fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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276 lines
9.8 KiB
276 lines
9.8 KiB
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include <stdint.h>
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#include <string>
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#ifdef ROCKSDB_MALLOC_USABLE_SIZE
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#ifdef OS_FREEBSD
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#include <malloc_np.h>
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#else
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#include <malloc.h>
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#endif
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#endif
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#include "rocksdb/options.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/status.h"
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#include "rocksdb/table.h"
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#include "options/cf_options.h"
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#include "port/port.h" // noexcept
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#include "table/persistent_cache_options.h"
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#include "util/file_reader_writer.h"
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namespace rocksdb {
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class RandomAccessFile;
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struct ReadOptions;
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extern bool ShouldReportDetailedTime(Env* env, Statistics* stats);
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// the length of the magic number in bytes.
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const int kMagicNumberLengthByte = 8;
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// BlockHandle is a pointer to the extent of a file that stores a data
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// block or a meta block.
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class BlockHandle {
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public:
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BlockHandle();
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BlockHandle(uint64_t offset, uint64_t size);
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// The offset of the block in the file.
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uint64_t offset() const { return offset_; }
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void set_offset(uint64_t _offset) { offset_ = _offset; }
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// The size of the stored block
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uint64_t size() const { return size_; }
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void set_size(uint64_t _size) { size_ = _size; }
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void EncodeTo(std::string* dst) const;
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Status DecodeFrom(Slice* input);
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Status DecodeSizeFrom(uint64_t offset, Slice* input);
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// Return a string that contains the copy of handle.
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std::string ToString(bool hex = true) const;
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// if the block handle's offset and size are both "0", we will view it
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// as a null block handle that points to no where.
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bool IsNull() const { return offset_ == 0 && size_ == 0; }
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static const BlockHandle& NullBlockHandle() { return kNullBlockHandle; }
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// Maximum encoding length of a BlockHandle
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enum { kMaxEncodedLength = 10 + 10 };
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private:
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uint64_t offset_;
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uint64_t size_;
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static const BlockHandle kNullBlockHandle;
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};
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inline uint32_t GetCompressFormatForVersion(
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CompressionType compression_type, uint32_t version) {
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#ifdef NDEBUG
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(void)compression_type;
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#endif
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// snappy is not versioned
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assert(compression_type != kSnappyCompression &&
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compression_type != kXpressCompression &&
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compression_type != kNoCompression);
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// As of version 2, we encode compressed block with
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// compress_format_version == 2. Before that, the version is 1.
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// DO NOT CHANGE THIS FUNCTION, it affects disk format
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return version >= 2 ? 2 : 1;
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}
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inline bool BlockBasedTableSupportedVersion(uint32_t version) {
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return version <= 4;
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}
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// Footer encapsulates the fixed information stored at the tail
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// end of every table file.
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class Footer {
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public:
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// Constructs a footer without specifying its table magic number.
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// In such case, the table magic number of such footer should be
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// initialized via @ReadFooterFromFile().
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// Use this when you plan to load Footer with DecodeFrom(). Never use this
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// when you plan to EncodeTo.
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Footer() : Footer(kInvalidTableMagicNumber, 0) {}
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// Use this constructor when you plan to write out the footer using
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// EncodeTo(). Never use this constructor with DecodeFrom().
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Footer(uint64_t table_magic_number, uint32_t version);
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// The version of the footer in this file
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uint32_t version() const { return version_; }
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// The checksum type used in this file
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ChecksumType checksum() const { return checksum_; }
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void set_checksum(const ChecksumType c) { checksum_ = c; }
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// The block handle for the metaindex block of the table
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const BlockHandle& metaindex_handle() const { return metaindex_handle_; }
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void set_metaindex_handle(const BlockHandle& h) { metaindex_handle_ = h; }
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// The block handle for the index block of the table
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const BlockHandle& index_handle() const { return index_handle_; }
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void set_index_handle(const BlockHandle& h) { index_handle_ = h; }
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uint64_t table_magic_number() const { return table_magic_number_; }
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void EncodeTo(std::string* dst) const;
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// Set the current footer based on the input slice.
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//
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// REQUIRES: table_magic_number_ is not set (i.e.,
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// HasInitializedTableMagicNumber() is true). The function will initialize the
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// magic number
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Status DecodeFrom(Slice* input);
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// Encoded length of a Footer. Note that the serialization of a Footer will
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// always occupy at least kMinEncodedLength bytes. If fields are changed
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// the version number should be incremented and kMaxEncodedLength should be
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// increased accordingly.
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enum {
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// Footer version 0 (legacy) will always occupy exactly this many bytes.
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// It consists of two block handles, padding, and a magic number.
