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authorAnas Nashif <anas.nashif@intel.com>2012-10-30 12:57:26 -0700
committerAnas Nashif <anas.nashif@intel.com>2012-10-30 12:57:26 -0700
commit1a78a62555be32868418fe52f8e330c9d0f95d5a (patch)
treed3765a80e7d3b9640ec2e930743630cd6b9fce2b /boost/smart_ptr/detail/sp_counted_base_aix.hpp
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+#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED
+#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED
+
+//
+// detail/sp_counted_base_aix.hpp
+// based on: detail/sp_counted_base_w32.hpp
+//
+// Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
+// Copyright 2004-2005 Peter Dimov
+// Copyright 2006 Michael van der Westhuizen
+//
+// 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)
+//
+//
+// Lock-free algorithm by Alexander Terekhov
+//
+// Thanks to Ben Hitchings for the #weak + (#shared != 0)
+// formulation
+//
+
+#include <boost/detail/sp_typeinfo.hpp>
+#include <builtins.h>
+#include <sys/atomic_op.h>
+
+namespace boost
+{
+
+namespace detail
+{
+
+inline void atomic_increment( int32_t* pw )
+{
+ // ++*pw;
+
+ fetch_and_add( pw, 1 );
+}
+
+inline int32_t atomic_decrement( int32_t * pw )
+{
+ // return --*pw;
+
+ int32_t originalValue;
+
+ __lwsync();
+ originalValue = fetch_and_add( pw, -1 );
+ __isync();
+
+ return (originalValue - 1);
+}
+
+inline int32_t atomic_conditional_increment( int32_t * pw )
+{
+ // if( *pw != 0 ) ++*pw;
+ // return *pw;
+
+ int32_t tmp = fetch_and_add( pw, 0 );
+ for( ;; )
+ {
+ if( tmp == 0 ) return 0;
+ if( compare_and_swap( pw, &tmp, tmp + 1 ) ) return (tmp + 1);
+ }
+}
+
+class sp_counted_base
+{
+private:
+
+ sp_counted_base( sp_counted_base const & );
+ sp_counted_base & operator= ( sp_counted_base const & );
+
+ int32_t use_count_; // #shared
+ int32_t weak_count_; // #weak + (#shared != 0)
+
+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
+
+ // destroy() is called when weak_count_ drops to zero.
+
+ virtual void destroy() // nothrow
+ {
+ delete this;
+ }
+
+ virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
+
+ void add_ref_copy()
+ {
+ atomic_increment( &use_count_ );
+ }
+
+ bool add_ref_lock() // true on success
+ {
+ return atomic_conditional_increment( &use_count_ ) != 0;
+ }
+
+ 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 )
+ {
+ destroy();
+ }
+ }
+
+ long use_count() const // nothrow
+ {
+ return fetch_and_add( const_cast<int32_t*>(&use_count_), 0 );
+ }
+};
+
+} // namespace detail
+
+} // namespace boost
+
+#endif // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED