libstdc++-v3/src/c++98/mt_allocator.cc

   1 // Allocator details.
   2
   3 // Copyright (C) 2004, 2005, 2006, 2009, 2010 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 //
  26 // ISO C++ 14882:
  27 //
  28
  29 #include <bits/c++config.h>
  30 #include <ext/concurrence.h>
  31 #include <ext/mt_allocator.h>
  32 #include <cstring>
  33
  34 namespace
  35 {
  36 #ifdef __GTHREADS
  37   struct __freelist
  38   {
  39     typedef __gnu_cxx::__pool<true>::_Thread_record _Thread_record;
  40     _Thread_record*     _M_thread_freelist;
  41     _Thread_record*     _M_thread_freelist_array;
  42     size_t              _M_max_threads;
  43     __gthread_key_t     _M_key;
  44
  45     ~__freelist()
  46     {
  47       if (_M_thread_freelist_array)
  48         {
  49           __gthread_key_delete(_M_key);
  50           ::operator delete(static_cast<void*>(_M_thread_freelist_array));
  51         }
  52     }
  53   };
  54
  55   __freelist&
  56   get_freelist()
  57   {
  58     static __freelist freelist;
  59     return freelist;
  60   }
  61
  62   __gnu_cxx::__mutex&
  63   get_freelist_mutex()
  64   {
  65     static __gnu_cxx::__mutex freelist_mutex;
  66     return freelist_mutex;
  67   }
  68
  69   static void
  70   _M_destroy_thread_key(void* __id)
  71   {
  72     // Return this thread id record to the front of thread_freelist.
  73     __freelist& freelist = get_freelist();
  74     {
  75       __gnu_cxx::__scoped_lock sentry(get_freelist_mutex());
  76       size_t _M_id = reinterpret_cast<size_t>(__id);
  77
  78       typedef __gnu_cxx::__pool<true>::_Thread_record _Thread_record;
  79       _Thread_record* __tr = &freelist._M_thread_freelist_array[_M_id - 1];
  80       __tr->_M_next = freelist._M_thread_freelist;
  81       freelist._M_thread_freelist = __tr;
  82     }
  83   }
  84 #endif
  85 } // anonymous namespace
  86
  87 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  88 {
  89 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  90
  91   void
  92   __pool<false>::_M_destroy() throw()
  93   {
  94     if (_M_init && !_M_options._M_force_new)
  95       {
  96         for (size_t __n = 0; __n < _M_bin_size; ++__n)
  97           {
  98             _Bin_record& __bin = _M_bin[__n];
  99             while (__bin._M_address)
 100               {
 101                 _Block_address* __tmp = __bin._M_address->_M_next;
 102                 ::operator delete(__bin._M_address->_M_initial);
 103                 __bin._M_address = __tmp;
 104               }
 105             ::operator delete(__bin._M_first);
 106           }
 107         ::operator delete(_M_bin);
 108         ::operator delete(_M_binmap);
 109       }
 110   }
 111
 112   void
 113   __pool<false>::_M_reclaim_block(char* __p, size_t __bytes) throw ()
 114   {
 115     // Round up to power of 2 and figure out which bin to use.
 116     const size_t __which = _M_binmap[__bytes];
 117     _Bin_record& __bin = _M_bin[__which];
 118
 119     char* __c = __p - _M_get_align();
 120     _Block_record* __block = reinterpret_cast<_Block_record*>(__c);
 121
 122     // Single threaded application - return to global pool.
 123     __block->_M_next = __bin._M_first[0];
 124     __bin._M_first[0] = __block;
 125   }
 126
 127   char*
 128   __pool<false>::_M_reserve_block(size_t __bytes, const size_t __thread_id)
 129   {
 130     // Round up to power of 2 and figure out which bin to use.
 131     const size_t __which = _M_binmap[__bytes];
 132     _Bin_record& __bin = _M_bin[__which];
 133     const _Tune& __options = _M_get_options();
 134     const size_t __bin_size = (__options._M_min_bin << __which)
 135                                + __options._M_align;
 136     size_t __block_count = __options._M_chunk_size - sizeof(_Block_address);
 137     __block_count /= __bin_size;
 138
 139     // Get a new block dynamically, set it up for use.
