Implement efficient compact_header storage
Header is now just 2 bytes, with optional additonal 4 bytes that are only allocated for every 85 nodes / 128 attributes.
This commit is contained in:
Arseny Kapoulkine
parent
e4c539a869
commit
dec4267fb1
1 changed files with 75 additions and 42 deletions
117
src/pugixml.cpp
117
src/pugixml.cpp
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@ -409,8 +409,16 @@ PUGI__NS_BEGIN
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#endif
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;
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#ifdef PUGIXML_COMPACT
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static const uintptr_t xml_memory_block_alignment = 4;
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static const uintptr_t xml_memory_page_alignment = sizeof(void*);
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#else
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static const uintptr_t xml_memory_block_alignment = sizeof(void*);
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static const uintptr_t xml_memory_page_alignment = 64;
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static const uintptr_t xml_memory_page_pointer_mask = ~(xml_memory_page_alignment - 1);
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#endif
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// extra metadata bits
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static const uintptr_t xml_memory_page_contents_shared_mask = 32;
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@ -422,15 +430,6 @@ PUGI__NS_BEGIN
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static const uintptr_t xml_memory_page_name_allocated_or_shared_mask = xml_memory_page_name_allocated_mask | xml_memory_page_contents_shared_mask;
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static const uintptr_t xml_memory_page_value_allocated_or_shared_mask = xml_memory_page_value_allocated_mask | xml_memory_page_contents_shared_mask;
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// all allocated blocks have a certain guaranteed alignment
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static const uintptr_t xml_memory_block_alignment =
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#ifdef PUGIXML_COMPACT
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4
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#else
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sizeof(void*)
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#endif
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;
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#ifdef PUGIXML_COMPACT
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#define PUGI__GETPAGE_IMPL(header) (header).get_page()
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#else
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@ -457,6 +456,7 @@ PUGI__NS_BEGIN
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#ifdef PUGIXML_COMPACT
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result->compact_string_base = 0;
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result->compact_shared_parent = 0;
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result->compact_page_marker = 0;
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#endif
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return result;
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@ -473,6 +473,7 @@ PUGI__NS_BEGIN
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#ifdef PUGIXML_COMPACT
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char_t* compact_string_base;
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void* compact_shared_parent;
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char* compact_page_marker;
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#endif
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};
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@ -537,6 +538,35 @@ PUGI__NS_BEGIN
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return buf;
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}
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void* allocate_object(size_t size, xml_memory_page*& out_page)
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{
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#ifdef PUGIXML_COMPACT
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void* result = allocate_memory(size + sizeof(uint32_t), out_page);
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if (!result) return 0;
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// adjust for marker
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if (PUGI__UNLIKELY(static_cast<uintptr_t>(static_cast<char*>(result) - out_page->compact_page_marker) >= 256 * xml_memory_block_alignment))
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{
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// insert new marker
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uint32_t* marker = static_cast<uint32_t*>(result);
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*marker = reinterpret_cast<char*>(marker) - reinterpret_cast<char*>(out_page);
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out_page->compact_page_marker = reinterpret_cast<char*>(marker);
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return marker + 1;
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}
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else
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{
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// roll back uint32_t part
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_busy_size -= sizeof(uint32_t);
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return result;
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}
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#else
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return allocate_memory(size, out_page);
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#endif
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}
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void deallocate_memory(void* ptr, size_t size, xml_memory_page* page)
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{
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if (page == _root) page->busy_size = _busy_size;
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@ -694,41 +724,39 @@ PUGI__NS_BEGIN
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{
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PUGI__STATIC_ASSERT(xml_memory_block_alignment == compact_alignment);
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PUGI__STATIC_ASSERT(sizeof(xml_memory_page) + xml_memory_page_size <= (1 << (16 + compact_alignment_log2)));
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PUGI__STATIC_ASSERT(xml_memory_page_pointer_mask & 0xff);
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ptrdiff_t page_offset = (reinterpret_cast<char*>(this) - reinterpret_cast<char*>(page)) >> compact_alignment_log2;
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assert(page_offset >= 0 && page_offset < (1 << 16));
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ptrdiff_t offset = (reinterpret_cast<char*>(this) - page->compact_page_marker);
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assert(offset >= 0 && offset < 256 << compact_alignment_log2);
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this->page0 = static_cast<unsigned char>(page_offset);
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this->page1 = static_cast<unsigned char>(page_offset >> 8);
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this->flags = static_cast<unsigned char>(flags);
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_page = static_cast<unsigned char>(offset >> compact_alignment_log2);
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_flags = static_cast<unsigned char>(flags);
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}
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void operator&=(uintptr_t mod)
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{
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flags &= mod;
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_flags &= mod;
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}
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void operator|=(uintptr_t mod)
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{
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flags |= mod;
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_flags |= mod;
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}
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uintptr_t operator&(uintptr_t mod) const
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{
