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Change compact_pointer_parent to use 2 bytes

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Parent pointers need to be able to reach everywhere within a page to
minimize shared parent pointer reuse unless it's absolutely necessary.
This reduces parent hash utilization on all test cases to <1%.

Rename compact_parent to compact_shared_parent.
This commit is contained in:
Arseny Kapoulkine 2014-10-08 20:09:29 -07:00
parent 58282fd36f
commit 224e702d1f
1 changed files with 34 additions and 23 deletions
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57
src/pugixml.cpp
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@ -297,7 +297,7 @@ PUGI__NS_BEGIN
#ifdef PUGIXML_COMPACT #ifdef PUGIXML_COMPACT
result->compact_string_base = 0; result->compact_string_base = 0;
result->compact_parent = 0; result->compact_shared_parent = 0;
#endif #endif
return result; return result;
@ -313,7 +313,7 @@ PUGI__NS_BEGIN
#ifdef PUGIXML_COMPACT #ifdef PUGIXML_COMPACT
char_t* compact_string_base; char_t* compact_string_base;
void* compact_parent; void* compact_shared_parent;
#endif #endif
}; };
@ -759,7 +759,7 @@ PUGI__NS_BEGIN
template <typename T, int header_offset, int tag> class compact_pointer_parent template <typename T, int header_offset, int tag> class compact_pointer_parent
{ {
public: public:
compact_pointer_parent(): _data(0) compact_pointer_parent(): _data0(0), _data1(0)
{ {
} }
@ -772,43 +772,55 @@ PUGI__NS_BEGIN
{ {
if (value) if (value)
{ {
ptrdiff_t offset = ((reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this) + int(compact_alignment - 1)) >> compact_alignment_log2) + 253; ptrdiff_t offset = ((reinterpret_cast<char*>(value) - reinterpret_cast<char*>(this) + int(compact_alignment - 1)) >> compact_alignment_log2) + 65533;
if (static_cast<uintptr_t>(offset) <= 253) if (static_cast<uintptr_t>(offset) <= 65533)
_data = static_cast<unsigned char>(offset + 1); {
_data0 = static_cast<unsigned char>(offset + 1);
_data1 = static_cast<unsigned char>((offset + 1) >> 8);
}
else else
{ {
xml_memory_page* page = compact_get_page(this, header_offset); xml_memory_page* page = compact_get_page(this, header_offset);
if (page->compact_parent == 0) if (page->compact_shared_parent == 0)
page->compact_parent = value; page->compact_shared_parent = value;
if (page->compact_parent == value) if (page->compact_shared_parent == value)
_data = 254; {
_data0 = 254;
_data1 = 255;
}
else else
{ {
compact_set_value<header_offset, tag>(this, value); compact_set_value<header_offset, tag>(this, value);
_data = 255; _data0 = 255;
_data1 = 255;
} }
} }
} }
else else
_data = 0; {
_data0 = 0;
_data1 = 0;
}
} }
operator T* const() const operator T* const() const
{ {
if (_data) unsigned int data = _data0 + (_data1 << 8);
if (data)
{ {
if (_data < 254) if (data < 65534)
{ {
uintptr_t base = reinterpret_cast<uintptr_t>(this) & ~(compact_alignment - 1); uintptr_t base = reinterpret_cast<uintptr_t>(this) & ~(compact_alignment - 1);
return reinterpret_cast<T*>(base + ((_data - (1 + 253)) << compact_alignment_log2)); return reinterpret_cast<T*>(base + ((data - (1 + 65533)) << compact_alignment_log2));
} }
else if (_data == 254) else if (data == 65534)
return static_cast<T*>(compact_get_page(this, header_offset)->compact_parent); return static_cast<T*>(compact_get_page(this, header_offset)->compact_shared_parent);
else else
return compact_get_value<header_offset, T>(this); return compact_get_value<header_offset, T>(this);
} }
@ -822,7 +834,8 @@ PUGI__NS_BEGIN
} }
private: private:
unsigned char _data; unsigned char _data0;
unsigned char _data1;
}; };
template <int header_offset, int tag> class compact_string template <int header_offset, int tag> class compact_string
@ -932,15 +945,13 @@ namespace pugi
impl::compact_header header; impl::compact_header header;
unsigned char padding; impl::compact_string<3, /*tag*/21> contents; ///< Pointer to element name.
impl::compact_string<4, /*tag*/21> contents; ///< Pointer to element name. impl::compact_pointer_parent<xml_node_struct, 6, /*tag*/22> parent; ///< Pointer to parent
impl::compact_pointer_parent<xml_node_struct, 7, /*tag*/22> parent; ///< Pointer to parent
impl::compact_pointer<xml_node_struct, 8, /*tag*/23, 0> first_child; ///< First child impl::compact_pointer<xml_node_struct, 8, /*tag*/23, 0> first_child; ///< First child
impl::compact_pointer<xml_node_struct, 9, /*tag*/24> prev_sibling_c; ///< Left brother (cyclic list) impl::compact_pointer<xml_node_struct, 9, /*tag*/24> prev_sibling_c; ///< Left brother (cyclic list)
impl::compact_pointer<xml_node_struct, 10, /*tag*/25, 0> next_sibling; ///< Right brother impl::compact_pointer<xml_node_struct, 10, /*tag*/25, 0> next_sibling; ///< Right brother
impl::compact_pointer<xml_attribute_struct, 11, /*tag*/26, 0> first_attribute; ///< First attribute impl::compact_pointer<xml_attribute_struct, 11, /*tag*/26, 0> first_attribute; ///< First attribute