Hi Colin,
I had soimilar problem using boost 1.25.8.
Here is my own modified implementation of smart
pointers based on the non thread safe boost one.
Hope this will help you,
Seb.
#ifndef BOOST_SMART_PTR_HPP
#define BOOST_SMART_PTR_HPP
#include // for broken compiler
workarounds
#include <cstddef> // for std::size_t
#include <memory> // for std::auto_ptr
#include <algorithm> // for std::swap
#include // for
boost::noncopyable, checked_delete,
checked_array_delete
#include <functional> // for std::less
#include // for
BOOST_STATIC_ASSERT
// Added by seb
#include
#ifdef BOOST_MSVC // moved here to work around VC++
compiler crash
# pragma warning(push)
# pragma warning(disable:4284) // return type for
'identifier::operator->' is not a UDT or reference to
a UDT. Will produce errors if applied using infix
notation
#endif
namespace boost {
// scoped_ptr
--------------------------------------------------------------//
// scoped_ptr mimics a built-in pointer except that
it guarantees deletion
// of the object pointed to, either on destruction of
the scoped_ptr or via
// an explicit reset(). scoped_ptr is a simple
solution for simple needs;
// see shared_ptr (below) or std::auto_ptr if your
needs are more complex.
template<typename T> class scoped_ptr : noncopyable {
T* ptr;
public:
typedef T element_type;
explicit scoped_ptr( T* p=0 ) : ptr(p) {} // never
throws
~scoped_ptr() { checked_delete(ptr);
}
void reset( T* p=0 ) { if ( ptr != p ) {
checked_delete(ptr); ptr = p; } }
T& operator*() const { return *ptr; } //
never throws
T* operator->() const { return ptr; } //
never throws
T* get() const { return ptr; } //
never throws
#ifdef BOOST_SMART_PTR_CONVERSION
// get() is safer! Define BOOST_SMART_PTR_CONVERSION
at your own risk!
operator T*() const { return ptr; } //
never throws
#endif
}; // scoped_ptr
// scoped_array
------------------------------------------------------------//
// scoped_array extends scoped_ptr to arrays.
Deletion of the array pointed to
// is guaranteed, either on destruction of the
scoped_array or via an explicit
// reset(). See shared_array or std::vector if your
needs are more complex.
template<typename T> class scoped_array : noncopyable
{
T* ptr;
public:
typedef T element_type;
explicit scoped_array( T* p=0 ) : ptr(p) {} //
never throws
~scoped_array() {
checked_array_delete(ptr); }
void reset( T* p=0 ) { if ( ptr != p )
{checked_array_delete(ptr); ptr=p;} }
T* get() const { return ptr; }
// never throws
#ifdef BOOST_SMART_PTR_CONVERSION
// get() is safer! Define BOOST_SMART_PTR_CONVERSION
at your own risk!
operator T*() const { return ptr; }
// never throws
#else
T& operator[](std::size_t i) const { return ptr[i];
} // never throws
#endif
}; // scoped_array
// shared_ptr
--------------------------------------------------------------//
// An enhanced relative of scoped_ptr with reference
counted copy semantics.
// The object pointed to is deleted when the last
shared_ptr pointing to it
// is destroyed or reset.
template<typename T> class shared_ptr {
public:
typedef T element_type;
explicit shared_ptr(T* p =0) : px(p) {
try
{
// Added by seb to be able to delete pn is new
throws
pn = NULL;
pn = new long(1);
// Added by seb.
pm = new mutex();
} // fix: prevent leak if new throws
catch (...) { checked_delete(p);
// Added by seb: delete mutex tom prevent memory
leaks
checked_delete(pm);
throw; }
}
~shared_ptr() { dispose(); }
#if !defined( BOOST_NO_MEMBER_TEMPLATES ) || defined
(BOOST_MSVC6_MEMBER_TEMPLATES)
template<typename Y>
shared_ptr(const shared_ptr<Y>& r) : px(r.px) {
// never throws
// Added by seb: Take the shared mutex here to be
safe when
// we are incrementing the reference count.
// First share the same mutex.
pm = r.pm;
mutex::scoped_lock l(*pm);
// End of seb's modif
++*(pn = r.pn);
}
#ifndef BOOST_NO_AUTO_PTR
template<typename Y>
explicit shared_ptr(std::auto_ptr<Y>& r) {
pn = new long(1); // may throw
// Added by seb.
