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7162fd750e
The <__threading_support> header is a huge beast and it's really difficult to navigate. I find myself struggling to find what I want every time I have to open it, and I've been considering splitting it up for years for that reason. This patch aims not to contain any functional change. The various implementations of the threading base are simply moved to separate headers and then the individual headers are simplified in mechanical ways. For example, we used to have redundant declarations of all the functions at the top of `__threading_support`, and those are removed since they are not needed anymore. The various #ifdefs are also simplified and removed when they become unnecessary. Finally, this patch adds documentation for the API we expect from any threading implementation.
245 lines
8.7 KiB
C++
245 lines
8.7 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___CONDITION_VARIABLE_CONDITION_VARIABLE_H
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#define _LIBCPP___CONDITION_VARIABLE_CONDITION_VARIABLE_H
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#include <__chrono/duration.h>
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#include <__chrono/steady_clock.h>
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#include <__chrono/system_clock.h>
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#include <__chrono/time_point.h>
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#include <__config>
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#include <__mutex/mutex.h>
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#include <__mutex/unique_lock.h>
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#include <__system_error/system_error.h>
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#include <__thread/support.h>
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#include <__type_traits/enable_if.h>
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#include <__type_traits/is_floating_point.h>
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#include <__utility/move.h>
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#include <limits>
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#include <ratio>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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_LIBCPP_PUSH_MACROS
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#include <__undef_macros>
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_LIBCPP_BEGIN_NAMESPACE_STD
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#ifndef _LIBCPP_HAS_NO_THREADS
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// enum class cv_status
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_LIBCPP_DECLARE_STRONG_ENUM(cv_status){no_timeout, timeout};
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_LIBCPP_DECLARE_STRONG_ENUM_EPILOG(cv_status)
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class _LIBCPP_EXPORTED_FROM_ABI condition_variable {
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__libcpp_condvar_t __cv_ = _LIBCPP_CONDVAR_INITIALIZER;
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public:
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_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR condition_variable() _NOEXCEPT = default;
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# ifdef _LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION
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~condition_variable() = default;
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# else
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~condition_variable();
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# endif
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condition_variable(const condition_variable&) = delete;
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condition_variable& operator=(const condition_variable&) = delete;
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void notify_one() _NOEXCEPT;
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void notify_all() _NOEXCEPT;
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void wait(unique_lock<mutex>& __lk) _NOEXCEPT;
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template <class _Predicate>
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_LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS void wait(unique_lock<mutex>& __lk, _Predicate __pred);
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template <class _Clock, class _Duration>
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_LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS cv_status
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wait_until(unique_lock<mutex>& __lk, const chrono::time_point<_Clock, _Duration>& __t);
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template <class _Clock, class _Duration, class _Predicate>
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_LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS bool
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wait_until(unique_lock<mutex>& __lk, const chrono::time_point<_Clock, _Duration>& __t, _Predicate __pred);
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template <class _Rep, class _Period>
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_LIBCPP_METHOD_TEMPLATE_IMPLICIT_INSTANTIATION_VIS cv_status
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wait_for(unique_lock<mutex>& __lk, const chrono::duration<_Rep, _Period>& __d);
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template <class _Rep, class _Period, class _Predicate>
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bool _LIBCPP_HIDE_FROM_ABI
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wait_for(unique_lock<mutex>& __lk, const chrono::duration<_Rep, _Period>& __d, _Predicate __pred);
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typedef __libcpp_condvar_t* native_handle_type;
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_LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return &__cv_; }
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private:
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void
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__do_timed_wait(unique_lock<mutex>& __lk, chrono::time_point<chrono::system_clock, chrono::nanoseconds>) _NOEXCEPT;
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# if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
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_LIBCPP_HIDE_FROM_ABI void
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__do_timed_wait(unique_lock<mutex>& __lk, chrono::time_point<chrono::steady_clock, chrono::nanoseconds>) _NOEXCEPT;
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# endif
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template <class _Clock>
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_LIBCPP_HIDE_FROM_ABI void
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__do_timed_wait(unique_lock<mutex>& __lk, chrono::time_point<_Clock, chrono::nanoseconds>) _NOEXCEPT;
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};
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#endif // !_LIBCPP_HAS_NO_THREADS
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template <class _Rep, class _Period, __enable_if_t<is_floating_point<_Rep>::value, int> = 0>
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inline _LIBCPP_HIDE_FROM_ABI chrono::nanoseconds __safe_nanosecond_cast(chrono::duration<_Rep, _Period> __d) {
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using namespace chrono;
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using __ratio = ratio_divide<_Period, nano>;
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using __ns_rep = nanoseconds::rep;
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_Rep __result_float = __d.count() * __ratio::num / __ratio::den;
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_Rep __result_max = numeric_limits<__ns_rep>::max();
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if (__result_float >= __result_max) {
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return nanoseconds::max();
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}
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_Rep __result_min = numeric_limits<__ns_rep>::min();
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if (__result_float <= __result_min) {
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return nanoseconds::min();
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}
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return nanoseconds(static_cast<__ns_rep>(__result_float));
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}
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template <class _Rep, class _Period, __enable_if_t<!is_floating_point<_Rep>::value, int> = 0>
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inline _LIBCPP_HIDE_FROM_ABI chrono::nanoseconds __safe_nanosecond_cast(chrono::duration<_Rep, _Period> __d) {
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using namespace chrono;
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if (__d.count() == 0) {
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return nanoseconds(0);
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}
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using __ratio = ratio_divide<_Period, nano>;
