#ifndef BOOST_THREAD_WIN32_SHARED_MUTEX_HPP #define BOOST_THREAD_WIN32_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/detail/interlocked.hpp> #include <boost/thread/win32/thread_primitives.hpp> #include <boost/static_assert.hpp> #include <limits.h> #include <boost/utility.hpp> #include <boost/thread/thread_time.hpp> #include <boost/config/abi_prefix.hpp> namespace boost { class shared_mutex: private boost::noncopyable { private: struct state_data { unsigned shared_count:11, shared_waiting:11, exclusive:1, upgrade:1, exclusive_waiting:7, exclusive_waiting_blocked:1; friend bool operator==(state_data const& lhs,state_data const& rhs) { return *reinterpret_cast<unsigned const*>(&lhs)==*reinterpret_cast<unsigned const*>(&rhs); } }; template<typename T> T interlocked_compare_exchange(T* target,T new_value,T comparand) { BOOST_STATIC_ASSERT(sizeof(T)==sizeof(long)); long const res=BOOST_INTERLOCKED_COMPARE_EXCHANGE(reinterpret_cast<long*>(target), *reinterpret_cast<long*>(&new_value), *reinterpret_cast<long*>(&comparand)); return *reinterpret_cast<T const*>(&res); } state_data state; detail::win32::handle semaphores[2]; detail::win32::handle &unlock_sem; detail::win32::handle &exclusive_sem; detail::win32::handle upgrade_sem; void release_waiters(state_data old_state) { if(old_state.exclusive_waiting) { BOOST_VERIFY(detail::win32::ReleaseSemaphore(exclusive_sem,1,0)!=0); } if(old_state.shared_waiting || old_state.exclusive_waiting) { BOOST_VERIFY(detail::win32::ReleaseSemaphore(unlock_sem,old_state.shared_waiting + (old_state.exclusive_waiting?1:0),0)!=0); } } public: shared_mutex(): unlock_sem(semaphores[0]), exclusive_sem(semaphores[1]) { unlock_sem=detail::win32::create_anonymous_semaphore(0,LONG_MAX); exclusive_sem=detail::win32::create_anonymous_semaphore(0,LONG_MAX); upgrade_sem=detail::win32::create_anonymous_semaphore(0,LONG_MAX); state_data state_={0}; state=state_; } ~shared_mutex() { detail::win32::CloseHandle(upgrade_sem); detail::win32::CloseHandle(unlock_sem); detail::win32::CloseHandle(exclusive_sem); } bool try_lock_shared() { state_data old_state=state; for(;;) { state_data new_state=old_state; if(!new_state.exclusive && !new_state.exclusive_waiting_blocked) { ++new_state.shared_count; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } return !(old_state.exclusive| old_state.exclusive_waiting_blocked); } void lock_shared() { BOOST_VERIFY(timed_lock_shared(::boost::detail::get_system_time_sentinel())); } template<typename TimeDuration> bool timed_lock_shared(TimeDuration const & relative_time) { return timed_lock_shared(get_system_time()+relative_time); } bool timed_lock_shared(boost::system_time const& wait_until) { for(;;) { state_data old_state=state; for(;;) { state_data new_state=old_state; if(new_state.exclusive || new_state.exclusive_waiting_blocked) { ++new_state.shared_waiting; } else { ++new_state.shared_count; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } if(!(old_state.exclusive| old_state.exclusive_waiting_blocked)) { return true; } unsigned long const res=detail::win32::WaitForSingleObject(unlock_sem,::boost::detail::get_milliseconds_until(wait_until)); if(res==detail::win32::timeout) { for(;;) { state_data new_state=old_state; if(new_state.exclusive || new_state.exclusive_waiting_blocked) { if(new_state.shared_waiting) { --new_state.shared_waiting; } } else { ++new_state.shared_count; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } if(!(old_state.exclusive| old_state.exclusive_waiting_blocked)) { return true; } return false; } BOOST_ASSERT(res==0); } } void unlock_shared() { state_data old_state=state; for(;;) { state_data new_state=old_state; bool const last_reader=!--new_state.shared_count; if(last_reader) { if(new_state.upgrade) { new_state.upgrade=false; new_state.exclusive=true; } else { if(new_state.exclusive_waiting) { --new_state.exclusive_waiting; new_state.exclusive_waiting_blocked=false; } new_state.shared_waiting=0; } } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { if(last_reader) { if(old_state.upgrade) { BOOST_VERIFY(detail::win32::ReleaseSemaphore(upgrade_sem,1,0)!