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return flags & mod;
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return _flags & mod;
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}
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xml_memory_page* get_page() const
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{
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unsigned int page_offset = page0 + (page1 << 8);
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const char* page_marker = reinterpret_cast<const char*>(this) - (_page << compact_alignment_log2);
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return const_cast<xml_memory_page*>(reinterpret_cast<const xml_memory_page*>(reinterpret_cast<const char*>(this) - (page_offset << compact_alignment_log2)));
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return const_cast<xml_memory_page*>(reinterpret_cast<const xml_memory_page*>(page_marker - *reinterpret_cast<const uint32_t*>(page_marker)));
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}
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private:
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unsigned char page0, page1;
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unsigned char flags;
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unsigned char _page;
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unsigned char _flags;
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};
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PUGI__FN xml_memory_page* compact_get_page(const void* object, int header_offset)
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@ -976,46 +1004,42 @@ namespace pugi
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{
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xml_attribute_struct(impl::xml_memory_page* page): header(page, 0), namevalue_base(0)
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{
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PUGI__STATIC_ASSERT(sizeof(xml_attribute_struct) == 12);
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PUGI__STATIC_ASSERT(sizeof(xml_attribute_struct) == 8);
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}
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impl::compact_header header;
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unsigned char padding[3];
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uint16_t namevalue_base;
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impl::compact_string<8, 2> name;
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impl::compact_string<9, 3> value;
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impl::compact_string<4, 2> name;
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impl::compact_string<5, 3> value;
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impl::compact_pointer<xml_attribute_struct, 10> prev_attribute_c;
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impl::compact_pointer<xml_attribute_struct, 11, 0> next_attribute;
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impl::compact_pointer<xml_attribute_struct, 6> prev_attribute_c;
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impl::compact_pointer<xml_attribute_struct, 7, 0> next_attribute;
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};
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struct xml_node_struct
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{
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xml_node_struct(impl::xml_memory_page* page, xml_node_type type): header(page, type - 1), namevalue_base(0)
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{
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PUGI__STATIC_ASSERT(sizeof(xml_node_struct) == 16);
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PUGI__STATIC_ASSERT(sizeof(xml_node_struct) == 12);
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}
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impl::compact_header header;
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unsigned char padding[3];
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uint16_t namevalue_base;
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impl::compact_string<8, 2> name;
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impl::compact_string<9, 3> value;
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impl::compact_string<4, 2> name;
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impl::compact_string<5, 3> value;
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impl::compact_pointer_parent<xml_node_struct, 10> parent;
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impl::compact_pointer_parent<xml_node_struct, 6> parent;
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impl::compact_pointer<xml_node_struct, 12, 0> first_child;
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impl::compact_pointer<xml_node_struct, 8, 0> first_child;
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impl::compact_pointer<xml_node_struct, 13> prev_sibling_c;
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impl::compact_pointer<xml_node_struct, 14, 0> next_sibling;
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impl::compact_pointer<xml_node_struct, 9> prev_sibling_c;
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impl::compact_pointer<xml_node_struct, 10, 0> next_sibling;
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impl::compact_pointer<xml_attribute_struct, 15, 0> first_attribute;
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impl::compact_pointer<xml_attribute_struct, 11, 0> first_attribute;
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};
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}
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#else
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@ -1104,7 +1128,7 @@ PUGI__NS_BEGIN
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inline xml_attribute_struct* allocate_attribute(xml_allocator& alloc)
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{
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xml_memory_page* page;
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void* memory = alloc.allocate_memory(sizeof(xml_attribute_struct), page);
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void* memory = alloc.allocate_object(sizeof(xml_attribute_struct), page);
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return new (memory) xml_attribute_struct(page);
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}
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@ -1112,7 +1136,7 @@ PUGI__NS_BEGIN
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inline xml_node_struct* allocate_node(xml_allocator& alloc, xml_node_type type)
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{
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xml_memory_page* page;
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void* memory = alloc.allocate_memory(sizeof(xml_node_struct), page);
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void* memory = alloc.allocate_object(sizeof(xml_node_struct), page);
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return new (memory) xml_node_struct(page, type);
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}
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@ -6657,7 +6681,16 @@ namespace pugi
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page->busy_size = impl::xml_memory_page_size;
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// allocate new root
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_root = new (reinterpret_cast<char*>(page) + sizeof(impl::xml_memory_page)) impl::xml_document_struct(page);
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#ifdef PUGIXML_COMPACT
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const size_t page_offset = sizeof(uint32_t);
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page->compact_page_marker = reinterpret_cast<char*>(page) + sizeof(impl::xml_memory_page);
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*reinterpret_cast<uint32_t*>(page->compact_page_marker) = sizeof(impl::xml_memory_page);
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#else
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const size_t page_offset = 0;
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#endif
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_root = new (reinterpret_cast<char*>(page) + sizeof(impl::xml_memory_page) + page_offset) impl::xml_document_struct(page);
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_root->prev_sibling_c = _root;
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// setup sentinel page
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