PODIntervalTree takes 1.7MB memory on www.nytimes.com.
https://bugs.webkit.org/show_bug.cgi?id=73712
Patch by Yongjun Zhang <yongjun_zhang@apple.com> on 2011-12-15
Reviewed by Kenneth Russell.
Source/WebCore:
For a RenderBlock which has floating objects inside, we will create a PODIntervalTree and a PODArena with
at least one 16KB chunk. A page could have a large number of such RenderBlocks and they could take huge
amount of memory. To fix that, we can create a shared PODArena in the root RenderView. Instead of having
their own PODArena, each RenderBlock with floating objects could share this PODArena to reduce memory consumption.
The shared PODArena could grow unboundedly if we keep removing and adding floating objects. We can fix that
by reusing the freed memory in each chunk. However, a PODArena could allocate objects of different sizes and
it would be complex to keep track of the size for each allocation in PODArena. To address that, this patch
added class PODFreeListArena<T> which only allocates objects of type T (hence the same size). We can then use a
free list to track freed nodes inside the chunk and reuse the free nodes in future allocations.
Manually tested on nytimes.com and the heap consumption of PODIntervalTree reduced from 1.7MB to 16KB. Performance
doesn't regress on test PerformanceTests/Layout/floats.html.
* WebCore.xcodeproj/project.pbxproj: add new header file PODFreeListArena.h.
* platform/PODArena.h:
(WebCore::PODArena::~PODArena): change dtor to virtual.
(WebCore::PODArena::Chunk::~Chunk): ditto.
* platform/PODFreeListArena.h: Added.
(WebCore::PODFreeListArena::create):
(WebCore::PODFreeListArena::allocateObject): allocate an object.
(WebCore::PODFreeListArena::freeObject): free an object, find the right chunk and update its free list.
(WebCore::PODFreeListArena::allocate): allocate memory from the free list or current chunk.
(WebCore::PODFreeListArena::FreeListChunk::FreeListChunk): add m_freeList to track freed cells.
(WebCore::PODFreeListArena::FreeListChunk::allocate): reuse a free cell if there is one.
(WebCore::PODFreeListArena::FreeListChunk::free): make the memory taken by this object is free, and link it to m_freeList.
(WebCore::PODFreeListArena::FreeListChunk::contains): check if a pointer is inside this chunk.
(WebCore::PODFreeListArena::FreeListChunk::hasFreeList): check if this chunk has free cells.
* platform/PODRedBlackTree.h:
(WebCore::PODRedBlackTree::PODRedBlackTree): take PODFreeListArena instead of PODArena, since nodes of a particular PODRedBlackTree
is always of the same size.
(WebCore::PODRedBlackTree::clear): mark all nodes before clearing the tree.
(WebCore::PODRedBlackTree::initIfNeeded): add initIfNeeded to take an external PODFreeListArena.
(WebCore::PODRedBlackTree::add):
(WebCore::PODRedBlackTree::deleteNode): mark the node free in arena after it is removed from the tree.
(WebCore::PODRedBlackTree::markFree): mark all node free in the tree.
* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::insertFloatingObject):
(WebCore::RenderBlock::addOverhangingFloats):
(WebCore::RenderBlock::addIntrudingFloats):
(WebCore::RenderBlock::FloatingObjects::computePlacedFloatsTree): passing the shared PODFreeListArena to m_placedFloatsTree.
* rendering/RenderBlock.h:
(WebCore::RenderBlock::FloatingObjects::FloatingObjects):
* rendering/RenderView.cpp:
(WebCore::RenderView::intervalArena): create the shared PODFreeListArena lazily.
* rendering/RenderView.h:
Source/WebKit/chromium:
Change the test code in chromium port since PODRedBlackTree now takes PODFreeListArena<T>
in its constructor.
* tests/PODRedBlackTreeTest.cpp:
(WebCore::TEST):
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@103030 268f45cc-cd09-0410-ab3c-d52691b4dbfc
11 files changed
