* the per thread freelist sizes (by returning excess back to
* "global").
*
- * Usage examples:
- * @code
- * vector<int, __gnu_cxx::__mt_alloc<int> > v1;
- *
- * typedef __gnu_cxx::__mt_alloc<char> > string_allocator;
- * std::basic_string<char, std::char_traits<char>, string_allocator> s1;
- * @endcode
+ * Further details:
+ * http://gcc.gnu.org/onlinedocs/libstdc++/ext/mt_allocator.html
*/
template<typename _Tp>
class __mt_alloc
// XXX
}
- __mt_alloc(const __mt_alloc&) throw()
+ __mt_alloc(const __mt_alloc&) throw()
{
// XXX
}
template<typename _Tp1>
- __mt_alloc(const __mt_alloc<_Tp1>&) throw()
+ __mt_alloc(const __mt_alloc<_Tp1>& obj) throw()
{
// XXX
}
void
destroy(pointer __p) { __p->~_Tp(); }
+ pointer
+ allocate(size_t __n, const void* = 0);
+
+ void
+ deallocate(pointer __p, size_type __n);
+
+ // Variables used to configure the behavior of the allocator,
+ // assigned and explained in detail below.
+ struct tune
+ {
+ // Allocation requests (after round-up to power of 2) below
+ // this value will be handled by the allocator. A raw new/
+ // call will be used for requests larger than this value.
+ size_t _M_max_bytes;
+
+ // In order to avoid fragmenting and minimize the number of
+ // new() calls we always request new memory using this
+ // value. Based on previous discussions on the libstdc++
+ // mailing list we have choosen the value below.
+ // See http://gcc.gnu.org/ml/libstdc++/2001-07/msg00077.html
+ size_t _M_chunk_size;
+
+ // The maximum number of supported threads. Our Linux 2.4.18
+ // reports 4070 in /proc/sys/kernel/threads-max
+ size_t _M_max_threads;
+
+ // Each time a deallocation occurs in a threaded application
+ // we make sure that there are no more than
+ // _M_freelist_headroom % of used memory on the freelist. If
+ // the number of additional records is more than
+ // _M_freelist_headroom % of the freelist, we move these
+ // records back to the global pool.
+ size_t _M_freelist_headroom;
+
+ // Set to true forces all allocations to use new().
+ bool _M_force_new;
+
+ explicit tune()
+ : _M_max_bytes(128), _M_chunk_size(4096 - 4 * sizeof(void*)),
+#ifdef __GTHREADS
+ _M_max_threads(4096),
+#else
+ _M_max_threads(0),
+#endif
+ _M_freelist_headroom(10),
+ _M_force_new(getenv("GLIBCXX_FORCE_NEW") ? true : false)
+ { }
+
+ explicit tune(size_t __maxb, size_t __chunk, size_t __maxthreads,
+ size_t __headroom, bool __force)
+ : _M_max_bytes(__maxb), _M_chunk_size(__chunk),
+ _M_max_threads(__maxthreads), _M_freelist_headroom(__headroom),
+ _M_force_new(__force)
+ { }
+ };
+
private:
- /*
- * We need to create the initial lists and set up some variables
- * before we can answer to the first request for memory.
- * The initialization of these variables is done at file scope
- * below class declaration.
- */
+ // We need to create the initial lists and set up some variables
+ // before we can answer to the first request for memory.
#ifdef __GTHREADS
- static __gthread_once_t _S_once_mt;
+ static __gthread_once_t _S_once;
#endif
- static bool volatile _S_initialized;
-
- /*
- * If the env var GLIBCXX_FORCE_NEW is set during _S_init()
- * we set this var to true which causes all allocations to use new()
- */
- static bool _S_force_new;
-
- /*
- * Using short int as type for the binmap implies we are never caching
- * blocks larger than 65535 with this allocator
- */
+ static bool _S_init;
+
+ static void
+ _S_initialize();
+
+ // Configuration options.
+ static tune _S_options;
+
+ static const tune
+ _S_get_options() { return _S_options; }
+
+ static void
+ _S_set_options(tune __t)
+ {
+ if (!_S_init)
+ _S_options = __t;
+ }
+
+ // Using short int as type for the binmap implies we are never
+ // caching blocks larger than 65535 with this allocator
typedef unsigned short int binmap_type;
- static binmap_type* _S_binmap;
-
- static void _S_init();
-
- /*
- * Variables used to "tune" the behavior of the allocator, assigned
- * and explained in detail below.
- */
- static size_t _S_max_bytes;
- static size_t _S_chunk_size;
- static size_t _S_max_threads;
- static size_t _S_no_of_bins;
- static size_t _S_freelist_headroom;
-
- /*
- * Each requesting thread is assigned an id ranging from 1 to
- * _S_max_threads. Thread id 0 is used as a global memory pool.
