// MT-optimized allocator -*- C++ -*-
-// Copyright (C) 2003 Free Software Foundation, Inc.
+// Copyright (C) 2003, 2004 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
#define _MT_ALLOCATOR_H 1
#include <new>
-#include <memory>
#include <cstdlib>
#include <bits/functexcept.h>
#include <bits/gthr.h>
* 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 _S_initialized;
+ static bool _S_init;
- /*
- * Using short int as type for the binmap implies we are never caching
- * blocks larger than 65535 with this allocator
- */
+ 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 back 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.
- */
- thread_record* next;
-
- /*
- * Thread id ranging from 1 to _S_max_threads.
- */
+ // 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.
size_t id;
};
- static thread_record* _S_thread_freelist_first;
- static thread_record* _S_thread_freelist_last;
- 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);
#endif
+ static size_t
+ _S_get_thread_id();
+
struct block_record
{
- /*
- * Points to the next block_record for its thread_id.
- */
- block_record* next;
-
- /*
- * The thread id of the thread which has requested this block.
- * All blocks are initially "owned" by global pool thread id 0.
- */
+ // 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.
+#ifdef __GTHREADS
size_t thread_id;
+#endif
};
struct bin_record
{
- /*
- * An "array" of pointers to the first/last free block for each
- * thread id. Memory to these "arrays" is allocated in _S_init()
- * for _S_max_threads + global pool 0.
- */
- block_record** first;
- block_record** last;
-
- /*
- * 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.
- */
- size_t* free;
- size_t* 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().
- */
+ // 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_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_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* _S_bin;
-
- public:
- pointer
- allocate(size_t __n, std::allocator<void>::const_pointer __h = 0)
- {
- /*
- * Requests larger than _S_max_bytes are handled by
- * new/delete directly
- */
- if (__n > _S_max_bytes)
- {
- void* __ret = malloc(__n * sizeof(_Tp));
- if (!__ret)
- __throw_bad_alloc();
- return static_cast<_Tp*>(__ret);
- }
-
- /*
- * 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)
- {
-#ifdef __GTHREADS
- if (__gthread_active_p())
- __gthread_once(&_S_once_mt, _S_init);
- else
-#endif
- {
- _S_max_threads = 0;
- _S_init();
- }
- }
+ // 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;
- /*
- * Round up to power of 2 and figure out which bin to use
- */
- size_t bin = _S_binmap[__n];
+ // 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
- size_t thread_id = _S_get_thread_id();
-#else
- size_t thread_id = 0;
+ if (__gthread_active_p())
+ __gthread_once(&_S_once, _S_initialize);
#endif
-
- block_record* block;
-
- /*
- * 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, lock and check if there are free blocks on the global
- * list (and if not add new ones), get the first one
- * and change 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.
- */
+ 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.
+ const size_t __which = _S_binmap[__bytes];
+ const size_t __thread_id = _S_get_thread_id();
+
+ // Find out if we have blocks on our freelist. If so, go ahead
+ // and use them directly without having to lock anything.
+ const bin_record& __bin = _S_bin[__which];
+ block_record* block = NULL;
+ if (__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())
- {
- __gthread_mutex_lock(_S_bin[bin].mutex);
-
- if (_S_bin[bin].first[0] == NULL)
- {
- _S_bin[bin].first[0] =
- (block_record*)malloc(_S_chunk_size);
-
- if (!_S_bin[bin].first[0])
- {
- __gthread_mutex_unlock(_S_bin[bin].mutex);
- __throw_bad_alloc();
- }
-
- size_t bin_t = 1 << bin;
- size_t block_count =
- _S_chunk_size /(bin_t + sizeof(block_record));
-
- _S_bin[bin].free[0] = block_count;
-
- 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;
- _S_bin[bin].last[0] = block;
- }
-
- block = _S_bin[bin].first[0];
-
- /*
- * Remove from list and count down the available counter on
- * global pool 0.
- */
- _S_bin[bin].first[0] = _S_bin[bin].first[0]->next;
- _S_bin[bin].free[0]--;
-
- __gthread_mutex_unlock(_S_bin[bin].mutex);
-
- /*
- * Now that we have removed the block from the global
- * freelist we can change owner and update the used
- * counter for this thread without locking.
