作者: 谢瑞阳 10225101483 徐翔宇 10225101535
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// 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.
#ifndef STORAGE_LEVELDB_DB_VERSION_EDIT_H_
#define STORAGE_LEVELDB_DB_VERSION_EDIT_H_
#include <set>
#include <utility>
#include <vector>
#include "db/dbformat.h"
namespace leveldb {
class VersionSet;
struct FileMetaData {
FileMetaData() : refs(0), allowed_seeks(1 << 30), file_size(0) {}
int refs;
int allowed_seeks; // Seeks allowed until compaction
uint64_t number;
uint64_t file_size; // File size in bytes
InternalKey smallest; // Smallest internal key served by table
InternalKey largest; // Largest internal key served by table
};
class VersionEdit {
public:
VersionEdit() { Clear(); }
~VersionEdit() = default;
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 SetCompactPointer(int level, const InternalKey& key) {
compact_pointers_.push_back(std::make_pair(level, key));
}
// 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,
const InternalKey& smallest, const InternalKey& largest) {
FileMetaData f;
f.number = file;
f.file_size = file_size;
f.smallest = smallest;
f.largest = largest;
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(std::make_pair(level, file));
}
void EncodeTo(std::string* dst) const;
Status DecodeFrom(const Slice& src);
std::string DebugString() const;
private:
friend class VersionSet;
typedef std::set<std::pair<int, uint64_t>> DeletedFileSet;
std::string comparator_;
uint64_t log_number_;
uint64_t prev_log_number_;
uint64_t next_file_number_;
SequenceNumber last_sequence_;
bool has_comparator_;
bool has_log_number_;
bool has_prev_log_number_;
bool has_next_file_number_;
bool has_last_sequence_;
std::vector<std::pair<int, InternalKey>> compact_pointers_;
DeletedFileSet deleted_files_;
std::vector<std::pair<int, FileMetaData>> new_files_;
};
} // namespace leveldb
#endif // STORAGE_LEVELDB_DB_VERSION_EDIT_H_