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// Allocator details.

// Copyright (C) 2004, 2005, 2006, 2009 Free Software Foundation, Inc.

//

// This file is part of the GNU ISO C++ Library.  This library 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 3, or (at your option)

// any later version.

// This library 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.

// Under Section 7 of GPL version 3, you are granted additional

// permissions described in the GCC Runtime Library Exception, version

// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and

// a copy of the GCC Runtime Library Exception along with this program;

// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

// <http://www.gnu.org/licenses/>.

//

// ISO C++ 14882:

//

#include <bits/c++config.h>

#include <cstdlib>

#include <ext/pool_allocator.h>

namespace

{

  __gnu_cxx::__mutex&

  get_palloc_mutex()

  {

    static __gnu_cxx::__mutex palloc_mutex;

    return palloc_mutex;

  }

} // anonymous namespace

namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  // Definitions for __pool_alloc_base.

  __pool_alloc_base::_Obj* volatile*

  __pool_alloc_base::_M_get_free_list(size_t __bytes) throw ()

  {

    size_t __i = ((__bytes + (size_t)_S_align - 1) / (size_t)_S_align - 1);

    return _S_free_list + __i;

  }

  __mutex&

  __pool_alloc_base::_M_get_mutex() throw ()

  { return get_palloc_mutex(); }

  // Allocate memory in large chunks in order to avoid fragmenting the

  // heap too much.  Assume that __n is properly aligned.  We hold the

  // allocation lock.

  char*

  __pool_alloc_base::_M_allocate_chunk(size_t __n, int& __nobjs)

  {

    char* __result;

    size_t __total_bytes = __n * __nobjs;

    size_t __bytes_left = _S_end_free - _S_start_free;

    if (__bytes_left >= __total_bytes)

      {

        __result = _S_start_free;

        _S_start_free += __total_bytes;

        return __result ;

      }

    else if (__bytes_left >= __n)

      {

        __nobjs = (int)(__bytes_left / __n);

        __total_bytes = __n * __nobjs;

        __result = _S_start_free;

        _S_start_free += __total_bytes;

        return __result;

      }

    else

      {

        // Try to make use of the left-over piece.

        if (__bytes_left > 0)

          {

            _Obj* volatile* __free_list = _M_get_free_list(__bytes_left);

            ((_Obj*)(void*)_S_start_free)->_M_free_list_link = *__free_list;

            *__free_list = (_Obj*)(void*)_S_start_free;

          }

        size_t __bytes_to_get = (2 * __total_bytes

                                 + _M_round_up(_S_heap_size >> 4));

        __try

          {

            _S_start_free = static_cast<char*>(::operator new(__bytes_to_get));

          }

        __catch(const std::bad_alloc&)

          {

            // Try to make do with what we have.  That can't hurt.  We

            // do not try smaller requests, since that tends to result

            // in disaster on multi-process machines.

            size_t __i = __n;

            for (; __i <= (size_t) _S_max_bytes; __i += (size_t) _S_align)

              {

                _Obj* volatile* __free_list = _M_get_free_list(__i);

                _Obj* __p = *__free_list;

                if (__p != 0)

                  {

                    *__free_list = __p->_M_free_list_link;

                    _S_start_free = (char*)__p;

                    _S_end_free = _S_start_free + __i;

                    return _M_allocate_chunk(__n, __nobjs);

                    // Any leftover piece will eventually make it to the

                    // right free list.

                  }

              }

            // What we have wasn't enough.  Rethrow.

            _S_start_free = _S_end_free = 0;   // We have no chunk.

            __throw_exception_again;

          }

        _S_heap_size += __bytes_to_get;

        _S_end_free = _S_start_free + __bytes_to_get;

        return _M_allocate_chunk(__n, __nobjs);

      }

  }

  // Returns an object of size __n, and optionally adds to "size

  // __n"'s free list.  We assume that __n is properly aligned.  We

  // hold the allocation lock.

  void*

  __pool_alloc_base::_M_refill(size_t __n)

  {

    int __nobjs = 20;

    char* __chunk = _M_allocate_chunk(__n, __nobjs);

    _Obj* volatile* __free_list;

    _Obj* __result;

    _Obj* __current_obj;

    _Obj* __next_obj;

    if (__nobjs == 1)

      return __chunk;

    __free_list = _M_get_free_list(__n);

    // Build free list in chunk.

    __result = (_Obj*)(void*)__chunk;

    *__free_list = __next_obj = (_Obj*)(void*)(__chunk + __n);

    for (int __i = 1; ; __i++)

      {

        __current_obj = __next_obj;

        __next_obj = (_Obj*)(void*)((char*)__next_obj + __n);

        if (__nobjs - 1 == __i)

          {

            __current_obj->_M_free_list_link = 0;

            break;

          }

        else

          __current_obj->_M_free_list_link = __next_obj;

      }

    return __result;

  }

  __pool_alloc_base::_Obj* volatile __pool_alloc_base::_S_free_list[_S_free_list_size];

  char* __pool_alloc_base::_S_start_free = 0;

  char* __pool_alloc_base::_S_end_free = 0;

  size_t __pool_alloc_base::_S_heap_size = 0;

  // Instantiations.

  template class __pool_alloc<char>;

  template class __pool_alloc<wchar_t>;

_GLIBCXX_END_NAMESPACE_VERSION

} // namespace