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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 <ext/concurrence.h>

#include <ext/mt_allocator.h>

#include <cstring>

namespace

{

#ifdef __GTHREADS

  struct __freelist

  {

    typedef __gnu_cxx::__pool<true>::_Thread_record _Thread_record;

    _Thread_record*     _M_thread_freelist;

    _Thread_record*     _M_thread_freelist_array;

    size_t              _M_max_threads;

    __gthread_key_t     _M_key;

    ~__freelist()

    {

      if (_M_thread_freelist_array)

        {

          __gthread_key_delete(_M_key);

          ::operator delete(static_cast<void*>(_M_thread_freelist_array));

        }

    }

  };

  __freelist&

  get_freelist()

  {

    static __freelist freelist;

    return freelist;

  }

  __gnu_cxx::__mutex&

  get_freelist_mutex()

  {

    static __gnu_cxx::__mutex freelist_mutex;

    return freelist_mutex;

  }

  static void

  _M_destroy_thread_key(void* __id)

  {

    // Return this thread id record to the front of thread_freelist.

    __freelist& freelist = get_freelist();

    {

      __gnu_cxx::__scoped_lock sentry(get_freelist_mutex());

      size_t _M_id = reinterpret_cast<size_t>(__id);

      typedef __gnu_cxx::__pool<true>::_Thread_record _Thread_record;

      _Thread_record* __tr = &freelist._M_thread_freelist_array[_M_id - 1];

      __tr->_M_next = freelist._M_thread_freelist;

      freelist._M_thread_freelist = __tr;

    }

  }

#endif

} // anonymous namespace

_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)

  void

  __pool<false>::_M_destroy() throw()

  {

    if (_M_init && !_M_options._M_force_new)

      {

        for (size_t __n = 0; __n < _M_bin_size; ++__n)

          {

            _Bin_record& __bin = _M_bin[__n];

            while (__bin._M_address)

              {

                _Block_address* __tmp = __bin._M_address->_M_next;

                ::operator delete(__bin._M_address->_M_initial);

                __bin._M_address = __tmp;

              }

            ::operator delete(__bin._M_first);

          }

        ::operator delete(_M_bin);

        ::operator delete(_M_binmap);

      }

  }

  void

  __pool<false>::_M_reclaim_block(char* __p, size_t __bytes) throw ()

  {

    // Round up to power of 2 and figure out which bin to use.

    const size_t __which = _M_binmap[__bytes];

    _Bin_record& __bin = _M_bin[__which];

    char* __c = __p - _M_get_align();

    _Block_record* __block = reinterpret_cast<_Block_record*>(__c);

    // Single threaded application - return to global pool.

    __block->_M_next = __bin._M_first[0];

    __bin._M_first[0] = __block;

  }

  char*

  __pool<false>::_M_reserve_block(size_t __bytes, const size_t __thread_id)

  {

    // Round up to power of 2 and figure out which bin to use.

    const size_t __which = _M_binmap[__bytes];

    _Bin_record& __bin = _M_bin[__which];

    const _Tune& __options = _M_get_options();

    const size_t __bin_size = (__options._M_min_bin << __which)

                               + __options._M_align;

    size_t __block_count = __options._M_chunk_size - sizeof(_Block_address);

    __block_count /= __bin_size;

    // Get a new block dynamically, set it up for use.

    void* __v = ::operator new(__options._M_chunk_size);

    _Block_address* __address = static_cast<_Block_address*>(__v);

    __address->_M_initial = __v;

    __address->_M_next = __bin._M_address;

    __bin._M_address = __address;

    char* __c = static_cast<char*>(__v) + sizeof(_Block_address);

    _Block_record* __block = reinterpret_cast<_Block_record*>(__c);

    __bin._M_first[__thread_id] = __block;

    while (--__block_count > 0)

      {

        __c += __bin_size;

        __block->_M_next = reinterpret_cast<_Block_record*>(__c);

        __block = __block->_M_next;

      }

    __block->_M_next = NULL;

    __block = __bin._M_first[__thread_id];

    __bin._M_first[__thread_id] = __block->_M_next;

    // NB: For alignment reasons, we can't use the first _M_align

    // bytes, even when sizeof(_Block_record) < _M_align.

    return reinterpret_cast<char*>(__block) + __options._M_align;

  }

  void

  __pool<false>::_M_initialize()

  {

    // _M_force_new must not change after the first allocate(), which

    // in turn calls this method, so if it's false, it's false forever

    // and we don't need to return here ever again.

    if (_M_options._M_force_new)

      {

        _M_init = true;

        return;

      }

    // Create the bins.