 140     void* __v = ::operator new(__options._M_chunk_size);
 141     _Block_address* __address = static_cast<_Block_address*>(__v);
 142     __address->_M_initial = __v;
 143     __address->_M_next = __bin._M_address;
 144     __bin._M_address = __address;
 145
 146     char* __c = static_cast<char*>(__v) + sizeof(_Block_address);
 147     _Block_record* __block = reinterpret_cast<_Block_record*>(__c);
 148     __bin._M_first[__thread_id] = __block;
 149     while (--__block_count > 0)
 150       {
 151         __c += __bin_size;
 152         __block->_M_next = reinterpret_cast<_Block_record*>(__c);
 153         __block = __block->_M_next;
 154       }
 155     __block->_M_next = 0;
 156
 157     __block = __bin._M_first[__thread_id];
 158     __bin._M_first[__thread_id] = __block->_M_next;
 159
 160     // NB: For alignment reasons, we can't use the first _M_align
 161     // bytes, even when sizeof(_Block_record) < _M_align.
 162     return reinterpret_cast<char*>(__block) + __options._M_align;
 163   }
 164
 165   void
 166   __pool<false>::_M_initialize()
 167   {
 168     // _M_force_new must not change after the first allocate(), which
 169     // in turn calls this method, so if it's false, it's false forever
 170     // and we don't need to return here ever again.
 171     if (_M_options._M_force_new)
 172       {
 173         _M_init = true;
 174         return;
 175       }
 176
 177     // Create the bins.
 178     // Calculate the number of bins required based on _M_max_bytes.
 179     // _M_bin_size is statically-initialized to one.
 180     size_t __bin_size = _M_options._M_min_bin;
 181     while (_M_options._M_max_bytes > __bin_size)
 182       {
 183         __bin_size <<= 1;
 184         ++_M_bin_size;
 185       }
 186
 187     // Setup the bin map for quick lookup of the relevant bin.
 188     const size_t __j = (_M_options._M_max_bytes + 1) * sizeof(_Binmap_type);
 189     _M_binmap = static_cast<_Binmap_type*>(::operator new(__j));
 190     _Binmap_type* __bp = _M_binmap;
 191     _Binmap_type __bin_max = _M_options._M_min_bin;
 192     _Binmap_type __bint = 0;
 193     for (_Binmap_type __ct = 0; __ct <= _M_options._M_max_bytes; ++__ct)
 194       {
 195         if (__ct > __bin_max)
 196           {
 197             __bin_max <<= 1;
 198             ++__bint;
 199           }
 200         *__bp++ = __bint;
 201       }
 202
 203     // Initialize _M_bin and its members.
 204     void* __v = ::operator new(sizeof(_Bin_record) * _M_bin_size);
 205     _M_bin = static_cast<_Bin_record*>(__v);
 206     for (size_t __n = 0; __n < _M_bin_size; ++__n)
 207       {
 208         _Bin_record& __bin = _M_bin[__n];
 209         __v = ::operator new(sizeof(_Block_record*));
 210         __bin._M_first = static_cast<_Block_record**>(__v);
 211         __bin._M_first[0] = 0;
 212         __bin._M_address = 0;
 213       }
 214     _M_init = true;
 215   }
 216
 217
 218 #ifdef __GTHREADS
 219   void
 220   __pool<true>::_M_destroy() throw()
 221   {
 222     if (_M_init && !_M_options._M_force_new)
 223       {
 224         if (__gthread_active_p())
 225           {
 226             for (size_t __n = 0; __n < _M_bin_size; ++__n)
 227               {
 228                 _Bin_record& __bin = _M_bin[__n];
 229                 while (__bin._M_address)
 230                   {
 231                     _Block_address* __tmp = __bin._M_address->_M_next;
 232                     ::operator delete(__bin._M_address->_M_initial);
 233                     __bin._M_address = __tmp;
 234                   }
 235                 ::operator delete(__bin._M_first);
 236                 ::operator delete(__bin._M_free);
 237                 ::operator delete(__bin._M_used);
 238                 ::operator delete(__bin._M_mutex);
 239               }
 240           }
 241         else
 242           {
 243             for (size_t __n = 0; __n < _M_bin_size; ++__n)
 244               {
 245                 _Bin_record& __bin = _M_bin[__n];
 246                 while (__bin._M_address)
 247                   {
 248                     _Block_address* __tmp = __bin._M_address->_M_next;
 249                     ::operator delete(__bin._M_address->_M_initial);
 250                     __bin._M_address = __tmp;
 251                   }
 252                 ::operator delete(__bin._M_first);
 253               }
 254           }
 255         ::operator delete(_M_bin);
 256         ::operator delete(_M_binmap);
 257       }
 258   }
 259
 260   void
 261   __pool<true>::_M_reclaim_block(char* __p, size_t __bytes) throw ()
 262   {
 263     // Round up to power of 2 and figure out which bin to use.
