| #ifndef BOOST_THREAD_PTHREAD_SHARED_MUTEX_HPP |
| #define BOOST_THREAD_PTHREAD_SHARED_MUTEX_HPP |
| |
| // (C) Copyright 2006-8 Anthony Williams |
| // |
| // 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/static_assert.hpp> |
| #include <boost/thread/mutex.hpp> |
| #include <boost/thread/thread.hpp> |
| #include <boost/thread/condition_variable.hpp> |
| |
| #include <boost/config/abi_prefix.hpp> |
| |
| namespace boost |
| { |
| class shared_mutex |
| { |
| private: |
| struct state_data |
| { |
| unsigned shared_count; |
| bool exclusive; |
| bool upgrade; |
| bool exclusive_waiting_blocked; |
| }; |
| |
| |
| |
| state_data state; |
| boost::mutex state_change; |
| boost::condition_variable shared_cond; |
| boost::condition_variable exclusive_cond; |
| boost::condition_variable upgrade_cond; |
| |
| void release_waiters() |
| { |
| exclusive_cond.notify_one(); |
| shared_cond.notify_all(); |
| } |
| |
| |
| public: |
| shared_mutex() |
| { |
| state_data state_={0,0,0,0}; |
| state=state_; |
| } |
| |
| ~shared_mutex() |
| { |
| } |
| |
| void lock_shared() |
| { |
| boost::this_thread::disable_interruption do_not_disturb; |
| boost::mutex::scoped_lock lk(state_change); |
| |
| while(state.exclusive || state.exclusive_waiting_blocked) |
| { |
| shared_cond.wait(lk); |
| } |
| ++state.shared_count; |
| } |
| |
| bool try_lock_shared() |
| { |
| boost::mutex::scoped_lock lk(state_change); |
| |
| if(state.exclusive || state.exclusive_waiting_blocked) |
| { |
| return false; |
| } |
| else |
| { |
| ++state.shared_count; |
| return true; |
| } |
| } |
| |
| bool timed_lock_shared(system_time const& timeout) |
| { |
| boost::this_thread::disable_interruption do_not_disturb; |
| boost::mutex::scoped_lock lk(state_change); |
| |
| while(state.exclusive || state.exclusive_waiting_blocked) |
| { |
| if(!shared_cond.timed_wait(lk,timeout)) |
| { |
| return false; |
| } |
| } |
| ++state.shared_count; |
| return true; |
| } |
| |
| template<typename TimeDuration> |
| bool timed_lock_shared(TimeDuration const & relative_time) |
| { |
| return timed_lock_shared(get_system_time()+relative_time); |
| } |
| |
| void unlock_shared() |
| { |
| boost::mutex::scoped_lock lk(state_change); |
| bool const last_reader=!--state.shared_count; |
| |
| if(last_reader) |
| { |
| if(state.upgrade) |
| { |
| state.upgrade=false; |
| state.exclusive=true; |
| upgrade_cond.notify_one(); |
| } |
| else |
| { |
| state.exclusive_waiting_blocked=false; |
| } |
| release_waiters(); |
| } |
| } |
| |
| void lock() |
| { |
| boost::this_thread::disable_interruption do_not_disturb; |
| boost::mutex::scoped_lock lk(state_change); |
| |
| while(state.shared_count || state.exclusive) |
| { |
| state.exclusive_waiting_blocked=true; |
| exclusive_cond.wait(lk); |
| } |
| state.exclusive=true; |
| } |
| |
| bool timed_lock(system_time const& timeout) |
| { |
| boost::this_thread::disable_interruption do_not_disturb; |
| boost::mutex::scoped_lock lk(state_change); |
| |
| while(state.shared_count || state.exclusive) |
| { |
| state.exclusive_waiting_blocked=true; |
| if(!exclusive_cond.timed_wait(lk,timeout)) |
| { |
| if(state.shared_count || state.exclusive) |
| { |
| state.exclusive_waiting_blocked=false; |
| exclusive_cond.notify_one(); |
