关于 Python Ctypes 调用 C callback function

from ctypes import *
_CMPFUNC = CFUNCTYPE(c_bool,c_char_p)



def __callback_function(output):
    """
    :return:
    """
    print output
    return True


callback = _CMPFUNC(__callback_function)

c_api.callbackfunc(callback)

请问这里我用multiprocessor 或者 Threading ，或者 yield 协程会影响c的接口的回调吗？
那我应该如何设计简单的callback 返回，我用消息队列还是其他的方式，还是通知什么的？callback 是一个实时运行的程序，不断的接受数据流。

callback

ctypes

cmpfunc

2 replies • 2015-06-18 01:18:08 +08:00

R4rvZ6agNVWr56V0

Jun 18, 2015

极大的概率会发生access violation的。。。

Make sure you keep references to CFUNCTYPE() objects as long as they are used from C code. ctypes doesn’t, and if you don’t, they may be garbage collected, crashing your program when a callback is made.
Also, note that if the callback function is called in a thread created outside of Python’s control (e.g. by the foreign code that calls the callback), ctypes creates a new dummy Python thread on every invocation. This behavior is correct for most purposes, but it means that values stored with threading.local will not survive across different callbacks, even when those calls are made from the same C thread.

ref:https://docs.python.org/2/library/ctypes.html#callback-functions

R4rvZ6agNVWr56V0

Jun 18, 2015

看走眼了。。。只要保证callback对象不被GC，Threading应该没啥问题，因为Callback到Py代码时候调用了PyGILState_Ensure()