From e6605637f8c22aac4155f83c1fac5de3b49a751d Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Sat, 16 Feb 2002 18:45:20 +0000
Subject: [PATCH] BOOST_LWM_WIN32_USE_CRITICAL_SECTION option.

[SVN r12842]
---
 include/boost/detail/lwm_win32.hpp | 59 +++++++++++++++++++++++++++++-
 shared_ptr_mt_test.cpp             |  9 ++++-
 2 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/include/boost/detail/lwm_win32.hpp b/include/boost/detail/lwm_win32.hpp
index 60388d5..8bcd469 100644
--- a/include/boost/detail/lwm_win32.hpp
+++ b/include/boost/detail/lwm_win32.hpp
@@ -16,12 +16,18 @@
 //  warranty, and with no claim as to its suitability for any purpose.
 //
 
+#ifndef BOOST_LWM_WIN32_USE_CRITICAL_SECTION
+# include <windows.h>
+#endif
+
 namespace boost
 {
 
 namespace detail
 {
 
+#ifndef BOOST_LWM_WIN32_USE_CRITICAL_SECTION
+
 // avoid including <windows.h>
 
 extern "C" __declspec(dllimport) long __stdcall InterlockedExchange(long volatile *, long);
@@ -67,13 +73,64 @@ public:
 
             // Note: adding a Sleep(0) here will make
             // the mutex more fair and will increase the overall
-            // performance of the application substantially in
+            // performance of some applications substantially in
             // high contention situations, but will penalize the
             // low contention / single thread case up to 5x
         }
     };
 };
 
+#else
+
+class lightweight_mutex
+{
+private:
+
+    CRITICAL_SECTION cs_;
+
+    lightweight_mutex(lightweight_mutex const &);
+    lightweight_mutex & operator=(lightweight_mutex const &);
+
+public:
+
+    lightweight_mutex()
+    {
+        ::InitializeCriticalSection(&cs_);
+    }
+
+    ~lightweight_mutex()
+    {
+        ::DeleteCriticalSection(&cs_);
+    }
+
+    class scoped_lock;
+    friend class scoped_lock;
+
+    class scoped_lock
+    {
+    private:
+
+        lightweight_mutex & m_;
+
+        scoped_lock(scoped_lock const &);
+        scoped_lock & operator=(scoped_lock const &);
+
+    public:
+
+        explicit scoped_lock(lightweight_mutex & m): m_(m)
+        {
+            ::EnterCriticalSection(&m_.cs_);
+        }
+
+        ~scoped_lock()
+        {
+            ::LeaveCriticalSection(&m_.cs_);
+        }
+    };
+};
+
+#endif
+
 } // namespace detail
 
 } // namespace boost
diff --git a/shared_ptr_mt_test.cpp b/shared_ptr_mt_test.cpp
index af48918..2511716 100644
--- a/shared_ptr_mt_test.cpp
+++ b/shared_ptr_mt_test.cpp
@@ -19,6 +19,9 @@
 #include <boost/shared_ptr.hpp>
 #include <boost/bind.hpp>
 
+#define BOOST_INCLUDE_MAIN
+#include <boost/test/test_tools.hpp>
+
 #include <vector>
 #include <memory>
 #include <stdexcept>
@@ -141,11 +144,11 @@ void test(boost::shared_ptr<int> const & pi)
 
 int const m = 16; // threads
 
-int main()
+int test_main( int, char ** )
 {
     std::puts(title);
 
-    boost::shared_ptr<int> pi(new int);
+    boost::shared_ptr<int> pi(new int(42));
 
     pthread_t a[m];
 
@@ -158,4 +161,6 @@ int main()
     {
         pthread_join(a[i], 0);
     }
+
+    return 0;
 }