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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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18
src/thread.cpp
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@@ -11,6 +11,7 @@
#include "exception"
#include "vector"
#include "future"
#include "limits"
#include <sys/types.h>
#if !_WIN32
#if !__sun__ && !__linux__
@@ -83,11 +84,22 @@ void
sleep_for(const chrono::nanoseconds& ns)
{
using namespace chrono;
if (ns >= nanoseconds::zero())
if (ns > nanoseconds::zero())
{
seconds s = duration_cast<seconds>(ns);
timespec ts;
ts.tv_sec = static_cast<decltype(ts.tv_sec)>(duration_cast<seconds>(ns).count());
ts.tv_nsec = static_cast<decltype(ts.tv_nsec)>((ns - seconds(ts.tv_sec)).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)>((ns-s).count());
}
else
{
ts.tv_sec = ts_sec_max;
ts.tv_nsec = giga::num - 1;
}
nanosleep(&ts, 0);
}
}