|
|
Boost : |
From: John Torjo (john.lists_at_[hidden])
Date: 2004-09-27 15:00:06
>
>
>>I wanted to say that the original implementation
>>(http://www.pdimov.com/cpp/shared_count_x86_exp2.hpp) has a bug.
>>Take a look at it please.
>
>
> The site seems to be inaccessible. Are you sure that its lock()
> doesn't call InterlockedCompareExchange when it sees not expired
> refcount?
>
Just to make sure, I paste here the code:
-----------------------------------
#ifndef BOOST_DETAIL_SHARED_COUNT_HPP_INCLUDED
#define BOOST_DETAIL_SHARED_COUNT_HPP_INCLUDED
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
//
// detail/shared_count_x86_exp.hpp
//
// An experimental version of shared_count.hpp that uses x86-32
// atomic instructions (the Interlocked* family)
//
// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
//
// Permission to copy, use, modify, sell and distribute this software
// is granted provided this copyright notice appears in all copies.
// This software is provided "as is" without express or implied
// warranty, and with no claim as to its suitability for any purpose.
//
#include <boost/config.hpp>
#if defined(BOOST_SP_USE_STD_ALLOCATOR) &&
defined(BOOST_SP_USE_QUICK_ALLOCATOR)
# error BOOST_SP_USE_STD_ALLOCATOR and BOOST_SP_USE_QUICK_ALLOCATOR are
incompatible.
#endif
#include <boost/checked_delete.hpp>
#include <boost/throw_exception.hpp>
#if defined(BOOST_SP_USE_QUICK_ALLOCATOR)
#include <boost/detail/quick_allocator.hpp>
#endif
#include <memory> // std::auto_ptr, std::allocator
#include <functional> // std::less
#include <exception> // std::exception
#include <new> // std::bad_alloc
#include <typeinfo> // std::type_info in get_deleter
#include <cstddef> // std::size_t
#ifdef __BORLANDC__
# pragma warn -8026 // Functions with excep. spec. are not expanded
inline
# pragma warn -8027 // Functions containing try are not expanded inline
#endif
// Interlocked*
extern "C"
{
long __cdecl _InterlockedIncrement(long volatile * destination);
long __cdecl _InterlockedDecrement(long volatile * destination);
long __cdecl _InterlockedCompareExchange(long volatile * destination,
long exchange, long comparand);
}
#pragma intrinsic(_InterlockedIncrement)
#pragma intrinsic(_InterlockedDecrement)
#pragma intrinsic(_InterlockedCompareExchange)
namespace boost
{
// Debug hooks
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
void sp_scalar_constructor_hook(void * px, std::size_t size, void * pn);
void sp_array_constructor_hook(void * px);
void sp_scalar_destructor_hook(void * px, std::size_t size, void * pn);
void sp_array_destructor_hook(void * px);
#endif
// The standard library that comes with Borland C++ 5.5.1
// defines std::exception and its members as having C calling
// convention (-pc). When the definition of bad_weak_ptr
// is compiled with -ps, the compiler issues an error.
// Hence, the temporary #pragma option -pc below. The version
// check is deliberately conservative.
#if defined(__BORLANDC__) && __BORLANDC__ == 0x551
# pragma option push -pc
#endif
class bad_weak_ptr: public std::exception
{
public:
virtual char const * what() const throw()
{
return "boost::bad_weak_ptr";
}
};
#if defined(__BORLANDC__) && __BORLANDC__ == 0x551
# pragma option pop
#endif
namespace detail
{
//
inline long atomic_increment(long volatile & value)
{
return _InterlockedIncrement(&value);
}
inline long atomic_decrement(long volatile & value)
{
return _InterlockedDecrement(&value);
}
inline long atomic_read(long volatile const & value)
{
return value;
}
inline long atomic_conditional_increment(long volatile & value)
{
for(;;)
{
long tmp = value;
if(tmp == 0) return 0;
if(_InterlockedCompareExchange(&value, tmp + 1, tmp) == tmp)
return tmp + 1;
}
}
//
class sp_counted_base
{
public:
sp_counted_base(): use_count_(1), weak_count_(1)
{
}
virtual ~sp_counted_base() // nothrow
{
}
// dispose() is called when use_count_ drops to zero, to release
// the resources managed by *this.
virtual void dispose() = 0; // nothrow
// destruct() is called when weak_count_ drops to zero.
