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/usr/include/boost/thread/v2/shared_mutex.hpp
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#ifndef BOOST_THREAD_V2_SHARED_MUTEX_HPP #define BOOST_THREAD_V2_SHARED_MUTEX_HPP // shared_mutex.hpp // // Copyright Howard Hinnant 2007-2010. // Copyright Vicente J. Botet Escriba 2012. // // 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) /* <shared_mutex> synopsis namespace boost { namespace thread_v2 { class shared_mutex { public: shared_mutex(); ~shared_mutex(); shared_mutex(const shared_mutex&) = delete; shared_mutex& operator=(const shared_mutex&) = delete; // Exclusive ownership void lock(); bool try_lock(); template <class Rep, class Period> bool try_lock_for(const boost::chrono::duration<Rep, Period>& rel_time); template <class Clock, class Duration> bool try_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time); void unlock(); // Shared ownership void lock_shared(); bool try_lock_shared(); template <class Rep, class Period> bool try_lock_shared_for(const boost::chrono::duration<Rep, Period>& rel_time); template <class Clock, class Duration> bool try_lock_shared_until( const boost::chrono::time_point<Clock, Duration>& abs_time); void unlock_shared(); }; class upgrade_mutex { public: upgrade_mutex(); ~upgrade_mutex(); upgrade_mutex(const upgrade_mutex&) = delete; upgrade_mutex& operator=(const upgrade_mutex&) = delete; // Exclusive ownership void lock(); bool try_lock(); template <class Rep, class Period> bool try_lock_for(const boost::chrono::duration<Rep, Period>& rel_time); template <class Clock, class Duration> bool try_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time); void unlock(); // Shared ownership void lock_shared(); bool try_lock_shared(); template <class Rep, class Period> bool try_lock_shared_for(const boost::chrono::duration<Rep, Period>& rel_time); template <class Clock, class Duration> bool try_lock_shared_until( const boost::chrono::time_point<Clock, Duration>& abs_time); void unlock_shared(); // Upgrade ownership void lock_upgrade(); bool try_lock_upgrade(); template <class Rep, class Period> bool try_lock_upgrade_for( const boost::chrono::duration<Rep, Period>& rel_time); template <class Clock, class Duration> bool try_lock_upgrade_until( const boost::chrono::time_point<Clock, Duration>& abs_time); void unlock_upgrade(); // Shared <-> Exclusive bool try_unlock_shared_and_lock(); template <class Rep, class Period> bool try_unlock_shared_and_lock_for( const boost::chrono::duration<Rep, Period>& rel_time); template <class Clock, class Duration> bool try_unlock_shared_and_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time); void unlock_and_lock_shared(); // Shared <-> Upgrade bool try_unlock_shared_and_lock_upgrade(); template <class Rep, class Period> bool try_unlock_shared_and_lock_upgrade_for( const boost::chrono::duration<Rep, Period>& rel_time); template <class Clock, class Duration> bool try_unlock_shared_and_lock_upgrade_until( const boost::chrono::time_point<Clock, Duration>& abs_time); void unlock_upgrade_and_lock_shared(); // Upgrade <-> Exclusive void unlock_upgrade_and_lock(); bool try_unlock_upgrade_and_lock(); template <class Rep, class Period> bool try_unlock_upgrade_and_lock_for( const boost::chrono::duration<Rep, Period>& rel_time); template <class Clock, class Duration> bool try_unlock_upgrade_and_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time); void unlock_and_lock_upgrade(); }; } // thread_v2 } // boost */ #include <boost/thread/detail/config.hpp> #include <boost/thread/mutex.hpp> #include <boost/thread/condition_variable.hpp> #include <boost/thread/mutex.hpp> #ifdef BOOST_THREAD_USES_CHRONO #include <boost/chrono.hpp> #endif #include <climits> #include <boost/system/system_error.hpp> #include <boost/bind/bind.hpp> namespace boost { namespace thread_v2 { class shared_mutex { typedef boost::mutex mutex_t; typedef boost::condition_variable cond_t; typedef unsigned count_t; mutex_t mut_; cond_t gate1_; // the gate2_ condition variable is only used by functions that // have taken write_entered_ but are