Revision 5fe4a65b lib/utils/mlock.py

b/lib/utils/mlock.py
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  ctypes = None
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# Flags for mlockall() (from bits/mman.h)


  		





  
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# Flags for mlockall(2) (from bits/mman.h)


  		





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_MCL_CURRENT = 1


  		





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_MCL_FUTURE = 2


  		





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def Mlockall(_ctypes=ctypes):


  		





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  """Lock current process' virtual address space into RAM.


  		





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  This is equivalent to the C call mlockall(MCL_CURRENT|MCL_FUTURE),


  		





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  see mlock(2) for more details. This function requires ctypes module.


  		





  
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  This is equivalent to the C call C{mlockall(MCL_CURRENT | MCL_FUTURE)}. See


  		





  
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  mlockall(2) for more details. This function requires the C{ctypes} module.


  		





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  @raises errors.NoCtypesError: if ctypes module is not found


  		





  
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  @raises errors.NoCtypesError: If the C{ctypes} module is not found


  		





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  """


  		





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  if _ctypes is None:


  		





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    logging.error("Cannot set memory lock, ctypes cannot load libc")


  		





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    return


  		





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  # Some older version of the ctypes module don't have built-in functionality


  		





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  # to access the errno global variable, where function error codes are stored.


  		





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  # By declaring this variable as a pointer to an integer we can then access


  		





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  # its value correctly, should the mlockall call fail, in order to see what


  		





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  # the actual error code was.


  		





  
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  # The ctypes module before Python 2.6 does not have built-in functionality to


  		





  
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  # access the global errno global (which, depending on the libc and build


  		





  
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  # options, is per thread), where function error codes are stored. Use GNU


  		





  
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  # libc's way to retrieve errno(3) instead, which is to use the pointer named


  		





  
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  # "__errno_location" (see errno.h and bits/errno.h).


  		





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  # pylint: disable=W0212


  		





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  libc.__errno_location.restype = _ctypes.POINTER(_ctypes.c_int)


  		





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