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using __ns_rep = nanoseconds::rep;
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__ns_rep __result_max = numeric_limits<__ns_rep>::max();
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if (__d.count() > 0 && __d.count() > __result_max / __ratio::num) {
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return nanoseconds::max();
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}
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__ns_rep __result_min = numeric_limits<__ns_rep>::min();
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if (__d.count() < 0 && __d.count() < __result_min / __ratio::num) {
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return nanoseconds::min();
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}
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__ns_rep __result = __d.count() * __ratio::num / __ratio::den;
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if (__result == 0) {
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return nanoseconds(1);
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}
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return nanoseconds(__result);
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}
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#ifndef _LIBCPP_HAS_NO_THREADS
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template <class _Predicate>
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void condition_variable::wait(unique_lock<mutex>& __lk, _Predicate __pred) {
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while (!__pred())
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wait(__lk);
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}
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template <class _Clock, class _Duration>
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cv_status condition_variable::wait_until(unique_lock<mutex>& __lk, const chrono::time_point<_Clock, _Duration>& __t) {
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using namespace chrono;
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using __clock_tp_ns = time_point<_Clock, nanoseconds>;
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typename _Clock::time_point __now = _Clock::now();
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if (__t <= __now)
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return cv_status::timeout;
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__clock_tp_ns __t_ns = __clock_tp_ns(std::__safe_nanosecond_cast(__t.time_since_epoch()));
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__do_timed_wait(__lk, __t_ns);
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return _Clock::now() < __t ? cv_status::no_timeout : cv_status::timeout;
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}
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template <class _Clock, class _Duration, class _Predicate>
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bool condition_variable::wait_until(
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unique_lock<mutex>& __lk, const chrono::time_point<_Clock, _Duration>& __t, _Predicate __pred) {
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while (!__pred()) {
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if (wait_until(__lk, __t) == cv_status::timeout)
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return __pred();
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}
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return true;
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}
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template <class _Rep, class _Period>
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cv_status condition_variable::wait_for(unique_lock<mutex>& __lk, const chrono::duration<_Rep, _Period>& __d) {
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using namespace chrono;
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if (__d <= __d.zero())
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return cv_status::timeout;
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using __ns_rep = nanoseconds::rep;
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steady_clock::time_point __c_now = steady_clock::now();
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# if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
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using __clock_tp_ns = time_point<steady_clock, nanoseconds>;
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__ns_rep __now_count_ns = std::__safe_nanosecond_cast(__c_now.time_since_epoch()).count();
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# else
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using __clock_tp_ns = time_point<system_clock, nanoseconds>;
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__ns_rep __now_count_ns = std::__safe_nanosecond_cast(system_clock::now().time_since_epoch()).count();
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# endif
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__ns_rep __d_ns_count = std::__safe_nanosecond_cast(__d).count();
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if (__now_count_ns > numeric_limits<__ns_rep>::max() - __d_ns_count) {
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__do_timed_wait(__lk, __clock_tp_ns::max());
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} else {
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__do_timed_wait(__lk, __clock_tp_ns(nanoseconds(__now_count_ns + __d_ns_count)));
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}
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return steady_clock::now() - __c_now < __d ? cv_status::no_timeout : cv_status::timeout;
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}
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template <class _Rep, class _Period, class _Predicate>
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inline bool
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condition_variable::wait_for(unique_lock<mutex>& __lk, const chrono::duration<_Rep, _Period>& __d, _Predicate __pred) {
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return wait_until(__lk, chrono::steady_clock::now() + __d, std::move(__pred));
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}
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# if defined(_LIBCPP_HAS_COND_CLOCKWAIT)
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inline void condition_variable::__do_timed_wait(
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unique_lock<mutex>& __lk, chrono::time_point<chrono::steady_clock, chrono::nanoseconds> __tp) _NOEXCEPT {
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using namespace chrono;
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if (!__lk.owns_lock())
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__throw_system_error(EPERM, "condition_variable::timed wait: mutex not locked");
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nanoseconds __d = __tp.time_since_epoch();
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timespec __ts;
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seconds __s = duration_cast<seconds>(__d);
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using __ts_sec = decltype(__ts.tv_sec);
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const __ts_sec __ts_sec_max = numeric_limits<__ts_sec>::max();
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if (__s.count() < __ts_sec_max) {
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__ts.tv_sec = static_cast<__ts_sec>(__s.count());
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__ts.tv_nsec = (__d - __s).count();
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} else {
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__ts.tv_sec = __ts_sec_max;
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__ts.tv_nsec = giga::num - 1;
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}
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int __ec = pthread_cond_clockwait(&__cv_, __lk.mutex()->native_handle(), CLOCK_MONOTONIC, &__ts);
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if (__ec != 0 && __ec != ETIMEDOUT)
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__throw_system_error(__ec, "condition_variable timed_wait failed");
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}
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# endif // _LIBCPP_HAS_COND_CLOCKWAIT
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template <class _Clock>
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inline void condition_variable::__do_timed_wait(unique_lock<mutex>& __lk,
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chrono::time_point<_Clock, chrono::nanoseconds> __tp) _NOEXCEPT {
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wait_for(__lk, __tp - _Clock::now());
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}
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#endif // _LIBCPP_HAS_NO_THREADS
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_LIBCPP_END_NAMESPACE_STD
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_LIBCPP_POP_MACROS
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#endif // _LIBCPP___CONDITION_VARIABLE_CONDITION_VARIABLE_H
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