waiting for no_readers() cond_t gate2_; count_t state_; static const count_t write_entered_ = 1U << (sizeof(count_t)*CHAR_BIT - 1); static const count_t n_readers_ = ~write_entered_; bool no_writer() const { return (state_ & write_entered_) == 0; } bool one_writer() const { return (state_ & write_entered_) != 0; } bool no_writer_no_readers() const { //return (state_ & write_entered_) == 0 && // (state_ & n_readers_) == 0; return state_ == 0; } bool no_writer_no_max_readers() const { return (state_ & write_entered_) == 0 && (state_ & n_readers_) != n_readers_; } bool no_readers() const { return (state_ & n_readers_) == 0; } bool one_or_more_readers() const { return (state_ & n_readers_) > 0; } shared_mutex(shared_mutex const&); shared_mutex& operator=(shared_mutex const&); public: shared_mutex(); ~shared_mutex(); // Exclusive ownership void lock(); bool try_lock(); #ifdef BOOST_THREAD_USES_CHRONO template <class Rep, class Period> bool try_lock_for(const boost::chrono::duration<Rep, Period>& rel_time) { return try_lock_until(chrono::steady_clock::now() + rel_time); } template <class Clock, class Duration> bool try_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time); #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool timed_lock(T const & abs_or_rel_time); #endif void unlock(); // Shared ownership void lock_shared(); bool try_lock_shared(); #ifdef BOOST_THREAD_USES_CHRONO template <class Rep, class Period> bool try_lock_shared_for(const boost::chrono::duration<Rep, Period>& rel_time) { return try_lock_shared_until(chrono::steady_clock::now() + rel_time); } template <class Clock, class Duration> bool try_lock_shared_until( const boost::chrono::time_point<Clock, Duration>& abs_time); #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool timed_lock_shared(T const & abs_or_rel_time); #endif void unlock_shared(); }; inline shared_mutex::shared_mutex() : state_(0) { } inline shared_mutex::~shared_mutex() { boost::lock_guard<mutex_t> _(mut_); } // Exclusive ownership inline void shared_mutex::lock() { boost::unique_lock<mutex_t> lk(mut_); gate1_.wait(lk, boost::bind(&shared_mutex::no_writer, boost::ref(*this))); state_ |= write_entered_; gate2_.wait(lk, boost::bind(&shared_mutex::no_readers, boost::ref(*this))); } inline bool shared_mutex::try_lock() { boost::unique_lock<mutex_t> lk(mut_); if (!no_writer_no_readers()) { return false; } state_ = write_entered_; return true; } #ifdef BOOST_THREAD_USES_CHRONO template <class Clock, class Duration> bool shared_mutex::try_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.wait_until(lk, abs_time, boost::bind( &shared_mutex::no_writer, boost::ref(*this)))) { return false; } state_ |= write_entered_; if (!gate2_.wait_until(lk, abs_time, boost::bind( &shared_mutex::no_readers, boost::ref(*this)))) { state_ &= ~write_entered_; return false; } return true; } #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool shared_mutex::timed_lock(T const & abs_or_rel_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.timed_wait(lk, abs_or_rel_time, boost::bind( &shared_mutex::no_writer, boost::ref(*this)))) { return false; } state_ |= write_entered_; if (!gate2_.timed_wait(lk, abs_or_rel_time, boost::bind( &shared_mutex::no_readers, boost::ref(*this)))) { state_ &= ~write_entered_; return false; } return true; } #endif inline void shared_mutex::unlock() { boost::lock_guard<mutex_t> _(mut_); BOOST_ASSERT(one_writer()); BOOST_ASSERT(no_readers()); state_ = 0; // notify all since multiple *lock_shared*() calls may be able // to proceed in response to this notification gate1_.notify_all(); } // Shared ownership inline void shared_mutex::lock_shared() { boost::unique_lock<mutex_t> lk(mut_); gate1_.wait(lk, boost::bind(&shared_mutex::no_writer_no_max_readers, boost::ref(*this))); count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= num_readers; } inline bool shared_mutex::try_lock_shared() { boost::unique_lock<mutex_t> lk(mut_); if (!no_writer_no_max_readers()) { return false; } count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= num_readers; return true; } #ifdef BOOST_THREAD_USES_CHRONO