    // Calculate the number of bins required based on _M_max_bytes.

    // _M_bin_size is statically-initialized to one.

    size_t __bin_size = _M_options._M_min_bin;

    while (_M_options._M_max_bytes > __bin_size)

      {

        __bin_size <<= 1;

        ++_M_bin_size;

      }

    // Setup the bin map for quick lookup of the relevant bin.

    const size_t __j = (_M_options._M_max_bytes + 1) * sizeof(_Binmap_type);

    _M_binmap = static_cast<_Binmap_type*>(::operator new(__j));

    _Binmap_type* __bp = _M_binmap;

    _Binmap_type __bin_max = _M_options._M_min_bin;

    _Binmap_type __bint = 0;

    for (_Binmap_type __ct = 0; __ct <= _M_options._M_max_bytes; ++__ct)

      {

        if (__ct > __bin_max)

          {

            __bin_max <<= 1;

            ++__bint;

          }

        *__bp++ = __bint;

      }

    // Initialize _M_bin and its members.

    void* __v = ::operator new(sizeof(_Bin_record) * _M_bin_size);

    _M_bin = static_cast<_Bin_record*>(__v);

    for (size_t __n = 0; __n < _M_bin_size; ++__n)

      {

        _Bin_record& __bin = _M_bin[__n];

        __v = ::operator new(sizeof(_Block_record*));

        __bin._M_first = static_cast<_Block_record**>(__v);

        __bin._M_first[0] = NULL;

        __bin._M_address = NULL;

      }

    _M_init = true;

  }

#ifdef __GTHREADS

  void

  __pool<true>::_M_destroy() throw()

  {

    if (_M_init && !_M_options._M_force_new)

      {

        if (__gthread_active_p())

          {

            for (size_t __n = 0; __n < _M_bin_size; ++__n)

              {

                _Bin_record& __bin = _M_bin[__n];

                while (__bin._M_address)

                  {

                    _Block_address* __tmp = __bin._M_address->_M_next;

                    ::operator delete(__bin._M_address->_M_initial);

                    __bin._M_address = __tmp;

                  }

                ::operator delete(__bin._M_first);

                ::operator delete(__bin._M_free);

                ::operator delete(__bin._M_used);

                ::operator delete(__bin._M_mutex);

              }

          }

        else

          {

            for (size_t __n = 0; __n < _M_bin_size; ++__n)

              {

                _Bin_record& __bin = _M_bin[__n];

                while (__bin._M_address)

                  {

                    _Block_address* __tmp = __bin._M_address->_M_next;

                    ::operator delete(__bin._M_address->_M_initial);

                    __bin._M_address = __tmp;

                  }

                ::operator delete(__bin._M_first);

              }

          }

        ::operator delete(_M_bin);

        ::operator delete(_M_binmap);

      }

  }

  void

  __pool<true>::_M_reclaim_block(char* __p, size_t __bytes) throw ()

  {

    // Round up to power of 2 and figure out which bin to use.

    const size_t __which = _M_binmap[__bytes];

    const _Bin_record& __bin = _M_bin[__which];

    // Know __p not null, assume valid block.

    char* __c = __p - _M_get_align();

    _Block_record* __block = reinterpret_cast<_Block_record*>(__c);

    if (__gthread_active_p())

      {

        // Calculate the number of records to remove from our freelist:

        // in order to avoid too much contention we wait until the

        // number of records is "high enough".

        const size_t __thread_id = _M_get_thread_id();

        const _Tune& __options = _M_get_options();

        const size_t __limit = (100 * (_M_bin_size - __which)

                                * __options._M_freelist_headroom);

        size_t __remove = __bin._M_free[__thread_id];

        __remove *= __options._M_freelist_headroom;

        // NB: We assume that reads of _Atomic_words are atomic.

        const size_t __max_threads = __options._M_max_threads + 1;

        _Atomic_word* const __reclaimed_base =

          reinterpret_cast<_Atomic_word*>(__bin._M_used + __max_threads);

        const _Atomic_word __reclaimed = __reclaimed_base[__thread_id];

        const size_t __net_used = __bin._M_used[__thread_id] - __reclaimed;

