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Change sleep_for, sleep_until, and the condition_variable timed wait

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functions to protect against duration and time_point overflow.  Since
we're about to wait anyway, we can afford to spend a few more cycles on
this checking.  I purposefully did not treat the timed try_locks with
overflow checking.  This fixes
http://llvm.org/bugs/show_bug.cgi?id=13721 .  I'm unsure if the standard
needs clarification in this area, or if this is simply QOI.  The
<chrono> facilities were never intended to overflow check, but just to
not overflow if durations stayed within +/- 292 years.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@162925 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Howard Hinnant
2012-08-30 19:14:33 +00:00
parent c417a802ed
commit cf115d2cc6
4 changed files with 53 additions and 31 deletions
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16
src/condition_variable.cpp
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@@ -51,10 +51,22 @@ condition_variable::__do_timed_wait(unique_lock<mutex>& lk,
__throw_system_error(EPERM,
"condition_variable::timed wait: mutex not locked");
nanoseconds d = tp.time_since_epoch();
if (d > nanoseconds(0x59682F000000E941))
d = nanoseconds(0x59682F000000E941);
timespec ts;
seconds s = duration_cast<seconds>(d);
ts.tv_sec = static_cast<decltype(ts.tv_sec)>(s.count());
ts.tv_nsec = static_cast<decltype(ts.tv_nsec)>((d - s).count());
typedef decltype(ts.tv_sec) ts_sec;
_LIBCPP_CONSTEXPR ts_sec ts_sec_max = numeric_limits<ts_sec>::max();
if (s.count() < ts_sec_max)
{
ts.tv_sec = static_cast<ts_sec>(s.count());
ts.tv_nsec = static_cast<decltype(ts.tv_nsec)>((d - s).count());
}
else
{
ts.tv_sec = ts_sec_max;
ts.tv_nsec = giga::num - 1;
}
int ec = pthread_cond_timedwait(&__cv_, lk.mutex()->native_handle(), &ts);
if (ec != 0 && ec != ETIMEDOUT)
__throw_system_error(ec, "condition_variable timed_wait failed");