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#ifndef BOOST_THREAD_WIN32_ONCE_HPP
#define BOOST_THREAD_WIN32_ONCE_HPP
// once.hpp
//
// (C) Copyright 2005-7 Anthony Williams
// (C) Copyright 2005 John Maddock
//
// 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 <cstring>
#include <cstddef>
#include <boost/assert.hpp>
#include <boost/static_assert.hpp>
#include <boost/detail/interlocked.hpp>
#include <boost/thread/win32/thread_primitives.hpp>
#include <boost/thread/win32/interlocked_read.hpp>
#include <boost/config/abi_prefix.hpp>
#ifdef BOOST_NO_STDC_NAMESPACE
namespace std
{
using ::memcpy;
using ::ptrdiff_t;
}
#endif
namespace boost
{
struct once_flag
{
long status;
long count;
};
#define BOOST_ONCE_INIT {0,0}
namespace detail
{
#ifdef BOOST_NO_ANSI_APIS
typedef wchar_t once_char_type;
#else
typedef char once_char_type;
#endif
unsigned const once_mutex_name_fixed_length=54;
unsigned const once_mutex_name_length=once_mutex_name_fixed_length+
sizeof(void*)*2+sizeof(unsigned long)*2+1;
template <class I>
void int_to_string(I p, once_char_type* buf)
{
for(unsigned i=0; i < sizeof(I)*2; ++i,++buf)
{
#ifdef BOOST_NO_ANSI_APIS
once_char_type const a=L'A';
#else
once_char_type const a='A';
#endif
*buf = a + static_cast<once_char_type>((p >> (i*4)) & 0x0f);
}
*buf = 0;
}
inline void name_once_mutex(once_char_type* mutex_name,void* flag_address)
{
#ifdef BOOST_NO_ANSI_APIS
static const once_char_type fixed_mutex_name[]=L"Local\\{C15730E2-145C-4c5e-B005-3BC753F42475}-once-flag";
#else
static const once_char_type fixed_mutex_name[]="Local\\{C15730E2-145C-4c5e-B005-3BC753F42475}-once-flag";
#endif
BOOST_STATIC_ASSERT(sizeof(fixed_mutex_name) ==
(sizeof(once_char_type)*(once_mutex_name_fixed_length+1)));
std::memcpy(mutex_name,fixed_mutex_name,sizeof(fixed_mutex_name));
detail::int_to_string(reinterpret_cast<std::ptrdiff_t>(flag_address),
mutex_name + once_mutex_name_fixed_length);
detail::int_to_string(win32::GetCurrentProcessId(),
mutex_name + once_mutex_name_fixed_length + sizeof(void*)*2);
}
inline void* open_once_event(once_char_type* mutex_name,void* flag_address)
{
if(!*mutex_name)
{
name_once_mutex(mutex_name,flag_address);
}
#ifdef BOOST_NO_ANSI_APIS
return ::boost::detail::win32::OpenEventW(
#else
return ::boost::detail::win32::OpenEventA(
#endif
::boost::detail::win32::synchronize |
::boost::detail::win32::event_modify_state,
false,
mutex_name);
}
inline void* create_once_event(once_char_type* mutex_name,void* flag_address)
{
if(!*mutex_name)
{
name_once_mutex(mutex_name,flag_address);
}
#ifdef BOOST_NO_ANSI_APIS
return ::boost::detail::win32::CreateEventW(
#else
return ::boost::detail::win32::CreateEventA(
#endif
0,::boost::detail::win32::manual_reset_event,
::boost::detail::win32::event_initially_reset,
mutex_name);
}
}
template<typename Function>
void call_once(once_flag& flag,Function f)
{
// Try for a quick win: if the procedure has already been called
// just skip through:
long const function_complete_flag_value=0xc15730e2;
long const running_value=0x7f0725e3;
long status;
bool counted=false;
detail::win32::handle_manager event_handle;
detail::once_char_type mutex_name[detail::once_mutex_name_length];
mutex_name[0]=0;
while((status=::boost::detail::interlocked_read_acquire(&flag.status))
!=function_complete_flag_value)
{
status=BOOST_INTERLOCKED_COMPARE_EXCHANGE(&flag.status,running_value,0);
if(!status)
{
try
{
if(!event_handle)
{
event_handle=detail::open_once_event(mutex_name,&flag);
}
if(event_handle)
{
::boost::detail::win32::ResetEvent(event_handle);
}
f();
if(!counted)
{
BOOST_INTERLOCKED_INCREMENT(&flag.count);
counted=true;
}
BOOST_INTERLOCKED_EXCHANGE(&flag.status,function_complete_flag_value);
if(!event_handle &&
(::boost::detail::interlocked_read_acquire(&flag.count)>1))
{
event_handle=detail::create_once_event(mutex_name,&flag);
}
if(event_handle)
{
::boost::detail::win32::SetEvent(event_handle);
}
break;
}
catch(...)
{
BOOST_INTERLOCKED_EXCHANGE(&flag.status,0);
if(!event_handle)
{
event_handle=detail::open_once_event(mutex_name,&flag);
}
if(event_handle)
{
::boost::detail::win32::SetEvent(event_handle);
}
throw;
}
}
if(!counted)
{
BOOST_INTERLOCKED_INCREMENT(&flag.count);
counted=true;
status=::boost::detail::interlocked_read_acquire(&flag.status);
if(status==function_complete_flag_value)
{
break;
}
if(!event_handle)
{
event_handle=detail::create_once_event(mutex_name,&flag);
continue;
}
}
BOOST_VERIFY(!::boost::detail::win32::WaitForSingleObject(
event_handle,::boost::detail::win32::infinite));
}
}
}
#include <boost/config/abi_suffix.hpp>
#endif
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Swift