On Mon, Oct 3, 2016 at 9:27 PM, Michael Felt <mich...@felt.demon.nl> wrote:
>
> int perfstat_subsystem_total(
> perfstat_id_t *name,
> perfstat_subsystem_total_t *userbuff,
> int sizeof_struct,
> int desired_number);
> ...
> +79 class cpu_total:
> +80 def __init__(self):
> +81 __perfstat__ = CDLL("libperfstat.a(shr_64.o)")
Move loading the library and defining function prototypes to either
the module or class body. Also, don't use dunder names. The convention
for a private attribute is a single underscore. For type safety,
define each function's argtypes (and restype where required, the
default is c_int). For a more Pythonic interface, define a ctypes
errcheck function that encapsulates raising an appropriate exception
when a C call fails. For example:
import ctypes
# If the following types are used generally, define them at
# the module level, else define them in the class namespace
# that uses them.
perfstat = ctypes.CDLL("libperfstat.a(shr_64.o)")
class perfstat_id_t(ctypes.Structure):
pass
IDENTIFIER_LENGTH = 64
class time64_t(ctypes._SimpleCData):
_type_ = ctypes.c_int64._type_
time_t = time64_t
class perfstat_cpu_total_t(ctypes.Structure):
_fields_ = (("ncpus", ctypes.c_int),
("ncpus_cfg", ctypes.c_int),
("description", ctypes.c_char * IDENTIFIER_LENGTH),
("buffer1", ctypes.c_ulonglong * 15),
("lbolt", time_t),
("loadavg", ctypes.c_ulonglong * 3),
("buffer2", ctypes.c_ulonglong * 29),
("ncpus_high", ctypes.c_int),
("puser", ctypes.c_ulonglong),
("psys", ctypes.c_ulonglong),
("pidle", ctypes.c_ulonglong),
("pwait", ctypes.c_ulonglong),
("buffer3", ctypes.c_ulonglong * 12))
def _perfstat_errcheck(result, func, args):
if result == -1:
# get error info and
raise SomeException()
return args
class CPUTotal(object):
# These may be defined here or just referenced here.
_perfstat = perfstat
_perfstat_id_t = perfstat_id_t
_perfstat_cpu_total_t = perfstat_cpu_total_t
_cpu_total = _perfstat.perfstat_cpu_total
_cpu_total.errcheck = _perfstat_errcheck
_cpu_total.argtypes = (
ctypes.POINTER(_perfstat_id_t),
ctypes.POINTER(_perfstat_cpu_total_t),
ctypes.c_int, ctypes.c_int)
def __init__(self):
self._tcpu = self._perfstat_cpu_total_t()
self._cpu_total(None,
ctypes.byref(self._tcpu),
ctypes.sizeof(self._tcpu), 1)
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