        // NB: For performance sake we don't resync every time, in order

        // to spare atomic ops.  Note that if __reclaimed increased by,

        // say, 1024, since the last sync, it means that the other

        // threads executed the atomic in the else below at least the

        // same number of times (at least, because _M_reserve_block may

        // have decreased the counter), therefore one more cannot hurt.

        if (__reclaimed > 1024)

          {

            __bin._M_used[__thread_id] -= __reclaimed;

            __atomic_add(&__reclaimed_base[__thread_id], -__reclaimed);

          }

        if (__remove >= __net_used)

          __remove -= __net_used;

        else

          __remove = 0;

        if (__remove > __limit && __remove > __bin._M_free[__thread_id])

          {

            _Block_record* __first = __bin._M_first[__thread_id];

            _Block_record* __tmp = __first;

            __remove /= __options._M_freelist_headroom;

            const size_t __removed = __remove;

            while (--__remove > 0)

              __tmp = __tmp->_M_next;

            __bin._M_first[__thread_id] = __tmp->_M_next;

            __bin._M_free[__thread_id] -= __removed;

            __gthread_mutex_lock(__bin._M_mutex);

            __tmp->_M_next = __bin._M_first[0];

            __bin._M_first[0] = __first;

            __bin._M_free[0] += __removed;

            __gthread_mutex_unlock(__bin._M_mutex);

          }

        // Return this block to our list and update counters and

        // owner id as needed.

        if (__block->_M_thread_id == __thread_id)

          --__bin._M_used[__thread_id];

        else

          __atomic_add(&__reclaimed_base[__block->_M_thread_id], 1);

        __block->_M_next = __bin._M_first[__thread_id];

        __bin._M_first[__thread_id] = __block;

        ++__bin._M_free[__thread_id];

      }

    else

      {

        // Not using threads, so single threaded application - return

        // to global pool.

        __block->_M_next = __bin._M_first[0];

        __bin._M_first[0] = __block;

      }

  }

  char*

  __pool<true>::_M_reserve_block(size_t __bytes, const size_t __thread_id)

  {

    // Round up to power of 2 and figure out which bin to use.

    const size_t __which = _M_binmap[__bytes];

    const _Tune& __options = _M_get_options();

    const size_t __bin_size = ((__options._M_min_bin << __which)

                               + __options._M_align);

    size_t __block_count = __options._M_chunk_size - sizeof(_Block_address);

    __block_count /= __bin_size;

    // Are we using threads?

    // - Yes, check if there are free blocks on the global

    //   list. If so, grab up to __block_count blocks in one

    //   lock and change ownership. If the global list is 

    //   empty, we allocate a new chunk and add those blocks 

    //   directly to our own freelist (with us as owner).

    // - No, all operations are made directly to global pool 0

    //   no need to lock or change ownership but check for free

    //   blocks on global list (and if not add new ones) and

    //   get the first one.

    _Bin_record& __bin = _M_bin[__which];

    _Block_record* __block = NULL;

    if (__gthread_active_p())

      {

        // Resync the _M_used counters.

        const size_t __max_threads = __options._M_max_threads + 1;

        _Atomic_word* const __reclaimed_base =

          reinterpret_cast<_Atomic_word*>(__bin._M_used + __max_threads);

        const _Atomic_word __reclaimed = __reclaimed_base[__thread_id];

        __bin._M_used[__thread_id] -= __reclaimed;

        __atomic_add(&__reclaimed_base[__thread_id], -__reclaimed);

        __gthread_mutex_lock(__bin._M_mutex);

        if (__bin._M_first[0] == NULL)

          {

            void* __v = ::operator new(__options._M_chunk_size);

            _Block_address* __address = static_cast<_Block_address*>(__v);

            __address->_M_initial = __v;

            __address->_M_next = __bin._M_address;

            __bin._M_address = __address;

            __gthread_mutex_unlock(__bin._M_mutex);

            // No need to hold the lock when we are adding a whole

            // chunk to our own list.

            char* __c = static_cast<char*>(__v) + sizeof(_Block_address);

            __block = reinterpret_cast<_Block_record*>(__c);

            __bin._M_free[__thread_id] = __block_count;

            __bin._M_first[__thread_id] = __block;

            while (--__block_count > 0)

              {

                __c += __bin_size;

                __block->_M_next = reinterpret_cast<_Block_record*>(__c);

                __block = __block->_M_next;

              }

            __block->_M_next = NULL;

          }

        else

          {

            // Is the number of required blocks greater than or equal

            // to the number that can be provided by the global free

            // list?