 264     const size_t __which = _M_binmap[__bytes];
 265     const _Bin_record& __bin = _M_bin[__which];
 266
 267     // Know __p not null, assume valid block.
 268     char* __c = __p - _M_get_align();
 269     _Block_record* __block = reinterpret_cast<_Block_record*>(__c);
 270     if (__gthread_active_p())
 271       {
 272         // Calculate the number of records to remove from our freelist:
 273         // in order to avoid too much contention we wait until the
 274         // number of records is "high enough".
 275         const size_t __thread_id = _M_get_thread_id();
 276         const _Tune& __options = _M_get_options();
 277         const size_t __limit = (100 * (_M_bin_size - __which)
 278                                 * __options._M_freelist_headroom);
 279
 280         size_t __remove = __bin._M_free[__thread_id];
 281         __remove *= __options._M_freelist_headroom;
 282
 283         // NB: We assume that reads of _Atomic_words are atomic.
 284         const size_t __max_threads = __options._M_max_threads + 1;
 285         _Atomic_word* const __reclaimed_base =
 286           reinterpret_cast<_Atomic_word*>(__bin._M_used + __max_threads);
 287         const _Atomic_word __reclaimed = __reclaimed_base[__thread_id];
 288         const size_t __net_used = __bin._M_used[__thread_id] - __reclaimed;
 289
 290         // NB: For performance sake we don't resync every time, in order
 291         // to spare atomic ops.  Note that if __reclaimed increased by,
 292         // say, 1024, since the last sync, it means that the other
 293         // threads executed the atomic in the else below at least the
 294         // same number of times (at least, because _M_reserve_block may
 295         // have decreased the counter), therefore one more cannot hurt.
 296         if (__reclaimed > 1024)
 297           {
 298             __bin._M_used[__thread_id] -= __reclaimed;
 299             __atomic_add(&__reclaimed_base[__thread_id], -__reclaimed);
 300           }
 301
 302         if (__remove >= __net_used)
 303           __remove -= __net_used;
 304         else
 305           __remove = 0;
 306         if (__remove > __limit && __remove > __bin._M_free[__thread_id])
 307           {
 308             _Block_record* __first = __bin._M_first[__thread_id];
 309             _Block_record* __tmp = __first;
 310             __remove /= __options._M_freelist_headroom;
 311             const size_t __removed = __remove;
 312             while (--__remove > 0)
 313               __tmp = __tmp->_M_next;
 314             __bin._M_first[__thread_id] = __tmp->_M_next;
 315             __bin._M_free[__thread_id] -= __removed;
 316
 317             __gthread_mutex_lock(__bin._M_mutex);
 318             __tmp->_M_next = __bin._M_first[0];
 319             __bin._M_first[0] = __first;
 320             __bin._M_free[0] += __removed;
 321             __gthread_mutex_unlock(__bin._M_mutex);
 322           }
 323
 324         // Return this block to our list and update counters and
 325         // owner id as needed.
