#ifndef _POOL_ALLOCATOR_H
#define _POOL_ALLOCATOR_H 1
+#include <bits/c++config.h>
#include <new>
#include <bits/functexcept.h>
-#include <bits/stl_threads.h>
#include <bits/atomicity.h>
+#include <bits/concurrence.h>
namespace __gnu_cxx
{
- using std::__throw_bad_alloc;
-
/**
* @if maint
- * Default node allocator. "SGI" style. Uses various allocators to
- * fulfill underlying requests (and makes as few requests as possible
- * when in default high-speed pool mode).
+ * Uses various allocators to fulfill underlying requests (and makes as
+ * few requests as possible when in default high-speed pool mode).
*
* Important implementation properties:
* 0. If globally mandated, then allocate objects from new
* information that we can return the object to the proper free list
* without permanently losing part of the object.
*
- * The first template parameter specifies whether more than one thread may
- * use this allocator. It is safe to allocate an object from one instance
- * of a default_alloc and deallocate it with another one. This effectively
- * transfers its ownership to the second one. This may have undesirable
- * effects on reference locality.
- *
- * The second parameter is unused and serves only to allow the
- * creation of multiple default_alloc instances. Note that
- * containers built on different allocator instances have different
- * types, limiting the utility of this approach. If you do not
- * wish to share the free lists with the main default_alloc
- * instance, instantiate this with a non-zero __inst.
- *
* @endif
* (See @link Allocators allocators info @endlink for more.)
*/
- template<bool __threads, int __inst>
- class __pool_alloc
+ class __pool_base
{
- private:
- enum {_S_align = 8};
- enum {_S_max_bytes = 128};
- enum {_S_freelists = _S_max_bytes / _S_align};
+ protected:
+ enum { _S_align = 8 };
+ enum { _S_max_bytes = 128 };
+ enum { _S_free_list_size = _S_max_bytes / _S_align };
+
union _Obj
{
- union _Obj* _M_free_list_link;
- char _M_client_data[1]; // The client sees this.
+ union _Obj* _M_free_list_link;
+ char _M_client_data[1]; // The client sees this.
};
-
- static _Obj* volatile _S_free_list[_S_freelists];
+
+ static _Obj* volatile _S_free_list[_S_free_list_size];
// Chunk allocation state.
static char* _S_start_free;
static char* _S_end_free;
- static size_t _S_heap_size;
-
- static _STL_mutex_lock _S_lock;
- static _Atomic_word _S_force_new;
-
- static size_t
- _S_round_up(size_t __bytes)
+ static size_t _S_heap_size;
+
+ size_t
+ _M_round_up(size_t __bytes)
{ return ((__bytes + (size_t)_S_align - 1) & ~((size_t)_S_align - 1)); }
-
- static size_t
- _S_freelist_index(size_t __bytes)
- { return ((__bytes + (size_t)_S_align - 1)/(size_t)_S_align - 1); }
+
+ _Obj* volatile*
+ _M_get_free_list(size_t __bytes);
+
+ __gthread_mutex_t&
+ _M_get_mutex();
// Returns an object of size __n, and optionally adds to size __n
// free list.
- static void*
- _S_refill(size_t __n);
-
+ void*
+ _M_refill(size_t __n);
+
// Allocates a chunk for nobjs of size size. nobjs may be reduced
// if it is inconvenient to allocate the requested number.
- static char*
- _S_chunk_alloc(size_t __n, int& __nobjs);
+ char*
+ _M_allocate_chunk(size_t __n, int& __nobjs);
+ };
- // It would be nice to use _STL_auto_lock here. But we need a
- // test whether threads are in use.
- struct _Lock
- {
- _Lock() { if (__threads) _S_lock._M_acquire_lock(); }
- ~_Lock() { if (__threads) _S_lock._M_release_lock(); }
- } __attribute__ ((__unused__));
- friend struct _Lock;
+
+ template<typename _Tp>
+ class __pool_alloc : private __pool_base
+ {
+ private:
+ static _Atomic_word _S_force_new;
public:
- // __n must be > 0
- static void*
- allocate(size_t __n);
+ typedef size_t size_type;
+ typedef ptrdiff_t difference_type;
+ typedef _Tp* pointer;
+ typedef const _Tp* const_pointer;
+ typedef _Tp& reference;
+ typedef const _Tp& const_reference;
+ typedef _Tp value_type;
+
+ template<typename _Tp1>
+ struct rebind
+ { typedef __pool_alloc<_Tp1> other; };
+
+ __pool_alloc() throw() { }
+
+ __pool_alloc(const __pool_alloc&) throw() { }
+
+ template<typename _Tp1>
+ __pool_alloc(const __pool_alloc<_Tp1>&) throw() { }
+
+ ~__pool_alloc() throw() { }
+
+ pointer
+ address(reference __x) const { return &__x; }
+
+ const_pointer
+ address(const_reference __x) const { return &__x; }
+
+ size_type
+ max_size() const throw()
+ { return size_t(-1) / sizeof(_Tp); }
+
+ // _GLIBCXX_RESOLVE_LIB_DEFECTS
+ // 402. wrong new expression in [some_] allocator::construct
+ void
+ construct(pointer __p, const _Tp& __val)
+ { ::new(__p) _Tp(__val); }
+
+ void
+ destroy(pointer __p) { __p->~_Tp(); }
+
+ pointer
+ allocate(size_type __n, const void* = 0);
- // __p may not be 0
- static void
- deallocate(void* __p, size_t __n);
+ void
+ deallocate(pointer __p, size_type __n);
};
- template<bool __threads, int __inst>
+ template<typename _Tp>
inline bool
- operator==(const __pool_alloc<__threads,__inst>&,
- const __pool_alloc<__threads,__inst>&)
+ operator==(const __pool_alloc<_Tp>&, const __pool_alloc<_Tp>&)
{ return true; }
- template<bool __threads, int __inst>
+ template<typename _Tp>
inline bool
- operator!=(const __pool_alloc<__threads,__inst>&,
- const __pool_alloc<__threads,__inst>&)
+ operator!=(const __pool_alloc<_Tp>&, const __pool_alloc<_Tp>&)
{ return false; }
+ template<typename _Tp>
+ _Atomic_word
+ __pool_alloc<_Tp>::_S_force_new;
- // Allocate memory in large chunks in order to avoid fragmenting the
- // heap too much. Assume that __n is properly aligned. We hold
- // the allocation lock.