template <class Clock, class Duration> bool shared_mutex::try_lock_shared_until( const boost::chrono::time_point<Clock, Duration>& abs_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.wait_until(lk, abs_time, boost::bind( &shared_mutex::no_writer_no_max_readers, boost::ref(*this)))) { return false; } count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= num_readers; return true; } #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool shared_mutex::timed_lock_shared(T const & abs_or_rel_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.timed_wait(lk, abs_or_rel_time, boost::bind( &shared_mutex::no_writer_no_max_readers, boost::ref(*this)))) { return false; } count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= num_readers; return true; } #endif inline void shared_mutex::unlock_shared() { boost::lock_guard<mutex_t> _(mut_); BOOST_ASSERT(one_or_more_readers()); count_t num_readers = (state_ & n_readers_) - 1; state_ &= ~n_readers_; state_ |= num_readers; if (no_writer()) { if (num_readers == n_readers_ - 1) gate1_.notify_one(); } else { if (num_readers == 0) gate2_.notify_one(); } } } // thread_v2 } // boost namespace boost { namespace thread_v2 { class upgrade_mutex { typedef boost::mutex mutex_t; typedef boost::condition_variable cond_t; typedef unsigned count_t; mutex_t mut_; cond_t gate1_; // the gate2_ condition variable is only used by functions that // have taken write_entered_ but are waiting for no_readers() cond_t gate2_; count_t state_; static const unsigned write_entered_ = 1U << (sizeof(count_t)*CHAR_BIT - 1); static const unsigned upgradable_entered_ = write_entered_ >> 1; static const unsigned n_readers_ = ~(write_entered_ | upgradable_entered_); bool no_writer() const { return (state_ & write_entered_) == 0; } bool one_writer() const { return (state_ & write_entered_) != 0; } bool no_writer_no_max_readers() const { return (state_ & write_entered_) == 0 && (state_ & n_readers_) != n_readers_; } bool no_writer_no_upgrader() const { return (state_ & (write_entered_ | upgradable_entered_)) == 0; } bool no_writer_no_upgrader_no_readers() const { //return (state_ & (write_entered_ | upgradable_entered_)) == 0 && // (state_ & n_readers_) == 0; return state_ == 0; } bool no_writer_no_upgrader_one_reader() const { //return (state_ & (write_entered_ | upgradable_entered_)) == 0 && // (state_ & n_readers_) == 1; return state_ == 1; } bool no_writer_no_upgrader_no_max_readers() const { return (state_ & (write_entered_ | upgradable_entered_)) == 0 && (state_ & n_readers_) != n_readers_; } bool no_upgrader() const { return (state_ & upgradable_entered_) == 0; } bool one_upgrader() const { return (state_ & upgradable_entered_) != 0; } bool no_readers() const { return (state_ & n_readers_) == 0; } bool one_reader() const { return (state_ & n_readers_) == 1; } bool one_or_more_readers() const { return (state_ & n_readers_) > 0; } upgrade_mutex(const upgrade_mutex&); upgrade_mutex& operator=(const upgrade_mutex&); public: upgrade_mutex(); ~upgrade_mutex(); // Exclusive ownership void lock(); bool try_lock(); #ifdef BOOST_THREAD_USES_CHRONO template <class Rep, class Period> bool try_lock_for(const boost::chrono::duration<Rep, Period>& rel_time) { return try_lock_until(chrono::steady_clock::now() + rel_time); } template <class Clock, class Duration> bool try_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time); #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool timed_lock(T const & abs_or_rel_time); #endif void unlock(); // Shared ownership void lock_shared(); bool try_lock_shared(); #ifdef BOOST_THREAD_USES_CHRONO template <class Rep, class Period> bool try_lock_shared_for(const boost::chrono::duration<Rep, Period>& rel_time) { return try_lock_shared_until(chrono::steady_clock::now() + rel_time); } template <class Clock, class Duration> bool try_lock_shared_until( const boost::chrono::time_point<Clock, Duration>& abs_time); #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool timed_lock_shared(T const & abs_or_rel_time); #endif void unlock_shared(); // Upgrade ownership void lock_upgrade(); bool