915fe26 | Michael Hanselmann | # main program. Functions from all previously loaded libraries can then be
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49 | 6915fe26 | Michael Hanselmann | # used.
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50 | 6915fe26 | Michael Hanselmann | mainprog = ct.CDLL(None)
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51 | 6915fe26 | Michael Hanselmann | |
52 | 6915fe26 | Michael Hanselmann | # The ctypes module before Python 2.6 does not have built-in functionality
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53 | 6915fe26 | Michael Hanselmann | # to access the global errno global (which, depending on the libc and build
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54 | 6915fe26 | Michael Hanselmann | # options, is per-thread), where function error codes are stored. Use GNU
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55 | 6915fe26 | Michael Hanselmann | # libc's way to retrieve errno(3) instead.
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56 | 6915fe26 | Michael Hanselmann | try:
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57 | 6915fe26 | Michael Hanselmann | errno_loc = getattr(mainprog, "__errno_location") |
58 | 6915fe26 | Michael Hanselmann | except AttributeError, err: |
59 | 6915fe26 | Michael Hanselmann | logging.debug("Unable to find errno location: %s", err)
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60 | 6915fe26 | Michael Hanselmann | errno_fn = None
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61 | 6915fe26 | Michael Hanselmann | else:
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62 | 6915fe26 | Michael Hanselmann | errno_loc.restype = ct.POINTER(ct.c_int) |
63 | 6915fe26 | Michael Hanselmann | errno_fn = lambda: errno_loc().contents.value
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64 | 6915fe26 | Michael Hanselmann | |
65 | 6915fe26 | Michael Hanselmann | self.errno_fn = errno_fn
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66 | 6915fe26 | Michael Hanselmann | |
67 | 6915fe26 | Michael Hanselmann | # Try to get mlockall(2)
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68 | 6915fe26 | Michael Hanselmann | self.mlockall_fn = getattr(mainprog, "mlockall", None) |
69 | 6915fe26 | Michael Hanselmann | |
70 | 6915fe26 | Michael Hanselmann | |
71 | 36a4acd4 | Michael Hanselmann | def Mlockall(_ctypes=ctypes): |
72 | 36a4acd4 | Michael Hanselmann | """Lock current process' virtual address space into RAM.
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73 | 36a4acd4 | Michael Hanselmann |
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74 | 6915fe26 | Michael Hanselmann | This is equivalent to the C call C{mlockall(MCL_CURRENT | MCL_FUTURE)}. See
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75 | 6915fe26 | Michael Hanselmann | mlockall(2) for more details. This function requires the C{ctypes} module.
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76 | 36a4acd4 | Michael Hanselmann |
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77 | 6915fe26 | Michael Hanselmann | @raises errors.NoCtypesError: If the C{ctypes} module is not found
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78 | 36a4acd4 | Michael Hanselmann |
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79 | 36a4acd4 | Michael Hanselmann | """
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80 | 36a4acd4 | Michael Hanselmann | if _ctypes is None: |
81 | 36a4acd4 | Michael Hanselmann | raise errors.NoCtypesError()
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82 | 36a4acd4 | Michael Hanselmann | |
83 | 6915fe26 | Michael Hanselmann | funcs = _FuncWrapper(_ctypes) |
84 | 6915fe26 | Michael Hanselmann | |
85 | 6915fe26 | Michael Hanselmann | if funcs.mlockall_fn is None: |
86 | 6915fe26 | Michael Hanselmann | logging.debug("libc doesn't support mlockall(2)")
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87 | 6915fe26 | Michael Hanselmann | else:
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88 | 6915fe26 | Michael Hanselmann | if funcs.mlockall_fn(_MCL_CURRENT | _MCL_FUTURE) == 0: |
89 | 6915fe26 | Michael Hanselmann | logging.debug("Memory lock set")
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90 | 6915fe26 | Michael Hanselmann | return True |
91 | 6915fe26 | Michael Hanselmann | |
92 | 6915fe26 | Michael Hanselmann | logging.error("Cannot set memory lock: %s", os.strerror(funcs.errno_fn()))
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93 | 6915fe26 | Michael Hanselmann | |
94 | 6915fe26 | Michael Hanselmann | return False |