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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <algorithm>
#include <set>
#include <utility>
#include <vector>
#include <string>
#include "rocksdb/cache.h"
#include "db/dbformat.h"
#include "util/arena.h"
#include "util/autovector.h"
namespace rocksdb {
class VersionSet;
const uint64_t kFileNumberMask = 0x3FFFFFFFFFFFFFFF;
extern uint64_t PackFileNumberAndPathId(uint64_t number, uint64_t path_id);
// A copyable structure contains information needed to read data from an SST
// file. It can contains a pointer to a table reader opened for the file, or
// file number and size, which can be used to create a new table reader for it.
// The behavior is undefined when a copied of the structure is used when the
// file is not in any live version any more.
struct FileDescriptor {
// Table reader in table_reader_handle
TableReader* table_reader;
uint64_t packed_number_and_path_id;
uint64_t file_size; // File size in bytes
FileDescriptor() : FileDescriptor(0, 0, 0) {}
FileDescriptor(uint64_t number, uint32_t path_id, uint64_t _file_size)
: table_reader(nullptr),
packed_number_and_path_id(PackFileNumberAndPathId(number, path_id)),
file_size(_file_size) {}
FileDescriptor& operator=(const FileDescriptor& fd) {
table_reader = fd.table_reader;
packed_number_and_path_id = fd.packed_number_and_path_id;
file_size = fd.file_size;
return *this;
uint64_t GetNumber() const {
return packed_number_and_path_id & kFileNumberMask;
uint32_t GetPathId() const {
return static_cast<uint32_t>(
packed_number_and_path_id / (kFileNumberMask + 1));
uint64_t GetFileSize() const { return file_size; }
struct FileSampledStats {
FileSampledStats() : num_reads_sampled(0) {}
FileSampledStats(const FileSampledStats& other) { *this = other; }
FileSampledStats& operator=(const FileSampledStats& other) {
num_reads_sampled = other.num_reads_sampled.load();
return *this;
// number of user reads to this file.
mutable std::atomic<uint64_t> num_reads_sampled;
struct FileMetaData {
FileDescriptor fd;
InternalKey smallest; // Smallest internal key served by table
InternalKey largest; // Largest internal key served by table
SequenceNumber smallest_seqno; // The smallest seqno in this file
SequenceNumber largest_seqno; // The largest seqno in this file
// Needs to be disposed when refs becomes 0.
Cache::Handle* table_reader_handle;
FileSampledStats stats;
// Stats for compensating deletion entries during compaction
// File size compensated by deletion entry.
// This is updated in Version::UpdateAccumulatedStats() first time when the
// file is created or loaded. After it is updated (!= 0), it is immutable.
uint64_t compensated_file_size;
// These values can mutate, but they can only be read or written from
// single-threaded LogAndApply thread
uint64_t num_entries; // the number of entries.
uint64_t num_deletions; // the number of deletion entries.
uint64_t raw_key_size; // total uncompressed key size.
uint64_t raw_value_size; // total uncompressed value size.
int refs; // Reference count
bool being_compacted; // Is this file undergoing compaction?
bool init_stats_from_file; // true if the data-entry stats of this file
// has initialized from file.
bool marked_for_compaction; // True if client asked us nicely to compact this
// file.
: smallest_seqno(kMaxSequenceNumber),
marked_for_compaction(false) {}
// REQUIRED: Keys must be given to the function in sorted order (it expects
// the last key to be the largest).
void UpdateBoundaries(const Slice& key, SequenceNumber seqno) {
if (smallest.size() == 0) {
smallest_seqno = std::min(smallest_seqno, seqno);
largest_seqno = std::max(largest_seqno, seqno);
// A compressed copy of file meta data that just contain minimum data needed
// to server read operations, while still keeping the pointer to full metadata
// of the file in case it is needed.