 326         if (__block->_M_thread_id == __thread_id)
 327           --__bin._M_used[__thread_id];
 328         else
 329           __atomic_add(&__reclaimed_base[__block->_M_thread_id], 1);
 330
 331         __block->_M_next = __bin._M_first[__thread_id];
 332         __bin._M_first[__thread_id] = __block;
 333
 334         ++__bin._M_free[__thread_id];
 335       }
 336     else
 337       {
 338         // Not using threads, so single threaded application - return
 339         // to global pool.
 340         __block->_M_next = __bin._M_first[0];
 341         __bin._M_first[0] = __block;
 342       }
 343   }
 344
 345   char*
 346   __pool<true>::_M_reserve_block(size_t __bytes, const size_t __thread_id)
 347   {
 348     // Round up to power of 2 and figure out which bin to use.
 349     const size_t __which = _M_binmap[__bytes];
 350     const _Tune& __options = _M_get_options();
 351     const size_t __bin_size = ((__options._M_min_bin << __which)
 352                                + __options._M_align);
 353     size_t __block_count = __options._M_chunk_size - sizeof(_Block_address);
 354     __block_count /= __bin_size;
 355
 356     // Are we using threads?
 357     // - Yes, check if there are free blocks on the global
 358     //   list. If so, grab up to __block_count blocks in one
 359     //   lock and change ownership. If the global list is
 360     //   empty, we allocate a new chunk and add those blocks
 361     //   directly to our own freelist (with us as owner).
 362     // - No, all operations are made directly to global pool 0
 363     //   no need to lock or change ownership but check for free
 364     //   blocks on global list (and if not add new ones) and
 365     //   get the first one.
 366     _Bin_record& __bin = _M_bin[__which];
 367     _Block_record* __block = 0;
 368     if (__gthread_active_p())
 369       {
 370         // Resync the _M_used counters.
 371         const size_t __max_threads = __options._M_max_threads + 1;
 372         _Atomic_word* const __reclaimed_base =
 373           reinterpret_cast<_Atomic_word*>(__bin._M_used + __max_threads);
 374         const _Atomic_word __reclaimed = __reclaimed_base[__thread_id];
 375         __bin._M_used[__thread_id] -= __reclaimed;
 376         __atomic_add(&__reclaimed_base[__thread_id], -__reclaimed);
 377
 378         __gthread_mutex_lock(__bin._M_mutex);
 379         if (__bin._M_first[0] == 0)
 380           {
 381             void* __v = ::operator new(__options._M_chunk_size);
 382             _Block_address* __address = static_cast<_Block_address*>(__v);
 383             __address->_M_initial = __v;
 384             __address->_M_next = __bin._M_address;
 385             __bin._M_address = __address;
 386             __gthread_mutex_unlock(__bin._M_mutex);
 387
 388             // No need to hold the lock when we are adding a whole
 389             // chunk to our own list.
 390             char* __c = static_cast<char*>(__v) + sizeof(_Block_address);
 391             __block = reinterpret_cast<_Block_record*>(__c);
 392             __bin._M_free[__thread_id] = __block_count;
 393             __bin._M_first[__thread_id] = __block;
 394             while (--__block_count > 0)
 395               {
 396                 __c += __bin_size;
 397                 __block->_M_next = reinterpret_cast<_Block_record*>(__c);
 398                 __block = __block->_M_next;
 399               }
 400             __block->_M_next = 0;
 401           }
 402         else
 403           {
 404             // Is the number of required blocks greater than or equal
 405             // to the number that can be provided by the global free
 406             // list?