- */
- block->thread_id = thread_id;
- _S_bin[bin].used[thread_id]++;
- }
- else
+ if (__gthread_active_p())
+ {
+ const size_t bin_size = (1 << __which) + sizeof(block_record);
+ size_t block_count = _S_options._M_chunk_size / bin_size;
+
+ __gthread_mutex_lock(__bin.mutex);
+ if (__bin.first[0] == NULL)
+ {
+ // No need to hold the lock when we are adding a
+ // whole chunk to our own list.
+ __gthread_mutex_unlock(__bin.mutex);
+
+ void* v = ::operator new(_S_options._M_chunk_size);
+ __bin.first[__thread_id] = static_cast<block_record*>(v);
+
+ __bin.free[__thread_id] = block_count;
+ block_count--;
+ block = __bin.first[__thread_id];
+
+ while (block_count > 0)
+ {
+ char* c = reinterpret_cast<char*>(block) + bin_size;
+ block->next = reinterpret_cast<block_record*>(c);
+ 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 (__bin.first[0] != NULL && global_count < block_count)
+ {
+ tmp = __bin.first[0]->next;
+ block = __bin.first[0];
+
+ if (__bin.first[__thread_id] == NULL)
+ {
+ __bin.first[__thread_id] = block;
+ block->next = NULL;
+ }
+ else
+ {
+ block->next = __bin.first[__thread_id];
+ __bin.first[__thread_id] = block;
+ }
+
+ block->thread_id = __thread_id;
+ __bin.free[__thread_id]++;
+ __bin.first[0] = tmp;
+ global_count++;
+ }
+ __gthread_mutex_unlock(__bin.mutex);
+ }
+
+ // Return the first newly added block in our list and
+ // update the counters
+ block = __bin.first[__thread_id];
+ __bin.first[__thread_id] = __bin.first[__thread_id]->next;
+ __bin.free[__thread_id]--;
+ __bin.used[__thread_id]++;
+ }
+ else
#endif
- {
- _S_bin[bin].first[0] = (block_record*)malloc(_S_chunk_size);
-
- if (!_S_bin[bin].first[0])
- __throw_bad_alloc();
-
- size_t bin_t = 1 << bin;
- size_t block_count =
- _S_chunk_size / (bin_t + sizeof(block_record));
-
- _S_bin[bin].free[0] = block_count;
-
- 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;
- _S_bin[bin].last[0] = block;
-
- block = _S_bin[bin].first[0];
-
- /*
- * Remove from list and count down the available counter on
- * global pool 0 and increase it's used counter.
- */
- _S_bin[bin].first[0] = _S_bin[bin].first[0]->next;
- _S_bin[bin].free[0]--;
- _S_bin[bin].used[0]++;
- }
- }
- 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].free[thread_id]--;
- _S_bin[bin].used[thread_id]++;
- }
-
- 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
- * malloc/free directly
- */
- if (__n > _S_max_bytes)
- {
- free(__p);
- return;
- }
-
- /*
- * Round up to power of 2 and figure out which bin to use
- */
- size_t bin = _S_binmap[__n];
+ {
+ void* __v = ::operator new(_S_options._M_chunk_size);
+ __bin.first[0] = static_cast<block_record*>(__v);
+
+ const size_t bin_size = (1 << __which) + sizeof(block_record);
+ size_t block_count = _S_options._M_chunk_size / bin_size;
+
+ block_count--;
+ block = __bin.first[0];
+ while (block_count > 0)
+ {
+ char* __c = reinterpret_cast<char*>(block) + bin_size;
+ block->next = reinterpret_cast<block_record*>(__c);
+ block = block->next;
+ block_count--;
+ }
+ block->next = NULL;
+
+ // Remove from list.
+ block = __bin.first[0];
+ __bin.first[0] = __bin.first[0]->next;
+ }
+ }
+ else
+ {
+ // "Default" operation - we have blocks on our own freelist
+ // grab the first record and update the counters.
