| #ifndef BOOST_BASIC_TIMED_MUTEX_WIN32_HPP |
| #define BOOST_BASIC_TIMED_MUTEX_WIN32_HPP |
| |
| // basic_timed_mutex_win32.hpp |
| // |
| // (C) Copyright 2006-8 Anthony Williams |
| // (C) Copyright 2011-2012 Vicente J. Botet Escriba |
| // |
| // Distributed under the Boost Software License, Version 1.0. (See |
| // accompanying file LICENSE_1_0.txt or copy at |
| // http://www.boost.org/LICENSE_1_0.txt) |
| |
| #include <boost/assert.hpp> |
| #include <boost/thread/win32/thread_primitives.hpp> |
| #include <boost/thread/win32/interlocked_read.hpp> |
| #include <boost/thread/thread_time.hpp> |
| #if defined BOOST_THREAD_USES_DATETIME |
| #include <boost/thread/xtime.hpp> |
| #endif |
| #include <boost/detail/interlocked.hpp> |
| #ifdef BOOST_THREAD_USES_CHRONO |
| #include <boost/chrono/system_clocks.hpp> |
| #include <boost/chrono/ceil.hpp> |
| #endif |
| #include <boost/thread/detail/platform_time.hpp> |
| |
| #include <boost/config/abi_prefix.hpp> |
| |
| namespace boost |
| { |
| namespace detail |
| { |
| struct basic_timed_mutex |
| { |
| BOOST_STATIC_CONSTANT(unsigned char,lock_flag_bit=31); |
| BOOST_STATIC_CONSTANT(unsigned char,event_set_flag_bit=30); |
| BOOST_STATIC_CONSTANT(long,lock_flag_value=1<<lock_flag_bit); |
| BOOST_STATIC_CONSTANT(long,event_set_flag_value=1<<event_set_flag_bit); |
| long active_count; |
| void* event; |
| |
| void initialize() |
| { |
| active_count=0; |
| event=0; |
| } |
| |
| void destroy() |
| { |
| #ifdef BOOST_MSVC |
| #pragma warning(push) |
| #pragma warning(disable:4312) |
| #endif |
| void* const old_event=BOOST_INTERLOCKED_EXCHANGE_POINTER(&event,0); |
| #ifdef BOOST_MSVC |
| #pragma warning(pop) |
| #endif |
| if(old_event) |
| { |
| winapi::CloseHandle(old_event); |
| } |
| } |
| |
| // Take the lock flag if it's available |
| bool try_lock() BOOST_NOEXCEPT |
| { |
| return !win32::interlocked_bit_test_and_set(&active_count,lock_flag_bit); |
| } |
| |
| void lock() |
| { |
| if(try_lock()) |
| { |
| return; |
| } |
| long old_count=active_count; |
| mark_waiting_and_try_lock(old_count); |
| |
| if(old_count&lock_flag_value) |
| { |
| void* const sem=get_event(); |
| |
| do |
| { |
| if(winapi::WaitForSingleObjectEx(sem,::boost::detail::win32::infinite,0)==0) |
| { |
| clear_waiting_and_try_lock(old_count); |
| } |
| } |
| while(old_count&lock_flag_value); |
| } |
| } |
| |
| // Loop until the number of waiters has been incremented or we've taken the lock flag |
| // The loop is necessary since this function may be called by multiple threads simultaneously |
| void mark_waiting_and_try_lock(long& old_count) |
| { |
| for(;;) |
| { |
| bool const was_locked=(old_count&lock_flag_value) ? true : false; |
| long const new_count=was_locked?(old_count+1):(old_count|lock_flag_value); |
| long const current=BOOST_INTERLOCKED_COMPARE_EXCHANGE(&active_count,new_count,old_count); |
| if(current==old_count) |
| { |
| if(was_locked) |
| old_count=new_count; |
| // else we've taken the lock flag |
| // don't update old_count so that the calling function can see that |
| // the old lock flag was 0 and know that we've taken the lock flag |
| break; |
| } |
| old_count=current; |
| } |
| } |
| |
| // Loop until someone else has taken the lock flag and cleared the event set flag or |
| // until we've taken the lock flag and cleared the event set flag and decremented the |
| // number of waiters |
| // The loop is necessary since this function may be called by multiple threads simultaneously |
| void clear_waiting_and_try_lock(long& old_count) |
| { |
| old_count&=~lock_flag_value; |
| old_count|=event_set_flag_value; |
| for(;;) |
| { |
| long const new_count=((old_count&lock_flag_value)?old_count:((old_count-1)|lock_flag_value))&~event_set_flag_value; |
| long const current=BOOST_INTERLOCKED_COMPARE_EXCHANGE(&active_count,new_count,old_count); |
| if(current==old_count) |
| { |
| // if someone else has taken the lock flag |
| // no need to update old_count since old_count == new_count (ignoring |
| // event_set_flag_value which the calling function doesn't care about) |
| // else we've taken the lock flag |
| // don't update old_count so that the calling function can see that |
| // the old lock flag was 0 and know that we've taken the lock flag |
| break; |
| } |
| old_count=current; |
| } |
| } |
| |
| private: |
| unsigned long getMs(detail::platform_duration const& d) |
| { |
| return static_cast<unsigned long>(d.getMs()); |
| } |
| |
| template <typename Duration> |
| unsigned long getMs(Duration const& d) |
| { |
| return static_cast<unsigned long>(chrono::ceil<chrono::milliseconds>(d).count()); |
| } |
| |
| template <typename Clock, typename Timepoint, typename Duration> |
