an error in python lib?
MRAB
python at mrabarnett.plus.com
Tue Oct 9 21:16:46 EDT 2012
On 2012-10-10 01:32, Wenhua Zhao wrote:
> Hi list,
>
> I just noticed that in /usr/lib/python2.7/threading.py
>
> class _Condition(_Verbose):
> ...
> def _is_owned(self):
> # Return True if lock is owned by current_thread.
> # This method is called only if __lock doesn't have
> _is_owned().
> if self.__lock.acquire(0):
> self.__lock.release()
> return False
> else:
> return True
>
> The return values seem to be wrong. They should be swapped:
>
> def _is_owned(self):
> if self.__lock.acquire(0):
> self.__lock.release()
> return True
> else:
> return False
>
> Or I understood it wrong here?
>
The .acquire method will return True if the attempt to acquire has been
successful. This can occur only if it is not currently owned.
In pseudocode:
if the attempt to acquire it succeeds:
no-one owed it before, but now I own it
release it
now no-one owns it
return False
else:
someone already owns it
return True
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