+ block = __bin.first[__thread_id];
+ __bin.first[__thread_id] = __bin.first[__thread_id]->next;
#ifdef __GTHREADS
- size_t thread_id = _S_get_thread_id();
-#else
- size_t thread_id = 0;
+ if (__gthread_active_p())
+ {
+ __bin.free[__thread_id]--;
+ __bin.used[__thread_id]++;
+ }
#endif
+ }
+ char* __c = reinterpret_cast<char*>(block) + sizeof(block_record);
+ return static_cast<_Tp*>(static_cast<void*>(__c));
+ }
+
- block_record* block = (block_record*)((char*)__p
- - sizeof(block_record));
-
- /*
- * This block will always be at the back of a list and thus
- * we set its next pointer to NULL.
- */
- block->next = NULL;
-
+ 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.
+ const size_t __bytes = __n * sizeof(_Tp);
+ if (__bytes > _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.
+ const size_t __which = _S_binmap[__bytes];
+ const size_t thread_id = _S_get_thread_id();
+ const bin_record& __bin = _S_bin[__which];
+
+ char* __c = reinterpret_cast<char*>(__p) - sizeof(block_record);
+ block_record* block = reinterpret_cast<block_record*>(__c);
+
#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);
-
- while (remove > 0)
- {
- if (_S_bin[bin].first[0] == NULL)
- _S_bin[bin].first[0] = _S_bin[bin].first[thread_id];
- else
- _S_bin[bin].last[0]->next = _S_bin[bin].first[thread_id];
-
- _S_bin[bin].last[0] = _S_bin[bin].first[thread_id];
-
- _S_bin[bin].first[thread_id] =
- _S_bin[bin].first[thread_id]->next;
-
- _S_bin[bin].free[0]++;
- _S_bin[bin].free[thread_id]--;
-
- remove--;
- }
-
- _S_bin[bin].last[0]->next = NULL;
-
- __gthread_mutex_unlock(_S_bin[bin].mutex);
- }
-
- /*
- * Did we allocate this block?
- * - Yes, return it to our freelist
- * - No, return it to global pool
- */
- if (thread_id == block->thread_id)
- {
- if (_S_bin[bin].first[thread_id] == NULL)
- _S_bin[bin].first[thread_id] = block;
- else
- _S_bin[bin].last[thread_id]->next = block;
-
- _S_bin[bin].last[thread_id] = block;
-
- _S_bin[bin].free[thread_id]++;
- _S_bin[bin].used[thread_id]--;
- }
- else
- {
- __gthread_mutex_lock(_S_bin[bin].mutex);
-
- if (_S_bin[bin].first[0] == NULL)
- _S_bin[bin].first[0] = block;
- else
- _S_bin[bin].last[0]->next = block;
-
- _S_bin[bin].last[0] = block;
-
- _S_bin[bin].free[0]++;
- _S_bin[bin].used[block->thread_id]--;
-
- __gthread_mutex_unlock(_S_bin[bin].mutex);
- }
- }
- else
+ if (__gthread_active_p())
+ {
+ // Calculate the number of records to remove from our freelist.
+ int remove = __bin.free[thread_id] -
+ (__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".
+ int __cond1 = static_cast<int>(100 * (_S_bin_size - __which));
+ int __cond2 = static_cast<int>(__bin.free[thread_id] / _S_options._M_freelist_headroom);
+ if (remove > __cond1 && remove > __cond2)
+ {
+ __gthread_mutex_lock(__bin.mutex);
+ block_record* tmp;
+ while (remove > 0)
+ {
+ tmp = __bin.first[thread_id]->next;
+ if (__bin.first[0] == NULL)
+ {
+ __bin.first[0] = __bin.first[thread_id];
+ __bin.first[0]->next = NULL;
+ }
+ else
+ {
+ __bin.first[thread_id]->next = __bin.first[0];
+ __bin.first[0] = __bin.first[thread_id];
+ }
+
+ __bin.first[thread_id] = tmp;
+ __bin.free[thread_id]--;
+ remove--;
+ }
+ __gthread_mutex_unlock(__bin.mutex);
+ }
+
+ // Return this block to our list and update counters and
+ // owner id as needed.
