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

   1 // Copyright (C) 2012-2014 Free Software Foundation, Inc.
   2 //
   3 // This file is part of GCC.
   4 //
   5 // GCC is free software; you can redistribute it and/or modify
   6 // it under the terms of the GNU General Public License as published by
   7 // the Free Software Foundation; either version 3, or (at your option)
   8 // any later version.
   9
  10 // GCC is distributed in the hope that it will be useful,
  11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 // GNU General Public License for more details.
  14
  15 // Under Section 7 of GPL version 3, you are granted additional
  16 // permissions described in the GCC Runtime Library Exception, version
  17 // 3.1, as published by the Free Software Foundation.
  18
  19 // You should have received a copy of the GNU General Public License and
  20 // a copy of the GCC Runtime Library Exception along with this program;
  21 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  22 // <http://www.gnu.org/licenses/>.
  23
  24 #include <cxxabi.h>
  25 #include <cstdlib>
  26 #include <new>
  27 #include "bits/gthr.h"
  28
  29 #if HAVE___CXA_THREAD_ATEXIT_IMPL
  30
  31 extern "C" int __cxa_thread_atexit_impl (void (*func) (void *),
  32                                          void *arg, void *d);
  33 extern "C" int
  34 __cxxabiv1::__cxa_thread_atexit (void (*dtor)(void *),
  35                                  void *obj, void *dso_handle)
  36   _GLIBCXX_NOTHROW
  37 {
  38   return __cxa_thread_atexit_impl (dtor, obj, dso_handle);
  39 }
  40
  41 #else /* HAVE___CXA_THREAD_ATEXIT_IMPL */
  42
  43 namespace {
  44   // One element in a singly-linked stack of cleanups.
  45   struct elt
  46   {
  47     void (*destructor)(void *);
  48     void *object;
  49     elt *next;
  50   };
  51
  52   // Keep a per-thread list of cleanups in gthread_key storage.
  53   __gthread_key_t key;
  54   // But also support non-threaded mode.
  55   elt *single_thread;
  56
  57   // Run the specified stack of cleanups.
  58   void run (void *p)
  59   {
  60     elt *e = static_cast<elt*>(p);
  61     while (e)
  62       {
  63         elt *old_e = e;
  64         e->destructor (e->object);
  65         e = e->next;
  66         delete (old_e);
  67       }
  68   }
  69
  70   // Run the stack of cleanups for the current thread.
  71   void run ()
  72   {
  73     void *e;
  74     if (__gthread_active_p ())
  75       {
  76         e = __gthread_getspecific (key);
  77         __gthread_setspecific (key, NULL);
  78       }
  79     else
  80       {
  81         e = single_thread;
  82         single_thread = NULL;
  83       }
  84     run (e);
  85   }
  86
  87   // Initialize the key for the cleanup stack.  We use a static local for
  88   // key init/delete rather than atexit so that delete is run on dlclose.
  89   void key_init() {
  90     struct key_s {
  91       key_s() { __gthread_key_create (&key, run); }
  92       ~key_s() { __gthread_key_delete (key); }
  93     };
  94     static key_s ks;
  95     // Also make sure the destructors are run by std::exit.
  96     // FIXME TLS cleanups should run before static cleanups and atexit
  97     // cleanups.
  98     std::atexit (run);
  99   }
 100 }
 101
 102 extern "C" int
 103 __cxxabiv1::__cxa_thread_atexit (void (*dtor)(void *), void *obj, void */*dso_handle*/)
 104   _GLIBCXX_NOTHROW
 105 {
 106   // Do this initialization once.
 107   if (__gthread_active_p ())
 108     {
 109       // When threads are active use __gthread_once.
 110       static __gthread_once_t once = __GTHREAD_ONCE_INIT;
 111       __gthread_once (&once, key_init);
 112     }
 113   else
 114     {
 115       // And when threads aren't active use a static local guard.
 116       static bool queued;
 117       if (!queued)
 118         {
 119           queued = true;
 120           std::atexit (run);
 121         }
 122     }
 123
 124   elt *first;
 125   if (__gthread_active_p ())
 126     first = static_cast<elt*>(__gthread_getspecific (key));
 127   else
 128     first = single_thread;
 129
 130   elt *new_elt = new (std::nothrow) elt;
 131   if (!new_elt)
 132     return -1;
 133   new_elt->destructor = dtor;
 134   new_elt->object = obj;
 135   new_elt->next = first;
 136
 137   if (__gthread_active_p ())
 138     __gthread_setspecific (key, new_elt);
 139   else
 140     single_thread = new_elt;
 141
 142   return 0;
 143 }
 144
 145 #endif /* HAVE___CXA_THREAD_ATEXIT_IMPL */