 407             __bin._M_first[__thread_id] = __bin._M_first[0];
 408             if (__block_count >= __bin._M_free[0])
 409               {
 410                 __bin._M_free[__thread_id] = __bin._M_free[0];
 411                 __bin._M_free[0] = 0;
 412                 __bin._M_first[0] = 0;
 413               }
 414             else
 415               {
 416                 __bin._M_free[__thread_id] = __block_count;
 417                 __bin._M_free[0] -= __block_count;
 418                 __block = __bin._M_first[0];
 419                 while (--__block_count > 0)
 420                   __block = __block->_M_next;
 421                 __bin._M_first[0] = __block->_M_next;
 422                 __block->_M_next = 0;
 423               }
 424             __gthread_mutex_unlock(__bin._M_mutex);
 425           }
 426       }
 427     else
 428       {
 429         void* __v = ::operator new(__options._M_chunk_size);
 430         _Block_address* __address = static_cast<_Block_address*>(__v);
 431         __address->_M_initial = __v;
 432         __address->_M_next = __bin._M_address;
 433         __bin._M_address = __address;
 434
 435         char* __c = static_cast<char*>(__v) + sizeof(_Block_address);
 436         __block = reinterpret_cast<_Block_record*>(__c);
 437         __bin._M_first[0] = __block;
 438         while (--__block_count > 0)
 439           {
 440             __c += __bin_size;
 441             __block->_M_next = reinterpret_cast<_Block_record*>(__c);
 442             __block = __block->_M_next;
 443           }
 444         __block->_M_next = 0;
 445       }
 446
 447     __block = __bin._M_first[__thread_id];
 448     __bin._M_first[__thread_id] = __block->_M_next;
 449
 450     if (__gthread_active_p())
 451       {
 452         __block->_M_thread_id = __thread_id;
 453         --__bin._M_free[__thread_id];
 454         ++__bin._M_used[__thread_id];
 455       }
 456
 457     // NB: For alignment reasons, we can't use the first _M_align
 458     // bytes, even when sizeof(_Block_record) < _M_align.
 459     return reinterpret_cast<char*>(__block) + __options._M_align;
 460   }
 461
 462   void
 463   __pool<true>::_M_initialize()
 464   {
 465     // _M_force_new must not change after the first allocate(),
 466     // which in turn calls this method, so if it's false, it's false
 467     // forever and we don't need to return here ever again.
 468     if (_M_options._M_force_new)
 469       {
 470         _M_init = true;
 471         return;
 472       }
 473
 474     // Create the bins.
 475     // Calculate the number of bins required based on _M_max_bytes.
 476     // _M_bin_size is statically-initialized to one.
 477     size_t __bin_size = _M_options._M_min_bin;
 478     while (_M_options._M_max_bytes > __bin_size)
 479       {
 480         __bin_size <<= 1;
 481         ++_M_bin_size;
 482       }
 483
 484     // Setup the bin map for quick lookup of the relevant bin.
 485     const size_t __j = (_M_options._M_max_bytes + 1) * sizeof(_Binmap_type);
 486     _M_binmap = static_cast<_Binmap_type*>(::operator new(__j));
 487     _Binmap_type* __bp = _M_binmap;
 488     _Binmap_type __bin_max = _M_options._M_min_bin;
 489     _Binmap_type __bint = 0;
 490     for (_Binmap_type __ct = 0; __ct <= _M_options._M_max_bytes; ++__ct)
 491       {
 492         if (__ct > __bin_max)
 493           {
 494             __bin_max <<= 1;
 495             ++__bint;
 496           }
 497         *__bp++ = __bint;
 498       }
 499
 500     // Initialize _M_bin and its members.
 501     void* __v = ::operator new(sizeof(_Bin_record) * _M_bin_size);
 502     _M_bin = static_cast<_Bin_record*>(__v);
 503
 504     // If __gthread_active_p() create and initialize the list of
 505     // free thread ids. Single threaded applications use thread id 0
 506     // directly and have no need for this.
 507     if (__gthread_active_p())
 508       {
 509         __freelist& freelist = get_freelist();
 510         {
 511           __gnu_cxx::__scoped_lock sentry(get_freelist_mutex());
 512
 513           if (!freelist._M_thread_freelist_array
 514               || freelist._M_max_threads < _M_options._M_max_threads)
 515             {
 516               const size_t __k = sizeof(_Thread_record)
 517                                  * _M_options._M_max_threads;
 518               __v = ::operator new(__k);
 519               _M_thread_freelist = static_cast<_Thread_record*>(__v);
 520
 521               // NOTE! The first assignable thread id is 1 since the
 522               // global pool uses id 0
 523               size_t __i;
 524               for (__i = 1; __i < _M_options._M_max_threads; ++__i)
 525                 {
 526                   _Thread_record& __tr = _M_thread_freelist[__i - 1];
 527                   __tr._M_next = &_M_thread_freelist[__i];
 528                   __tr._M_id = __i;
 529                 }
 530
 531               // Set last record.