- * In order to get constant performance on the thread assignment
- * routine, we keep a list of free ids. When a thread first requests
- * memory we remove the first record in this list and stores the address
- * in a __gthread_key. When initializing the __gthread_key
- * we specify a destructor. When this destructor (i.e. the thread dies)
- * is called, we return the thread id to the front of this list.
- */
+ static binmap_type* _S_binmap;
+
+ // Each requesting thread is assigned an id ranging from 1 to
+ // _S_max_threads. Thread id 0 is used as a global memory pool.
+ // In order to get constant performance on the thread assignment
+ // routine, we keep a list of free ids. When a thread first
+ // requests memory we remove the first record in this list and
+ // stores the address in a __gthread_key. When initializing the
+ // __gthread_key we specify a destructor. When this destructor
+ // (i.e. the thread dies) is called, we return the thread id to
+ // the front of this list.
#ifdef __GTHREADS
struct thread_record
{
- /*
- * Points to next free thread id record. NULL if last record in list.
- */
+ // Points to next free thread id record. NULL if last record in list.
thread_record* volatile next;
- /*
- * Thread id ranging from 1 to _S_max_threads.
- */
+ // Thread id ranging from 1 to _S_max_threads.
size_t id;
};
- static thread_record* volatile _S_thread_freelist_first;
- static __gthread_mutex_t _S_thread_freelist_mutex;
- static void _S_thread_key_destr(void* freelist_pos);
- static __gthread_key_t _S_thread_key;
- static size_t _S_get_thread_id();
+ static thread_record* volatile _S_thread_freelist_first;
+ static __gthread_mutex_t _S_thread_freelist_mutex;
+ static __gthread_key_t _S_thread_key;
+
+ static void
+ _S_destroy_thread_key(void* freelist_pos);
+
+ static size_t
+ _S_get_thread_id();
#endif
struct block_record
{
- /*
- * Points to the next block_record for its thread_id.
- */
+ // Points to the next block_record for its thread_id.
block_record* volatile next;
- /*
- * The thread id of the thread which has requested this block.
- */
+ // The thread id of the thread which has requested this block.
#ifdef __GTHREADS
size_t thread_id;
#endif
struct bin_record
{
- /*
- * An "array" of pointers to the first free block for each
- * thread id. Memory to this "array" is allocated in _S_init()
- * for _S_max_threads + global pool 0.
- */
+ // An "array" of pointers to the first free block for each
+ // thread id. Memory to this "array" is allocated in _S_initialize()
+ // for _S_max_threads + global pool 0.
block_record** volatile first;
- /*
- * An "array" of counters used to keep track of the amount of blocks
- * that are on the freelist/used for each thread id.
- * Memory to these "arrays" is allocated in _S_init()
- * for _S_max_threads + global pool 0.
- */
+ // An "array" of counters used to keep track of the amount of
+ // blocks that are on the freelist/used for each thread id.
+ // Memory to these "arrays" is allocated in _S_initialize() for
+ // _S_max_threads + global pool 0.
size_t* volatile free;
size_t* volatile used;
- /*
- * Each bin has its own mutex which is used to ensure data integrity
- * while changing "ownership" on a block.
- * The mutex is initialized in _S_init().
- */
+ // Each bin has its own mutex which is used to ensure data
+ // integrity while changing "ownership" on a block. The mutex
+ // is initialized in _S_initialize().
#ifdef __GTHREADS
__gthread_mutex_t* mutex;
#endif
};
- /*
- * An "array" of bin_records each of which represents a specific
- * power of 2 size. Memory to this "array" is allocated in _S_init().
- */
- static bin_record* volatile _S_bin;
+ // An "array" of bin_records each of which represents a specific
+ // power of 2 size. Memory to this "array" is allocated in
+ // _S_initialize().
+ static bin_record* volatile _S_bin;
- public:
- pointer
- allocate(size_t __n, const void* = 0)
- {
- /*
- * Although the test in __gthread_once() would suffice, we
- * wrap test of the once condition in our own unlocked
- * check. This saves one function call to pthread_once()
- * (which itself only tests for the once value unlocked anyway
- * and immediately returns if set)
- */
- if (!_S_initialized)
- {
+ // Actual value calculated in _S_initialize().