virtual void destruct() // nothrow
{
delete this;
}
virtual void * get_deleter(std::type_info const & ti) = 0;
void add_ref_copy()
{
atomic_increment(use_count_);
}
void add_ref_lock()
{
if(atomic_conditional_increment(use_count_) == 0)
boost::throw_exception(boost::bad_weak_ptr());
}
void release() // nothrow
{
if(atomic_decrement(use_count_) == 0)
{
dispose();
weak_release();
}
}
void weak_add_ref() // nothrow
{
atomic_increment(weak_count_);
}
void weak_release() // nothrow
{
if(atomic_decrement(weak_count_) == 0)
{
destruct();
}
}
long use_count() const // nothrow
{
return atomic_read(use_count_);
}
private:
sp_counted_base(sp_counted_base const &);
sp_counted_base & operator= (sp_counted_base const &);
long use_count_;
long weak_count_; // weak_count + (use_count == 0)
};
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
template<class T> void cbi_call_constructor_hook(sp_counted_base * pn, T
* px, checked_deleter<T> const &, int)
{
boost::sp_scalar_constructor_hook(px, sizeof(T), pn);
}
template<class T> void cbi_call_constructor_hook(sp_counted_base *, T *
px, checked_array_deleter<T> const &, int)
{
boost::sp_array_constructor_hook(px);
}
template<class P, class D> void
cbi_call_constructor_hook(sp_counted_base *, P const &, D const &, long)
{
}
template<class T> void cbi_call_destructor_hook(sp_counted_base * pn, T
* px, checked_deleter<T> const &, int)
{
boost::sp_scalar_destructor_hook(px, sizeof(T), pn);
}
template<class T> void cbi_call_destructor_hook(sp_counted_base *, T *
px, checked_array_deleter<T> const &, int)
{
boost::sp_array_destructor_hook(px);
}
template<class P, class D> void cbi_call_destructor_hook(sp_counted_base
*, P const &, D const &, long)
{
}
#endif
//
// Borland's Codeguard trips up over the -Vx- option here:
//
#ifdef __CODEGUARD__
# pragma option push -Vx-
#endif
template<class P, class D> class sp_counted_base_impl: public
sp_counted_base
{
private:
P ptr; // copy constructor must not throw
D del; // copy constructor must not throw
sp_counted_base_impl(sp_counted_base_impl const &);
sp_counted_base_impl & operator= (sp_counted_base_impl const &);
typedef sp_counted_base_impl<P, D> this_type;
public:
// pre: initial_use_count <= initial_weak_count, d(p) must not throw
sp_counted_base_impl(P p, D d): ptr(p), del(d)
{
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
detail::cbi_call_constructor_hook(this, p, d, 0);
#endif
}
virtual void dispose() // nothrow
{
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
detail::cbi_call_destructor_hook(this, ptr, del, 0);
#endif
del(ptr);
}
virtual void * get_deleter(std::type_info const & ti)
{
return ti == typeid(D)? &del: 0;
}
#if defined(BOOST_SP_USE_STD_ALLOCATOR)
void * operator new(std::size_t)
{
return std::allocator<this_type>().allocate(1,
static_cast<this_type *>(0));
}
void operator delete(void * p)
{
std::allocator<this_type>().deallocate(static_cast<this_type
*>(p), 1);
}
#endif
#if defined(BOOST_SP_USE_QUICK_ALLOCATOR)
void * operator new(std::size_t)
{
return quick_allocator<this_type>::alloc();
}
void operator delete(void * p)
{
quick_allocator<this_type>::dealloc(p);
}
#endif
};
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
int const shared_count_id = 0x2C35F101;
int const weak_count_id = 0x298C38A4;
#endif
class weak_count;
class shared_count
{
private:
sp_counted_base * pi_;
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
int id_;
#endif
friend class weak_count;
public:
shared_count(): pi_(0) // nothrow
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
, id_(shared_count_id)
#endif
{
}
template<class P, class D> shared_count(P p, D d): pi_(0)
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
, id_(shared_count_id)
#endif
{
#ifndef BOOST_NO_EXCEPTIONS
try
{
pi_ = new sp_counted_base_impl<P, D>(p, d);
}
catch(...)