+ if (__bin.first[thread_id] == NULL)
+ {
+ __bin.first[thread_id] = block;
+ block->next = NULL;
+ }
+ else
+ {
+ block->next = __bin.first[thread_id];
+ __bin.first[thread_id] = block;
+ }
+
+ __bin.free[thread_id]++;
+
+ if (thread_id == block->thread_id)
+ __bin.used[thread_id]--;
+ else
+ {
+ __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;
- else
- _S_bin[bin].last[0]->next = block;
-
- _S_bin[bin].last[0] = block;
-
- _S_bin[bin].free[0]++;
- _S_bin[bin].used[0]--;
- }
- }
- };
-
+ {
+ // Single threaded application - return to global pool.
+ if (__bin.first[0] == NULL)
+ {
+ __bin.first[0] = block;
+ block->next = NULL;
+ }
+ else
+ {
+ block->next = __bin.first[0];
+ __bin.first[0] = block;
+ }
+ }
+ }
+
template<typename _Tp>
void
__mt_alloc<_Tp>::
- _S_init()
+ _S_initialize()
{
- /*
- * 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++;
- }
- }
-
- /*
- * Setup the bin map for quick lookup of the relevant bin
- */
- _S_binmap = (binmap_type*)
- malloc ((_S_max_bytes + 1) * sizeof(binmap_type));
+ 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++;
+ }
- if (!_S_binmap)
- __throw_bad_alloc();
+ // Setup the bin map for quick lookup of the relevant bin.
+ const size_t __j = (_S_options._M_max_bytes + 1) * sizeof(binmap_type);
+ _S_binmap = static_cast<binmap_type*>(::operator new(__j));
- 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++)
+ binmap_type* __bp = _S_binmap;
+ binmap_type __bin_max = 1;
+ binmap_type __bint = 0;
+ for (binmap_type __ct = 0; __ct <= _S_options._M_max_bytes; __ct++)
{
- if (ct > bin_max_t)
+ if (__ct > __bin_max)
{
- bin_max_t <<= 1;
- bin_t++;
+ __bin_max <<= 1;
+ __bint++;
}
- *bp_t++ = bin_t;
+ *__bp++ = __bint;
}
- /*
- * 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.
+ void* __v;
#ifdef __GTHREADS
if (__gthread_active_p())
{
- _S_thread_freelist_first =
- (thread_record*)malloc(sizeof(thread_record) * _S_max_threads);
-
- if (!_S_thread_freelist_first)
- __throw_bad_alloc();
-
- /*
- * 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++)
+ const size_t __k = sizeof(thread_record) * _S_options._M_max_threads;
+ __v = ::operator new(__k);
+ _S_thread_freelist_first = 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 < _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 and pointer to this
- */
- _S_thread_freelist_first[i - 1].next = NULL;
- _S_thread_freelist_first[i - 1].id = i;
- _S_thread_freelist_last = &_S_thread_freelist_first[i - 1];
-
- /*
- * Initialize per thread key to hold pointer to
- * _S_thread_freelist NOTE! Here's an ugly workaround - if
- * _S_thread_key_destr is not explicitly called at least
- * once it won't be linked into the application. This is the
- * behavior of template methods and __gthread_key_create()
- * takes only a pointer to the function and does not cause
- * the compiler to create an instance.
- */
- _S_thread_key_destr(NULL);
- __gthread_key_create(&_S_thread_key, _S_thread_key_destr);
+ // Set last record.
+ _S_thread_freelist_first[__i - 1].next = NULL;
+ _S_thread_freelist_first[__i - 1].id = __i;
+
+
+ // Make sure this is initialized.
+#ifndef __GTHREAD_MUTEX_INIT
+ __GTHREAD_MUTEX_INIT_FUNCTION(&_S_thread_freelist_mutex);
+#endif
+ // 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
- */
- _S_bin = (bin_record*)malloc(sizeof(bin_record) * _S_no_of_bins);
-
- if (!_S_bin)
- __throw_bad_alloc();
+ // Initialize _S_bin and its members.
+ __v = ::operator new(sizeof(bin_record) * _S_bin_size);
+ _S_bin = static_cast<bin_record*>(__v);
+
+ // Maximum number of threads.
