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rocksdb/db/compaction_picker.h

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// 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 "db/version_set.h"
#include "db/compaction.h"
#include "rocksdb/status.h"
#include "rocksdb/options.h"
#include <vector>
#include <memory>
#include <set>
namespace rocksdb {
class Compaction;
class Version;
class CompactionPicker {
public:
CompactionPicker(const ColumnFamilyOptions* options,
const InternalKeyComparator* icmp);
virtual ~CompactionPicker();
// Pick level and inputs for a new compaction.
// Returns nullptr if there is no compaction to be done.
// Otherwise returns a pointer to a heap-allocated object that
// describes the compaction. Caller should delete the result.
virtual Compaction* PickCompaction(Version* version) = 0;
// Return a compaction object for compacting the range [begin,end] in
// the specified level. Returns nullptr if there is nothing in that
// level that overlaps the specified range. Caller should delete
// the result.
//
// The returned Compaction might not include the whole requested range.
// In that case, compaction_end will be set to the next key that needs
// compacting. In case the compaction will compact the whole range,
// compaction_end will be set to nullptr.
// Client is responsible for compaction_end storage -- when called,
// *compaction_end should point to valid InternalKey!
Compaction* CompactRange(Version* version, int input_level, int output_level,
const InternalKey* begin, const InternalKey* end,
InternalKey** compaction_end);
// Free up the files that participated in a compaction
void ReleaseCompactionFiles(Compaction* c, Status status);
// Return the total amount of data that is undergoing
// compactions per level
void SizeBeingCompacted(std::vector<uint64_t>& sizes);
// Returns maximum total overlap bytes with grandparent
// level (i.e., level+2) before we stop building a single
// file in level->level+1 compaction.
uint64_t MaxGrandParentOverlapBytes(int level);
// Returns maximum total bytes of data on a given level.
double MaxBytesForLevel(int level);
// Get the max file size in a given level.
uint64_t MaxFileSizeForLevel(int level) const;
protected:
int NumberLevels() const { return num_levels_; }
// Stores the minimal range that covers all entries in inputs in
// *smallest, *largest.
// REQUIRES: inputs is not empty
void GetRange(const std::vector<FileMetaData*>& inputs, InternalKey* smallest,
InternalKey* largest);
// Stores the minimal range that covers all entries in inputs1 and inputs2
// in *smallest, *largest.
// REQUIRES: inputs is not empty
void GetRange(const std::vector<FileMetaData*>& inputs1,
const std::vector<FileMetaData*>& inputs2,
InternalKey* smallest, InternalKey* largest);
// Add more files to the inputs on "level" to make sure that
// no newer version of a key is compacted to "level+1" while leaving an older
// version in a "level". Otherwise, any Get() will search "level" first,
// and will likely return an old/stale value for the key, since it always
// searches in increasing order of level to find the value. This could
// also scramble the order of merge operands. This function should be
// called any time a new Compaction is created, and its inputs_[0] are
// populated.
//
// Will return false if it is impossible to apply this compaction.
bool ExpandWhileOverlapping(Compaction* c);
uint64_t ExpandedCompactionByteSizeLimit(int level);
// Returns true if any one of the specified files are being compacted
bool FilesInCompaction(std::vector<FileMetaData*>& files);
// Returns true if any one of the parent files are being compacted
bool ParentRangeInCompaction(Version* version, const InternalKey* smallest,
const InternalKey* largest, int level,
int* index);
void SetupOtherInputs(Compaction* c);
// record all the ongoing compactions for all levels
std::vector<std::set<Compaction*>> compactions_in_progress_;
// Per-level target file size.
std::unique_ptr<uint64_t[]> max_file_size_;
// Per-level max bytes
std::unique_ptr<uint64_t[]> level_max_bytes_;
const ColumnFamilyOptions* const options_;
private:
int num_levels_;
const InternalKeyComparator* const icmp_;
};
class UniversalCompactionPicker : public CompactionPicker {
public:
UniversalCompactionPicker(const ColumnFamilyOptions* options,
const InternalKeyComparator* icmp)
: CompactionPicker(options, icmp) {}
virtual Compaction* PickCompaction(Version* version) override;
private:
// Pick Universal compaction to limit read amplification
Compaction* PickCompactionUniversalReadAmp(Version* version, double score,
unsigned int ratio,
unsigned int num_files);
// Pick Universal compaction to limit space amplification.
Compaction* PickCompactionUniversalSizeAmp(Version* version, double score);
};
class LevelCompactionPicker : public CompactionPicker {
public:
LevelCompactionPicker(const ColumnFamilyOptions* options,
const InternalKeyComparator* icmp)
: CompactionPicker(options, icmp) {}
virtual Compaction* PickCompaction(Version* version) override;
private:
// For the specfied level, pick a compaction.
// Returns nullptr if there is no compaction to be done.
// If level is 0 and there is already a compaction on that level, this
// function will return nullptr.
Compaction* PickCompactionBySize(Version* version, int level, double score);
};
} // namespace rocksdb