PR c++/18378

[official-gcc.git] / libstdc++-v3 / src / mt_allocator.cc

// Allocator details.

// Copyright (C) 2004 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Librarbooly.  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 2, 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.

// You should have received a copy of the GNU General Public License along
// with this library; 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.

//
// ISO C++ 14882:
//

#include <bits/c++config.h>
#include <bits/concurrence.h>
#include <ext/mt_allocator.h>

namespace __gnu_internal
{
  __glibcxx_mutex_define_initialized(freelist_mutex);

#ifdef __GTHREADS
  __gthread_key_t freelist_key;
#endif
}

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)
  {
    // 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);
              }
            ::operator delete(_M_thread_freelist_initial);
          }
        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)
  {
    // 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 unsigned long __limit = 100 * (_M_bin_size - __which)
                                      * __options._M_freelist_headroom;

        unsigned long __remove = __bin._M_free[__thread_id];
        __remove *= __options._M_freelist_headroom;
        if (__remove >= __bin._M_used[__thread_id])
          __remove -= __bin._M_used[__thread_id];
        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 unsigned long __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.
        --__bin._M_used[__block->_M_thread_id];
        
        __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())
      {
        __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_record* __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(__destroy_handler __d)
  {
    // _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())
      {
        const size_t __k = sizeof(_Thread_record) * _M_options._M_max_threads;
        __v = ::operator new(__k);
        _M_thread_freelist = static_cast<_Thread_record*>(__v);
        _M_thread_freelist_initial = __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;
          
        // Initialize per thread key to hold pointer to
        // _M_thread_freelist.
        __gthread_key_create(&__gnu_internal::freelist_key, __d);
          
        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);
            __bin._M_first = static_cast<_Block_record**>(__v);

            __bin._M_address = NULL;

            __v = ::operator new(sizeof(size_t) * __max_threads);
            __bin._M_free = static_cast<size_t*>(__v);
              
            __v = ::operator new(sizeof(size_t) * __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
            for (size_t __threadn = 0; __threadn < __max_threads; ++__threadn)
              {
                __bin._M_first[__threadn] = NULL;
                __bin._M_free[__threadn] = 0;
                __bin._M_used[__threadn] = 0;
              }
          }
      }
    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 it's id.
    if (__gthread_active_p())
      {
        void* v = __gthread_getspecific(__gnu_internal::freelist_key);
        _Thread_record* __freelist_pos = static_cast<_Thread_record*>(v); 
        if (__freelist_pos == NULL)
          {
            // Since _M_options._M_max_threads must be larger than
            // the theoretical max number of threads of the OS the
            // list can never be empty.
            {
              __gnu_cxx::lock sentry(__gnu_internal::freelist_mutex);
              __freelist_pos = _M_thread_freelist;
              _M_thread_freelist = _M_thread_freelist->_M_next;
            }
              
            __gthread_setspecific(__gnu_internal::freelist_key, 
                                  static_cast<void*>(__freelist_pos));
          }
        return __freelist_pos->_M_id;
      }

    // Otherwise (no thread support or inactive) all requests are
    // served from the global pool 0.
    return 0;
  }

  void
  __pool<true>::_M_destroy_thread_key(void* __freelist_pos)
  {
    // Return this thread id record to front of thread_freelist.
    __gnu_cxx::lock sentry(__gnu_internal::freelist_mutex);
    _Thread_record* __tr = static_cast<_Thread_record*>(__freelist_pos);
    __tr->_M_next = _M_thread_freelist; 
    _M_thread_freelist = __tr;
  }
#endif

  // Instantiations.
  template class __mt_alloc<char>;
  template class __mt_alloc<wchar_t>;
} // namespace __gnu_cxx