{
d(p); // delete p
throw;
}
#else
pi_ = new sp_counted_base_impl<P, D>(p, d);
if(pi_ == 0)
{
d(p); // delete p
boost::throw_exception(std::bad_alloc());
}
#endif
}
#ifndef BOOST_NO_AUTO_PTR
// auto_ptr<Y> is special cased to provide the strong guarantee
template<class Y>
explicit shared_count(std::auto_ptr<Y> & r): pi_(new
sp_counted_base_impl< Y *, checked_deleter<Y> >(r.get(),
checked_deleter<Y>()))
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
, id_(shared_count_id)
#endif
{
r.release();
}
#endif
~shared_count() // nothrow
{
if(pi_ != 0) pi_->release();
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
id_ = 0;
#endif
}
shared_count(shared_count const & r): pi_(r.pi_) // nothrow
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
, id_(shared_count_id)
#endif
{
if(pi_ != 0) pi_->add_ref_copy();
}
explicit shared_count(weak_count const & r); // throws bad_weak_ptr
when r.use_count() == 0
shared_count & operator= (shared_count const & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
if(tmp != 0) tmp->add_ref_copy();
if(pi_ != 0) pi_->release();
pi_ = tmp;
return *this;
}
void swap(shared_count & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
r.pi_ = pi_;
pi_ = tmp;
}
long use_count() const // nothrow
{
return pi_ != 0? pi_->use_count(): 0;
}
bool unique() const // nothrow
{
return use_count() == 1;
}
friend inline bool operator==(shared_count const & a, shared_count
const & b)
{
return a.pi_ == b.pi_;
}
friend inline bool operator<(shared_count const & a, shared_count
const & b)
{
return std::less<sp_counted_base *>()(a.pi_, b.pi_);
}
void * get_deleter(std::type_info const & ti) const
{
return pi_? pi_->get_deleter(ti): 0;
}
};
#ifdef __CODEGUARD__
# pragma option pop
#endif
class weak_count
{
private:
sp_counted_base * pi_;
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
int id_;
#endif
friend class shared_count;
public:
weak_count(): pi_(0) // nothrow
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
, id_(weak_count_id)
#endif
{
}
weak_count(shared_count const & r): pi_(r.pi_) // nothrow
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
, id_(shared_count_id)
#endif
{
if(pi_ != 0) pi_->weak_add_ref();
}
weak_count(weak_count const & r): pi_(r.pi_) // nothrow
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
, id_(shared_count_id)
#endif
{
if(pi_ != 0) pi_->weak_add_ref();
}
~weak_count() // nothrow
{
if(pi_ != 0) pi_->weak_release();
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
id_ = 0;
#endif
}
weak_count & operator= (shared_count const & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
if(tmp != 0) tmp->weak_add_ref();
if(pi_ != 0) pi_->weak_release();
pi_ = tmp;
return *this;
}
weak_count & operator= (weak_count const & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
if(tmp != 0) tmp->weak_add_ref();
if(pi_ != 0) pi_->weak_release();
pi_ = tmp;
return *this;
}
void swap(weak_count & r) // nothrow
{
sp_counted_base * tmp = r.pi_;
r.pi_ = pi_;
pi_ = tmp;
}
long use_count() const // nothrow
{
return pi_ != 0? pi_->use_count(): 0;
}
friend inline bool operator==(weak_count const & a, weak_count
const & b)
{
return a.pi_ == b.pi_;
}
friend inline bool operator<(weak_count const & a, weak_count const
& b)
{
return std::less<sp_counted_base *>()(a.pi_, b.pi_);
}
};
inline shared_count::shared_count(weak_count const & r): pi_(r.pi_)
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
, id_(shared_count_id)
#endif
{
if(pi_ != 0)
{
pi_->add_ref_lock();
}
else
{
boost::throw_exception(boost::bad_weak_ptr());
}
}
} // namespace detail
} // namespace boost
#ifdef __BORLANDC__
# pragma warn .8027 // Functions containing try are not expanded inline
# pragma warn .8026 // Functions with excep. spec. are not expanded
inline
#endif
#endif // #ifndef BOOST_DETAIL_SHARED_COUNT_HPP_INCLUDED
-------------------------
--
John Torjo
-- john_at_[hidden]
Contributing editor, C/C++ Users Journal
-- "Win32 GUI Generics" -- generics & GUI do mix, after all
-- http://www.torjo.com/win32gui/
-- v1.4 - save_dlg - true binding of your data to UI controls!
+ easily add validation rules (win32gui/examples/smart_dlg)
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk