Changed memory management so that the document node lives inside document; this way a default-constructed document does not allocate any dynamic memory

git-svn-id: http://pugixml.googlecode.com/svn/trunk@445 99668b35-9821-0410-8761-19e4c4f06640
This commit is contained in:
arseny.kapoulkine 2010-05-25 07:55:44 +00:00
parent 4e05568c4d
commit ece9147611
3 changed files with 96 additions and 96 deletions

View File

@ -238,12 +238,47 @@ namespace pugi
namespace pugi
{
static const size_t xml_memory_page_size = 32768;
static const uintptr_t xml_memory_page_alignment = 32;
static const uintptr_t xml_memory_page_pointer_mask = ~(xml_memory_page_alignment - 1);
static const uintptr_t xml_memory_page_name_allocated_mask = 16;
static const uintptr_t xml_memory_page_value_allocated_mask = 8;
static const uintptr_t xml_memory_page_type_mask = 7;
struct xml_allocator;
struct xml_memory_page
{
static xml_memory_page* construct(void* memory)
{
if (!memory) return 0;
xml_memory_page* result = static_cast<xml_memory_page*>(memory);
result->allocator = 0;
result->memory = 0;
result->prev = 0;
result->next = 0;
result->busy_size = 0;
result->freed_size = 0;
return result;
}
xml_allocator* allocator;
void* memory;
xml_memory_page* prev;
xml_memory_page* next;
size_t busy_size;
size_t freed_size;
char data[1];
};
struct xml_memory_string_header
{
xml_memory_page* page;
@ -258,13 +293,7 @@ namespace pugi
xml_memory_page* allocate_page(size_t data_size)
{
#ifdef __GNUC__
// To avoid offsetof warning (xml_memory_page is not POD)
xml_memory_page* dummy_page = 0;
size_t size = ((size_t)(uintptr_t)&dummy_page->data) + data_size;
#else
size_t size = offsetof(xml_memory_page, data) + data_size;
#endif
// allocate block with some alignment, leaving memory for worst-case padding
void* memory = global_allocate(size + xml_memory_page_alignment);
@ -273,7 +302,7 @@ namespace pugi
void* page_memory = reinterpret_cast<void*>((reinterpret_cast<uintptr_t>(memory) + (xml_memory_page_alignment - 1)) & ~(xml_memory_page_alignment - 1));
// prepare page structure
xml_memory_page* page = new (page_memory) xml_memory_page();
xml_memory_page* page = xml_memory_page::construct(page_memory);
page->memory = memory;
page->allocator = _root->allocator;
@ -451,6 +480,13 @@ namespace pugi
xml_allocator allocator;
const char_t* buffer;
};
inline xml_allocator& get_allocator(const xml_node_struct* node)
{
assert(node);
return *reinterpret_cast<xml_memory_page*>(node->header & xml_memory_page_pointer_mask)->allocator;
}
}
// Low-level DOM operations
@ -3305,13 +3341,6 @@ namespace pugi
return !_root;
}
xml_allocator& xml_node::get_allocator() const
{
assert(_root);
return *reinterpret_cast<xml_memory_page*>(_root->header & xml_memory_page_pointer_mask)->allocator;
}
const char_t* xml_node::name() const
{
return (_root && _root->name) ? _root->name : PUGIXML_TEXT("");
@ -3524,7 +3553,7 @@ namespace pugi
{
if (type() != node_element && type() != node_declaration) return xml_attribute();
xml_attribute a(append_attribute_ll(_root, get_allocator()));
xml_attribute a(append_attribute_ll(_root, get_allocator(_root)));
a.set_name(name);
return a;
@ -3541,7 +3570,7 @@ namespace pugi
if (cur != _root->first_attribute) return xml_attribute();
xml_attribute a(allocate_attribute(get_allocator()));
xml_attribute a(allocate_attribute(get_allocator(_root)));
a.set_name(name);
if (attr._attr->prev_attribute_c->next_attribute)
@ -3567,7 +3596,7 @@ namespace pugi
if (cur != _root->first_attribute) return xml_attribute();
xml_attribute a(allocate_attribute(get_allocator()));
xml_attribute a(allocate_attribute(get_allocator(_root)));
a.set_name(name);
if (attr._attr->next_attribute)
@ -3616,7 +3645,7 @@ namespace pugi
{
if ((this->type() != node_element && this->type() != node_document) || type == node_document || type == node_null) return xml_node();
return xml_node(append_node(_root, get_allocator(), type));
return xml_node(append_node(_root, get_allocator(_root), type));
}
xml_node xml_node::insert_child_before(xml_node_type type, const xml_node& node)
@ -3624,7 +3653,7 @@ namespace pugi
if ((this->type() != node_element && this->type() != node_document) || type == node_document || type == node_null) return xml_node();
if (node.parent() != *this) return xml_node();
xml_node n(allocate_node(get_allocator(), type));
xml_node n(allocate_node(get_allocator(_root), type));
n._root->parent = _root;
if (node._root->prev_sibling_c->next_sibling)
@ -3644,7 +3673,7 @@ namespace pugi
if ((this->type() != node_element && this->type() != node_document) || type == node_document || type == node_null) return xml_node();
if (node.parent() != *this) return xml_node();
xml_node n(allocate_node(get_allocator(), type));
xml_node n(allocate_node(get_allocator(_root), type));
n._root->parent = _root;
if (node._root->next_sibling)
@ -3708,7 +3737,7 @@ namespace pugi
if (a._attr->prev_attribute_c->next_attribute) a._attr->prev_attribute_c->next_attribute = a._attr->next_attribute;
else _root->first_attribute = a._attr->next_attribute;
destroy_attribute(a._attr, get_allocator());
destroy_attribute(a._attr, get_allocator(_root));
}
void xml_node::remove_child(const char_t* name)
@ -3726,7 +3755,7 @@ namespace pugi
if (n._root->prev_sibling_c->next_sibling) n._root->prev_sibling_c->next_sibling = n._root->next_sibling;
else _root->first_child = n._root->next_sibling;
destroy_node(n._root, get_allocator());
destroy_node(n._root, get_allocator(_root));
}
xml_node xml_node::find_child_by_attribute(const char_t* name, const char_t* attr_name, const char_t* attr_value) const
@ -4102,10 +4131,6 @@ namespace pugi
return temp;
}
xml_memory_page::xml_memory_page(): allocator(0), memory(0), prev(0), next(0), busy_size(0), freed_size(0)
{
}
const char* xml_parse_result::description() const
{
switch (status)
@ -4141,13 +4166,6 @@ namespace pugi
xml_document::~xml_document()
{
destroy();
if (_memory.next)
{
assert(!_memory.next->next);
xml_allocator::deallocate_page(_memory.next);
}
}
void xml_document::create()
@ -4155,22 +4173,26 @@ namespace pugi
destroy();
// initialize sentinel page
_memory.busy_size = xml_memory_page_size;
assert(offsetof(xml_memory_page, data) + sizeof(xml_document_struct) + xml_memory_page_alignment <= sizeof(_memory));
// align upwards to page boundary
void* page_memory = reinterpret_cast<void*>((reinterpret_cast<uintptr_t>(_memory) + (xml_memory_page_alignment - 1)) & ~(xml_memory_page_alignment - 1));
// prepare page structure
xml_memory_page* page = xml_memory_page::construct(page_memory);
page->busy_size = xml_memory_page_size;
// allocate new root
xml_allocator alloc(_memory.next ? _memory.next : &_memory);
_root = allocate_document(alloc);
_root = new (page->data) xml_document_struct(page);
_root->prev_sibling_c = _root;
// setup allocator
xml_allocator& a = static_cast<xml_document_struct*>(_root)->allocator;
a = alloc;
a = xml_allocator(page);
// setup page
assert(_memory.next);
_memory.next->allocator = &a;
// setup sentinel page
page->allocator = &a;
}
void xml_document::destroy()
@ -4182,13 +4204,14 @@ namespace pugi
_buffer = 0;
}
// destroy dynamic storage, leave sentinel page and next page (if any)
// destroy dynamic storage, leave sentinel page (it's in static memory)
if (_root)
{
assert(_memory.next);
xml_memory_page* root_page = reinterpret_cast<xml_memory_page*>(_root->header & xml_memory_page_pointer_mask);
assert(root_page && !root_page->prev && !root_page->memory);
// destroy all pages
for (xml_memory_page* page = _memory.next->next; page; )
for (xml_memory_page* page = root_page->next; page; )
{
xml_memory_page* next = page->next;
@ -4197,17 +4220,13 @@ namespace pugi
page = next;
}
// cleanup next page
_memory.next->allocator = 0;
_memory.next->next = 0;
_memory.next->busy_size = _memory.next->freed_size = 0;
// cleanup root page
root_page->allocator = 0;
root_page->next = 0;
root_page->busy_size = root_page->freed_size = 0;
_root = 0;
}
else
{
assert(!_memory.next);
}
}
#ifndef PUGIXML_NO_STL

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@ -130,13 +130,6 @@ namespace pugi
// Parsing options
/**
* Memory page size, used for fast allocator. Memory for DOM tree is allocated in pages of
* xml_memory_page_size + size of header (approximately 64 bytes)
* This value affects size of xml_memory_page class.
*/
const size_t xml_memory_page_size = 32768;
/**
* Minimal parsing mode. Equivalent to turning all other flags off. This set of flags means
* that pugixml does not add pi/cdata sections or comments to DOM tree and does not perform
@ -329,8 +322,6 @@ namespace pugi
struct xml_attribute_struct;
struct xml_node_struct;
struct xml_allocator;
class xml_node_iterator;
class xml_attribute_iterator;
@ -787,9 +778,6 @@ namespace pugi
/// \internal Initializing ctor
explicit xml_node(xml_node_struct* p);
/// \internal Get allocator
xml_allocator& get_allocator() const;
private:
template <typename OutputIterator> void all_elements_by_name_w_helper(const char_t* name, OutputIterator it) const
{
@ -1762,24 +1750,6 @@ namespace pugi
virtual bool end(xml_node&);
};
/// \internal Memory page
struct PUGIXML_CLASS xml_memory_page
{
xml_memory_page();
xml_allocator* allocator;
void* memory;
xml_memory_page* prev;
xml_memory_page* next;
size_t busy_size;
size_t freed_size;
char data[1];
};
/**
* Struct used to distinguish parsing with ownership transfer from parsing without it.
* \see xml_document::parse
@ -1847,7 +1817,7 @@ namespace pugi
private:
char_t* _buffer;
xml_memory_page _memory;
char _memory[192];
xml_document(const xml_document&);
const xml_document& operator=(const xml_document&);

View File

@ -34,20 +34,31 @@ TEST(custom_memory_management)
{
// parse document
xml_document doc;
CHECK(allocate_count == 0 && deallocate_count == 0);
CHECK(doc.load(STR("<node />")));
CHECK(allocate_count == 2);
CHECK(deallocate_count == 0);
CHECK(allocate_count == 2 && deallocate_count == 0);
// modify document
doc.child(STR("node")).set_name(STR("foobars"));
// modify document (no new page)
CHECK(doc.first_child().set_name(STR("foobars")));
CHECK(allocate_count == 2 && deallocate_count == 0);
CHECK(allocate_count == 2);
CHECK(deallocate_count == 0);
// modify document (new page)
std::basic_string<pugi::char_t> s(65536, 'x');
CHECK(doc.first_child().set_name(s.c_str()));
CHECK(allocate_count == 3 && deallocate_count == 0);
// modify document (new page, old one should die)
s += s;
CHECK(doc.first_child().set_name(s.c_str()));
CHECK(allocate_count == 4 && deallocate_count == 1);
}
CHECK(allocate_count == 2);
CHECK(deallocate_count == 2);
CHECK(allocate_count == 4 && deallocate_count == 4);
// restore old functions
set_memory_management_functions(old_allocate, old_deallocate);
@ -67,7 +78,7 @@ TEST(large_allocations)
{
xml_document doc;
CHECK(allocate_count == 1 && deallocate_count == 0);
CHECK(allocate_count == 0 && deallocate_count == 0);
// initial fill
for (size_t i = 0; i < 128; ++i)
@ -77,7 +88,7 @@ TEST(large_allocations)
CHECK(doc.append_child(node_pcdata).set_value(s.c_str()));
}
CHECK(allocate_count > 1 && deallocate_count == 0);
CHECK(allocate_count > 0 && deallocate_count == 0);
// grow-prune loop
while (doc.first_child())
@ -103,12 +114,12 @@ TEST(large_allocations)
}
}
CHECK(allocate_count == deallocate_count + 2); // only two live pages left: one contains document node, another one waits for new allocations
CHECK(allocate_count == deallocate_count + 1); // only one live page left (it waits for new allocations)
char buffer;
CHECK(doc.load_buffer_inplace(&buffer, 0, parse_default, get_native_encoding()));
CHECK(allocate_count == deallocate_count + 1); // only one live page left (it contains document node)
CHECK(allocate_count == deallocate_count); // no live pages left
}
CHECK(allocate_count == deallocate_count); // everything is freed