Package ganeti :: Package utils :: Module mlock
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Source Code for Module ganeti.utils.mlock

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 2  # 
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29   
30  """Wrapper around mlockall(2). 
31   
32  """ 
33   
34  import os 
35  import logging 
36   
37  from ganeti import errors 
38   
39  try: 
40    # pylint: disable=F0401 
41    import ctypes 
42  except ImportError: 
43    ctypes = None 
44   
45   
46  # Flags for mlockall(2) (from bits/mman.h) 
47  _MCL_CURRENT = 1 
48  _MCL_FUTURE = 2 
49   
50   
51 -def Mlockall(_ctypes=ctypes):
52 """Lock current process' virtual address space into RAM. 53 54 This is equivalent to the C call C{mlockall(MCL_CURRENT | MCL_FUTURE)}. See 55 mlockall(2) for more details. This function requires the C{ctypes} module. 56 57 @raises errors.NoCtypesError: If the C{ctypes} module is not found 58 59 """ 60 if _ctypes is None: 61 raise errors.NoCtypesError() 62 63 try: 64 libc = _ctypes.cdll.LoadLibrary("libc.so.6") 65 except EnvironmentError, err: 66 logging.error("Failure trying to load libc: %s", err) 67 libc = None 68 if libc is None: 69 logging.error("Cannot set memory lock, ctypes cannot load libc") 70 return 71 72 # The ctypes module before Python 2.6 does not have built-in functionality to 73 # access the global errno global (which, depending on the libc and build 74 # options, is per thread), where function error codes are stored. Use GNU 75 # libc's way to retrieve errno(3) instead, which is to use the pointer named 76 # "__errno_location" (see errno.h and bits/errno.h). 77 # pylint: disable=W0212 78 libc.__errno_location.restype = _ctypes.POINTER(_ctypes.c_int) 79 80 if libc.mlockall(_MCL_CURRENT | _MCL_FUTURE): 81 # pylint: disable=W0212 82 logging.error("Cannot set memory lock: %s", 83 os.strerror(libc.__errno_location().contents.value)) 84 return 85 86 logging.debug("Memory lock set")
87