try_lock_upgrade(); #ifdef BOOST_THREAD_USES_CHRONO template <class Rep, class Period> bool try_lock_upgrade_for( const boost::chrono::duration<Rep, Period>& rel_time) { return try_lock_upgrade_until(chrono::steady_clock::now() + rel_time); } template <class Clock, class Duration> bool try_lock_upgrade_until( const boost::chrono::time_point<Clock, Duration>& abs_time); #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool timed_lock_upgrade(T const & abs_or_rel_time); #endif void unlock_upgrade(); // Shared <-> Exclusive #ifdef BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSIONS //bool unlock_shared_and_lock(); // can cause a deadlock if used bool try_unlock_shared_and_lock(); #ifdef BOOST_THREAD_USES_CHRONO template <class Rep, class Period> bool try_unlock_shared_and_lock_for( const boost::chrono::duration<Rep, Period>& rel_time) { return try_unlock_shared_and_lock_until(chrono::steady_clock::now() + rel_time); } template <class Clock, class Duration> bool try_unlock_shared_and_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time); #endif #endif void unlock_and_lock_shared(); // Shared <-> Upgrade #ifdef BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSIONS //bool unlock_shared_and_lock_upgrade(); // can cause a deadlock if used bool try_unlock_shared_and_lock_upgrade(); #ifdef BOOST_THREAD_USES_CHRONO template <class Rep, class Period> bool try_unlock_shared_and_lock_upgrade_for( const boost::chrono::duration<Rep, Period>& rel_time) { return try_unlock_shared_and_lock_upgrade_until(chrono::steady_clock::now() + rel_time); } template <class Clock, class Duration> bool try_unlock_shared_and_lock_upgrade_until( const boost::chrono::time_point<Clock, Duration>& abs_time); #endif #endif void unlock_upgrade_and_lock_shared(); // Upgrade <-> Exclusive void unlock_upgrade_and_lock(); bool try_unlock_upgrade_and_lock(); #ifdef BOOST_THREAD_USES_CHRONO template <class Rep, class Period> bool try_unlock_upgrade_and_lock_for( const boost::chrono::duration<Rep, Period>& rel_time) { return try_unlock_upgrade_and_lock_until(chrono::steady_clock::now() + rel_time); } template <class Clock, class Duration> bool try_unlock_upgrade_and_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time); #endif void unlock_and_lock_upgrade(); }; inline upgrade_mutex::upgrade_mutex() : gate1_(), gate2_(), state_(0) { } inline upgrade_mutex::~upgrade_mutex() { boost::lock_guard<mutex_t> _(mut_); } // Exclusive ownership inline void upgrade_mutex::lock() { boost::unique_lock<mutex_t> lk(mut_); gate1_.wait(lk, boost::bind(&upgrade_mutex::no_writer_no_upgrader, boost::ref(*this))); state_ |= write_entered_; gate2_.wait(lk, boost::bind(&upgrade_mutex::no_readers, boost::ref(*this))); } inline bool upgrade_mutex::try_lock() { boost::unique_lock<mutex_t> lk(mut_); if (!no_writer_no_upgrader_no_readers()) { return false; } state_ = write_entered_; return true; } #ifdef BOOST_THREAD_USES_CHRONO template <class Clock, class Duration> bool upgrade_mutex::try_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.wait_until(lk, abs_time, boost::bind( &upgrade_mutex::no_writer_no_upgrader, boost::ref(*this)))) { return false; } state_ |= write_entered_; if (!gate2_.wait_until(lk, abs_time, boost::bind( &upgrade_mutex::no_readers, boost::ref(*this)))) { state_ &= ~write_entered_; return false; } return true; } #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool upgrade_mutex::timed_lock(T const & abs_or_rel_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.timed_wait(lk, abs_or_rel_time, boost::bind( &upgrade_mutex::no_writer_no_upgrader, boost::ref(*this)))) { return false; } state_ |= write_entered_; if (!gate2_.timed_wait(lk, abs_or_rel_time, boost::bind( &upgrade_mutex::no_readers, boost::ref(*this)))) { state_ &= ~write_entered_; return false; } return true; } #endif inline void upgrade_mutex::unlock() { boost::lock_guard<mutex_t> _(mut_); BOOST_ASSERT(one_writer()); BOOST_ASSERT(no_upgrader()); BOOST_ASSERT(no_readers()); state_ = 0; // notify all since multiple *lock_shared*() calls and a *lock_upgrade*() // call may be able to