Add a spinlock to atomic_shared_ptr

doc/smart_ptr/atomic_shared_ptr.adoc

@@ -36,7 +36,7 @@ namespace boost {
   public:
 
     atomic_shared_ptr() noexcept = default;
-    constexpr atomic_shared_ptr( shared_ptr<T> p ) noexcept;
+    atomic_shared_ptr( shared_ptr<T> p ) noexcept;
 
     atomic_shared_ptr& operator=( shared_ptr<T> r ) noexcept;
 
@@ -65,7 +65,7 @@ namespace boost {
 ## Members
 
 ```
-constexpr atomic_shared_ptr( shared_ptr<T> p ) noexcept;
+atomic_shared_ptr( shared_ptr<T> p ) noexcept;
 ```
 [none]
 * {blank}

include/boost/smart_ptr/atomic_shared_ptr.hpp

@@ -14,6 +14,8 @@
 //
 
 #include <boost/smart_ptr/shared_ptr.hpp>
+#include <boost/smart_ptr/detail/spinlock.hpp>
+#include <cstring>
 
 namespace boost
 {
@@ -24,35 +26,59 @@ private:
 
     boost::shared_ptr<T> p_;
 
+    mutable boost::detail::spinlock l_;
+
     atomic_shared_ptr(const atomic_shared_ptr&);
     atomic_shared_ptr& operator=(const atomic_shared_ptr&);
 
+private:
+
+    bool compare_exchange( shared_ptr<T>& v, shared_ptr<T> w ) BOOST_SP_NOEXCEPT
+    {
+        l_.lock();
+
+        if( p_._internal_equiv( v ) )
+        {
+            p_.swap( w );
+
+            l_.unlock();
+            return true;
+        }
+        else
+        {
+            shared_ptr<T> tmp( p_ );
+
+            l_.unlock();
+
+            tmp.swap( v );
+            return false;
+        }
+    }
+
 public:
 
     atomic_shared_ptr() BOOST_SP_NOEXCEPT
     {
+        boost::detail::spinlock init = BOOST_DETAIL_SPINLOCK_INIT;
+        std::memcpy( &l_, &init, sizeof( init ) );
     }
 
-    BOOST_CONSTEXPR atomic_shared_ptr( shared_ptr<T> p ) BOOST_SP_NOEXCEPT
+    atomic_shared_ptr( shared_ptr<T> p ) BOOST_SP_NOEXCEPT
 #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
         : p_( std::move( p ) )
 #else
         : p_( p )
 #endif
     {
+        boost::detail::spinlock init = BOOST_DETAIL_SPINLOCK_INIT;
+        std::memcpy( &l_, &init, sizeof( init ) );
     }
 
     atomic_shared_ptr& operator=( shared_ptr<T> r ) BOOST_SP_NOEXCEPT
     {
-#if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
+        boost::detail::spinlock::scoped_lock lock( l_ );
+        p_.swap( r );
 
-        atomic_store( &p_, std::move( r ) );
-
-#else
-
-        atomic_store( &p_, r );
-
-#endif
         return *this;
     }
 
@@ -63,80 +89,80 @@ public:
 
     shared_ptr<T> load( int = 0 ) const BOOST_SP_NOEXCEPT
     {
-        return atomic_load( &p_ );
+        boost::detail::spinlock::scoped_lock lock( l_ );
+        return p_;
     }
 
     operator shared_ptr<T>() const BOOST_SP_NOEXCEPT
     {
-        return atomic_load( &p_ );
+        boost::detail::spinlock::scoped_lock lock( l_ );
+        return p_;
     }
 
     void store( shared_ptr<T> r, int = 0 ) BOOST_SP_NOEXCEPT
     {
-#if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
+        boost::detail::spinlock::scoped_lock lock( l_ );
-
+        p_.swap( r );
-        atomic_store( &p_, std::move( r ) );
-
-#else
-
-        atomic_store( &p_, r );
-
-#endif
     }
 
     shared_ptr<T> exchange( shared_ptr<T> r, int = 0 ) BOOST_SP_NOEXCEPT
     {
+        {
+            boost::detail::spinlock::scoped_lock lock( l_ );
+            p_.swap( r );
+        }
+
 #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
 
-        return atomic_exchange( &p_, std::move( r ) );
+        return std::move( r );
 
 #else
 
-        return atomic_exchange( &p_, r );
+        return r;
 
 #endif
     }
 
     bool compare_exchange_weak( shared_ptr<T>& v, const shared_ptr<T>& w, int, int ) BOOST_SP_NOEXCEPT
     {
-        return atomic_compare_exchange( &p_, &v, w );
+        return compare_exchange( v, w );
     }
 
     bool compare_exchange_weak( shared_ptr<T>& v, const shared_ptr<T>& w, int = 0 ) BOOST_SP_NOEXCEPT
     {
-        return atomic_compare_exchange( &p_, &v, w );
+        return compare_exchange( v, w );
     }
 
     bool compare_exchange_strong( shared_ptr<T>& v, const shared_ptr<T>& w, int, int ) BOOST_SP_NOEXCEPT
     {
-        return atomic_compare_exchange( &p_, &v, w );
+        return compare_exchange( v, w );
     }
 
     bool compare_exchange_strong( shared_ptr<T>& v, const shared_ptr<T>& w, int = 0 ) BOOST_SP_NOEXCEPT
     {
-        return atomic_compare_exchange( &p_, &v, w );
+        return compare_exchange( v, w );
     }
 
 #if !defined( BOOST_NO_CXX11_RVALUE_REFERENCES )
 
     bool compare_exchange_weak( shared_ptr<T>& v, shared_ptr<T>&& w, int, int ) BOOST_SP_NOEXCEPT
     {
-        return atomic_compare_exchange( &p_, &v, std::move( w ) );
+        return compare_exchange( v, std::move( w ) );
     }
 
     bool compare_exchange_weak( shared_ptr<T>& v, shared_ptr<T>&& w, int = 0 ) BOOST_SP_NOEXCEPT
     {
-        return atomic_compare_exchange( &p_, &v, std::move( w ) );
+        return compare_exchange( v, std::move( w ) );
     }
 
     bool compare_exchange_strong( shared_ptr<T>& v, shared_ptr<T>&& w, int, int ) BOOST_SP_NOEXCEPT
     {
-        return atomic_compare_exchange( &p_, &v, std::move( w ) );
+        return compare_exchange( v, std::move( w ) );
     }
 
     bool compare_exchange_strong( shared_ptr<T>& v, shared_ptr<T>&& w, int = 0 ) BOOST_SP_NOEXCEPT
     {
-        return atomic_compare_exchange( &p_, &v, std::move( w ) );
+        return compare_exchange( v, std::move( w ) );
     }
 
 #endif