+ static size_t _S_bin_size;
+ };
+
+ template<typename _Tp>
+ typename __mt_alloc<_Tp>::pointer
+ __mt_alloc<_Tp>::
+ allocate(size_t __n, const void*)
+ {
+ // Although the test in __gthread_once() would suffice, we wrap
+ // test of the once condition in our own unlocked check. This
+ // saves one function call to pthread_once() (which itself only
+ // tests for the once value unlocked anyway and immediately
+ // returns if set)
+ if (!_S_init)
+ {
#ifdef __GTHREADS
- if (__gthread_active_p())
- __gthread_once(&_S_once_mt, _S_init);
- else
+ if (__gthread_active_p())
+ __gthread_once(&_S_once, _S_initialize);
#endif
- {
- _S_max_threads = 0;
- _S_init();
- }
- }
-
- /*
- * Requests larger than _S_max_bytes are handled by
- * new/delete directly
- */
- if (__n * sizeof(_Tp) > _S_max_bytes || _S_force_new)
- {
- void* __ret = ::operator new(__n * sizeof(_Tp));
- if (!__ret)
- std::__throw_bad_alloc();
- return static_cast<_Tp*>(__ret);
- }
-
- /*
- * Round up to power of 2 and figure out which bin to use
- */
- size_t bin = _S_binmap[__n * sizeof(_Tp)];
-
+ if (!_S_init)
+ _S_initialize();
+ }
+
+ // Requests larger than _M_max_bytes are handled by new/delete
+ // directly.
+ const size_t __bytes = __n * sizeof(_Tp);
+ if (__bytes > _S_options._M_max_bytes || _S_options._M_force_new)
+ {
+ void* __ret = ::operator new(__bytes);
+ return static_cast<_Tp*>(__ret);
+ }
+
+ // Round up to power of 2 and figure out which bin to use.
+ size_t bin = _S_binmap[__bytes];
+
#ifdef __GTHREADS
- size_t thread_id = _S_get_thread_id();
+ size_t thread_id = _S_get_thread_id();
#else
- size_t thread_id = 0;
+ size_t thread_id = 0;
#endif
-
- block_record* block = NULL;
-
- /*
- * Find out if we have blocks on our freelist.
- * If so, go ahead and use them directly without
- * having to lock anything.
- */
- if (_S_bin[bin].first[thread_id] == NULL)
- {
- /*
- * 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.
- */
+
+ // Find out if we have blocks on our freelist. If so, go ahead
+ // and use them directly without having to lock anything.
+ block_record* block = NULL;
+ if (_S_bin[bin].first[thread_id] == NULL)
+ {
+ // 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.
#ifdef __GTHREADS
- if (__gthread_active_p())
- {
- size_t bin_t = 1 << bin;
- size_t block_count =
- _S_chunk_size /(bin_t + sizeof(block_record));
-
- __gthread_mutex_lock(_S_bin[bin].mutex);
-
- if (_S_bin[bin].first[0] == NULL)
- {
- /*
- * No need to hold the lock when we are adding a
- * whole chunk to our own list
- */
- __gthread_mutex_unlock(_S_bin[bin].mutex);
-
- _S_bin[bin].first[thread_id] =
- static_cast<block_record*>(::operator new(_S_chunk_size));
-
- if (!_S_bin[bin].first[thread_id])
- std::__throw_bad_alloc();
-
- _S_bin[bin].free[thread_id] = block_count;
-
- block_count--;
- block = _S_bin[bin].first[thread_id];
-
- while (block_count > 0)
- {
- block->next = (block_record*)((char*)block +
- (bin_t + sizeof(block_record)));
- block->thread_id = thread_id;
- block = block->next;
- block_count--;
- }
-
- block->next = NULL;
- block->thread_id = thread_id;
- }
- else
- {
- size_t global_count = 0;
-
- block_record* tmp;
-
- while( _S_bin[bin].first[0] != NULL &&
- global_count < block_count )
- {
- tmp = _S_bin[bin].first[0]->next;
-
- block = _S_bin[bin].first[0];
-
- if (_S_bin[bin].first[thread_id] == NULL)
- {
- _S_bin[bin].first[thread_id] = block;
- block->next = NULL;
- }
- else
- {
- block->next = _S_bin[bin].first[thread_id];
- _S_bin[bin].first[thread_id] = block;
- }
-
- block->thread_id = thread_id;
-
- _S_bin[bin].free[thread_id]++;
-
- _S_bin[bin].first[0] = tmp;
-
- global_count++;
- }
-
- __gthread_mutex_unlock(_S_bin[bin].mutex);
- }
-
- /*
- * Return the first newly added block in our list and
- * update the counters
- */
- block = _S_bin[bin].first[thread_id];
- _S_bin[bin].first[thread_id] =
- _S_bin[bin].first[thread_id]->next;
-
- _S_bin[bin].free[thread_id]--;
- _S_bin[bin].used[thread_id]++;
- }
- else
+ if (__gthread_active_p())
+ {
+ size_t bin_t = 1 << bin;
+ size_t block_count =
+ _S_options._M_chunk_size /(bin_t + sizeof(block_record));
+
+ __gthread_mutex_lock(_S_bin[bin].mutex);
+
+ if (_S_bin[bin].first[0] == NULL)
+ {
+ // No need to hold the lock when we are adding a
+ // whole chunk to our own list.
