From b51965dddbed68f23c5e8c169c23c794313ce5f6 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 28 Jun 2011 17:17:23 +0200
Subject: Add boost subset as an implementation detail

---
 .../boost/smart_ptr/detail/atomic_count.hpp        | 119 +++++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 cutl/details/boost/smart_ptr/detail/atomic_count.hpp

(limited to 'cutl/details/boost/smart_ptr/detail/atomic_count.hpp')

diff --git a/cutl/details/boost/smart_ptr/detail/atomic_count.hpp b/cutl/details/boost/smart_ptr/detail/atomic_count.hpp
new file mode 100644
index 0000000..f9de4a4
--- /dev/null
+++ b/cutl/details/boost/smart_ptr/detail/atomic_count.hpp
@@ -0,0 +1,119 @@
+#ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_HPP_INCLUDED
+#define BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_HPP_INCLUDED
+
+// MS compatible compilers support #pragma once
+
+#if defined(_MSC_VER) && (_MSC_VER >= 1020)
+# pragma once
+#endif
+
+//
+//  boost/detail/atomic_count.hpp - thread/SMP safe reference counter
+//
+//  Copyright (c) 2001, 2002 Peter Dimov and Multi Media Ltd.
+//
+// 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)
+//
+//  typedef <implementation-defined> cutl_details_boost::detail::atomic_count;
+//
+//  atomic_count a(n);
+//
+//    (n is convertible to long)
+//
+//    Effects: Constructs an atomic_count with an initial value of n
+//
+//  a;
+//
+//    Returns: (long) the current value of a
+//
+//  ++a;
+//
+//    Effects: Atomically increments the value of a
+//    Returns: (long) the new value of a
+//
+//  --a;
+//
+//    Effects: Atomically decrements the value of a
+//    Returns: (long) the new value of a
+//
+//    Important note: when --a returns zero, it must act as a
+//      read memory barrier (RMB); i.e. the calling thread must
+//      have a synchronized view of the memory
+//
+//    On Intel IA-32 (x86) memory is always synchronized, so this
+//      is not a problem.
+//
+//    On many architectures the atomic instructions already act as
+//      a memory barrier.
+//
+//    This property is necessary for proper reference counting, since
+//      a thread can update the contents of a shared object, then
+//      release its reference, and another thread may immediately
+//      release the last reference causing object destruction.
+//
+//    The destructor needs to have a synchronized view of the
+//      object to perform proper cleanup.
+//
+//    Original example by Alexander Terekhov:
+//
+//    Given:
+//
+//    - a mutable shared object OBJ;
+//    - two threads THREAD1 and THREAD2 each holding 
+//      a private smart_ptr object pointing to that OBJ.
+//
+//    t1: THREAD1 updates OBJ (thread-safe via some synchronization)
+//      and a few cycles later (after "unlock") destroys smart_ptr;
+//
+//    t2: THREAD2 destroys smart_ptr WITHOUT doing any synchronization 
+//      with respect to shared mutable object OBJ; OBJ destructors
+//      are called driven by smart_ptr interface...
+//
+
+#include <cutl/details/boost/config.hpp>
+#include <cutl/details/boost/smart_ptr/detail/sp_has_sync.hpp>
+
+#ifndef BOOST_HAS_THREADS
+
+namespace cutl_details_boost
+{
+
+namespace detail
+{
+
+typedef long atomic_count;
+
+}
+
+}
+
+#elif defined(BOOST_AC_USE_PTHREADS)
+#  include <cutl/details/boost/smart_ptr/detail/atomic_count_pthreads.hpp>
+
+#elif defined( __GNUC__ ) && ( defined( __i386__ ) || defined( __x86_64__ ) )
+#  include <cutl/details/boost/smart_ptr/detail/atomic_count_gcc_x86.hpp>
+
+#elif defined(WIN32) || defined(_WIN32) || defined(__WIN32__) || defined(__CYGWIN__)
+#  include <cutl/details/boost/smart_ptr/detail/atomic_count_win32.hpp>
+
+#elif defined( BOOST_SP_HAS_SYNC )
+#  include <cutl/details/boost/smart_ptr/detail/atomic_count_sync.hpp>
+
+#elif defined(__GLIBCPP__) || defined(__GLIBCXX__)
+#  include <cutl/details/boost/smart_ptr/detail/atomic_count_gcc.hpp>
+
+#elif defined(BOOST_HAS_PTHREADS)
+
+#  define BOOST_AC_USE_PTHREADS
+#  include <cutl/details/boost/smart_ptr/detail/atomic_count_pthreads.hpp>
+
+#else
+
+// Use #define BOOST_DISABLE_THREADS to avoid the error
+#error Unrecognized threading platform
+
+#endif
+
+#endif // #ifndef BOOST_SMART_PTR_DETAIL_ATOMIC_COUNT_HPP_INCLUDED
-- 
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