From d8296b393300828ea3077c1763f694eea3ad7ec2 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Wed, 9 Apr 2008 19:58:54 +0000
Subject: [PATCH] sp_counted_base_spin.hpp added, enabled by
 BOOST_SP_USE_SPINLOCK.

[SVN r44137]
---
 include/boost/detail/sp_counted_base.hpp      |   4 +
 include/boost/detail/sp_counted_base_spin.hpp | 131 ++++++++++++++++++
 include/boost/detail/spinlock_pool.hpp        |   4 +-
 3 files changed, 137 insertions(+), 2 deletions(-)
 create mode 100644 include/boost/detail/sp_counted_base_spin.hpp

diff --git a/include/boost/detail/sp_counted_base.hpp b/include/boost/detail/sp_counted_base.hpp
index f925a5d..241b2de 100644
--- a/include/boost/detail/sp_counted_base.hpp
+++ b/include/boost/detail/sp_counted_base.hpp
@@ -23,6 +23,10 @@
 
 # include <boost/detail/sp_counted_base_nt.hpp>
 
+#elif defined( BOOST_SP_USE_SPINLOCK )
+
+# include <boost/detail/sp_counted_base_spin.hpp>
+
 #elif defined( BOOST_SP_USE_PTHREADS )
 
 # include <boost/detail/sp_counted_base_pt.hpp>
diff --git a/include/boost/detail/sp_counted_base_spin.hpp b/include/boost/detail/sp_counted_base_spin.hpp
new file mode 100644
index 0000000..610a468
--- /dev/null
+++ b/include/boost/detail/sp_counted_base_spin.hpp
@@ -0,0 +1,131 @@
+#ifndef BOOST_DETAIL_SP_COUNTED_BASE_SPIN_HPP_INCLUDED
+#define BOOST_DETAIL_SP_COUNTED_BASE_SPIN_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+//
+//  detail/sp_counted_base_spin.hpp - spinlock pool atomic emulation
+//
+//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
+//  Copyright 2004-2008 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/detail/spinlock_pool.hpp>
+
+namespace boost
+{
+
+namespace detail
+{
+
+inline int atomic_exchange_and_add( int * pw, int dv )
+{
+    spinlock_pool<1>::scoped_lock lock( pw );
+
+    int r = *pw;
+    *pw += dv;
+    return r;
+}
+
+inline void atomic_increment( int * pw )
+{
+    spinlock_pool<1>::scoped_lock lock( pw );
+    ++*pw;
+}
+
+inline int atomic_conditional_increment( int * pw )
+{
+    spinlock_pool<1>::scoped_lock lock( pw );
+
+    int rv = *pw;
+    if( rv != 0 ) ++*pw;
+    return rv;
+}
+
+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)
+
+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_exchange_and_add( &use_count_, -1 ) == 1 )
+        {
+            dispose();
+            weak_release();
+        }
+    }
+
+    void weak_add_ref() // nothrow
+    {
+        atomic_increment( &weak_count_ );
+    }
+
+    void weak_release() // nothrow
+    {
+        if( atomic_exchange_and_add( &weak_count_, -1 ) == 1 )
+        {
+            destroy();
+        }
+    }
+
+    long use_count() const // nothrow
+    {
+        spinlock_pool<1>::scoped_lock lock( &use_count_ );
+        return use_count_;
+    }
+};
+
+} // namespace detail
+
+} // namespace boost
+
+#endif  // #ifndef BOOST_DETAIL_SP_COUNTED_BASE_SPIN_HPP_INCLUDED
diff --git a/include/boost/detail/spinlock_pool.hpp b/include/boost/detail/spinlock_pool.hpp
index b50ccb5..92d26cb 100644
--- a/include/boost/detail/spinlock_pool.hpp
+++ b/include/boost/detail/spinlock_pool.hpp
@@ -37,7 +37,7 @@ private:
 
 public:
 
-    static spinlock & spinlock_for( void * pv )
+    static spinlock & spinlock_for( void const * pv )
     {
         size_t i = reinterpret_cast< size_t >( pv ) % 41;
         return pool_[ i ];
@@ -54,7 +54,7 @@ public:
 
     public:
 
-        explicit scoped_lock( void * pv ): sp_( spinlock_for( pv ) )
+        explicit scoped_lock( void const * pv ): sp_( spinlock_for( pv ) )
         {
             sp_.lock();
         }