+ __gthread_mutex_unlock(_S_bin[bin].mutex);
+
+ _S_bin[bin].first[thread_id] =
+ static_cast<block_record*>(::operator new(_S_options._M_chunk_size));
+
+ if (!_S_bin[bin].first[thread_id])
+ std::__throw_bad_alloc();
+
+ _S_bin[bin].free[thread_id] = block_count;
+
+ block_count--;
+ block = _S_bin[bin].first[thread_id];
+
+ while (block_count > 0)
+ {
+ block->next = (block_record*)((char*)block +
+ (bin_t + sizeof(block_record)));
+ block->thread_id = thread_id;
+ block = block->next;
+ block_count--;
+ }
+
+ block->next = NULL;
+ block->thread_id = thread_id;
+ }
+ else
+ {
+ size_t global_count = 0;
+ block_record* tmp;
+ while (_S_bin[bin].first[0] != NULL
+ && global_count < block_count)
+ {
+ tmp = _S_bin[bin].first[0]->next;
+ block = _S_bin[bin].first[0];
+
+ if (_S_bin[bin].first[thread_id] == NULL)
+ {
+ _S_bin[bin].first[thread_id] = block;
+ block->next = NULL;
+ }
+ else
+ {
+ block->next = _S_bin[bin].first[thread_id];
+ _S_bin[bin].first[thread_id] = block;
+ }
+
+ block->thread_id = thread_id;
+ _S_bin[bin].free[thread_id]++;
+ _S_bin[bin].first[0] = tmp;
+ global_count++;
+ }
+ __gthread_mutex_unlock(_S_bin[bin].mutex);
+ }
+
+ // Return the first newly added block in our list and
+ // update the counters
+ block = _S_bin[bin].first[thread_id];
+ _S_bin[bin].first[thread_id] =
+ _S_bin[bin].first[thread_id]->next;
+ _S_bin[bin].free[thread_id]--;
+ _S_bin[bin].used[thread_id]++;
+ }
+ else
#endif
- {
- _S_bin[bin].first[0] =
- static_cast<block_record*>(::operator new(_S_chunk_size));
-
- if (!_S_bin[bin].first[0])
- std::__throw_bad_alloc();
-
- size_t bin_t = 1 << bin;
- size_t block_count =
- _S_chunk_size / (bin_t + sizeof(block_record));
-
- block_count--;
- block = _S_bin[bin].first[0];
-
- while (block_count > 0)
- {
- block->next = (block_record*)((char*)block +
- (bin_t + sizeof(block_record)));
- block = block->next;
- block_count--;
- }
-
- block->next = NULL;
-
- block = _S_bin[bin].first[0];
-
- /*
- * Remove from list
- */
- _S_bin[bin].first[0] = _S_bin[bin].first[0]->next;
- }
- }
- else
- {
- /*
- * "Default" operation - we have blocks on our own freelist
- * grab the first record and update the counters.
- */
- block = _S_bin[bin].first[thread_id];
-
- _S_bin[bin].first[thread_id] = _S_bin[bin].first[thread_id]->next;
-
+ {
+ _S_bin[bin].first[0] =
+ static_cast<block_record*>(::operator new(_S_options._M_chunk_size));
+
+ size_t bin_t = 1 << bin;
+ size_t block_count =
+ _S_options._M_chunk_size / (bin_t + sizeof(block_record));
+
+ block_count--;
+ block = _S_bin[bin].first[0];
+ while (block_count > 0)
+ {
+ block->next = (block_record*)((char*)block +
+ (bin_t + sizeof(block_record)));
+ block = block->next;
+ block_count--;
+ }
+ block->next = NULL;
+ block = _S_bin[bin].first[0];
+
+ // Remove from list.
+ _S_bin[bin].first[0] = _S_bin[bin].first[0]->next;
+ }
+ }
+ else
+ {
+ // "Default" operation - we have blocks on our own
+ // freelist grab the first record and update the counters.
+ block = _S_bin[bin].first[thread_id];
+
+ _S_bin[bin].first[thread_id] = _S_bin[bin].first[thread_id]->next;
+
#ifdef __GTHREADS
- if (__gthread_active_p())
- {
- _S_bin[bin].free[thread_id]--;
- _S_bin[bin].used[thread_id]++;
- }
+ if (__gthread_active_p())
+ {
+ _S_bin[bin].free[thread_id]--;
+ _S_bin[bin].used[thread_id]++;
+ }
#endif
- }
-
- return static_cast<_Tp*>(static_cast<void*>((char*)block +
- sizeof(block_record)));
- }
-
- void
- deallocate(pointer __p, size_type __n)
- {
- /*
- * Requests larger than _S_max_bytes are handled by
- * operators new/delete directly
- */
- if (__n * sizeof(_Tp) > _S_max_bytes || _S_force_new)
- {
- ::operator delete(__p);
- return;
- }
-
- /*
- * Round up to power of 2 and figure out which bin to use
- */
- size_t bin = _S_binmap[__n * sizeof(_Tp)];
-
+ }
+ return static_cast<_Tp*>(static_cast<void*>((char*)block +
+ sizeof(block_record)));
+ }
+
+ template<typename _Tp>
+ void
+ __mt_alloc<_Tp>::
+ deallocate(pointer __p, size_type __n)
+ {
+ // Requests larger than _M_max_bytes are handled by operators
+ // new/delete directly.