- template<bool __threads, int __inst>
- char*
- __pool_alloc<__threads, __inst>::_S_chunk_alloc(size_t __n, int& __nobjs)
+ template<typename _Tp>
+ _Tp*
+ __pool_alloc<_Tp>::allocate(size_type __n, const void*)
{
- char* __result;
- size_t __total_bytes = __n * __nobjs;
- size_t __bytes_left = _S_end_free - _S_start_free;
-
- if (__bytes_left >= __total_bytes)
- {
- __result = _S_start_free;
- _S_start_free += __total_bytes;
- return __result ;
- }
- else if (__bytes_left >= __n)
- {
- __nobjs = (int)(__bytes_left/__n);
- __total_bytes = __n * __nobjs;
- __result = _S_start_free;
- _S_start_free += __total_bytes;
- return __result;
- }
- else
- {
- size_t __bytes_to_get =
- 2 * __total_bytes + _S_round_up(_S_heap_size >> 4);
- // Try to make use of the left-over piece.
- if (__bytes_left > 0)
- {
- _Obj* volatile* __free_list =
- _S_free_list + _S_freelist_index(__bytes_left);
-
- ((_Obj*)(void*)_S_start_free)->_M_free_list_link = *__free_list;
- *__free_list = (_Obj*)(void*)_S_start_free;
- }
- _S_start_free = static_cast<char*>(::operator new(__bytes_to_get));
- if (_S_start_free == 0)
- {
- size_t __i;
- _Obj* volatile* __free_list;
- _Obj* __p;
- // Try to make do with what we have. That can't hurt. We
- // do not try smaller requests, since that tends to result
- // in disaster on multi-process machines.
- __i = __n;
- for (; __i <= (size_t) _S_max_bytes; __i += (size_t) _S_align)
- {
- __free_list = _S_free_list + _S_freelist_index(__i);
- __p = *__free_list;
- if (__p != 0)
- {
- *__free_list = __p -> _M_free_list_link;
- _S_start_free = (char*)__p;
- _S_end_free = _S_start_free + __i;
- return _S_chunk_alloc(__n, __nobjs);
- // Any leftover piece will eventually make it to the
- // right free list.
- }
- }
- _S_end_free = 0; // In case of exception.
- _S_start_free = static_cast<char*>(::operator new(__bytes_to_get));
- // This should either throw an exception or remedy the situation.
- // Thus we assume it succeeded.
- }
- _S_heap_size += __bytes_to_get;
- _S_end_free = _S_start_free + __bytes_to_get;
- return _S_chunk_alloc(__n, __nobjs);
- }
- }
-
- // Returns an object of size __n, and optionally adds to "size
- // __n"'s free list. We assume that __n is properly aligned. We
- // hold the allocation lock.
- template<bool __threads, int __inst>
- void*
- __pool_alloc<__threads, __inst>::_S_refill(size_t __n)
- {
- int __nobjs = 20;
- char* __chunk = _S_chunk_alloc(__n, __nobjs);
- _Obj* volatile* __free_list;
- _Obj* __result;
- _Obj* __current_obj;
- _Obj* __next_obj;
- int __i;
-
- if (1 == __nobjs)
- return __chunk;
- __free_list = _S_free_list + _S_freelist_index(__n);
-
- // Build free list in chunk.
- __result = (_Obj*)(void*)__chunk;
- *__free_list = __next_obj = (_Obj*)(void*)(__chunk + __n);
- for (__i = 1; ; __i++)
- {
- __current_obj = __next_obj;
- __next_obj = (_Obj*)(void*)((char*)__next_obj + __n);
- if (__nobjs - 1 == __i)
+ pointer __ret = 0;
+ if (__n)
+ {
+ if (__n <= max_size())
{
- __current_obj -> _M_free_list_link = 0;
- break;
+ // If there is a race through here, assume answer from getenv
+ // will resolve in same direction. Inspired by techniques
+ // to efficiently support threading found in basic_string.h.