            __bin._M_first[__thread_id] = __bin._M_first[0];

            if (__block_count >= __bin._M_free[0])

              {

                __bin._M_free[__thread_id] = __bin._M_free[0];

                __bin._M_free[0] = 0;

                __bin._M_first[0] = NULL;

              }

            else

              {

                __bin._M_free[__thread_id] = __block_count;

                __bin._M_free[0] -= __block_count;

                __block = __bin._M_first[0];

                while (--__block_count > 0)

                  __block = __block->_M_next;

                __bin._M_first[0] = __block->_M_next;

                __block->_M_next = NULL;

              }

            __gthread_mutex_unlock(__bin._M_mutex);

          }

      }

    else

      {

        void* __v = ::operator new(__options._M_chunk_size);

        _Block_address* __address = static_cast<_Block_address*>(__v);

        __address->_M_initial = __v;

        __address->_M_next = __bin._M_address;

        __bin._M_address = __address;

        char* __c = static_cast<char*>(__v) + sizeof(_Block_address);

        __block = reinterpret_cast<_Block_record*>(__c);

        __bin._M_first[0] = __block;

        while (--__block_count > 0)

          {

            __c += __bin_size;

            __block->_M_next = reinterpret_cast<_Block_record*>(__c);

            __block = __block->_M_next;

          }

        __block->_M_next = NULL;

      }

    __block = __bin._M_first[__thread_id];

    __bin._M_first[__thread_id] = __block->_M_next;

    if (__gthread_active_p())

      {

        __block->_M_thread_id = __thread_id;

        --__bin._M_free[__thread_id];

        ++__bin._M_used[__thread_id];

      }

    // NB: For alignment reasons, we can't use the first _M_align

    // bytes, even when sizeof(_Block_record) < _M_align.

    return reinterpret_cast<char*>(__block) + __options._M_align;

  }

  void

  __pool<true>::_M_initialize()

  {

    // _M_force_new must not change after the first allocate(),

    // which in turn calls this method, so if it's false, it's false

    // forever and we don't need to return here ever again.

    if (_M_options._M_force_new)

      {

        _M_init = true;

        return;

      }

    // Create the bins.

    // Calculate the number of bins required based on _M_max_bytes.

    // _M_bin_size is statically-initialized to one.

    size_t __bin_size = _M_options._M_min_bin;

    while (_M_options._M_max_bytes > __bin_size)

      {

        __bin_size <<= 1;

        ++_M_bin_size;

      }

    // Setup the bin map for quick lookup of the relevant bin.

    const size_t __j = (_M_options._M_max_bytes + 1) * sizeof(_Binmap_type);

    _M_binmap = static_cast<_Binmap_type*>(::operator new(__j));

    _Binmap_type* __bp = _M_binmap;

    _Binmap_type __bin_max = _M_options._M_min_bin;

    _Binmap_type __bint = 0;

    for (_Binmap_type __ct = 0; __ct <= _M_options._M_max_bytes; ++__ct)

      {

        if (__ct > __bin_max)

          {

            __bin_max <<= 1;

            ++__bint;

          }

        *__bp++ = __bint;

      }

    // Initialize _M_bin and its members.

    void* __v = ::operator new(sizeof(_Bin_record) * _M_bin_size);

    _M_bin = static_cast<_Bin_record*>(__v);

    // If __gthread_active_p() create and initialize the list of

    // free thread ids. Single threaded applications use thread id 0

    // directly and have no need for this.

    if (__gthread_active_p())

      {

        __freelist& freelist = get_freelist();

        {

          __gnu_cxx::__scoped_lock sentry(get_freelist_mutex());

          if (!freelist._M_thread_freelist_array

              || freelist._M_max_threads < _M_options._M_max_threads)

            {

              const size_t __k = sizeof(_Thread_record)

                                 * _M_options._M_max_threads;

              __v = ::operator new(__k);

              _M_thread_freelist = static_cast<_Thread_record*>(__v);

              // NOTE! The first assignable thread id is 1 since the

              // global pool uses id 0

              size_t __i;

              for (__i = 1; __i < _M_options._M_max_threads; ++__i)

                {

                  _Thread_record& __tr = _M_thread_freelist[__i - 1];

                  __tr._M_next = &_M_thread_freelist[__i];

                  __tr._M_id = __i;

                }

              // Set last record.