 532               _M_thread_freelist[__i - 1]._M_next = 0;
 533               _M_thread_freelist[__i - 1]._M_id = __i;
 534
 535               if (!freelist._M_thread_freelist_array)
 536                 {
 537                   // Initialize per thread key to hold pointer to
 538                   // _M_thread_freelist.
 539                   __gthread_key_create(&freelist._M_key,
 540                                        ::_M_destroy_thread_key);
 541                   freelist._M_thread_freelist = _M_thread_freelist;
 542                 }
 543               else
 544                 {
 545                   _Thread_record* _M_old_freelist
 546                     = freelist._M_thread_freelist;
 547                   _Thread_record* _M_old_array
 548                     = freelist._M_thread_freelist_array;
 549                   freelist._M_thread_freelist
 550                     = &_M_thread_freelist[_M_old_freelist - _M_old_array];
 551                   while (_M_old_freelist)
 552                     {
 553                       size_t next_id;
 554                       if (_M_old_freelist->_M_next)
 555                         next_id = _M_old_freelist->_M_next - _M_old_array;
 556                       else
 557                         next_id = freelist._M_max_threads;
 558                       _M_thread_freelist[_M_old_freelist->_M_id - 1]._M_next
 559                         = &_M_thread_freelist[next_id];
 560                       _M_old_freelist = _M_old_freelist->_M_next;
 561                     }
 562                   ::operator delete(static_cast<void*>(_M_old_array));
 563                 }
 564               freelist._M_thread_freelist_array = _M_thread_freelist;
 565               freelist._M_max_threads = _M_options._M_max_threads;
 566             }
 567         }
 568
 569         const size_t __max_threads = _M_options._M_max_threads + 1;
 570         for (size_t __n = 0; __n < _M_bin_size; ++__n)
 571           {
 572             _Bin_record& __bin = _M_bin[__n];
 573             __v = ::operator new(sizeof(_Block_record*) * __max_threads);
 574             std::memset(__v, 0, sizeof(_Block_record*) * __max_threads);
 575             __bin._M_first = static_cast<_Block_record**>(__v);
 576
 577             __bin._M_address = 0;
 578
 579             __v = ::operator new(sizeof(size_t) * __max_threads);
 580             std::memset(__v, 0, sizeof(size_t) * __max_threads);
 581
 582             __bin._M_free = static_cast<size_t*>(__v);
 583
 584             __v = ::operator new(sizeof(size_t) * __max_threads
 585                                  + sizeof(_Atomic_word) * __max_threads);
 586             std::memset(__v, 0, (sizeof(size_t) * __max_threads
 587                                  + sizeof(_Atomic_word) * __max_threads));
 588             __bin._M_used = static_cast<size_t*>(__v);
 589
 590             __v = ::operator new(sizeof(__gthread_mutex_t));
 591             __bin._M_mutex = static_cast<__gthread_mutex_t*>(__v);
 592
 593 #ifdef __GTHREAD_MUTEX_INIT
 594             {
 595               // Do not copy a POSIX/gthr mutex once in use.
 596               __gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
 597               *__bin._M_mutex = __tmp;
 598             }
 599 #else
 600             { __GTHREAD_MUTEX_INIT_FUNCTION(__bin._M_mutex); }
 601 #endif
 602           }
 603       }
 604     else
 605       {
 606         for (size_t __n = 0; __n < _M_bin_size; ++__n)
 607           {
 608             _Bin_record& __bin = _M_bin[__n];
 609             __v = ::operator new(sizeof(_Block_record*));
 610             __bin._M_first = static_cast<_Block_record**>(__v);
 611             __bin._M_first[0] = 0;
 612             __bin._M_address = 0;
 613           }
 614       }
 615     _M_init = true;
 616   }
 617
 618   size_t
 619   __pool<true>::_M_get_thread_id()
 620   {
 621     // If we have thread support and it's active we check the thread
 622     // key value and return its id or if it's not set we take the
 623     // first record from _M_thread_freelist and sets the key and
 624     // returns its id.