+ size_t __max_threads = 1;
+#ifdef __GTHREADS
+ if (__gthread_active_p())
+ __max_threads = _S_options._M_max_threads + 1;
+#endif
- for (size_t bin = 0; bin < _S_no_of_bins; bin++)
+ for (size_t __n = 0; __n < _S_bin_size; __n++)
{
- std::size_t __n = _S_max_threads + 1;
-
- _S_bin[bin].first = (block_record**)
- malloc(sizeof(block_record*) * __n);
-
- if (!_S_bin[bin].first)
- __throw_bad_alloc();
+ bin_record& __bin = _S_bin[__n];
+ __v = ::operator new(sizeof(block_record*) * __max_threads);
+ __bin.first = static_cast<block_record**>(__v);
- _S_bin[bin].last = (block_record**)
- malloc(sizeof(block_record*) * __n);
-
- if (!_S_bin[bin].last)
- __throw_bad_alloc();
-
- _S_bin[bin].free = (size_t*) malloc(sizeof(size_t) * __n);
-
- if (!_S_bin[bin].free)
- __throw_bad_alloc();
-
- _S_bin[bin].used = (size_t*) malloc(sizeof(size_t) * __n);
+#ifdef __GTHREADS
+ if (__gthread_active_p())
+ {
+ __v = ::operator new(sizeof(size_t) * __max_threads);
+ __bin.free = static_cast<size_t*>(__v);
- if (!_S_bin[bin].used)
- __throw_bad_alloc();
+ __v = ::operator new(sizeof(size_t) * __max_threads);
+ __bin.used = static_cast<size_t*>(__v);
-#ifdef __GTHREADS
- _S_bin[bin].mutex =(__gthread_mutex_t*) malloc(sizeof(__gthread_mutex_t));
+ __v = ::operator new(sizeof(__gthread_mutex_t));
+ __bin.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;
- *_S_bin[bin].mutex = __tmp;
- }
+ {
+ // Do not copy a POSIX/gthr mutex once in use.
+ __gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
+ *__bin.mutex = __tmp;
+ }
#else
- { __GTHREAD_MUTEX_INIT_FUNCTION (_S_bin[bin].mutex); }
+ { __GTHREAD_MUTEX_INIT_FUNCTION(__bin.mutex); }
#endif
+ }
#endif
- for (size_t thread = 0; thread <= _S_max_threads; thread++)
+ for (size_t __threadn = 0; __threadn < __max_threads; __threadn++)
{
- _S_bin[bin].first[thread] = NULL;
- _S_bin[bin].last[thread] = NULL;
- _S_bin[bin].free[thread] = 0;
- _S_bin[bin].used[thread] = 0;
- }
- }
-
- _S_initialized = true;
- }
-
+ __bin.first[__threadn] = NULL;
#ifdef __GTHREADS
- template<typename _Tp>
- void
- __mt_alloc<_Tp>::
- _S_thread_key_destr(void* freelist_pos)
- {
- /*
- * If the thread - when it dies - still has records on its
- * freelist we return them to the global pool here.
- */
- for (size_t bin = 0; bin < _S_no_of_bins; bin++)
- {
- block_record* block =
- _S_bin[bin].first[((thread_record*)freelist_pos)->id];
-
- if (block != NULL)
- {
- __gthread_mutex_lock(_S_bin[bin].mutex);
- while (block != NULL)
+ if (__gthread_active_p())
{
- if (_S_bin[bin].first[0] == NULL)
- _S_bin[bin].first[0] = block;
- else
- _S_bin[bin].last[0]->next = block;
-
- _S_bin[bin].last[0] = block;
- block = block->next;
- _S_bin[bin].free[0]++;
+ __bin.free[__threadn] = 0;
+ __bin.used[__threadn] = 0;
}
-
- _S_bin[bin].last[0]->next = NULL;
- __gthread_mutex_unlock(_S_bin[bin].mutex);
+#endif
}
}
-
- /*
- * Return this thread id record to thread_freelist
- */
- __gthread_mutex_lock(&_S_thread_freelist_mutex);
- _S_thread_freelist_last->next = (thread_record*)freelist_pos;
- _S_thread_freelist_last = (thread_record*)freelist_pos;
- _S_thread_freelist_last->next = NULL;
- __gthread_mutex_unlock(&_S_thread_freelist_mutex);
+ _S_init = true;
}
template<typename _Tp>
__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.
- */
+#ifdef __GTHREADS
+ // 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;
+ __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);
-
- /*
- * Since thread_ids may/will be reused (espcially in
- * producer/consumer applications) we make sure that the
- * list pointers and free counter is reset BUT as the
- * "old" thread may still be owner of some memory (which
- * is referred to by other threads and thus not freed)
- * we don't reset the used counter.
