libstdc++-v3/src/mutex.cc

   1 // mutex -*- C++ -*-
   2
   3 // Copyright (C) 2008, 2009 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 #include <mutex>
  26
  27 #if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
  28 #ifndef _GLIBCXX_HAVE_TLS
  29 namespace
  30 {
  31   inline std::unique_lock<std::mutex>*&
  32   __get_once_functor_lock_ptr()
  33   {
  34     static std::unique_lock<std::mutex>* __once_functor_lock_ptr = 0;
  35     return __once_functor_lock_ptr;
  36   }
  37 }
  38 #endif
  39
  40 namespace std
  41 {
  42   const defer_lock_t defer_lock = defer_lock_t();
  43   const try_to_lock_t try_to_lock = try_to_lock_t();
  44   const adopt_lock_t adopt_lock = adopt_lock_t();
  45
  46 #ifdef _GLIBCXX_HAVE_TLS
  47   __thread void* __once_callable;
  48   __thread void (*__once_call)();
  49 #else
  50   // Explicit instantiation due to -fno-implicit-instantiation.
  51   template class function<void()>;
  52   function<void()> __once_functor;
  53
  54   mutex&
  55   __get_once_mutex()
  56   {
  57     static mutex once_mutex;
  58     return once_mutex;
  59   }
  60
  61   // code linked against ABI 3.4.12 and later uses this
  62   void
  63   __set_once_functor_lock_ptr(unique_lock<mutex>* __ptr)
  64   {
  65     __get_once_functor_lock_ptr() = __ptr;
  66   }
  67
  68   // unsafe - retained for compatibility with ABI 3.4.11
  69   unique_lock<mutex>&
  70   __get_once_functor_lock()
  71   {
  72     static unique_lock<mutex> once_functor_lock(__get_once_mutex(), defer_lock);
  73     return once_functor_lock;
  74   }
  75 #endif
  76
  77   extern "C"
  78   {
  79     void __once_proxy()
  80     {
  81 #ifndef _GLIBCXX_HAVE_TLS
  82       function<void()> __once_call = std::move(__once_functor);
  83       if (unique_lock<mutex>* __lock = __get_once_functor_lock_ptr())
  84       {
  85         // caller is using new ABI and provided lock ptr
  86         __get_once_functor_lock_ptr() = 0;
  87         __lock->unlock();
  88       }
  89       else
  90         __get_once_functor_lock().unlock();  // global lock
  91 #endif
  92       __once_call();
  93     }
  94   }
  95 }
  96
  97 #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1