Revert "Revert "Implement std::condition_variable via pthread_cond_clockwait() where available""

With the fix for non-Linux.

This reverts commit c1c519d2f1a66dd2eeaa4c321d8d7b50f623eb71.

llvm-svn: 372242

2 files changed, 138 insertions, 17 deletions

diff --git a/libcxx/include/__config b/libcxx/include/__config
index 0a5e8e5ddf4..ee7351e9313 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -1087,6 +1087,16 @@ _LIBCPP_FUNC_VIS extern "C" void __sanitizer_annotate_contiguous_container(
 #  endif // _LIBCPP_HAS_THREAD_API
 #endif // _LIBCPP_HAS_NO_THREADS
 
+#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
+#if defined(__ANDROID__) && __ANDROID_API__ >= 30
+#define _LIBCPP_HAS_COND_CLOCKWAIT
+#elif defined(_LIBCPP_GLIBC_PREREQ)
+#if _LIBCPP_GLIBC_PREREQ(2, 30)
+#define _LIBCPP_HAS_COND_CLOCKWAIT
+#endif
+#endif
+#endif
+
 #if defined(_LIBCPP_HAS_NO_THREADS) && defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
 #error _LIBCPP_HAS_THREAD_API_PTHREAD may only be defined when \
        _LIBCPP_HAS_NO_THREADS is not defined.
diff --git a/libcxx/include/__mutex_base b/libcxx/include/__mutex_base
index a85ded8341e..a4ac36161cb 100644
--- a/libcxx/include/__mutex_base
+++ b/libcxx/include/__mutex_base
@@ -15,6 +15,7 @@
 #include <system_error>
 #include <__threading_support>
 
+#include <time.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
@@ -337,23 +338,75 @@ public:
 private:
     void __do_timed_wait(unique_lock<mutex>& __lk,
        chrono::time_point<chrono::system_clock, chrono::nanoseconds>) _NOEXCEPT;
+#if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
+    void __do_timed_wait(unique_lock<mutex>& __lk,
+       chrono::time_point<chrono::steady_clock, chrono::nanoseconds>) _NOEXCEPT;
+#endif
+    template <class _Clock>
+    void __do_timed_wait(unique_lock<mutex>& __lk,
+       chrono::time_point<_Clock, chrono::nanoseconds>) _NOEXCEPT;
 };
 #endif // !_LIBCPP_HAS_NO_THREADS
 
-template <class _To, class _Rep, class _Period>
+template <class _Rep, class _Period>
 inline _LIBCPP_INLINE_VISIBILITY
 typename enable_if
 <
-    chrono::__is_duration<_To>::value,
-    _To
+    is_floating_point<_Rep>::value,
+    chrono::nanoseconds
 >::type
-__ceil(chrono::duration<_Rep, _Period> __d)
+__safe_nanosecond_cast(chrono::duration<_Rep, _Period> __d)
 {
     using namespace chrono;
-    _To __r = duration_cast<_To>(__d);
-    if (__r < __d)
-        ++__r;
-    return __r;
+    using __ratio = ratio_divide<_Period, nano>;
+    using __ns_rep = nanoseconds::rep;
+    _Rep __result_float = __d.count() * __ratio::num / __ratio::den;
+
+    _Rep __result_max = numeric_limits<__ns_rep>::max();
+    if (__result_float >= __result_max) {
+        return nanoseconds::max();
+    }
+
+    _Rep __result_min = numeric_limits<__ns_rep>::min();
+    if (__result_float <= __result_min) {
+        return nanoseconds::min();
+    }
+
+    return nanoseconds(static_cast<__ns_rep>(__result_float));
+}
+
+template <class _Rep, class _Period>
+inline _LIBCPP_INLINE_VISIBILITY
+typename enable_if
+<
+    !is_floating_point<_Rep>::value,
+    chrono::nanoseconds
+>::type
+__safe_nanosecond_cast(chrono::duration<_Rep, _Period> __d)
+{
+    using namespace chrono;
+    if (__d.count() == 0) {
+        return nanoseconds(0);
+    }
+
+    using __ratio = ratio_divide<_Period, nano>;
+    using __ns_rep = nanoseconds::rep;
+    __ns_rep __result_max = std::numeric_limits<__ns_rep>::max();
+    if (__d.count() > 0 && __d.count() > __result_max / __ratio::num) {
+        return nanoseconds::max();
+    }
+
+    __ns_rep __result_min = std::numeric_limits<__ns_rep>::min();
+    if (__d.count() < 0 && __d.count() < __result_min / __ratio::num) {
+        return nanoseconds::min();
+    }
+
+    __ns_rep __result = __d.count() * __ratio::num / __ratio::den;
+    if (__result == 0) {
+        return nanoseconds(1);
+    }
+
+    return nanoseconds(__result);
 }
 