proceed in response to this notification gate1_.notify_all(); } // Shared ownership inline void upgrade_mutex::lock_shared() { boost::unique_lock<mutex_t> lk(mut_); gate1_.wait(lk, boost::bind(&upgrade_mutex::no_writer_no_max_readers, boost::ref(*this))); count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= num_readers; } inline bool upgrade_mutex::try_lock_shared() { boost::unique_lock<mutex_t> lk(mut_); if (!no_writer_no_max_readers()) { return false; } count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= num_readers; return true; } #ifdef BOOST_THREAD_USES_CHRONO template <class Clock, class Duration> bool upgrade_mutex::try_lock_shared_until( const boost::chrono::time_point<Clock, Duration>& abs_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.wait_until(lk, abs_time, boost::bind( &upgrade_mutex::no_writer_no_max_readers, boost::ref(*this)))) { return false; } count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= num_readers; return true; } #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool upgrade_mutex::timed_lock_shared(T const & abs_or_rel_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.timed_wait(lk, abs_or_rel_time, boost::bind( &upgrade_mutex::no_writer_no_max_readers, boost::ref(*this)))) { return false; } count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= num_readers; return true; } #endif inline void upgrade_mutex::unlock_shared() { boost::lock_guard<mutex_t> _(mut_); BOOST_ASSERT(one_or_more_readers()); count_t num_readers = (state_ & n_readers_) - 1; state_ &= ~n_readers_; state_ |= num_readers; if (no_writer()) { if (num_readers == n_readers_ - 1) gate1_.notify_one(); } else { if (num_readers == 0) gate2_.notify_one(); } } // Upgrade ownership inline void upgrade_mutex::lock_upgrade() { boost::unique_lock<mutex_t> lk(mut_); gate1_.wait(lk, boost::bind(&upgrade_mutex::no_writer_no_upgrader_no_max_readers, boost::ref(*this))); count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= upgradable_entered_ | num_readers; } inline bool upgrade_mutex::try_lock_upgrade() { boost::unique_lock<mutex_t> lk(mut_); if (!no_writer_no_upgrader_no_max_readers()) { return false; } count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= upgradable_entered_ | num_readers; return true; } #ifdef BOOST_THREAD_USES_CHRONO template <class Clock, class Duration> bool upgrade_mutex::try_lock_upgrade_until( const boost::chrono::time_point<Clock, Duration>& abs_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.wait_until(lk, abs_time, boost::bind( &upgrade_mutex::no_writer_no_upgrader_no_max_readers, boost::ref(*this)))) { return false; } count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= upgradable_entered_ | num_readers; return true; } #endif #if defined BOOST_THREAD_USES_DATETIME template<typename T> bool upgrade_mutex::timed_lock_upgrade(T const & abs_or_rel_time) { boost::unique_lock<mutex_t> lk(mut_); if (!gate1_.timed_wait(lk, abs_or_rel_time, boost::bind( &upgrade_mutex::no_writer_no_upgrader_no_max_readers, boost::ref(*this)))) { return false; } count_t num_readers = (state_ & n_readers_) + 1; state_ &= ~n_readers_; state_ |= upgradable_entered_ | num_readers; return true; } #endif inline void upgrade_mutex::unlock_upgrade() { boost::lock_guard<mutex_t> _(mut_); BOOST_ASSERT(no_writer()); BOOST_ASSERT(one_upgrader()); BOOST_ASSERT(one_or_more_readers()); count_t num_readers = (state_ & n_readers_) - 1; state_ &= ~(upgradable_entered_ | n_readers_); state_ |= num_readers; // notify all since both a *lock*() and a *lock_shared*() call // may be able to proceed in response to this notification gate1_.notify_all(); } // Shared <-> Exclusive #ifdef BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSIONS inline bool upgrade_mutex::try_unlock_shared_and_lock() { boost::unique_lock<mutex_t> lk(mut_); BOOST_ASSERT(one_or_more_readers()); if (!no_writer_no_upgrader_one_reader()) { return false; } state_ = write_entered_; return true; } #ifdef BOOST_THREAD_USES_CHRONO template <class Clock, class Duration> bool