6acbe0fc45
Summary: Merge multiple multiple memtables in memory before writing it out to a file in L0. There is a new config parameter min_write_buffer_number_to_merge that specifies the number of write buffers that should be merged together to a single file in storage. The system will not flush wrte buffers to storage unless at least these many buffers have accumulated in memory. The default value of this new parameter is 1, which means that a write buffer will be immediately flushed to disk as soon it is ready. Test Plan: make check Differential Revision: https://reviews.facebook.net/D11241
121 lines
3.3 KiB
C++
121 lines
3.3 KiB
C++
// 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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#ifndef STORAGE_LEVELDB_DB_VERSION_EDIT_H_
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#define STORAGE_LEVELDB_DB_VERSION_EDIT_H_
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#include <set>
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#include <utility>
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#include <vector>
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#include "db/dbformat.h"
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namespace leveldb {
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class VersionSet;
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struct FileMetaData {
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int refs;
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int allowed_seeks; // Seeks allowed until compaction
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uint64_t number;
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uint64_t file_size; // File size in bytes
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InternalKey smallest; // Smallest internal key served by table
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InternalKey largest; // Largest internal key served by table
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bool being_compacted; // Is this file undergoing compaction?
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FileMetaData() : refs(0), allowed_seeks(1 << 30), file_size(0),
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being_compacted(false) { }
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};
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class VersionEdit {
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public:
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/* implicit */ VersionEdit(int number_levels) :
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number_levels_(number_levels) {
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Clear();
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}
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~VersionEdit() { }
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void Clear();
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void SetComparatorName(const Slice& name) {
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has_comparator_ = true;
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comparator_ = name.ToString();
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}
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void SetLogNumber(uint64_t num) {
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has_log_number_ = true;
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log_number_ = num;
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}
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void SetPrevLogNumber(uint64_t num) {
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has_prev_log_number_ = true;
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prev_log_number_ = num;
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}
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void SetNextFile(uint64_t num) {
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has_next_file_number_ = true;
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next_file_number_ = num;
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}
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void SetLastSequence(SequenceNumber seq) {
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has_last_sequence_ = true;
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last_sequence_ = seq;
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}
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void SetCompactPointer(int level, const InternalKey& key) {
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compact_pointers_.push_back(std::make_pair(level, key));
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}
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// Add the specified file at the specified number.
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// REQUIRES: This version has not been saved (see VersionSet::SaveTo)
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// REQUIRES: "smallest" and "largest" are smallest and largest keys in file
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void AddFile(int level, uint64_t file,
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uint64_t file_size,
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const InternalKey& smallest,
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const InternalKey& largest) {
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FileMetaData f;
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f.number = file;
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f.file_size = file_size;
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f.smallest = smallest;
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f.largest = largest;
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new_files_.push_back(std::make_pair(level, f));
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}
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// Delete the specified "file" from the specified "level".
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void DeleteFile(int level, uint64_t file) {
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deleted_files_.insert(std::make_pair(level, file));
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}
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// Number of edits
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int NumEntries() {
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return new_files_.size() + deleted_files_.size();
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}
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void EncodeTo(std::string* dst) const;
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Status DecodeFrom(const Slice& src);
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std::string DebugString() const;
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private:
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friend class VersionSet;
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typedef std::set< std::pair<int, uint64_t> > DeletedFileSet;
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bool GetLevel(Slice* input, int* level, const char** msg);
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int number_levels_;
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std::string comparator_;
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uint64_t log_number_;
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uint64_t prev_log_number_;
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uint64_t next_file_number_;
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SequenceNumber last_sequence_;
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bool has_comparator_;
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bool has_log_number_;
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bool has_prev_log_number_;
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bool has_next_file_number_;
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bool has_last_sequence_;
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std::vector< std::pair<int, InternalKey> > compact_pointers_;
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DeletedFileSet deleted_files_;
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std::vector< std::pair<int, FileMetaData> > new_files_;
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};
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_DB_VERSION_EDIT_H_
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