 625     if (__gthread_active_p())
 626       {
 627         __freelist& freelist = get_freelist();
 628         void* v = __gthread_getspecific(freelist._M_key);
 629         size_t _M_id = (size_t)v;
 630         if (_M_id == 0)
 631           {
 632             {
 633               __gnu_cxx::__scoped_lock sentry(get_freelist_mutex());
 634               if (freelist._M_thread_freelist)
 635                 {
 636                   _M_id = freelist._M_thread_freelist->_M_id;
 637                   freelist._M_thread_freelist
 638                     = freelist._M_thread_freelist->_M_next;
 639                 }
 640             }
 641
 642             __gthread_setspecific(freelist._M_key, (void*)_M_id);
 643           }
 644         return _M_id >= _M_options._M_max_threads ? 0 : _M_id;
 645       }
 646
 647     // Otherwise (no thread support or inactive) all requests are
 648     // served from the global pool 0.
 649     return 0;
 650   }
 651
 652   // XXX GLIBCXX_ABI Deprecated
 653   void
 654   __pool<true>::_M_destroy_thread_key(void*) throw () { }
 655
 656   // XXX GLIBCXX_ABI Deprecated
 657   void
 658   __pool<true>::_M_initialize(__destroy_handler)
 659   {
 660     // _M_force_new must not change after the first allocate(),
 661     // which in turn calls this method, so if it's false, it's false
 662     // forever and we don't need to return here ever again.
 663     if (_M_options._M_force_new)
 664       {
 665         _M_init = true;
 666         return;
 667       }
 668
 669     // Create the bins.
 670     // Calculate the number of bins required based on _M_max_bytes.
 671     // _M_bin_size is statically-initialized to one.
 672     size_t __bin_size = _M_options._M_min_bin;
 673     while (_M_options._M_max_bytes > __bin_size)
 674       {
 675         __bin_size <<= 1;
 676         ++_M_bin_size;
 677       }
 678
 679     // Setup the bin map for quick lookup of the relevant bin.
 680     const size_t __j = (_M_options._M_max_bytes + 1) * sizeof(_Binmap_type);
 681     _M_binmap = static_cast<_Binmap_type*>(::operator new(__j));
 682     _Binmap_type* __bp = _M_binmap;
 683     _Binmap_type __bin_max = _M_options._M_min_bin;
 684     _Binmap_type __bint = 0;
 685     for (_Binmap_type __ct = 0; __ct <= _M_options._M_max_bytes; ++__ct)
 686       {
 687         if (__ct > __bin_max)
 688           {
 689             __bin_max <<= 1;
 690             ++__bint;
 691           }
 692         *__bp++ = __bint;
 693       }
 694
 695     // Initialize _M_bin and its members.
 696     void* __v = ::operator new(sizeof(_Bin_record) * _M_bin_size);
 697     _M_bin = static_cast<_Bin_record*>(__v);
 698
 699     // If __gthread_active_p() create and initialize the list of
 700     // free thread ids. Single threaded applications use thread id 0
 701     // directly and have no need for this.
 702     if (__gthread_active_p())
 703       {
 704         __freelist& freelist = get_freelist();
 705         {
 706           __gnu_cxx::__scoped_lock sentry(get_freelist_mutex());
 707
 708           if (!freelist._M_thread_freelist_array
 709               || freelist._M_max_threads < _M_options._M_max_threads)
 710             {
 711               const size_t __k = sizeof(_Thread_record)
 712                                  * _M_options._M_max_threads;
 713               __v = ::operator new(__k);
 714               _M_thread_freelist = static_cast<_Thread_record*>(__v);
 715
 716               // NOTE! The first assignable thread id is 1 since the
 717               // global pool uses id 0
 718               size_t __i;
 719               for (__i = 1; __i < _M_options._M_max_threads; ++__i)
 720                 {
 721                   _Thread_record& __tr = _M_thread_freelist[__i - 1];
 722                   __tr._M_next = &_M_thread_freelist[__i];
 723                   __tr._M_id = __i;
 724                 }
 725
 726               // Set last record.
