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fdc782c1d1
This would be a lot better as an LRU. Right now it's a 32-slot hash table with random eviction.
101 lines
2.6 KiB
C++
101 lines
2.6 KiB
C++
#include "DiskBackedFileSystem.h"
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#ifdef SERENITY
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#include "i386.h"
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#else
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typedef int InterruptDisabler;
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#endif
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//#define DBFS_DEBUG
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DiskBackedFileSystem::DiskBackedFileSystem(RetainPtr<DiskDevice>&& device)
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: m_device(move(device))
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{
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ASSERT(m_device);
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}
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DiskBackedFileSystem::~DiskBackedFileSystem()
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{
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}
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bool DiskBackedFileSystem::writeBlock(unsigned index, const ByteBuffer& data)
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{
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ASSERT(data.size() == blockSize());
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#ifdef DBFS_DEBUG
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kprintf("DiskBackedFileSystem::writeBlock %u\n", index);
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#endif
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DiskOffset baseOffset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(blockSize());
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return device().write(baseOffset, blockSize(), data.pointer());
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}
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bool DiskBackedFileSystem::writeBlocks(unsigned index, unsigned count, const ByteBuffer& data)
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{
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#ifdef DBFS_DEBUG
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kprintf("DiskBackedFileSystem::writeBlocks %u x%u\n", index, count);
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#endif
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DiskOffset baseOffset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(blockSize());
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return device().write(baseOffset, count * blockSize(), data.pointer());
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}
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ByteBuffer DiskBackedFileSystem::readBlock(unsigned index) const
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{
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#ifdef DBFS_DEBUG
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kprintf("DiskBackedFileSystem::readBlock %u\n", index);
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#endif
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{
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InterruptDisabler disabler;
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auto it = m_blockCache.find(index);
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if (it != m_blockCache.end()) {
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return (*it).value;
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}
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}
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auto buffer = ByteBuffer::createUninitialized(blockSize());
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DiskOffset baseOffset = static_cast<DiskOffset>(index) * static_cast<DiskOffset>(blockSize());
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auto* bufferPointer = buffer.pointer();
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device().read(baseOffset, blockSize(), bufferPointer);
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ASSERT(buffer.size() == blockSize());
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{
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InterruptDisabler disabler;
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if (m_blockCache.size() >= 32)
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m_blockCache.removeOneRandomly();
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m_blockCache.set(index, buffer);
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}
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return buffer;
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}
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ByteBuffer DiskBackedFileSystem::readBlocks(unsigned index, unsigned count) const
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{
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if (!count)
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return nullptr;
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if (count == 1)
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return readBlock(index);
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auto blocks = ByteBuffer::createUninitialized(count * blockSize());
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byte* out = blocks.pointer();
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for (unsigned i = 0; i < count; ++i) {
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auto block = readBlock(index + i);
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if (!block)
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return nullptr;
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memcpy(out, block.pointer(), block.size());
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out += blockSize();
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}
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return blocks;
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}
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void DiskBackedFileSystem::setBlockSize(unsigned blockSize)
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{
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if (blockSize == m_blockSize)
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return;
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m_blockSize = blockSize;
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invalidateCaches();
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}
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void DiskBackedFileSystem::invalidateCaches()
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{
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InterruptDisabler disabler;
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m_blockCache.clear();
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}
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