+ if (__n * sizeof(_Tp) > _S_options._M_max_bytes
+ || _S_options._M_force_new)
+ {
+ ::operator delete(__p);
+ return;
+ }
+
+ // Round up to power of 2 and figure out which bin to use.
+ size_t bin = _S_binmap[__n * sizeof(_Tp)];
+
#ifdef __GTHREADS
- size_t thread_id = _S_get_thread_id();
+ size_t thread_id = _S_get_thread_id();
#else
- size_t thread_id = 0;
+ size_t thread_id = 0;
#endif
-
- block_record* block = (block_record*)((char*)__p
- - sizeof(block_record));
-
+
+ block_record* block = (block_record*)((char*)__p
+ - sizeof(block_record));
+
#ifdef __GTHREADS
- if (__gthread_active_p())
- {
- /*
- * Calculate the number of records to remove from our freelist
- */
- int remove = _S_bin[bin].free[thread_id] -
- (_S_bin[bin].used[thread_id] / _S_freelist_headroom);
-
- /*
- * The calculation above will almost always tell us to
- * remove one or two records at a time, but this creates
- * too much contention when locking and therefore we
- * wait until the number of records is "high enough".
- */
- if (remove > (int)(100 * (_S_no_of_bins - bin)) &&
- remove > (int)(_S_bin[bin].free[thread_id] /
- _S_freelist_headroom))
- {
- __gthread_mutex_lock(_S_bin[bin].mutex);
-
- block_record* tmp;
-
- while (remove > 0)
- {
- tmp = _S_bin[bin].first[thread_id]->next;
-
- if (_S_bin[bin].first[0] == NULL)
- {
- _S_bin[bin].first[0] = _S_bin[bin].first[thread_id];
- _S_bin[bin].first[0]->next = NULL;
- }
- else
- {
- _S_bin[bin].first[thread_id]->next = _S_bin[bin].first[0];
- _S_bin[bin].first[0] = _S_bin[bin].first[thread_id];
- }
-
- _S_bin[bin].first[thread_id] = tmp;
-
- _S_bin[bin].free[thread_id]--;
-
- remove--;
- }
-
- __gthread_mutex_unlock(_S_bin[bin].mutex);
- }
-
- /*
- * Return this block to our list and update
- * counters and owner id as needed
- */
- if (_S_bin[bin].first[thread_id] == NULL)
- {
- _S_bin[bin].first[thread_id] = block;
- block->next = NULL;
- }
- else
- {
- block->next = _S_bin[bin].first[thread_id];
- _S_bin[bin].first[thread_id] = block;
- }
-
- _S_bin[bin].free[thread_id]++;
-
- if (thread_id == block->thread_id)
- _S_bin[bin].used[thread_id]--;
- else
- {
- _S_bin[bin].used[block->thread_id]--;
- block->thread_id = thread_id;
- }
- }
- else
+ if (__gthread_active_p())
+ {
+ // Calculate the number of records to remove from our freelist.
+ int remove = _S_bin[bin].free[thread_id] -
+ (_S_bin[bin].used[thread_id] / _S_options._M_freelist_headroom);
+
+ // The calculation above will almost always tell us to
+ // remove one or two records at a time, but this creates too
+ // much contention when locking and therefore we wait until
+ // the number of records is "high enough".
+ if (remove > (int)(100 * (_S_bin_size - bin)) &&
+ remove > (int)(_S_bin[bin].free[thread_id] /
+ _S_options._M_freelist_headroom))
+ {
+ __gthread_mutex_lock(_S_bin[bin].mutex);
+ block_record* tmp;
+ while (remove > 0)
+ {
+ tmp = _S_bin[bin].first[thread_id]->next;
+ if (_S_bin[bin].first[0] == NULL)
+ {
+ _S_bin[bin].first[0] = _S_bin[bin].first[thread_id];
+ _S_bin[bin].first[0]->next = NULL;
+ }
+ else
+ {
+ _S_bin[bin].first[thread_id]->next = _S_bin[bin].first[0];
+ _S_bin[bin].first[0] = _S_bin[bin].first[thread_id];
+ }
+
+ _S_bin[bin].first[thread_id] = tmp;
+ _S_bin[bin].free[thread_id]--;
+ remove--;
+ }
+ __gthread_mutex_unlock(_S_bin[bin].mutex);
+ }
+
+ // Return this block to our list and update counters and
+ // owner id as needed.
