/usr/include/quickfix/SharedArray.h is in libquickfix-dev 1.14.4+dfsg-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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/****************************************************************************
** Copyright (c) 2001-2014
**
** This file is part of the QuickFIX FIX Engine
**
** This file may be distributed under the terms of the quickfixengine.org
** license as defined by quickfixengine.org and appearing in the file
** LICENSE included in the packaging of this file.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
** See http://www.quickfixengine.org/LICENSE for licensing information.
**
** Contact ask@quickfixengine.org if any conditions of this licensing are
** not clear to you.
**
****************************************************************************/
#ifndef SHARED_ARRAY
#define SHARED_ARRAY
#include "AtomicCount.h"
namespace FIX
{
/// Shared array with atomic reference count
template<typename T>
class shared_array
{
public:
shared_array()
: m_size(0)
, m_buffer(0)
{}
shared_array(const shared_array& rhs)
: m_size(rhs.m_size)
, m_buffer(rhs.m_buffer)
{
rhs.attach();
}
~shared_array()
{ release(); }
shared_array& operator=(const shared_array& rhs)
{
if( &rhs == this )
return *this;
rhs.attach();
release();
m_size = rhs.m_size;
m_buffer = rhs.m_buffer;
return *this;
}
std::size_t size() const
{ return m_size; }
bool empty() const
{ return m_buffer == 0; }
operator T* () const
{ return m_buffer; }
//optimized function to allocate storage for buffer and counter object at once
static shared_array create(const std::size_t nSize)
{
if(nSize <= 0)
return shared_array();
//verify the needed buffer size to allocate counter object and nSize elements
const std::size_t sizeToAllocate = nSize + ( sizeof(atomic_count) / sizeof(T) + 1 );
//allocate and zero-fill the buffer
T* storage = new T[ sizeToAllocate ];
memset(storage, 0, sizeToAllocate * sizeof(T));
// create the counter object at the end of the storage
// with initial reference count set to 1
new (&storage[nSize]) atomic_count( 1 );
return shared_array(storage, nSize);
}
private:
shared_array( T * buff, std::size_t nSize )
: m_size(nSize)
, m_buffer(buff)
{
}
atomic_count* get_counter() const
{
return reinterpret_cast<atomic_count*>( &m_buffer[ size() ] );
}
void increment_reference_count() const
{
atomic_count* counter = get_counter();
++(*counter);
}
long decrement_reference_count()
{
atomic_count* counter = get_counter();
return --(*counter);
}
void attach() const
{
if( !empty() )
increment_reference_count();
}
void release()
{
if( empty() )
return;
//free object if reference count has decreased to zero
if( decrement_reference_count() == 0)
{
T * tmpBuff = m_buffer;
atomic_count* tmpCounter = get_counter();
m_buffer = 0;
m_size = 0;
//explicitly call destructor for the counter object
tmpCounter->~atomic_count();
delete [] tmpBuff;
}
}
std::size_t m_size;
T * m_buffer;
};
}
#endif
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