pm = new mutex(); // may throw
px = r.release(); // fix: moved here to stop
leak if new throws
}
#endif
template<typename Y>
shared_ptr& operator=(const shared_ptr<Y>& r) {
share(r.px,r.pn, r.pm);
return *this;
}
#ifndef BOOST_NO_AUTO_PTR
template<typename Y>
shared_ptr& operator=(std::auto_ptr<Y>& r) {
// code choice driven by guarantee of "no
effect if new throws"
// Added by seb - synchronize all this thing
mutex::scoped_lock l(*pm);
if (*pn == 1) { checked_delete(px); }
else { // allocate new reference counter
long * tmp = new long(1); // may throw
--*pn; // only decrement once danger of new
throwing is past
pn = tmp;
} // allocate new reference counter
px = r.release(); // fix: moved here so
doesn't leak if new throws
return *this;
}
#endif
#else
#ifndef BOOST_NO_AUTO_PTR
explicit shared_ptr(std::auto_ptr<T>& r) {
pn = new long(1); // may throw
// Added by seb - Instanciate the mutex
pm = new mutex();
px = r.release(); // fix: moved here to stop
leak if new throws
}
shared_ptr& operator=(std::auto_ptr<T>& r) {
// code choice driven by guarantee of "no
effect if new throws"
mutex::scoped_lock l(*pm);
if (*pn == 1) { checked_delete(px); }
else { // allocate new reference counter
long * tmp = new long(1); // may throw
--*pn; // only decrement once danger of new
throwing is past
pn = tmp;
} // allocate new reference counter
px = r.release(); // fix: moved here so
doesn't leak if new throws
return *this;
}
#endif
#endif
// Added by seb to be able to downcast a shared_ptr
template<class Derived>
void downcasted_copy_to(shared_ptr<Derived>& q)
const
{
Derived* rawq = dynamic_cast(px);
if(!rawq || !px)
{
q = shared_ptr<Derived>();
}
else
{
shared_ptr<Derived> ptmp;
ptmp.px = rawq;
{
mutex::scoped_lock l(*pm);
++*pn;
}
ptmp.pn = pn;
ptmp.pm = pm;
q.swap(ptmp);
}
}
// End seb's addition
// The assignment operator and the copy constructor
must come after
// the templated versions for MSVC6 to work. (Gary
Powell)
shared_ptr(const shared_ptr& r) : px(r.px),
// Added by seb
pm(r.pm)
{
// Added by seb
mutex::scoped_lock l(*pm);
++*(pn = r.pn);
} // never throws
shared_ptr& operator=(const shared_ptr& r) {
share(r.px,r.pn, r.pm);
return *this;
}
void reset(T* p=0) {
if ( px == p ) return; // fix: self-assignment
safe
// Added by seb
mutex::scoped_lock l(*pm);
if (--*pn == 0) { checked_delete(px); }
else { // allocate new reference counter
try {
// Added by seb
pm = NULL;
pn = new long;
// Added by seb
pm = new mutex();
} // fix: prevent leak if new throws
catch (...) {
++*pn; // undo effect of --*pn above to
meet effects guarantee
checked_delete(p);
// Added by seb
checked_delete(pm);
throw;
} // catch
} // allocate new reference counter
// If an other smart pointer had a reference of
the pointer,
// then we have taken the common mutex.
// In the other case, our pointer is not yet
shared, therefore
// we don't need to take a lock here.
*pn = 1;
px = p;
} // reset
T& operator*() const { return *px; } //
never throws
T* operator->() const { return px; } //
never throws
T* get() const { return px; } //
never throws
#ifdef BOOST_SMART_PTR_CONVERSION
// get() is safer! Define
BOOST_SMART_PTR_CONVERSION at your own risk!
operator T*() const { return px; } //
never throws
#endif
long use_count() const
{
// Added by Seb
mutex::scoped_lock l(*pm);
return *pn;
} // never throws
bool unique() const
{
mutex::scoped_lock l(*pm);
return *pn == 1;
} // never throws
void swap(shared_ptr<T>& other) // never throws
{ std::swap(px,other.px); std::swap(pn,other.pn);
// Added by seb
std::swap(pm, other.pm); }
// Tasteless as this may seem, making all members
public allows member templates
// to work in the absence of member template friends.