+ if (_S_bin[bin].first[thread_id] == NULL)
+ {
+ _S_bin[bin].first[thread_id] = block;
+ block->next = NULL;
+ }
+ else
+ {
+ block->next = _S_bin[bin].first[thread_id];
+ _S_bin[bin].first[thread_id] = block;
+ }
+
+ _S_bin[bin].free[thread_id]++;
+
+ if (thread_id == block->thread_id)
+ _S_bin[bin].used[thread_id]--;
+ else
+ {
+ _S_bin[bin].used[block->thread_id]--;
+ block->thread_id = thread_id;
+ }
+ }
+ else
#endif
- {
- /*
- * Single threaded application - return to global pool
- */
- if (_S_bin[bin].first[0] == NULL)
- {
- _S_bin[bin].first[0] = block;
- block->next = NULL;
- }
- else
- {
- block->next = _S_bin[bin].first[0];
- _S_bin[bin].first[0] = block;
- }
- }
- }
- };
-
+ {
+ // Single threaded application - return to global pool.
+ if (_S_bin[bin].first[0] == NULL)
+ {
+ _S_bin[bin].first[0] = block;
+ block->next = NULL;
+ }
+ else
+ {
+ block->next = _S_bin[bin].first[0];
+ _S_bin[bin].first[0] = block;
+ }
+ }
+ }
+
template<typename _Tp>
void
__mt_alloc<_Tp>::
- _S_init()
+ _S_initialize()
{
- if (getenv("GLIBCXX_FORCE_NEW"))
- {
- _S_force_new = true;
- _S_initialized = true;
-
- /*
- * Since none of the code in allocate/deallocate ever will be
- * executed due to that the GLIBCXX_FORCE_NEW flag is set
- * there is no need to create the internal structures either.
- */
- return;
- }
-
- /*
- * Calculate the number of bins required based on _S_max_bytes,
- * _S_no_of_bins is initialized to 1 below.
- */
- {
- size_t bin_t = 1;
- while (_S_max_bytes > bin_t)
- {
- bin_t = bin_t << 1;
- _S_no_of_bins++;
- }
- }
+ if (_S_options._M_force_new)
+ return;
+
+ // Calculate the number of bins required based on _M_max_bytes.
+ // _S_bin_size is statically-initialized to one.
+ size_t bin_size = 1;
+ while (_S_options._M_max_bytes > bin_size)
+ {
+ bin_size = bin_size << 1;
+ _S_bin_size++;
+ }
- /*
- * Setup the bin map for quick lookup of the relevant bin
- */
+ // Setup the bin map for quick lookup of the relevant bin.
_S_binmap = (binmap_type*)
- ::operator new ((_S_max_bytes + 1) * sizeof(binmap_type));
-
- if (!_S_binmap)
- std::__throw_bad_alloc();
+ ::operator new ((_S_options._M_max_bytes + 1) * sizeof(binmap_type));
binmap_type* bp_t = _S_binmap;
binmap_type bin_max_t = 1;
binmap_type bin_t = 0;
- for (binmap_type ct = 0; ct <= _S_max_bytes; ct++)
+ for (binmap_type ct = 0; ct <= _S_options._M_max_bytes; ct++)
{
if (ct > bin_max_t)
{
*bp_t++ = bin_t;
}
- /*
- * 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() create and initialize the list of
+ // free thread ids. Single threaded applications use thread id 0
+ // directly and have no need for this.
#ifdef __GTHREADS
if (__gthread_active_p())
{
_S_thread_freelist_first =
static_cast<thread_record*>(::operator
- new(sizeof(thread_record) * _S_max_threads));
+ new(sizeof(thread_record) * _S_options._M_max_threads));
- if (!_S_thread_freelist_first)
- std::__throw_bad_alloc();
-
- /*
- * NOTE! The first assignable thread id is 1 since the global
- * pool uses id 0
- */
+ // NOTE! The first assignable thread id is 1 since the
+ // global pool uses id 0
size_t i;
- for (i = 1; i < _S_max_threads; i++)
+ for (i = 1; i < _S_options._M_max_threads; i++)
{
- _S_thread_freelist_first[i - 1].next =
- &_S_thread_freelist_first[i];
-
- _S_thread_freelist_first[i - 1].id = i;
+ thread_record& tr = _S_thread_freelist_first[i - 1];
+ tr.next = &_S_thread_freelist_first[i];
+ tr.id = i;
}
- /*
- * Set last record
- */
+ // Set last record.
_S_thread_freelist_first[i - 1].next = NULL;
_S_thread_freelist_first[i - 1].id = i;
- /*
- * Initialize per thread key to hold pointer to
- * _S_thread_freelist
- */
- __gthread_key_create(&_S_thread_key, _S_thread_key_destr);
+ // Initialize per thread key to hold pointer to
+ // _S_thread_freelist.
+ __gthread_key_create(&_S_thread_key, _S_destroy_thread_key);
}
#endif
- /*
- * Initialize _S_bin and its members
- */
+ // Initialize _S_bin and its members.
