Jacques Lucke
d8678e02ec
The main focus here was to improve the docs significantly. Furthermore, I reimplemented `Set`, `Map` and `VectorSet`. They are now (usually) faster, simpler and more customizable. I also rewrote `Stack` to make it more efficient by avoiding unnecessary copies. Thanks to everyone who helped with constructive feedback. Approved by brecht and sybren. Differential Revision: https://developer.blender.org/D7931
105 lines
3.5 KiB
C++
105 lines
3.5 KiB
C++
/*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#ifndef __BLI_ALLOCATOR_HH__
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#define __BLI_ALLOCATOR_HH__
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/** \file
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* \ingroup bli
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*
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* An `Allocator` can allocate and deallocate memory. It is used by containers such as BLI::Vector.
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* The allocators defined in this file do not work with standard library containers such as
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* std::vector.
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*
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* Every allocator has to implement two methods:
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* void *allocate(size_t size, size_t alignment, const char *name);
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* void deallocate(void *ptr);
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*
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* We don't use the std::allocator interface, because it does more than is really necessary for an
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* allocator and has some other quirks. It mixes the concepts of allocation and construction. It is
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* essentially forced to be a template, even though the allocator should not care about the type.
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* Also see http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2271.html#std_allocator. Some
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* of these aspects have been improved in new versions of C++, so we might have to reevaluate the
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* strategy later on.
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*
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* The allocator interface dictated by this file is very simplistic, but for now that is all we
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* need. More complexity can be added when it seems necessary.
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*/
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#include <algorithm>
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#include <stdlib.h>
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#include "MEM_guardedalloc.h"
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#include "BLI_math_base.h"
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#include "BLI_utildefines.h"
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namespace BLI {
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/**
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* Use Blender's guarded allocator (aka MEM_*). This should always be used except there is a
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* good reason not to use it.
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*/
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class GuardedAllocator {
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public:
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void *allocate(size_t size, size_t alignment, const char *name)
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{
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/* Should we use MEM_mallocN, when alignment is small? If yes, how small must alignment be? */
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return MEM_mallocN_aligned(size, alignment, name);
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}
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void deallocate(void *ptr)
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{
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MEM_freeN(ptr);
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}
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};
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/**
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* This is a wrapper around malloc/free. Only use this when the GuardedAllocator cannot be
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* used. This can be the case when the allocated memory might live longer than Blender's
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* allocator. For example, when the memory is owned by a static variable.
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*/
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class RawAllocator {
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private:
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struct MemHead {
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int offset;
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};
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public:
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void *allocate(size_t size, size_t alignment, const char *UNUSED(name))
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{
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BLI_assert(is_power_of_2_i((int)alignment));
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void *ptr = malloc(size + alignment + sizeof(MemHead));
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void *used_ptr = (void *)((uintptr_t)POINTER_OFFSET(ptr, alignment + sizeof(MemHead)) &
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~((uintptr_t)alignment - 1));
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uint offset = (uint)((uintptr_t)used_ptr - (uintptr_t)ptr);
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BLI_assert(offset >= sizeof(MemHead));
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((MemHead *)used_ptr - 1)->offset = (int)offset;
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return used_ptr;
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}
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void deallocate(void *ptr)
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{
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MemHead *head = (MemHead *)ptr - 1;
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int offset = -head->offset;
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void *actual_pointer = POINTER_OFFSET(ptr, offset);
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free(actual_pointer);
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}
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};
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} // namespace BLI
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#endif /* __BLI_ALLOCATOR_HH__ */
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