gcc/libstdc++-v3/libsupc++/guard.cc

183 lines
4.4 KiB
C++

// Copyright (C) 2002 Free Software Foundation, Inc.
//
// This file is part of GCC.
//
// GCC is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.
// GCC is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with GCC; see the file COPYING. If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.
// As a special exception, you may use this file as part of a free software
// library without restriction. Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
// this file and link it with other files to produce an executable, this
// file does not by itself cause the resulting executable to be covered by
// the GNU General Public License. This exception does not however
// invalidate any other reasons why the executable file might be covered by
// the GNU General Public License.
// Written by Mark Mitchell, CodeSourcery LLC, <mark@codesourcery.com>
#include <cxxabi.h>
#include <exception>
#include <bits/c++config.h>
#include <bits/gthr.h>
// The IA64/generic ABI uses the first byte of the guard variable.
// The ARM EABI uses the least significant bit.
// Thread-safe static local initialization support.
#ifdef __GTHREADS
namespace
{
// static_mutex is a single mutex controlling all static initializations.
// This is a static class--the need for a static initialization function
// to pass to __gthread_once precludes creating multiple instances, though
// I suppose you could achieve the same effect with a template.
class static_mutex
{
static __gthread_recursive_mutex_t mutex;
#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION
static void init();
#endif
public:
static void lock();
static void unlock();
};
__gthread_recursive_mutex_t static_mutex::mutex
#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT
= __GTHREAD_RECURSIVE_MUTEX_INIT
#endif
;
#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION
void static_mutex::init()
{
__GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION (&mutex);
}
#endif
void static_mutex::lock()
{
#ifdef __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION
static __gthread_once_t once = __GTHREAD_ONCE_INIT;
__gthread_once (&once, init);
#endif
__gthread_recursive_mutex_lock (&mutex);
}
void static_mutex::unlock ()
{
__gthread_recursive_mutex_unlock (&mutex);
}
}
#endif
namespace __gnu_cxx
{
// 6.7[stmt.dcl]/4: If control re-enters the declaration (recursively)
// while the object is being initialized, the behavior is undefined.
// Since we already have a library function to handle locking, we might
// as well check for this situation and throw an exception.
// We use the second byte of the guard variable to remember that we're
// in the middle of an initialization.
class recursive_init: public std::exception
{
public:
recursive_init() throw() { }
virtual ~recursive_init() throw ();
};
recursive_init::~recursive_init() throw() { }
}
namespace __cxxabiv1
{
static int
acquire_1 (__guard *g)
{
if (_GLIBCXX_GUARD_ACQUIRE (g))
{
if (((char *)g)[1]++)
{
#ifdef __EXCEPTIONS
throw __gnu_cxx::recursive_init();
#else
abort ();
#endif
}
return 1;
}
return 0;
}
extern "C"
int __cxa_guard_acquire (__guard *g)
{
#ifdef __GTHREADS
if (__gthread_active_p ())
{
// Simple wrapper for exception safety.
struct mutex_wrapper
{
bool unlock;
mutex_wrapper (): unlock(true)
{
static_mutex::lock ();
}
~mutex_wrapper ()
{
if (unlock)
static_mutex::unlock ();
}
} mw;
if (acquire_1 (g))
{
mw.unlock = false;
return 1;
}
return 0;
}
#endif
return acquire_1 (g);
}
extern "C"
void __cxa_guard_abort (__guard *g)
{
((char *)g)[1]--;
#ifdef __GTHREADS
if (__gthread_active_p ())
static_mutex::unlock ();
#endif
}
extern "C"
void __cxa_guard_release (__guard *g)
{
((char *)g)[1]--;
_GLIBCXX_GUARD_RELEASE (g);
#ifdef __GTHREADS
if (__gthread_active_p ())
static_mutex::unlock ();
#endif
}
}