 727               _M_thread_freelist[__i - 1]._M_next = 0;
 728               _M_thread_freelist[__i - 1]._M_id = __i;
 729
 730               if (!freelist._M_thread_freelist_array)
 731                 {
 732                   // Initialize per thread key to hold pointer to
 733                   // _M_thread_freelist.
 734                   __gthread_key_create(&freelist._M_key,
 735                                        ::_M_destroy_thread_key);
 736                   freelist._M_thread_freelist = _M_thread_freelist;
 737                 }
 738               else
 739                 {
 740                   _Thread_record* _M_old_freelist
 741                     = freelist._M_thread_freelist;
 742                   _Thread_record* _M_old_array
 743                     = freelist._M_thread_freelist_array;
 744                   freelist._M_thread_freelist
 745                     = &_M_thread_freelist[_M_old_freelist - _M_old_array];
 746                   while (_M_old_freelist)
 747                     {
 748                       size_t next_id;
 749                       if (_M_old_freelist->_M_next)
 750                         next_id = _M_old_freelist->_M_next - _M_old_array;
 751                       else
 752                         next_id = freelist._M_max_threads;
 753                       _M_thread_freelist[_M_old_freelist->_M_id - 1]._M_next
 754                         = &_M_thread_freelist[next_id];
 755                       _M_old_freelist = _M_old_freelist->_M_next;
 756                     }
 757                   ::operator delete(static_cast<void*>(_M_old_array));
 758                 }
 759               freelist._M_thread_freelist_array = _M_thread_freelist;
 760               freelist._M_max_threads = _M_options._M_max_threads;
 761             }
 762         }
 763
 764         const size_t __max_threads = _M_options._M_max_threads + 1;
 765         for (size_t __n = 0; __n < _M_bin_size; ++__n)
 766           {
 767             _Bin_record& __bin = _M_bin[__n];
 768             __v = ::operator new(sizeof(_Block_record*) * __max_threads);
 769             std::memset(__v, 0, sizeof(_Block_record*) * __max_threads);
 770             __bin._M_first = static_cast<_Block_record**>(__v);
 771
 772             __bin._M_address = 0;
 773
 774             __v = ::operator new(sizeof(size_t) * __max_threads);
 775             std::memset(__v, 0, sizeof(size_t) * __max_threads);
 776             __bin._M_free = static_cast<size_t*>(__v);
 777
 778             __v = ::operator new(sizeof(size_t) * __max_threads +
 779                                  sizeof(_Atomic_word) * __max_threads);
 780             std::memset(__v, 0, (sizeof(size_t) * __max_threads
 781                                  + sizeof(_Atomic_word) * __max_threads));
 782             __bin._M_used = static_cast<size_t*>(__v);
 783
 784             __v = ::operator new(sizeof(__gthread_mutex_t));
 785             __bin._M_mutex = static_cast<__gthread_mutex_t*>(__v);
 786
 787 #ifdef __GTHREAD_MUTEX_INIT
 788             {
 789               // Do not copy a POSIX/gthr mutex once in use.
 790               __gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
 791               *__bin._M_mutex = __tmp;
 792             }
 793 #else
 794             { __GTHREAD_MUTEX_INIT_FUNCTION(__bin._M_mutex); }
 795 #endif
 796           }
 797       }
 798     else
 799       {
 800         for (size_t __n = 0; __n < _M_bin_size; ++__n)
 801           {
 802             _Bin_record& __bin = _M_bin[__n];
 803             __v = ::operator new(sizeof(_Block_record*));
 804             __bin._M_first = static_cast<_Block_record**>(__v);
 805             __bin._M_first[0] = 0;
 806             __bin._M_address = 0;
 807           }
 808       }
 809     _M_init = true;
 810   }
 811 #endif
 812
 813   // Instantiations.
 814   template class __mt_alloc<char>;
 815   template class __mt_alloc<wchar_t>;
 816
 817 _GLIBCXX_END_NAMESPACE_VERSION
 818 } // namespace