- */
- for (size_t bin = 0; bin < _S_no_of_bins; bin++)
- {
- _S_bin[bin].first[freelist_pos->id] = NULL;
- _S_bin[bin].last[freelist_pos->id] = NULL;
- _S_bin[bin].free[freelist_pos->id] = 0;
- }
+ __gthread_setspecific(_S_thread_key,
+ static_cast<void*>(__freelist_pos));
}
-
- return freelist_pos->id;
+ return __freelist_pos->id;
}
-
- /*
- * Otherwise (no thread support or inactive) all requests are
- * served from the global pool 0.
- */
+#endif
+ // 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;
+#ifdef __GTHREADS
+ template<typename _Tp>
+ void
+ __mt_alloc<_Tp>::
+ _S_destroy_thread_key(void* __freelist_pos)
+ {
+ // Return this thread id record to front of thread_freelist.
+ __gthread_mutex_lock(&_S_thread_freelist_mutex);
+ thread_record* __tr = static_cast<thread_record*>(__freelist_pos);
+ __tr->next = _S_thread_freelist_first;
+ _S_thread_freelist_first = __tr;
+ __gthread_mutex_unlock(&_S_thread_freelist_mutex);
+ }
#endif
- template<typename _Tp> bool
- __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> typename __mt_alloc<_Tp>::binmap_type*
- __mt_alloc<_Tp>::_S_binmap = NULL;
+ template<typename _Tp>
+ bool __mt_alloc<_Tp>::_S_init = false;
- /*
- * Allocation requests (after round-up to power of 2) below this
- * value will be handled by the allocator. A raw malloc/free() 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 malloc()
- * 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>::tune __mt_alloc<_Tp>::_S_options;
- /*
- * 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>::binmap_type* __mt_alloc<_Tp>::_S_binmap;
- /*
- * 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>
+ typename __mt_alloc<_Tp>::bin_record* volatile __mt_alloc<_Tp>::_S_bin;
- /*
- * Actual initialization in _S_init()
- */
+ template<typename _Tp>
+ size_t __mt_alloc<_Tp>::_S_bin_size = 1;
+
+ // Actual initialization in _S_initialize().
#ifdef __GTHREADS
- template<typename _Tp> typename __mt_alloc<_Tp>::thread_record*
- __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*
- __mt_alloc<_Tp>::_S_thread_freelist_last = NULL;
+ template<typename _Tp>
+ typename __mt_alloc<_Tp>::thread_record*
+ volatile __mt_alloc<_Tp>::_S_thread_freelist_first = NULL;
- template<typename _Tp> __gthread_mutex_t
- __mt_alloc<_Tp>::_S_thread_freelist_mutex = __GTHREAD_MUTEX_INIT;
+ template<typename _Tp>
+ __gthread_key_t __mt_alloc<_Tp>::_S_thread_key;
- /*
- * Actual initialization in _S_init()
- */
- template<typename _Tp> __gthread_key_t
- __mt_alloc<_Tp>::_S_thread_key;
+ template<typename _Tp>
+ __gthread_mutex_t
+#ifdef __GTHREAD_MUTEX_INIT
+ __mt_alloc<_Tp>::_S_thread_freelist_mutex = __GTHREAD_MUTEX_INIT;
+#else
+ __mt_alloc<_Tp>::_S_thread_freelist_mutex;
+#endif
#endif
-
- template<typename _Tp> typename __mt_alloc<_Tp>::bin_record*
- __mt_alloc<_Tp>::_S_bin = NULL;
} // namespace __gnu_cxx
#endif
OSDN Git Service
