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/*
* Copyright (C) 2011 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef BlockStack_h
#define BlockStack_h
#include <wtf/Assertions.h>
#include <wtf/FastMalloc.h>
#include <wtf/Vector.h>
namespace WTF {
template <typename T> class BlockStack {
public:
static const size_t blockSize = 4096;
static const size_t blockLength = blockSize / sizeof(T);
BlockStack();
~BlockStack();
T* grow();
void shrink(T*);
const Vector<T*>& blocks();
private:
Vector<T*> m_blocks;
T* m_spareBlock; // Used to avoid thrash at block boundaries.
};
template <typename T> BlockStack<T>::BlockStack()
: m_spareBlock(0)
{
}
template <typename T> BlockStack<T>::~BlockStack()
{
if (m_spareBlock)
fastFree(m_spareBlock);
for (size_t i = 0; i < m_blocks.size(); ++i)
fastFree(m_blocks[i]);
}
template <typename T> inline const Vector<T*>& BlockStack<T>::blocks()
{
return m_blocks;
}
template <typename T> T* BlockStack<T>::grow()
{
T* block = m_spareBlock ? m_spareBlock : static_cast<T*>(fastMalloc(blockSize));
m_spareBlock = 0;
m_blocks.append(block);
return block;
}
template <typename T> void BlockStack<T>::shrink(T* newEnd)
{
ASSERT(newEnd != m_blocks.last() + blockLength);
m_spareBlock = m_blocks.last();
m_blocks.removeLast();
while (m_blocks.last() + blockLength != newEnd) {
fastFree(m_blocks.last());
m_blocks.removeLast();
}
}
}
using WTF::BlockStack;
#endif
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