sp_counted_base_pt.hpp

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#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_PT_HPP_INCLUDED
#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_PT_HPP_INCLUDED
 
// MS compatible compilers support #pragma once
 
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
 
//
//  detail/sp_counted_base_pt.hpp
//
//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
//  Copyright 2004-2005 Peter Dimov
//
// 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 <boost/detail/sp_typeinfo.hpp>
#include <boost/assert.hpp>
#include <pthread.h>
 
namespace boost
{
 
namespace detail
{
 
class sp_counted_base
{
private:
 
    sp_counted_base( sp_counted_base const & );
    sp_counted_base & operator= ( sp_counted_base const & );
 
    long use_count_;        // #shared
    long weak_count_;       // #weak + (#shared != 0)
 
    mutable pthread_mutex_t m_;
 
public:
 
    sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
    {
// HPUX 10.20 / DCE has a nonstandard pthread_mutex_init
 
#if defined(__hpux) && defined(_DECTHREADS_)
        BOOST_VERIFY( pthread_mutex_init( &m_, pthread_mutexattr_default ) == 0 );
#else
        BOOST_VERIFY( pthread_mutex_init( &m_, 0 ) == 0 );
#endif
    }
 
    virtual ~sp_counted_base() // nothrow
    {
        BOOST_VERIFY( pthread_mutex_destroy( &m_ ) == 0 );
    }
 
    // dispose() is called when use_count_ drops to zero, to release
    // the resources managed by *this.
 
    virtual void dispose() = 0; // nothrow
 
    // destroy() is called when weak_count_ drops to zero.
 
    virtual void destroy() // nothrow
    {
        delete this;
    }
 
    virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
    virtual void * get_untyped_deleter() = 0;
 
    void add_ref_copy()
    {
        BOOST_VERIFY( pthread_mutex_lock( &m_ ) == 0 );
        ++use_count_;
        BOOST_VERIFY( pthread_mutex_unlock( &m_ ) == 0 );
    }
 
    bool add_ref_lock() // true on success
    {
        BOOST_VERIFY( pthread_mutex_lock( &m_ ) == 0 );
        bool r = use_count_ == 0? false: ( ++use_count_, true );
        BOOST_VERIFY( pthread_mutex_unlock( &m_ ) == 0 );
        return r;
    }
 
    void release() // nothrow
    {
        BOOST_VERIFY( pthread_mutex_lock( &m_ ) == 0 );
        long new_use_count = --use_count_;
        BOOST_VERIFY( pthread_mutex_unlock( &m_ ) == 0 );
 
        if( new_use_count == 0 )
        {
            dispose();
            weak_release();
        }
    }
 
    void weak_add_ref() // nothrow
    {
        BOOST_VERIFY( pthread_mutex_lock( &m_ ) == 0 );
        ++weak_count_;
        BOOST_VERIFY( pthread_mutex_unlock( &m_ ) == 0 );
    }
 
    void weak_release() // nothrow
    {
        BOOST_VERIFY( pthread_mutex_lock( &m_ ) == 0 );
        long new_weak_count = --weak_count_;
        BOOST_VERIFY( pthread_mutex_unlock( &m_ ) == 0 );
 
        if( new_weak_count == 0 )
        {
            destroy();
        }
    }
 
    long use_count() const // nothrow
    {
        BOOST_VERIFY( pthread_mutex_lock( &m_ ) == 0 );
        long r = use_count_;
        BOOST_VERIFY( pthread_mutex_unlock( &m_ ) == 0 );
 
        return r;
    }
};
 
} // namespace detail
 
} // namespace boost
 
#endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_PT_HPP_INCLUDED