 #ifndef _LIBCPP_HAS_NO_THREADS
@@ -371,7 +424,15 @@ condition_variable::wait_until(unique_lock<mutex>& __lk,
                                const chrono::time_point<_Clock, _Duration>& __t)
 {
     using namespace chrono;
-    wait_for(__lk, __t - _Clock::now());
+    using __clock_tp_ns = time_point<_Clock, nanoseconds>;
+
+    typename _Clock::time_point __now = _Clock::now();
+    if (__t <= __now)
+        return cv_status::timeout;
+
+    __clock_tp_ns __t_ns = __clock_tp_ns(__safe_nanosecond_cast(__t.time_since_epoch()));
+
+    __do_timed_wait(__lk, __t_ns);
     return _Clock::now() < __t ? cv_status::no_timeout : cv_status::timeout;
 }
 
@@ -397,15 +458,25 @@ condition_variable::wait_for(unique_lock<mutex>& __lk,
     using namespace chrono;
     if (__d <= __d.zero())
         return cv_status::timeout;
-    typedef time_point<system_clock, duration<long double, nano> > __sys_tpf;
-    typedef time_point<system_clock, nanoseconds> __sys_tpi;
-    __sys_tpf _Max = __sys_tpi::max();
+    using __ns_rep = nanoseconds::rep;
     steady_clock::time_point __c_now = steady_clock::now();
-    system_clock::time_point __s_now = system_clock::now();
-    if (_Max - __d > __s_now)
-        __do_timed_wait(__lk, __s_now + __ceil<nanoseconds>(__d));
-    else
-        __do_timed_wait(__lk, __sys_tpi::max());
+
+#if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
+    using __clock_tp_ns = time_point<steady_clock, nanoseconds>;
+    __ns_rep __now_count_ns = __safe_nanosecond_cast(__c_now.time_since_epoch()).count();
+#else
+    using __clock_tp_ns = time_point<system_clock, nanoseconds>;
+    __ns_rep __now_count_ns = __safe_nanosecond_cast(system_clock::now().time_since_epoch()).count();
+#endif
+
+    __ns_rep __d_ns_count = __safe_nanosecond_cast(__d).count();
+
+    if (__now_count_ns > numeric_limits<__ns_rep>::max() - __d_ns_count) {
+        __do_timed_wait(__lk, __clock_tp_ns::max());
+    } else {
+        __do_timed_wait(__lk, __clock_tp_ns(nanoseconds(__now_count_ns + __d_ns_count)));
+    }
+
     return steady_clock::now() - __c_now < __d ? cv_status::no_timeout :
                                                  cv_status::timeout;
 }
@@ -421,6 +492,46 @@ condition_variable::wait_for(unique_lock<mutex>& __lk,
                       _VSTD::move(__pred));
 }
 
+#if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
+inline
+void
+condition_variable::__do_timed_wait(unique_lock<mutex>& __lk,
+     chrono::time_point<chrono::steady_clock, chrono::nanoseconds> __tp) _NOEXCEPT
+{
+    using namespace chrono;
+    if (!__lk.owns_lock())
+        __throw_system_error(EPERM,
+                            "condition_variable::timed wait: mutex not locked");
+    nanoseconds __d = __tp.time_since_epoch();
+    timespec __ts;
+    seconds __s = duration_cast<seconds>(__d);
+    using __ts_sec = decltype(__ts.tv_sec);
+    const __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 = (__d - __s).count();
+    }
+    else
+    {
+        __ts.tv_sec = __ts_sec_max;
+        __ts.tv_nsec = giga::num - 1;
+    }
+    int __ec = pthread_cond_clockwait(&__cv_, __lk.mutex()->native_handle(), CLOCK_MONOTONIC, &__ts);
+    if (__ec != 0 && __ec != ETIMEDOUT)
+        __throw_system_error(__ec, "condition_variable timed_wait failed");
+}
+#endif // _LIBCPP_HAS_COND_CLOCKWAIT
+
+template <class _Clock>
+inline
+void
+condition_variable::__do_timed_wait(unique_lock<mutex>& __lk,
+     chrono::time_point<_Clock, chrono::nanoseconds> __tp) _NOEXCEPT
+{
+    wait_for(__lk, __tp - _Clock::now());
+}
+
 #endif // !_LIBCPP_HAS_NO_THREADS
 
 _LIBCPP_END_NAMESPACE_STD