_S_bin = static_cast<bin_record*>(::operator
- new(sizeof(bin_record) * _S_no_of_bins));
-
- if (!_S_bin)
- std::__throw_bad_alloc();
-
- std::size_t __n = 1;
+ new(sizeof(bin_record) * _S_bin_size));
+ // Maximum number of threads.
+ size_t __n = 1;
#ifdef __GTHREADS
if (__gthread_active_p())
- __n = _S_max_threads + 1;
+ __n = _S_options._M_max_threads + 1;
#endif
- for (size_t bin = 0; bin < _S_no_of_bins; bin++)
+ for (size_t bin = 0; bin < _S_bin_size; bin++)
{
- _S_bin[bin].first = static_cast<block_record**>(::operator
- new(sizeof(block_record*) * __n));
-
- if (!_S_bin[bin].first)
- std::__throw_bad_alloc();
+ bin_record& br = _S_bin[bin];
+ br.first = static_cast<block_record**>(::operator new(sizeof(block_record*) * __n));
#ifdef __GTHREADS
if (__gthread_active_p())
{
- _S_bin[bin].free = static_cast<size_t*>(::operator
- new(sizeof(size_t) * __n));
-
- if (!_S_bin[bin].free)
- std::__throw_bad_alloc();
-
- _S_bin[bin].used = static_cast<size_t*>(::operator
- new(sizeof(size_t) * __n));
-
- if (!_S_bin[bin].used)
- std::__throw_bad_alloc();
-
- _S_bin[bin].mutex = static_cast<__gthread_mutex_t*>(::operator
- new(sizeof(__gthread_mutex_t)));
+ br.free = static_cast<size_t*>(::operator new(sizeof(size_t)
+ * __n));
+ br.used = static_cast<size_t*>(::operator new(sizeof(size_t)
+ * __n));
+ br.mutex = static_cast<__gthread_mutex_t*>(::operator new(sizeof(__gthread_mutex_t)));
#ifdef __GTHREAD_MUTEX_INIT
{
// Do not copy a POSIX/gthr mutex once in use.
__gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
- *_S_bin[bin].mutex = __tmp;
+ *br.mutex = __tmp;
}
#else
- { __GTHREAD_MUTEX_INIT_FUNCTION (_S_bin[bin].mutex); }
+ { __GTHREAD_MUTEX_INIT_FUNCTION (br.mutex); }
#endif
}
#endif
for (size_t thread = 0; thread < __n; thread++)
{
- _S_bin[bin].first[thread] = NULL;
+ br.first[thread] = NULL;
#ifdef __GTHREADS
if (__gthread_active_p())
{
- _S_bin[bin].free[thread] = 0;
- _S_bin[bin].used[thread] = 0;
+ br.free[thread] = 0;
+ br.used[thread] = 0;
}
#endif
}
}
-
- _S_initialized = true;
+ _S_init = true;
}
#ifdef __GTHREADS
template<typename _Tp>
void
__mt_alloc<_Tp>::
- _S_thread_key_destr(void* freelist_pos)
+ _S_destroy_thread_key(void* freelist_pos)
{
- /*
- * Return this thread id record to front of thread_freelist
- */
+ // Return this thread id record to front of thread_freelist.
__gthread_mutex_lock(&_S_thread_freelist_mutex);
((thread_record*)freelist_pos)->next = _S_thread_freelist_first;
_S_thread_freelist_first = (thread_record*)freelist_pos;
__mt_alloc<_Tp>::
_S_get_thread_id()
{
- /*
- * If we have thread support and it's active we check the thread
- * key value and return it's id or if it's not set we take the
- * first record from _S_thread_freelist and sets the key and
- * returns it's id.
- */
+ // If we have thread support and it's active we check the thread
+ // key value and return it's id or if it's not set we take the
+ // first record from _S_thread_freelist and sets the key and
+ // returns it's id.
if (__gthread_active_p())
{
- thread_record* freelist_pos;
-
- if ((freelist_pos =
- (thread_record*)__gthread_getspecific(_S_thread_key)) == NULL)
+ thread_record* freelist_pos = static_cast<thread_record*>(__gthread_getspecific(_S_thread_key));
+ if (freelist_pos == NULL)
{
- /*
- * Since _S_max_threads must be larger than the
- * theoretical max number of threads of the OS the list
- * can never be empty.
- */
+ // Since _S_options._M_max_threads must be larger than
+ // the theoretical max number of threads of the OS the
+ // list can never be empty.
__gthread_mutex_lock(&_S_thread_freelist_mutex);
freelist_pos = _S_thread_freelist_first;
_S_thread_freelist_first = _S_thread_freelist_first->next;
__gthread_mutex_unlock(&_S_thread_freelist_mutex);
- __gthread_setspecific(_S_thread_key, (void*)freelist_pos);
+ __gthread_setspecific(_S_thread_key,
+ static_cast<void*>(freelist_pos));
}
-
return freelist_pos->id;
}
- /*
- * Otherwise (no thread support or inactive) all requests are
- * served from the global pool 0.
