Lisandro Dalcin wrote:
> > It's a bit less efficient than what I proposed, as, when an error occurs:
> > - it restores the thread context before Pyx_CppExn2PyErr(),
> > - saves the thread context after Pyx_CppExn2PyErr(),
> > - restores it in the /*finally:*/ block.
> > whereas what I proposed only restores once the context (before
> > Pyx_CppExn2PyErr(), skipped in the
> > /*finally:*/ block).
>
> Indeed (but only when an error occurs)... However, I'm a bit confused:
> Is my added restore in the finally block actually necessary?
Yes, to re-acquire the GIL.
> Is you
> original implementation correct if you do not restore in the finally
> block?
You need to restore in case you reach this block through the normal flow (no
exceptions).
Note that you can restore at the end of the /*try:*/ block, instead of in the
/*finally:*/ block:
{ PyThreadState *_save;
Py_UNBLOCK_THREADS
/*try:*/ {
try {foo();} catch(...) {Py_BLOCK_THREADS __Pyx_CppExn2PyErr();
{__pyx_filename = __pyx_f[0]; __pyx_lineno = 6; __pyx_clineno = __LINE__; goto
__pyx_L6;}}
Py_BLOCK_THREADS
}
/*finally:*/ {
int __pyx_why;
__pyx_why = 0; goto __pyx_L7;
__pyx_L6: __pyx_why = 4; goto __pyx_L7;
__pyx_L7:;
switch (__pyx_why) {
case 4: goto __pyx_L1_error;
}
}
}
(it's exactly equivalent to my original proposal, but maybe cleaner that way...)
> >
> > But do we have to really care of performance when an error occurs?
> >
>
> I do not advocate using exceptions for control flow (though I do it in
> a few cases), so I do not care about performance in this case.
Fine.
Stephane
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