boost/smart_ptr/detail/spinlock_w32.hpp

   1 #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_W32_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SPINLOCK_W32_HPP_INCLUDED
   3
   4 // MS compatible compilers support #pragma once
   5
   6 #if defined(_MSC_VER) && (_MSC_VER >= 1020)
   7 # pragma once
   8 #endif
   9
  10 //
  11 //  Copyright (c) 2008 Peter Dimov
  12 //
  13 //  Distributed under the Boost Software License, Version 1.0.
  14 //  See accompanying file LICENSE_1_0.txt or copy at
  15 //  http://www.boost.org/LICENSE_1_0.txt)
  16 //
  17
  18 #include <boost/detail/interlocked.hpp>
  19 #include <boost/smart_ptr/detail/yield_k.hpp>
  20
  21 // BOOST_COMPILER_FENCE
  22
  23 #if defined(__INTEL_COMPILER)
  24
  25 #define BOOST_COMPILER_FENCE __memory_barrier();
  26
  27 #elif defined( _MSC_VER ) && _MSC_VER >= 1310
  28
  29 extern "C" void _ReadWriteBarrier();
  30 #pragma intrinsic( _ReadWriteBarrier )
  31
  32 #define BOOST_COMPILER_FENCE _ReadWriteBarrier();
  33
  34 #elif defined(__GNUC__)
  35
  36 #define BOOST_COMPILER_FENCE __asm__ __volatile__( "" : : : "memory" );
  37
  38 #else
  39
  40 #define BOOST_COMPILER_FENCE
  41
  42 #endif
  43
  44 //
  45
  46 namespace boost
  47 {
  48
  49 namespace detail
  50 {
  51
  52 class spinlock
  53 {
  54 public:
  55
  56     long v_;
  57
  58 public:
  59
  60     bool try_lock()
  61     {
  62         long r = BOOST_INTERLOCKED_EXCHANGE( &v_, 1 );
  63
  64         BOOST_COMPILER_FENCE
  65
  66         return r == 0;
  67     }
  68
  69     void lock()
  70     {
  71         for( unsigned k = 0; !try_lock(); ++k )
  72         {
  73             boost::detail::yield( k );
  74         }
  75     }
  76
  77     void unlock()
  78     {
  79         BOOST_COMPILER_FENCE
  80         *const_cast< long volatile* >( &v_ ) = 0;
  81     }
  82
  83 public:
  84
  85     class scoped_lock
  86     {
  87     private:
  88
  89         spinlock & sp_;
  90
  91         scoped_lock( scoped_lock const & );
  92         scoped_lock & operator=( scoped_lock const & );
  93
  94     public:
  95
  96         explicit scoped_lock( spinlock & sp ): sp_( sp )
  97         {
  98             sp.lock();
  99         }
 100
 101         ~scoped_lock()
 102         {
 103             sp_.unlock();
 104         }
 105     };
 106 };
 107
 108 } // namespace detail
 109 } // namespace boost
 110
 111 #define BOOST_DETAIL_SPINLOCK_INIT {0}
 112
 113 #endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_W32_HPP_INCLUDED