- */
+ // Otherwise (no thread support or inactive) all requests are
+ // served from the global pool 0.
return 0;
}
-
- template<typename _Tp> __gthread_once_t
- __mt_alloc<_Tp>::_S_once_mt = __GTHREAD_ONCE_INIT;
#endif
- template<typename _Tp>
- bool volatile __mt_alloc<_Tp>::_S_initialized = false;
+ template<typename _Tp>
+ inline bool
+ operator==(const __mt_alloc<_Tp>&, const __mt_alloc<_Tp>&)
+ { return true; }
+
+ template<typename _Tp>
+ inline bool
+ operator!=(const __mt_alloc<_Tp>&, const __mt_alloc<_Tp>&)
+ { return false; }
- template<typename _Tp> bool
- __mt_alloc<_Tp>::_S_force_new = false;
+ template<typename _Tp>
+ bool __mt_alloc<_Tp>::_S_init = false;
- template<typename _Tp> typename __mt_alloc<_Tp>::binmap_type*
- __mt_alloc<_Tp>::_S_binmap = NULL;
+ template<typename _Tp>
+ typename __mt_alloc<_Tp>::tune __mt_alloc<_Tp>::_S_options;
- /*
- * Allocation requests (after round-up to power of 2) below this
- * value will be handled by the allocator. A raw new/ call
- * will be used for requests larger than this value.
- */
- template<typename _Tp> size_t
- __mt_alloc<_Tp>::_S_max_bytes = 128;
-
- /*
- * In order to avoid fragmenting and minimize the number of new()
- * calls we always request new memory using this value. Based on
- * previous discussions on the libstdc++ mailing list we have
- * choosen the value below. See
- * http://gcc.gnu.org/ml/libstdc++/2001-07/msg00077.html
- */
- template<typename _Tp> size_t
- __mt_alloc<_Tp>::_S_chunk_size = 4096 - 4 * sizeof(void*);
+ template<typename _Tp>
+ typename __mt_alloc<_Tp>::binmap_type* __mt_alloc<_Tp>::_S_binmap;
- /*
- * The maximum number of supported threads. Our Linux 2.4.18 reports
- * 4070 in /proc/sys/kernel/threads-max
- */
- template<typename _Tp> size_t
- __mt_alloc<_Tp>::_S_max_threads = 4096;
+ template<typename _Tp>
+ typename __mt_alloc<_Tp>::bin_record* volatile __mt_alloc<_Tp>::_S_bin;
- /*
- * Actual value calculated in _S_init()
- */
- template<typename _Tp> size_t
- __mt_alloc<_Tp>::_S_no_of_bins = 1;
-
- /*
- * Each time a deallocation occurs in a threaded application we make
- * sure that there are no more than _S_freelist_headroom % of used
- * memory on the freelist. If the number of additional records is
- * more than _S_freelist_headroom % of the freelist, we move these
- * records back to the global pool.
- */
- template<typename _Tp> size_t
- __mt_alloc<_Tp>::_S_freelist_headroom = 10;
+ template<typename _Tp>
+ size_t __mt_alloc<_Tp>::_S_bin_size = 1;
- /*
- * Actual initialization in _S_init()
- */
+ // Actual initialization in _S_initialize().
#ifdef __GTHREADS
- template<typename _Tp> typename __mt_alloc<_Tp>::thread_record*
- volatile __mt_alloc<_Tp>::_S_thread_freelist_first = NULL;
+ template<typename _Tp>
+ __gthread_once_t __mt_alloc<_Tp>::_S_once = __GTHREAD_ONCE_INIT;
+
+ template<typename _Tp>
+ typename __mt_alloc<_Tp>::thread_record*
+ volatile __mt_alloc<_Tp>::_S_thread_freelist_first = NULL;
+
+ template<typename _Tp>
+ __gthread_key_t __mt_alloc<_Tp>::_S_thread_key;
template<typename _Tp> __gthread_mutex_t
#ifdef __GTHREAD_MUTEX_INIT
// XXX
__mt_alloc<_Tp>::_S_thread_freelist_mutex;
#endif
-
- /*
- * Actual initialization in _S_init()
- */
- template<typename _Tp> __gthread_key_t
- __mt_alloc<_Tp>::_S_thread_key;
#endif
-
- template<typename _Tp> typename __mt_alloc<_Tp>::bin_record*
- volatile __mt_alloc<_Tp>::_S_bin = NULL;
-
- template<typename _Tp>
- inline bool
- operator==(const __mt_alloc<_Tp>&, const __mt_alloc<_Tp>&)
- { return true; }
-
- template<typename _Tp>
- inline bool
- operator!=(const __mt_alloc<_Tp>&, const __mt_alloc<_Tp>&)
- { return false; }
} // namespace __gnu_cxx
#endif
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