| return false; |
| } |
| break; |
| } |
| } |
| state.exclusive=true; |
| return true; |
| } |
| |
| template<typename TimeDuration> |
| bool timed_lock(TimeDuration const & relative_time) |
| { |
| return timed_lock(get_system_time()+relative_time); |
| } |
| |
| bool try_lock() |
| { |
| boost::mutex::scoped_lock lk(state_change); |
| |
| if(state.shared_count || state.exclusive) |
| { |
| return false; |
| } |
| else |
| { |
| state.exclusive=true; |
| return true; |
| } |
| |
| } |
| |
| void unlock() |
| { |
| boost::mutex::scoped_lock lk(state_change); |
| state.exclusive=false; |
| state.exclusive_waiting_blocked=false; |
| release_waiters(); |
| } |
| |
| void lock_upgrade() |
| { |
| boost::this_thread::disable_interruption do_not_disturb; |
| boost::mutex::scoped_lock lk(state_change); |
| while(state.exclusive || state.exclusive_waiting_blocked || state.upgrade) |
| { |
| shared_cond.wait(lk); |
| } |
| ++state.shared_count; |
| state.upgrade=true; |
| } |
| |
| bool timed_lock_upgrade(system_time const& timeout) |
| { |
| boost::this_thread::disable_interruption do_not_disturb; |
| boost::mutex::scoped_lock lk(state_change); |
| while(state.exclusive || state.exclusive_waiting_blocked || state.upgrade) |
| { |
| if(!shared_cond.timed_wait(lk,timeout)) |
| { |
| if(state.exclusive || state.exclusive_waiting_blocked || state.upgrade) |
| { |
| return false; |
| } |
| break; |
| } |
| } |
| ++state.shared_count; |
| state.upgrade=true; |
| return true; |
| } |
| |
| template<typename TimeDuration> |
| bool timed_lock_upgrade(TimeDuration const & relative_time) |
| { |
| return timed_lock(get_system_time()+relative_time); |
| } |
| |
| bool try_lock_upgrade() |
| { |
| boost::mutex::scoped_lock lk(state_change); |
| if(state.exclusive || state.exclusive_waiting_blocked || state.upgrade) |
| { |
| return false; |
| } |
| else |
| { |
| ++state.shared_count; |
| state.upgrade=true; |
| return true; |
| } |
| } |
| |
| void unlock_upgrade() |
| { |
| boost::mutex::scoped_lock lk(state_change); |
| state.upgrade=false; |
| bool const last_reader=!--state.shared_count; |
| |
| if(last_reader) |
| { |
| state.exclusive_waiting_blocked=false; |
| release_waiters(); |
| } |
| } |
| |
| void unlock_upgrade_and_lock() |
| { |
| boost::this_thread::disable_interruption do_not_disturb; |
| boost::mutex::scoped_lock lk(state_change); |
| --state.shared_count; |
| while(state.shared_count) |
| { |
| upgrade_cond.wait(lk); |
| } |
| state.upgrade=false; |
| state.exclusive=true; |
| } |
| |
| void unlock_and_lock_upgrade() |
| { |
| boost::mutex::scoped_lock lk(state_change); |
| state.exclusive=false; |
| state.upgrade=true; |
| ++state.shared_count; |
| state.exclusive_waiting_blocked=false; |
| release_waiters(); |
| } |
| |
| void unlock_and_lock_shared() |
| { |
| boost::mutex::scoped_lock lk(state_change); |
| state.exclusive=false; |
| ++state.shared_count; |
| state.exclusive_waiting_blocked=false; |
| release_waiters(); |
| } |
| |
| void unlock_upgrade_and_lock_shared() |
| { |
| boost::mutex::scoped_lock lk(state_change); |
| state.upgrade=false; |
| state.exclusive_waiting_blocked=false; |
| release_waiters(); |
| } |
| }; |
| } |
| |
| #include <boost/config/abi_suffix.hpp> |
| |
| #endif |