libcryfs/implementations/onblocks/datanodestore/DataNodeView.h

140 lines
3.5 KiB
C++

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