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595 lines
20 KiB
C++
595 lines
20 KiB
C++
#ifndef BOOST_THREAD_WIN32_SHARED_MUTEX_HPP_MODIFIED
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#define BOOST_THREAD_WIN32_SHARED_MUTEX_HPP_MODIFIED
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// (C) Copyright 2006-8 Anthony Williams
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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/* MongoDB :
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Slightly modified boost file to not die above 127 pending writes
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Here is what changed (from boost 1.42.0 shared_mutex.hpp):
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1,2c1,2
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< #ifndef BOOST_THREAD_WIN32_SHARED_MUTEX_HPP
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< #define BOOST_THREAD_WIN32_SHARED_MUTEX_HPP
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---
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> #ifndef BOOST_THREAD_WIN32_SHARED_MUTEX_HPP_MODIFIED
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> #define BOOST_THREAD_WIN32_SHARED_MUTEX_HPP_MODIFIED
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22c27
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< class shared_mutex:
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---
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> class modified_shared_mutex:
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73c78
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< shared_mutex():
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---
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> modified_shared_mutex():
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84c89
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< ~shared_mutex()
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---
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> ~modified_shared_mutex()
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283a289,290
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> if( new_state.exclusive_waiting == 127 ) // the maximum already!
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> break;
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*/
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#include <boost/assert.hpp>
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#include <boost/detail/interlocked.hpp>
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#include <boost/thread/win32/thread_primitives.hpp>
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#include <boost/static_assert.hpp>
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#include <limits.h>
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#include <boost/utility.hpp>
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#include <boost/thread/thread_time.hpp>
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#include <boost/config/abi_prefix.hpp>
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namespace boost
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{
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class modified_shared_mutex:
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private boost::noncopyable
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{
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private:
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struct state_data
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{
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unsigned shared_count:11,
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shared_waiting:11,
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exclusive:1,
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upgrade:1,
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exclusive_waiting:7,
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exclusive_waiting_blocked:1;
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friend bool operator==(state_data const& lhs,state_data const& rhs)
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{
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return *reinterpret_cast<unsigned const*>(&lhs)==*reinterpret_cast<unsigned const*>(&rhs);
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}
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};
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template<typename T>
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T interlocked_compare_exchange(T* target,T new_value,T comparand)
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{
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BOOST_STATIC_ASSERT(sizeof(T)==sizeof(long));
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long const res=BOOST_INTERLOCKED_COMPARE_EXCHANGE(reinterpret_cast<long*>(target),
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*reinterpret_cast<long*>(&new_value),
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*reinterpret_cast<long*>(&comparand));
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return *reinterpret_cast<T const*>(&res);
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}
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state_data state;
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detail::win32::handle semaphores[2];
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detail::win32::handle &unlock_sem;
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detail::win32::handle &exclusive_sem;
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detail::win32::handle upgrade_sem;
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void release_waiters(state_data old_state)
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{
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if(old_state.exclusive_waiting)
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{
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BOOST_VERIFY(detail::win32::ReleaseSemaphore(exclusive_sem,1,0)!=0);
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}
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if(old_state.shared_waiting || old_state.exclusive_waiting)
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{
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BOOST_VERIFY(detail::win32::ReleaseSemaphore(unlock_sem,old_state.shared_waiting + (old_state.exclusive_waiting?1:0),0)!=0);
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}
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}
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public:
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modified_shared_mutex():
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unlock_sem(semaphores[0]),
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exclusive_sem(semaphores[1])
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{
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unlock_sem=detail::win32::create_anonymous_semaphore(0,LONG_MAX);
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exclusive_sem=detail::win32::create_anonymous_semaphore(0,LONG_MAX);
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upgrade_sem=detail::win32::create_anonymous_semaphore(0,LONG_MAX);
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state_data state_={0};
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state=state_;
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}
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~modified_shared_mutex()
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{
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detail::win32::CloseHandle(upgrade_sem);
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detail::win32::CloseHandle(unlock_sem);
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detail::win32::CloseHandle(exclusive_sem);
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}
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bool try_lock_shared()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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if(!new_state.exclusive && !new_state.exclusive_waiting_blocked)
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{
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++new_state.shared_count;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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return !(old_state.exclusive| old_state.exclusive_waiting_blocked);
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}
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void lock_shared()
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{
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BOOST_VERIFY(timed_lock_shared(::boost::detail::get_system_time_sentinel()));
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}
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template<typename TimeDuration>
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bool timed_lock_shared(TimeDuration const & relative_time)
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{
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return timed_lock_shared(get_system_time()+relative_time);
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}
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bool timed_lock_shared(boost::system_time const& wait_until)
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{
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for(;;)
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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if(new_state.exclusive || new_state.exclusive_waiting_blocked)
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{
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++new_state.shared_waiting;
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}
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else
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{
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++new_state.shared_count;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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if(!(old_state.exclusive| old_state.exclusive_waiting_blocked))
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{
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return true;
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}
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unsigned long const res=detail::win32::WaitForSingleObject(unlock_sem,::boost::detail::get_milliseconds_until(wait_until));
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if(res==detail::win32::timeout)
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{
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for(;;)
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{
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state_data new_state=old_state;
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if(new_state.exclusive || new_state.exclusive_waiting_blocked)
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{
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if(new_state.shared_waiting)
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{
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--new_state.shared_waiting;
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}
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}
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else
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{
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++new_state.shared_count;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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if(!(old_state.exclusive| old_state.exclusive_waiting_blocked))
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{
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return true;
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}
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return false;
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}
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BOOST_ASSERT(res==0);
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}
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}
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void unlock_shared()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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bool const last_reader=!--new_state.shared_count;
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if(last_reader)
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{
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if(new_state.upgrade)
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{
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new_state.upgrade=false;
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new_state.exclusive=true;
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}
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else
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{
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if(new_state.exclusive_waiting)
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{
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--new_state.exclusive_waiting;
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new_state.exclusive_waiting_blocked=false;
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}
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new_state.shared_waiting=0;
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}
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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if(last_reader)
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{
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if(old_state.upgrade)
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{
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BOOST_VERIFY(detail::win32::ReleaseSemaphore(upgrade_sem,1,0)!=0);
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}
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else
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{
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release_waiters(old_state);
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}
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}
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break;
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}
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old_state=current_state;
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}
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}
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void lock()
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{
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BOOST_VERIFY(timed_lock(::boost::detail::get_system_time_sentinel()));
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}
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template<typename TimeDuration>
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bool timed_lock(TimeDuration const & relative_time)
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{
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return timed_lock(get_system_time()+relative_time);
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}
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bool try_lock()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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if(new_state.shared_count || new_state.exclusive)
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{
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return false;
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}
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else
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{
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new_state.exclusive=true;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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return true;
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}
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bool timed_lock(boost::system_time const& wait_until)
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{
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for(;;)
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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if(new_state.shared_count || new_state.exclusive)
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{
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if( new_state.exclusive_waiting == 127 ) // the maximum already!
