Ticket #6667: sp_counted_base_vacpp_ppc.hpp.patch

boost/smart_ptr/detail/sp_counted_base_vacpp_ppc.hpp

@@ +1 @@
+#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
+#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED
+
+//
+//  detail/sp_counted_base_vacpp_ppc.hpp - xlC(vacpp) on POWER
+//   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
+//  Copyright 2012 IBM Corp.
+//
+//  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>
+
+extern "builtin" void __lwsync(void);
+extern "builtin" void __isync(void);
+extern "builtin" int __fetch_and_add(volatile int* addr, int val);
+extern "builtin" int __compare_and_swap(volatile int*, int*, int);
+
+namespace boost
+{
+
+namespace detail
+{
+
+inline void atomic_increment( int *pw )
+{
+   // ++*pw;
+   __lwsync();
+   __fetch_and_add(pw, 1);
+   __isync();
+} 
+
+inline int atomic_decrement( int *pw )
+{
+   // return --*pw;
+   __lwsync();
+   int originalValue = __fetch_and_add(pw, -1);
+   __isync();
+
+   return (originalValue - 1);
+}
+
+inline int atomic_conditional_increment( int *pw )
+{
+   // if( *pw != 0 ) ++*pw;
+   // return *pw;
+
+   __lwsync();
+   int v = *const_cast<volatile int*>(pw);
+   for (;;)
+   // loop until state is known
+   {
+      if (v == 0) return 0;
+      if (__compare_and_swap(pw, &v, v + 1))
+      {
+         __isync(); return (v + 1);
+      }
+   }
+}
+
+class sp_counted_base
+{
+private:
+
+    sp_counted_base( sp_counted_base const & );
+    sp_counted_base & operator= ( sp_counted_base const & );
+
+    int use_count_;        // #shared
+    int weak_count_;       // #weak + (#shared != 0)
+    char pad[64] __attribute__((__aligned__(64)));
+            // pad to prevent false sharing
+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 *const_cast<volatile int*>(&use_count_); 
+    }
+};
+
+} // namespace detail
+
+} // namespace boost
+
+#endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_VACPP_PPC_HPP_INCLUDED