              _M_thread_freelist[__i - 1]._M_next = NULL;

              _M_thread_freelist[__i - 1]._M_id = __i;

              if (!freelist._M_thread_freelist_array)

                {

                  // Initialize per thread key to hold pointer to

                  // _M_thread_freelist.

                  __gthread_key_create(&freelist._M_key,

                                       ::_M_destroy_thread_key);

                  freelist._M_thread_freelist = _M_thread_freelist;

                }

              else

                {

                  _Thread_record* _M_old_freelist

                    = freelist._M_thread_freelist;

                  _Thread_record* _M_old_array

                    = freelist._M_thread_freelist_array;

                  freelist._M_thread_freelist

                    = &_M_thread_freelist[_M_old_freelist - _M_old_array];

                  while (_M_old_freelist)

                    {

                      size_t next_id;

                      if (_M_old_freelist->_M_next)

                        next_id = _M_old_freelist->_M_next - _M_old_array;

                      else

                        next_id = freelist._M_max_threads;

                      _M_thread_freelist[_M_old_freelist->_M_id - 1]._M_next

                        = &_M_thread_freelist[next_id];

                      _M_old_freelist = _M_old_freelist->_M_next;

                    }

                  ::operator delete(static_cast<void*>(_M_old_array));

                }

              freelist._M_thread_freelist_array = _M_thread_freelist;

              freelist._M_max_threads = _M_options._M_max_threads;

            }

        }

        const size_t __max_threads = _M_options._M_max_threads + 1;

        for (size_t __n = 0; __n < _M_bin_size; ++__n)

          {

            _Bin_record& __bin = _M_bin[__n];

            __v = ::operator new(sizeof(_Block_record*) * __max_threads);

            std::memset(__v, 0, sizeof(_Block_record*) * __max_threads);

            __bin._M_first = static_cast<_Block_record**>(__v);

            __bin._M_address = NULL;

            __v = ::operator new(sizeof(size_t) * __max_threads);

            std::memset(__v, 0, sizeof(size_t) * __max_threads);

            __bin._M_free = static_cast<size_t*>(__v);

            __v = ::operator new(sizeof(size_t) * __max_threads

                                 + sizeof(_Atomic_word) * __max_threads);

            std::memset(__v, 0, (sizeof(size_t) * __max_threads

                                 + sizeof(_Atomic_word) * __max_threads));

            __bin._M_used = static_cast<size_t*>(__v);

            __v = ::operator new(sizeof(__gthread_mutex_t));

            __bin._M_mutex = static_cast<__gthread_mutex_t*>(__v);

#ifdef __GTHREAD_MUTEX_INIT

            {

              // Do not copy a POSIX/gthr mutex once in use.

              __gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;

              *__bin._M_mutex = __tmp;

            }

#else

            { __GTHREAD_MUTEX_INIT_FUNCTION(__bin._M_mutex); }

#endif

          }

      }

    else

      {

        for (size_t __n = 0; __n < _M_bin_size; ++__n)

          {

            _Bin_record& __bin = _M_bin[__n];

            __v = ::operator new(sizeof(_Block_record*));

            __bin._M_first = static_cast<_Block_record**>(__v);

            __bin._M_first[0] = NULL;

            __bin._M_address = NULL;

          }

      }

    _M_init = true;

  }

  size_t

  __pool<true>::_M_get_thread_id()

  {

    // If we have thread support and it's active we check the thread

    // key value and return its id or if it's not set we take the

    // first record from _M_thread_freelist and sets the key and

    // returns its id.

    if (__gthread_active_p())

      {

        __freelist& freelist = get_freelist();

        void* v = __gthread_getspecific(freelist._M_key);

        size_t _M_id = (size_t)v;

        if (_M_id == 0)

          {

            {

              __gnu_cxx::__scoped_lock sentry(get_freelist_mutex());

              if (freelist._M_thread_freelist)

                {

                  _M_id = freelist._M_thread_freelist->_M_id;

                  freelist._M_thread_freelist

                    = freelist._M_thread_freelist->_M_next;

                }

            }

            __gthread_setspecific(freelist._M_key, (void*)_M_id);

          }

        return _M_id >= _M_options._M_max_threads ? 0 : _M_id;

      }

    // Otherwise (no thread support or inactive) all requests are

    // served from the global pool 0.