upgrade_mutex::try_unlock_shared_and_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time) { boost::unique_lock<mutex_t> lk(mut_); BOOST_ASSERT(one_or_more_readers()); if (!gate1_.wait_until(lk, abs_time, boost::bind( &upgrade_mutex::no_writer_no_upgrader, boost::ref(*this)))) { return false; } count_t num_readers = (state_ & n_readers_) - 1; state_ &= ~n_readers_; state_ |= (write_entered_ | num_readers); if (!gate2_.wait_until(lk, abs_time, boost::bind( &upgrade_mutex::no_readers, boost::ref(*this)))) { ++num_readers; state_ &= ~(write_entered_ | n_readers_); state_ |= num_readers; return false; } return true; } #endif #endif inline void upgrade_mutex::unlock_and_lock_shared() { boost::lock_guard<mutex_t> _(mut_); BOOST_ASSERT(one_writer()); BOOST_ASSERT(no_upgrader()); BOOST_ASSERT(no_readers()); state_ = 1; // notify all since multiple *lock_shared*() calls and a *lock_upgrade*() // call may be able to proceed in response to this notification gate1_.notify_all(); } // Shared <-> Upgrade #ifdef BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSIONS inline bool upgrade_mutex::try_unlock_shared_and_lock_upgrade() { boost::unique_lock<mutex_t> lk(mut_); BOOST_ASSERT(one_or_more_readers()); if (!no_writer_no_upgrader()) { return false; } state_ |= upgradable_entered_; return true; } #ifdef BOOST_THREAD_USES_CHRONO template <class Clock, class Duration> bool upgrade_mutex::try_unlock_shared_and_lock_upgrade_until( const boost::chrono::time_point<Clock, Duration>& abs_time) { boost::unique_lock<mutex_t> lk(mut_); BOOST_ASSERT(one_or_more_readers()); if (!gate1_.wait_until(lk, abs_time, boost::bind( &upgrade_mutex::no_writer_no_upgrader, boost::ref(*this)))) { return false; } state_ |= upgradable_entered_; return true; } #endif #endif inline void upgrade_mutex::unlock_upgrade_and_lock_shared() { boost::lock_guard<mutex_t> _(mut_); BOOST_ASSERT(no_writer()); BOOST_ASSERT(one_upgrader()); BOOST_ASSERT(one_or_more_readers()); state_ &= ~upgradable_entered_; // notify all since only one *lock*() or *lock_upgrade*() call can win and // proceed in response to this notification, but a *lock_shared*() call may // also be waiting and could steal the notification gate1_.notify_all(); } // Upgrade <-> Exclusive inline void upgrade_mutex::unlock_upgrade_and_lock() { boost::unique_lock<mutex_t> lk(mut_); BOOST_ASSERT(no_writer()); BOOST_ASSERT(one_upgrader()); BOOST_ASSERT(one_or_more_readers()); count_t num_readers = (state_ & n_readers_) - 1; state_ &= ~(upgradable_entered_ | n_readers_); state_ |= write_entered_ | num_readers; gate2_.wait(lk, boost::bind(&upgrade_mutex::no_readers, boost::ref(*this))); } inline bool upgrade_mutex::try_unlock_upgrade_and_lock() { boost::unique_lock<mutex_t> lk(mut_); BOOST_ASSERT(no_writer()); BOOST_ASSERT(one_upgrader()); BOOST_ASSERT(one_or_more_readers()); if (!one_reader()) { return false; } state_ = write_entered_; return true; } #ifdef BOOST_THREAD_USES_CHRONO template <class Clock, class Duration> bool upgrade_mutex::try_unlock_upgrade_and_lock_until( const boost::chrono::time_point<Clock, Duration>& abs_time) { boost::unique_lock<mutex_t> lk(mut_); BOOST_ASSERT(no_writer()); BOOST_ASSERT(one_upgrader()); BOOST_ASSERT(one_or_more_readers()); count_t num_readers = (state_ & n_readers_) - 1; state_ &= ~(upgradable_entered_ | n_readers_); state_ |= (write_entered_ | num_readers); if (!gate2_.wait_until(lk, abs_time, boost::bind( &upgrade_mutex::no_readers, boost::ref(*this)))) { ++num_readers; state_ &= ~(write_entered_ | n_readers_); state_ |= (upgradable_entered_ | num_readers); return false; } return true; } #endif inline void upgrade_mutex::unlock_and_lock_upgrade() { boost::lock_guard<mutex_t> _(mut_); BOOST_ASSERT(one_writer()); BOOST_ASSERT(no_upgrader()); BOOST_ASSERT(no_readers()); state_ = upgradable_entered_ | 1; // notify all since multiple *lock_shared*() calls may be able // to proceed in response to this notification gate1_.notify_all(); } } // thread_v2 } // boost namespace boost { //using thread_v2::shared_mutex; using thread_v2::upgrade_mutex; typedef thread_v2::upgrade_mutex shared_mutex; } #endif
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