Kristján Valur Jónsson added the comment:
Hi there.
When I said "4000", that was because of the conversion to microseconds which
happens early on.
I'm not trying to be difficult here Tim, it's just that you've pointed out a
problem and I'd like us to have a comprehensive fix.
"unsigned long", I realized, is also not super, because on unix that can be
either 32 or 64 bits :)
The reason 24 hour waits work on 2.7 is that the conversion to microseconds is
never done, rather it uses a DWORD of milliseconds. I agree that this is a
regression that needs fixing. Even if there is a theroetical maximum, it
should be higher than that :)
My latest suggestion? Let's just go ahead and use a "double" for the argument
in PyCOND_TIMEDWAIT().
We then have two conversion cases:
1) to a DWORD of milliseconds for both windows apis. Here we should truncate
to the max size of a DWORD
2) to the timeval used on pthreads.
for 1, that can be done like:
if (ds*1e3 > (double)DWORD_MAX)
ms = DWORD_MAX;
else
ms = (DWORD)(ds*1e3)
for 2, modifying the PyCOND_ADD_MICROSECONDS macro into something like:
#define PyCOND_ADD_MICROSECONDS(tv, ds)
do {
long oldsec, sec, usec;
assert(ds >= 0.0);
// truncate ds into theoretical maximum
if (ds > (double)long_max)
ds = (double)long_max; // whatever that may be
sec = (long)ds;
usec = (long)((ds - (double)sec) * 1e6))
oldsec = tv.tv_sec;
tv.tv_usec += usec;
tv.tv_sec += sec;
if (usec >= 1000000) {
tv.tv_usec -= 1000000;
tv.tv_sec += 1;
}
if (tv.tv_sec < oldsec)
/* detect overflow */
tv.sec = max_long;
I'm not super experienced with integer arithmetic like this or the pitfalls of
overflow, so this might need some pondering. Perhaps it is better to do the
tv_sec and tv_usec arithmetic in doubles before converting them back.
Does this sound ok?
Let me see if I can cook up an alternative patch.
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<http://bugs.python.org/issue20737>
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