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kVersion0EncodedLength = 2 * BlockHandle::kMaxEncodedLength + 8,
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// Footer of versions 1 and higher will always occupy exactly this many
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// bytes. It consists of the checksum type, two block handles, padding,
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// a version number (bigger than 1), and a magic number
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kNewVersionsEncodedLength = 1 + 2 * BlockHandle::kMaxEncodedLength + 4 + 8,
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kMinEncodedLength = kVersion0EncodedLength,
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kMaxEncodedLength = kNewVersionsEncodedLength,
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};
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static const uint64_t kInvalidTableMagicNumber = 0;
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// convert this object to a human readable form
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std::string ToString() const;
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private:
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// REQUIRES: magic number wasn't initialized.
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void set_table_magic_number(uint64_t magic_number) {
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assert(!HasInitializedTableMagicNumber());
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table_magic_number_ = magic_number;
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}
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// return true if @table_magic_number_ is set to a value different
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// from @kInvalidTableMagicNumber.
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bool HasInitializedTableMagicNumber() const {
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return (table_magic_number_ != kInvalidTableMagicNumber);
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}
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uint32_t version_;
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ChecksumType checksum_;
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BlockHandle metaindex_handle_;
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BlockHandle index_handle_;
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uint64_t table_magic_number_ = 0;
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};
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// Read the footer from file
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// If enforce_table_magic_number != 0, ReadFooterFromFile() will return
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// corruption if table_magic number is not equal to enforce_table_magic_number
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Status ReadFooterFromFile(RandomAccessFileReader* file,
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FilePrefetchBuffer* prefetch_buffer,
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uint64_t file_size, Footer* footer,
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uint64_t enforce_table_magic_number = 0);
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// 1-byte type + 32-bit crc
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static const size_t kBlockTrailerSize = 5;
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struct BlockContents {
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Slice data; // Actual contents of data
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bool cachable; // True iff data can be cached
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CompressionType compression_type;
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std::unique_ptr<char[]> allocation;
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BlockContents() : cachable(false), compression_type(kNoCompression) {}
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BlockContents(const Slice& _data, bool _cachable,
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CompressionType _compression_type)
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: data(_data), cachable(_cachable), compression_type(_compression_type) {}
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BlockContents(std::unique_ptr<char[]>&& _data, size_t _size, bool _cachable,
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CompressionType _compression_type)
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: data(_data.get(), _size),
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cachable(_cachable),
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compression_type(_compression_type),
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allocation(std::move(_data)) {}
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// The additional memory space taken by the block data.
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size_t usable_size() const {
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if (allocation.get() != nullptr) {
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#ifdef ROCKSDB_MALLOC_USABLE_SIZE
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return malloc_usable_size(allocation.get());
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#else
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return data.size();
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#endif // ROCKSDB_MALLOC_USABLE_SIZE
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} else {
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return 0; // no extra memory is occupied by the data
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}
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}
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BlockContents(BlockContents&& other) ROCKSDB_NOEXCEPT {
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*this = std::move(other);
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}
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BlockContents& operator=(BlockContents&& other) {
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data = std::move(other.data);
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cachable = other.cachable;
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compression_type = other.compression_type;
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allocation = std::move(other.allocation);
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return *this;
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}
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};
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// Read the block identified by "handle" from "file". On failure
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// return non-OK. On success fill *result and return OK.
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extern Status ReadBlockContents(
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RandomAccessFileReader* file, FilePrefetchBuffer* prefetch_buffer,
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const Footer& footer, const ReadOptions& options, const BlockHandle& handle,
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BlockContents* contents, const ImmutableCFOptions& ioptions,
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bool do_uncompress = true, const Slice& compression_dict = Slice(),
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const PersistentCacheOptions& cache_options = PersistentCacheOptions());
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// The 'data' points to the raw block contents read in from file.
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// This method allocates a new heap buffer and the raw block
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// contents are uncompresed into this buffer. This buffer is
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// returned via 'result' and it is upto the caller to
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// free this buffer.
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// For description of compress_format_version and possible values, see
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// util/compression.h
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extern Status UncompressBlockContents(
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const UncompressionContext& uncompression_ctx, const char* data, size_t n,
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BlockContents* contents, uint32_t compress_format_version,
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const ImmutableCFOptions& ioptions);
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// This is an extension to UncompressBlockContents that accepts
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// a specific compression type. This is used by un-wrapped blocks
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// with no compression header.
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extern Status UncompressBlockContentsForCompressionType(
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const UncompressionContext& uncompression_ctx, const char* data, size_t n,
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BlockContents* contents, uint32_t compress_format_version,
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const ImmutableCFOptions& ioptions);
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// Implementation details follow. Clients should ignore,
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// TODO(andrewkr): we should prefer one way of representing a null/uninitialized
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// BlockHandle. Currently we use zeros for null and use negation-of-zeros for
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// uninitialized.
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inline BlockHandle::BlockHandle()
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: BlockHandle(~static_cast<uint64_t>(0), ~static_cast<uint64_t>(0)) {}
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inline BlockHandle::BlockHandle(uint64_t _offset, uint64_t _size)
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: offset_(_offset), size_(_size) {}
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} // namespace rocksdb
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