libstdc++-v3/libsupc++/new_handler.cc

   1 // Implementation file for the -*- C++ -*- dynamic memory management header.
   2
   3 // Copyright (C) 1996-2017 Free Software Foundation, Inc.
   4 //
   5 // This file is part of GCC.
   6 //
   7 // GCC is free software; you can redistribute it and/or modify
   8 // it under the terms of the GNU General Public License as published by
   9 // the Free Software Foundation; either version 3, or (at your option)
  10 // any later version.
  11 //
  12 // GCC is distributed in the hope that it will be useful,
  13 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 // GNU General Public License for more details.
  16 //
  17 // Under Section 7 of GPL version 3, you are granted additional
  18 // permissions described in the GCC Runtime Library Exception, version
  19 // 3.1, as published by the Free Software Foundation.
  20
  21 // You should have received a copy of the GNU General Public License and
  22 // a copy of the GCC Runtime Library Exception along with this program;
  23 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 // <http://www.gnu.org/licenses/>.
  25
  26 #include "new"
  27 #include <bits/atomic_lockfree_defines.h>
  28
  29 #if ATOMIC_POINTER_LOCK_FREE < 2
  30 #include <ext/concurrence.h>
  31 namespace
  32 {
  33   __gnu_cxx::__mutex mx;
  34 }
  35 #endif
  36
  37 const std::nothrow_t std::nothrow = std::nothrow_t{ };
  38
  39 using std::new_handler;
  40 namespace
  41 {
  42   new_handler __new_handler;
  43 }
  44
  45 new_handler
  46 std::set_new_handler (new_handler handler) throw()
  47 {
  48   new_handler prev_handler;
  49 #if ATOMIC_POINTER_LOCK_FREE > 1
  50   __atomic_exchange (&__new_handler, &handler, &prev_handler,
  51                      __ATOMIC_ACQ_REL);
  52 #else
  53   __gnu_cxx::__scoped_lock l(mx);
  54   prev_handler = __new_handler;
  55   __new_handler = handler;
  56 #endif
  57   return prev_handler;
  58 }
  59
  60 new_handler
  61 std::get_new_handler () noexcept
  62 {
  63   new_handler handler;
  64 #if ATOMIC_POINTER_LOCK_FREE > 1
  65   __atomic_load (&__new_handler, &handler, __ATOMIC_ACQUIRE);
  66 #else
  67   __gnu_cxx::__scoped_lock l(mx);
  68   handler = __new_handler;
  69 #endif
  70   return handler;
  71 }