struct FdWithKeyRange {
FileDescriptor fd;
FileMetaData* file_metadata; // Point to all metadata
Slice smallest_key; // slice that contain smallest key
Slice largest_key; // slice that contain largest key
: fd(),
largest_key() {
FdWithKeyRange(FileDescriptor _fd, Slice _smallest_key, Slice _largest_key,
FileMetaData* _file_metadata)
: fd(_fd),
largest_key(_largest_key) {}
// Data structure to store an array of FdWithKeyRange in one level
// Actual data is guaranteed to be stored closely
struct LevelFilesBrief {
size_t num_files;
FdWithKeyRange* files;
LevelFilesBrief() {
num_files = 0;
files = nullptr;
class VersionEdit {
VersionEdit() { Clear(); }
~VersionEdit() { }
void Clear();
void SetComparatorName(const Slice& name) {
has_comparator_ = true;
comparator_ = name.ToString();
void SetLogNumber(uint64_t num) {
has_log_number_ = true;
log_number_ = num;
void SetPrevLogNumber(uint64_t num) {
has_prev_log_number_ = true;
prev_log_number_ = num;
void SetNextFile(uint64_t num) {
has_next_file_number_ = true;
next_file_number_ = num;
void SetLastSequence(SequenceNumber seq) {
has_last_sequence_ = true;
last_sequence_ = seq;
void SetMaxColumnFamily(uint32_t max_column_family) {
has_max_column_family_ = true;
max_column_family_ = max_column_family;
// Add the specified file at the specified number.
// REQUIRES: This version has not been saved (see VersionSet::SaveTo)
// REQUIRES: "smallest" and "largest" are smallest and largest keys in file
void AddFile(int level, uint64_t file, uint32_t file_path_id,
uint64_t file_size, const InternalKey& smallest,
const InternalKey& largest, const SequenceNumber& smallest_seqno,
const SequenceNumber& largest_seqno,
bool marked_for_compaction) {
assert(smallest_seqno <= largest_seqno);
FileMetaData f;
f.fd = FileDescriptor(file, file_path_id, file_size);
f.smallest = smallest;
f.largest = largest;
f.smallest_seqno = smallest_seqno;
f.largest_seqno = largest_seqno;
f.marked_for_compaction = marked_for_compaction;
new_files_.emplace_back(level, std::move(f));
void AddFile(int level, const FileMetaData& f) {
assert(f.smallest_seqno <= f.largest_seqno);
new_files_.emplace_back(level, f);
// Delete the specified "file" from the specified "level".
void DeleteFile(int level, uint64_t file) {
deleted_files_.insert({level, file});
// Number of edits
size_t NumEntries() { return new_files_.size() + deleted_files_.size(); }
bool IsColumnFamilyManipulation() {
return is_column_family_add_ || is_column_family_drop_;
void SetColumnFamily(uint32_t column_family_id) {
column_family_ = column_family_id;
// set column family ID by calling SetColumnFamily()
void AddColumnFamily(const std::string& name) {
assert(NumEntries() == 0);
is_column_family_add_ = true;
column_family_name_ = name;
// set column family ID by calling SetColumnFamily()
void DropColumnFamily() {
assert(NumEntries() == 0);
is_column_family_drop_ = true;
// return true on success.
bool EncodeTo(std::string* dst) const;
Status DecodeFrom(const Slice& src);
const char* DecodeNewFile4From(Slice* input);
typedef std::set<std::pair<int, uint64_t>> DeletedFileSet;
const DeletedFileSet& GetDeletedFiles() { return deleted_files_; }
const std::vector<std::pair<int, FileMetaData>>& GetNewFiles() {
return new_files_;
std::string DebugString(bool hex_key = false) const;
std::string DebugJSON(int edit_num, bool hex_key = false) const;
friend class VersionSet;
friend class Version;
bool GetLevel(Slice* input, int* level, const char** msg);
int max_level_;
std::string comparator_;
uint64_t log_number_;
uint64_t prev_log_number_;
uint64_t next_file_number_;
uint32_t max_column_family_;
SequenceNumber last_sequence_;
bool has_comparator_;
bool has_log_number_;
bool has_prev_log_number_;
bool has_next_file_number_;
bool has_last_sequence_;
bool has_max_column_family_;
DeletedFileSet deleted_files_;
std::vector<std::pair<int, FileMetaData>> new_files_;
// Each version edit record should have column_family_id set
// If it's not set, it is default (0)
uint32_t column_family_;
// a version edit can be either column_family add or
// column_family drop. If it's column family add,
// it also includes column family name.
bool is_column_family_drop_;
bool is_column_family_add_;
std::string column_family_name_;
} // namespace rocksdb