| bool do_lock_until(Timepoint const& t, Duration const& max) |
| { |
| if(try_lock()) |
| { |
| return true; |
| } |
| |
| long old_count=active_count; |
| mark_waiting_and_try_lock(old_count); |
| |
| if(old_count&lock_flag_value) |
| { |
| void* const sem=get_event(); |
| |
| // If the clock is the system clock, it may jump while this function |
| // is waiting. To compensate for this and time out near the correct |
| // time, we call WaitForSingleObjectEx() in a loop with a short |
| // timeout and recheck the time remaining each time through the loop. |
| do |
| { |
| Duration d(t - Clock::now()); |
| if(d <= Duration::zero()) // timeout occurred |
| { |
| BOOST_INTERLOCKED_DECREMENT(&active_count); |
| return false; |
| } |
| if(max != Duration::zero()) |
| { |
| d = (std::min)(d, max); |
| } |
| if(winapi::WaitForSingleObjectEx(sem,getMs(d),0)==0) |
| { |
| clear_waiting_and_try_lock(old_count); |
| } |
| } |
| while(old_count&lock_flag_value); |
| } |
| return true; |
| } |
| public: |
| |
| #if defined BOOST_THREAD_USES_DATETIME |
| bool timed_lock(::boost::system_time const& wait_until) |
| { |
| const detail::real_platform_timepoint t(wait_until); |
| return do_lock_until<detail::real_platform_clock>(t, detail::platform_milliseconds(BOOST_THREAD_POLL_INTERVAL_MILLISECONDS)); |
| } |
| |
| template<typename Duration> |
| bool timed_lock(Duration const& timeout) |
| { |
| const detail::mono_platform_timepoint t(detail::mono_platform_clock::now() + detail::platform_duration(timeout)); |
| // The reference clock is steady and so no need to poll periodically, thus 0 ms max (i.e. no max) |
| return do_lock_until<detail::mono_platform_clock>(t, detail::platform_duration::zero()); |
| } |
| |
| bool timed_lock(boost::xtime const& timeout) |
| { |
| return timed_lock(boost::system_time(timeout)); |
| } |
| #endif |
| #ifdef BOOST_THREAD_USES_CHRONO |
| template <class Rep, class Period> |
| bool try_lock_for(const chrono::duration<Rep, Period>& rel_time) |
| { |
| const chrono::steady_clock::time_point t(chrono::steady_clock::now() + rel_time); |
| typedef typename chrono::duration<Rep, Period> Duration; |
| typedef typename common_type<Duration, typename chrono::steady_clock::duration>::type common_duration; |
| // The reference clock is steady and so no need to poll periodically, thus 0 ms max (i.e. no max) |
| return do_lock_until<chrono::steady_clock>(t, common_duration::zero()); |
| } |
| template <class Duration> |
| bool try_lock_until(const chrono::time_point<chrono::steady_clock, Duration>& t) |
| { |
| typedef typename common_type<Duration, typename chrono::steady_clock::duration>::type common_duration; |
| // The reference clock is steady and so no need to poll periodically, thus 0 ms max (i.e. no max) |
| return do_lock_until<chrono::steady_clock>(t, common_duration::zero()); |
| } |
| template <class Clock, class Duration> |
| bool try_lock_until(const chrono::time_point<Clock, Duration>& t) |
| { |
| typedef typename common_type<Duration, typename Clock::duration>::type common_duration; |
| return do_lock_until<Clock>(t, common_duration(chrono::milliseconds(BOOST_THREAD_POLL_INTERVAL_MILLISECONDS))); |
| } |
| #endif |
| |
| void unlock() |
| { |
| // Clear the lock flag using atomic addition (works since long is always 32 bits on Windows) |
| long const old_count=BOOST_INTERLOCKED_EXCHANGE_ADD(&active_count,lock_flag_value); |
| // If someone is waiting to take the lock, set the event set flag and, if |
| // the event set flag hadn't already been set, send an event. |
| if(!(old_count&event_set_flag_value) && (old_count>lock_flag_value)) |
| { |
| if(!win32::interlocked_bit_test_and_set(&active_count,event_set_flag_bit)) |
| { |
| winapi::SetEvent(get_event()); |
| } |
| } |
| } |
| |
| private: |
| // Create an event in a thread-safe way |
| // The first thread to create the event wins and all other thread will use that event |
| void* get_event() |
| { |
| void* current_event=::boost::detail::interlocked_read_acquire(&event); |
| |
| if(!current_event) |
| { |
| void* const new_event=win32::create_anonymous_event(win32::auto_reset_event,win32::event_initially_reset); |
| #ifdef BOOST_MSVC |
| #pragma warning(push) |
| #pragma warning(disable:4311) |
| #pragma warning(disable:4312) |
| #endif |
| void* const old_event=BOOST_INTERLOCKED_COMPARE_EXCHANGE_POINTER(&event,new_event,0); |
| #ifdef BOOST_MSVC |
| #pragma warning(pop) |
| #endif |
| if(old_event!=0) |
| { |
| winapi::CloseHandle(new_event); |
| return old_event; |
| } |
| else |
| { |
| return new_event; |
| } |
| } |
| return current_event; |
| } |
| |
| }; |
| |
| } |
| } |
| |
| #define BOOST_BASIC_TIMED_MUTEX_INITIALIZER {0} |
| |
| #include <boost/config/abi_suffix.hpp> |
| |
| #endif |