boost/smart_ptr/detail/spinlock_sync.hpp

   1 #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_SYNC_HPP_INCLUDED
   2 #define BOOST_SMART_PTR_DETAIL_SPINLOCK_SYNC_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/smart_ptr/detail/yield_k.hpp>
  19
  20 #if defined( __ia64__ ) && defined( __INTEL_COMPILER )
  21 # include <ia64intrin.h>
  22 #endif
  23
  24 namespace boost
  25 {
  26
  27 namespace detail
  28 {
  29
  30 class spinlock
  31 {
  32 public:
  33
  34     int v_;
  35
  36 public:
  37
  38     bool try_lock()
  39     {
  40         int r = __sync_lock_test_and_set( &v_, 1 );
  41         return r == 0;
  42     }
  43
  44     void lock()
  45     {
  46         for( unsigned k = 0; !try_lock(); ++k )
  47         {
  48             boost::detail::yield( k );
  49         }
  50     }
  51
  52     void unlock()
  53     {
  54         __sync_lock_release( &v_ );
  55     }
  56
  57 public:
  58
  59     class scoped_lock
  60     {
  61     private:
  62
  63         spinlock & sp_;
  64
  65         scoped_lock( scoped_lock const & );
  66         scoped_lock & operator=( scoped_lock const & );
  67
  68     public:
  69
  70         explicit scoped_lock( spinlock & sp ): sp_( sp )
  71         {
  72             sp.lock();
  73         }
  74
  75         ~scoped_lock()
  76         {
  77             sp_.unlock();
  78         }
  79     };
  80 };
  81
  82 } // namespace detail
  83 } // namespace boost
  84
  85 #define BOOST_DETAIL_SPINLOCK_INIT {0}
  86
  87 #endif // #ifndef BOOST_SMART_PTR_DETAIL_SPINLOCK_SYNC_HPP_INCLUDED