=0); } else { release_waiters(old_state); } } break; } old_state=current_state; } } void lock() { BOOST_VERIFY(timed_lock(::boost::detail::get_system_time_sentinel())); } template<typename TimeDuration> bool timed_lock(TimeDuration const & relative_time) { return timed_lock(get_system_time()+relative_time); } bool try_lock() { state_data old_state=state; for(;;) { state_data new_state=old_state; if(new_state.shared_count || new_state.exclusive) { return false; } else { new_state.exclusive=true; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } return true; } bool timed_lock(boost::system_time const& wait_until) { for(;;) { state_data old_state=state; for(;;) { state_data new_state=old_state; if(new_state.shared_count || new_state.exclusive) { ++new_state.exclusive_waiting; new_state.exclusive_waiting_blocked=true; } else { new_state.exclusive=true; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } if(!old_state.shared_count && !old_state.exclusive) { return true; } unsigned long const wait_res=detail::win32::WaitForMultipleObjects(2,semaphores,true,::boost::detail::get_milliseconds_until(wait_until)); if(wait_res==detail::win32::timeout) { for(;;) { state_data new_state=old_state; if(new_state.shared_count || new_state.exclusive) { if(new_state.exclusive_waiting) { if(!--new_state.exclusive_waiting) { new_state.exclusive_waiting_blocked=false; } } } else { new_state.exclusive=true; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } if(!old_state.shared_count && !old_state.exclusive) { return true; } return false; } BOOST_ASSERT(wait_res<2); } } void unlock() { state_data old_state=state; for(;;) { state_data new_state=old_state; new_state.exclusive=false; if(new_state.exclusive_waiting) { --new_state.exclusive_waiting; new_state.exclusive_waiting_blocked=false; } new_state.shared_waiting=0; state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } release_waiters(old_state); } void lock_upgrade() { for(;;) { state_data old_state=state; for(;;) { state_data new_state=old_state; if(new_state.exclusive || new_state.exclusive_waiting_blocked || new_state.upgrade) { ++new_state.shared_waiting; } else { ++new_state.shared_count; new_state.upgrade=true; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } if(!(old_state.exclusive|| old_state.exclusive_waiting_blocked|| old_state.upgrade)) { return; } BOOST_VERIFY(!detail::win32::WaitForSingleObject(unlock_sem,detail::win32::infinite)); } } bool try_lock_upgrade() { state_data old_state=state; for(;;) { state_data new_state=old_state; if(new_state.exclusive || new_state.exclusive_waiting_blocked || new_state.upgrade) { return false; } else { ++new_state.shared_count; new_state.upgrade=true; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } return true; } void unlock_upgrade() { state_data old_state=state; for(;;) { state_data new_state=old_state; new_state.upgrade=false; bool const last_reader=!--new_state.shared_count; if(last_reader) { if(new_state.exclusive_waiting) { --new_state.exclusive_waiting; new_state.exclusive_waiting_blocked=false; } new_state.shared_waiting=0; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { if(last_reader) { release_waiters(old_state); } break; } old_state=current_state; } } void unlock_upgrade_and_lock() { state_data old_state=state; for(;;) { state_data new_state=old_state; bool const last_reader=!--new_state.shared_count; if(last_reader) { new_state.upgrade=false; new_state.exclusive=true; } state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { if(!last_reader) { BOOST_VERIFY(!detail::win32::WaitForSingleObject(upgrade_sem,detail::win32::infinite)); } break; } old_state=current_state; } } void unlock_and_lock_upgrade() { state_data old_state=state; for(;;) { state_data new_state=old_state; new_state.exclusive=false; new_state.upgrade=true; ++new_state.shared_count; if(new_state.exclusive_waiting) { --new_state.exclusive_waiting; new_state.exclusive_waiting_blocked=false; } new_state.shared_waiting=0; state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } release_waiters(old_state); } void unlock_and_lock_shared() { state_data old_state=state; for(;;) { state_data new_state=old_state; new_state.exclusive=false; ++new_state.shared_count; if(new_state.exclusive_waiting) { --new_state.exclusive_waiting; new_state.exclusive_waiting_blocked=false; } new_state.shared_waiting=0; state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } release_waiters(old_state); } void unlock_upgrade_and_lock_shared() { state_data old_state=state; for(;;) { state_data new_state=old_state; new_state.upgrade=false; if(new_state.exclusive_waiting) { --new_state.exclusive_waiting; new_state.exclusive_waiting_blocked=false; } new_state.shared_waiting=0; state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state); if(current_state==old_state) { break; } old_state=current_state; } release_waiters(old_state); } }; } #include <boost/config/abi_suffix.hpp> #endif