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rocksdb/db/version_edit.h

251 lines
7.6 KiB

// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same 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 <set>
#include <utility>
#include <vector>
#include <string>
#include "rocksdb/cache.h"
#include "db/dbformat.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 packed_number_and_path_id / (kFileNumberMask + 1);
}
uint64_t GetFileSize() const { return file_size; }
};
struct FileMetaData {
int refs;
FileDescriptor fd;
InternalKey smallest; // Smallest internal key served by table
InternalKey largest; // Largest internal key served by table
bool being_compacted; // Is this file undergoing compaction?
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;
// Stats for compensating deletion entries during compaction
// File size compensated by deletion entry.
// This is updated in Version::UpdateTemporaryStats() first time when the
// file is created or loaded. After it is updated, it is immutable.
uint64_t compensated_file_size;
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.
FileMetaData()
: refs(0),
being_compacted(false),
table_reader_handle(nullptr),
compensated_file_size(0),
num_entries(0),
num_deletions(0),
raw_key_size(0),
raw_value_size(0) {}
};
// A compressed copy of file meta data that just contain
// smallest and largest key's slice
struct FdWithKeyRange {
FileDescriptor fd;
Slice smallest_key; // slice that contain smallest key
Slice largest_key; // slice that contain largest key
FdWithKeyRange()
: fd(),
smallest_key(),
largest_key() {
}
FdWithKeyRange(FileDescriptor fd,
Slice smallest_key, Slice largest_key)
: fd(fd),
smallest_key(smallest_key),
largest_key(largest_key) {
}
};
// Data structure to store an array of FdWithKeyRange in one level
// Actual data is guaranteed to be stored closely
struct FileLevel {
size_t num_files;
FdWithKeyRange* files;
FileLevel() {
num_files = 0;
files = nullptr;
}
};
class VersionEdit {
public:
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, uint64_t file_size,
uint64_t file_path_id, const InternalKey& smallest,
const InternalKey& largest, const SequenceNumber& smallest_seqno,
const SequenceNumber& largest_seqno) {
assert(smallest_seqno <= largest_seqno);
FileMetaData f;
f.fd = FileDescriptor(file, file_size, file_path_id);
f.smallest = smallest;
f.largest = largest;
f.smallest_seqno = smallest_seqno;
f.largest_seqno = largest_seqno;
new_files_.push_back(std::make_pair(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
int 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(!is_column_family_drop_);
assert(!is_column_family_add_);
assert(NumEntries() == 0);
is_column_family_add_ = true;
column_family_name_ = name;
}
// set column family ID by calling SetColumnFamily()
void DropColumnFamily() {
assert(!is_column_family_drop_);
assert(!is_column_family_add_);
assert(NumEntries() == 0);
is_column_family_drop_ = true;
}
void EncodeTo(std::string* dst) const;
Status DecodeFrom(const Slice& src);
std::string DebugString(bool hex_key = false) const;
private:
friend class VersionSet;
friend class Version;
typedef std::set< std::pair<int, uint64_t>> DeletedFileSet;
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