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break;
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++new_state.exclusive_waiting;
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new_state.exclusive_waiting_blocked=true;
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}
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else
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{
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new_state.exclusive=true;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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if(!old_state.shared_count && !old_state.exclusive)
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{
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return true;
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}
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unsigned long const wait_res=detail::win32::WaitForMultipleObjects(2,semaphores,true,::boost::detail::get_milliseconds_until(wait_until));
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if(wait_res==detail::win32::timeout)
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{
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for(;;)
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{
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state_data new_state=old_state;
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if(new_state.shared_count || new_state.exclusive)
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{
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if(new_state.exclusive_waiting)
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{
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if(!--new_state.exclusive_waiting)
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{
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new_state.exclusive_waiting_blocked=false;
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}
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}
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}
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else
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{
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new_state.exclusive=true;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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if(!old_state.shared_count && !old_state.exclusive)
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{
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return true;
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}
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return false;
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}
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BOOST_ASSERT(wait_res<2);
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}
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}
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void unlock()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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new_state.exclusive=false;
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if(new_state.exclusive_waiting)
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{
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--new_state.exclusive_waiting;
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new_state.exclusive_waiting_blocked=false;
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}
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new_state.shared_waiting=0;
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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release_waiters(old_state);
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}
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void lock_upgrade()
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{
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for(;;)
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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if(new_state.exclusive || new_state.exclusive_waiting_blocked || new_state.upgrade)
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{
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++new_state.shared_waiting;
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}
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else
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{
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++new_state.shared_count;
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new_state.upgrade=true;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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if(!(old_state.exclusive|| old_state.exclusive_waiting_blocked|| old_state.upgrade))
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{
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return;
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}
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BOOST_VERIFY(!detail::win32::WaitForSingleObject(unlock_sem,detail::win32::infinite));
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}
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}
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bool try_lock_upgrade()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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if(new_state.exclusive || new_state.exclusive_waiting_blocked || new_state.upgrade)
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{
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return false;
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}
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else
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{
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++new_state.shared_count;
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new_state.upgrade=true;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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return true;
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}
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void unlock_upgrade()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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new_state.upgrade=false;
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bool const last_reader=!--new_state.shared_count;
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if(last_reader)
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{
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if(new_state.exclusive_waiting)
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{
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--new_state.exclusive_waiting;
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new_state.exclusive_waiting_blocked=false;
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}
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new_state.shared_waiting=0;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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if(last_reader)
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{
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release_waiters(old_state);
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}
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break;
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}
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old_state=current_state;
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}
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}
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void unlock_upgrade_and_lock()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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bool const last_reader=!--new_state.shared_count;
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if(last_reader)
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{
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new_state.upgrade=false;
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new_state.exclusive=true;
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}
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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if(!last_reader)
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{
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BOOST_VERIFY(!detail::win32::WaitForSingleObject(upgrade_sem,detail::win32::infinite));
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}
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break;
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}
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old_state=current_state;
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}
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}
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void unlock_and_lock_upgrade()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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new_state.exclusive=false;
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new_state.upgrade=true;
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++new_state.shared_count;
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if(new_state.exclusive_waiting)
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{
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--new_state.exclusive_waiting;
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new_state.exclusive_waiting_blocked=false;
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}
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new_state.shared_waiting=0;
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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release_waiters(old_state);
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}
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void unlock_and_lock_shared()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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new_state.exclusive=false;
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++new_state.shared_count;
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if(new_state.exclusive_waiting)
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{
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--new_state.exclusive_waiting;
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new_state.exclusive_waiting_blocked=false;
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}
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new_state.shared_waiting=0;
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state_data const current_state=interlocked_compare_exchange(&state,new_state,old_state);
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if(current_state==old_state)
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{
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break;
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}
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old_state=current_state;
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}
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release_waiters(old_state);
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}
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void unlock_upgrade_and_lock_shared()
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{
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state_data old_state=state;
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for(;;)
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{
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state_data new_state=old_state;
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new_state.upgrade=false;
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if(new_state.exclusive_waiting)
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{
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--new_state.exclusive_waiting;
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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
|