(Matthew Langston)
// Don't split this line into two; that causes
problems for some GCC 2.95.2 builds
#if ( defined(BOOST_NO_MEMBER_TEMPLATES) &&
!defined(BOOST_MSVC6_MEMBER_TEMPLATES) ) || !defined(
BOOST_NO_MEMBER_TEMPLATE_FRIENDS )
private:
#endif
T* px; // contained pointer
long* pn; // ptr to reference counter
// Added by seb
mutex* pm;
// Don't split this line into two; that causes
problems for some GCC 2.95.2 builds
#if !defined( BOOST_NO_MEMBER_TEMPLATES ) && !defined(
BOOST_NO_MEMBER_TEMPLATE_FRIENDS )
template<typename Y> friend class shared_ptr;
#endif
void dispose()
{
long ref;
{
mutex::scoped_lock l(*pm);
ref = --*pn;
}
if (ref == 0)
{
checked_delete(px);
delete pn;
// Added by seb
delete pm;
}
}
// rpm added by seb
void share(T* rpx, long* rpn, mutex* rpm) {
mutex::scoped_lock l(*rpm);
if (pn != rpn) { // Q: why not px != rpx? A:
fails when both == 0
++*rpn; // done before dispose() in case rpn
transitively
// dependent on *this (bug reported
by Ken Johnson)
dispose();
px = rpx;
pn = rpn;
pm = rpm;
}
} // share
}; // shared_ptr
template
inline bool operator==(const shared_ptr<T>& a, const
shared_ptr<U>& b)
{ return a.get() == b.get(); }
template
inline bool operator!=(const shared_ptr<T>& a, const
shared_ptr<U>& b)
{ return a.get() != b.get(); }
// shared_array
------------------------------------------------------------//
// shared_array extends shared_ptr to arrays.
// The array pointed to is deleted when the last
shared_array pointing to it
// is destroyed or reset.
template<typename T> class shared_array {
public:
typedef T element_type;
explicit shared_array(T* p =0) : px(p) {
try { pn = new long(1); } // fix: prevent leak
if new throws
catch (...) { checked_array_delete(p); throw; }
}
shared_array(const shared_array& r) : px(r.px) //
never throws
{ ++*(pn = r.pn); }
~shared_array() { dispose(); }
shared_array& operator=(const shared_array& r) {
if (pn != r.pn) { // Q: why not px != r.px? A:
fails when both px == 0
++*r.pn; // done before dispose() in case
r.pn transitively
// dependent on *this (bug reported
by Ken Johnson)
dispose();
px = r.px;
pn = r.pn;
}
return *this;
} // operator=
void reset(T* p=0) {
if ( px == p ) return; // fix: self-assignment
safe
if (--*pn == 0) { checked_array_delete(px); }
else { // allocate new reference counter
try { pn = new long; } // fix: prevent leak
if new throws
catch (...) {
++*pn; // undo effect of --*pn above to
meet effects guarantee
checked_array_delete(p);
throw;
} // catch
} // allocate new reference counter
*pn = 1;
px = p;
} // reset
T* get() const { return px; }
// never throws
#ifdef BOOST_SMART_PTR_CONVERSION
// get() is safer! Define
BOOST_SMART_PTR_CONVERSION at your own risk!
operator T*() const { return px; }
// never throws
#else
T& operator[](std::size_t i) const { return px[i];
} // never throws
#endif
long use_count() const { return *pn; }
// never throws
bool unique() const { return *pn ==
1; } // never throws
void swap(shared_array<T>& other) // never throws
{ std::swap(px,other.px); std::swap(pn,other.pn);
}
private:
T* px; // contained pointer
long* pn; // ptr to reference counter
void dispose() { if (--*pn == 0) {
checked_array_delete(px); delete pn; } }
}; // shared_array
template<typename T>
inline bool operator==(const shared_array<T>& a,
const shared_array<T>& b)
{ return a.get() == b.get(); }
template<typename T>
inline bool operator!=(const shared_array<T>& a,
const shared_array<T>& b)
{ return a.get() != b.get(); }
// Added by seb for downcasting capability
template
shared_ptr<Tout> do_dynamic_cast(const
shared_ptr<Tin>& p)
{
shared_ptr<Tout> pout;
p.downcasted_copy_to(pout);
return pout;
}
} // namespace boost
// specializations for things in namespace std
-----------------------------//
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
namespace std {
// Specialize std::swap to use the fast, non-throwing
swap that's provided
// as a member function instead of using the default
algorithm which creates
// a temporary and uses assignment.
template<typename T>
inline void swap(boost::shared_ptr<T>& a,
boost::shared_ptr<T>& b)
{ a.swap(b); }
template<typename T>
inline void swap(boost::shared_array<T>& a,
boost::shared_array<T>& b)
{ a.swap(b); }
// Specialize std::less so we can use shared pointers
and arrays as keys in
// associative collections.
// It's still a controversial question whether this is
better than supplying
// a full range of comparison operators (<, >, <=,
=).
template<typename T>
struct less< boost::shared_ptr<T> >
: binary_function
{
bool operator()(const boost::shared_ptr<T>& a,
const boost::shared_ptr<T>& b) const
{ return less()(a.get(),b.get()); }
};
template<typename T>
struct less< boost::shared_array<T> >
: binary_function
{
bool operator()(const boost::shared_array<T>& a,
const boost::shared_array<T>& b) const
{ return less()(a.get(),b.get()); }
};
} // namespace std
#endif // ifndef
BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
#ifdef BOOST_MSVC
# pragma warning(pop)
#endif
#endif // BOOST_SMART_PTR_HPP
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