140 lines
3.5 KiB
C++
140 lines
3.5 KiB
C++
#pragma once
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#ifndef BLOBSTORE_IMPLEMENTATIONS_ONBLOCKS_DATANODESTORE_DATANODEVIEW_H_
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#define BLOBSTORE_IMPLEMENTATIONS_ONBLOCKS_DATANODESTORE_DATANODEVIEW_H_
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#include "messmer/blockstore/interface/Block.h"
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#include "../BlobStoreOnBlocks.h"
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#include "DataInnerNode_ChildEntry.h"
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#include "messmer/cpp-utils/macros.h"
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#include <memory>
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#include <stdexcept>
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namespace blobstore {
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namespace onblocks {
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namespace datanodestore {
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//TODO Move DataNodeLayout into own file
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class DataNodeLayout {
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public:
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constexpr DataNodeLayout(uint32_t blocksizeBytes)
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:_blocksizeBytes(
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(HEADERSIZE_BYTES + 2*sizeof(DataInnerNode_ChildEntry) <= blocksizeBytes)
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? blocksizeBytes
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: throw std::logic_error("Blocksize too small, not enough space to store two children in an inner node")) {
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}
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//Total size of the header
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static constexpr uint32_t HEADERSIZE_BYTES = 8;
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//Where in the header is the depth field
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static constexpr uint32_t DEPTH_OFFSET_BYTES = 0;
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//Where in the header is the size field (for inner nodes: number of children, for leafs: content data size)
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static constexpr uint32_t SIZE_OFFSET_BYTES = 4;
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//Size of a block (header + data region)
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constexpr uint32_t blocksizeBytes() const {
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return _blocksizeBytes;
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}
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//Number of bytes in the data region of a node
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constexpr uint32_t datasizeBytes() const {
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return _blocksizeBytes - HEADERSIZE_BYTES;
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}
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//Maximum number of children an inner node can store
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constexpr uint32_t maxChildrenPerInnerNode() const {
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return datasizeBytes() / sizeof(DataInnerNode_ChildEntry);
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}
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//Maximum number of bytes a leaf can store
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constexpr uint32_t maxBytesPerLeaf() const {
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return datasizeBytes();
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}
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private:
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uint32_t _blocksizeBytes;
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};
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class DataNodeView {
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public:
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DataNodeView(std::unique_ptr<blockstore::Block> block): _block(std::move(block)) {
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}
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virtual ~DataNodeView() {}
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DataNodeView(DataNodeView &&rhs) = default;
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const uint8_t *Depth() const {
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return GetOffset<DataNodeLayout::DEPTH_OFFSET_BYTES, uint8_t>();
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}
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uint8_t *Depth() {
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return const_cast<uint8_t*>(const_cast<const DataNodeView*>(this)->Depth());
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}
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const uint32_t *Size() const {
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return GetOffset<DataNodeLayout::SIZE_OFFSET_BYTES, uint32_t>();
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}
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uint32_t *Size() {
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return const_cast<uint32_t*>(const_cast<const DataNodeView*>(this)->Size());
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}
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template<typename Entry>
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const Entry *DataBegin() const {
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return GetOffset<DataNodeLayout::HEADERSIZE_BYTES, Entry>();
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}
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template<typename Entry>
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Entry *DataBegin() {
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return const_cast<Entry*>(const_cast<const DataNodeView*>(this)->DataBegin<Entry>());
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}
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DataNodeLayout layout() const {
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return DataNodeLayout(_block->size());
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}
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template<typename Entry>
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const Entry *DataEnd() const {
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const unsigned int NUM_ENTRIES = layout().datasizeBytes() / sizeof(Entry);
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return DataBegin<Entry>() + NUM_ENTRIES;
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}
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template<typename Entry>
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Entry *DataEnd() {
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return const_cast<Entry*>(const_cast<const DataNodeView*>(this)->DataEnd<Entry>());
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}
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std::unique_ptr<blockstore::Block> releaseBlock() {
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return std::move(_block);
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}
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const blockstore::Block &block() const {
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return *_block;
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}
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const blockstore::Key &key() const {
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return _block->key();
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}
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void flush() const {
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_block->flush();
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}
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private:
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template<int offset, class Type>
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const Type *GetOffset() const {
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return (Type*)(((const int8_t*)_block->data())+offset);
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}
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std::unique_ptr<blockstore::Block> _block;
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DISALLOW_COPY_AND_ASSIGN(DataNodeView);
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};
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}
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}
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}
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#endif
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