+ if (_S_force_new == 0)
+ {
+ if (getenv("GLIBCXX_FORCE_NEW"))
+ __atomic_add(&_S_force_new, 1);
+ else
+ __atomic_add(&_S_force_new, -1);
+ }
+
+ const size_t __bytes = __n * sizeof(_Tp);
+ if (__bytes > size_t(_S_max_bytes) || _S_force_new == 1)
+ __ret = static_cast<_Tp*>(::operator new(__bytes));
+ else
+ {
+ _Obj* volatile* __free_list = _M_get_free_list(__bytes);
+
+ lock sentry(_M_get_mutex());
+ _Obj* __restrict__ __result = *__free_list;
+ if (__builtin_expect(__result == 0, 0))
+ __ret = static_cast<_Tp*>(_M_refill(_M_round_up(__bytes)));
+ else
+ {
+ *__free_list = __result->_M_free_list_link;
+ __ret = reinterpret_cast<_Tp*>(__result);
+ }
+ if (__builtin_expect(__ret == 0, 0))
+ std::__throw_bad_alloc();
+ }
}
else
- __current_obj -> _M_free_list_link = __next_obj;
+ std::__throw_bad_alloc();
}
- return __result;
+ return __ret;
}
- template<bool __threads, int __inst>
- void*
- __pool_alloc<__threads, __inst>::allocate(size_t __n)
+ template<typename _Tp>
+ void
+ __pool_alloc<_Tp>::deallocate(pointer __p, size_type __n)
{
- void* __ret = 0;
-
- // If there is a race through here, assume answer from getenv
- // will resolve in same direction. Inspired by techniques
- // to efficiently support threading found in basic_string.h.
- if (_S_force_new == 0)
+ if (__n)
{
- if (getenv("GLIBCXX_FORCE_NEW"))
- __atomic_add(&_S_force_new, 1);
- else
- __atomic_add(&_S_force_new, -1);
- }
-
- if ((__n > (size_t) _S_max_bytes) || (_S_force_new > 0))
- __ret = ::operator new(__n);
- else
- {
- _Obj* volatile* __free_list = _S_free_list + _S_freelist_index(__n);
- // Acquire the lock here with a constructor call. This
- // ensures that it is released in exit or during stack
- // unwinding.
- _Lock __lock_instance;
- _Obj* __restrict__ __result = *__free_list;
- if (__builtin_expect(__result == 0, 0))
- __ret = _S_refill(_S_round_up(__n));
+ const size_t __bytes = __n * sizeof(_Tp);
+ if (__bytes > static_cast<size_t>(_S_max_bytes) || _S_force_new == 1)
+ ::operator delete(__p);
else
{
- *__free_list = __result -> _M_free_list_link;
- __ret = __result;
- }
- if (__builtin_expect(__ret == 0, 0))
- __throw_bad_alloc();
- }
- return __ret;
- }
+ _Obj* volatile* __free_list = _M_get_free_list(__bytes);
+ _Obj* __q = reinterpret_cast<_Obj*>(__p);
- template<bool __threads, int __inst>
- void
- __pool_alloc<__threads, __inst>::deallocate(void* __p, size_t __n)
- {
- if ((__n > (size_t) _S_max_bytes) || (_S_force_new > 0))
- ::operator delete(__p);
- else
- {
- _Obj* volatile* __free_list = _S_free_list + _S_freelist_index(__n);
- _Obj* __q = (_Obj*)__p;
-
- // Acquire the lock here with a constructor call. This
- // ensures that it is released in exit or during stack
- // unwinding.
- _Lock __lock_instance;
- __q -> _M_free_list_link = *__free_list;
- *__free_list = __q;
+ lock sentry(_M_get_mutex());
+ __q ->_M_free_list_link = *__free_list;
+ *__free_list = __q;
+ }
}
}
-
- template<bool __threads, int __inst>
- typename __pool_alloc<__threads, __inst>::_Obj* volatile
- __pool_alloc<__threads, __inst>::_S_free_list[_S_freelists];
-
- template<bool __threads, int __inst>
- char* __pool_alloc<__threads, __inst>::_S_start_free = 0;
-
- template<bool __threads, int __inst>
- char* __pool_alloc<__threads, __inst>::_S_end_free = 0;
-
- template<bool __threads, int __inst>
- size_t __pool_alloc<__threads, __inst>::_S_heap_size = 0;
-
- template<bool __threads, int __inst>
- _STL_mutex_lock
- __pool_alloc<__threads, __inst>::_S_lock __STL_MUTEX_INITIALIZER;
-
- template<bool __threads, int __inst> _Atomic_word
- __pool_alloc<__threads, __inst>::_S_force_new = 0;
-
- // Inhibit implicit instantiations for required instantiations,
- // which are defined via explicit instantiations elsewhere.
- // NB: This syntax is a GNU extension.
-#if _GLIBCXX_EXTERN_TEMPLATE
- extern template class __pool_alloc<true, 0>;
-#endif
} // namespace __gnu_cxx
#endif
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