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XPath: Refactor block allocation

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Extract memory page size and block alignment into named constants.
This commit is contained in:
Arseny Kapoulkine 2015-07-25 17:01:30 -04:00
parent a562bf6d3c
commit 66f242a4a9
1 changed files with 16 additions and 12 deletions
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28
src/pugixml.cpp
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@ -7259,18 +7259,22 @@ PUGI__NS_END
// Allocator used for AST and evaluation stacks // Allocator used for AST and evaluation stacks
PUGI__NS_BEGIN PUGI__NS_BEGIN
struct xpath_memory_block static const size_t xpath_memory_page_size =
{
xpath_memory_block* next;
size_t capacity;
char data[
#ifdef PUGIXML_MEMORY_XPATH_PAGE_SIZE #ifdef PUGIXML_MEMORY_XPATH_PAGE_SIZE
PUGIXML_MEMORY_XPATH_PAGE_SIZE PUGIXML_MEMORY_XPATH_PAGE_SIZE
#else #else
4096 4096
#endif #endif
]; ;
static const uintptr_t xpath_memory_block_alignment = sizeof(void*);
struct xpath_memory_block
{
xpath_memory_block* next;
size_t capacity;
char data[xpath_memory_page_size];
}; };
class xpath_allocator class xpath_allocator
@ -7292,8 +7296,8 @@ PUGI__NS_BEGIN
void* allocate_nothrow(size_t size) void* allocate_nothrow(size_t size)
{ {
// align size so that we're able to store pointers in subsequent blocks // round size up to block alignment boundary
size = (size + sizeof(void*) - 1) & ~(sizeof(void*) - 1); size = (size + xpath_memory_block_alignment - 1) & ~(xpath_memory_block_alignment - 1);
if (_root_size + size <= _root->capacity) if (_root_size + size <= _root->capacity)
{ {
@ -7342,9 +7346,9 @@ PUGI__NS_BEGIN
void* reallocate(void* ptr, size_t old_size, size_t new_size) void* reallocate(void* ptr, size_t old_size, size_t new_size)
{ {
// align size so that we're able to store pointers in subsequent blocks // round size up to block alignment boundary
old_size = (old_size + sizeof(void*) - 1) & ~(sizeof(void*) - 1); old_size = (old_size + xpath_memory_block_alignment - 1) & ~(xpath_memory_block_alignment - 1);
new_size = (new_size + sizeof(void*) - 1) & ~(sizeof(void*) - 1); new_size = (new_size + xpath_memory_block_alignment - 1) & ~(xpath_memory_block_alignment - 1);
// we can only reallocate the last object // we can only reallocate the last object
assert(ptr == 0 || static_cast<char*>(ptr) + old_size == _root->data + _root_size); assert(ptr == 0 || static_cast<char*>(ptr) + old_size == _root->data + _root_size);