rocksdb/db/compaction.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 "util/arena.h"
#include "util/autovector.h"
#include "db/version_set.h"
namespace rocksdb {
// The structure that manages compaction input files associated
// with the same physical level.
struct CompactionInputFiles {
int level;
std::vector<FileMetaData*> files;
inline bool empty() const { return files.empty(); }
inline size_t size() const { return files.size(); }
inline void clear() { files.clear(); }
inline FileMetaData* operator[](int i) const { return files[i]; }
};
class Version;
class ColumnFamilyData;
// A Compaction encapsulates information about a compaction.
class Compaction {
public:
// No copying allowed
Compaction(const Compaction&) = delete;
void operator=(const Compaction&) = delete;
~Compaction();
// Returns the level associated to the specified compaction input level.
// If compaction_input_level is not specified, then input_level is set to 0.
int level(int compaction_input_level = 0) const {
return inputs_[compaction_input_level].level;
}
// Outputs will go to this level
int output_level() const { return output_level_; }
// Returns the number of input levels in this compaction.
int num_input_levels() const { return inputs_.size(); }
// Return the object that holds the edits to the descriptor done
// by this compaction.
VersionEdit* edit() const { return edit_; }
// Returns the number of input files associated to the specified
// compaction input level.
// The function will return 0 if when "compaction_input_level" < 0
// or "compaction_input_level" >= "num_input_levels()".
int num_input_files(size_t compaction_input_level) const {
if (compaction_input_level < inputs_.size()) {
return inputs_[compaction_input_level].size();
}
return 0;
}
// Returns input version of the compaction
Version* input_version() const { return input_version_; }
// Returns the ColumnFamilyData associated with the compaction.
ColumnFamilyData* column_family_data() const { return cfd_; }
// Returns the file meta data of the 'i'th input file at the
// specified compaction input level.
// REQUIREMENT: "compaction_input_level" must be >= 0 and
// < "input_levels()"
FileMetaData* input(size_t compaction_input_level, int i) const {
assert(compaction_input_level < inputs_.size());
return inputs_[compaction_input_level][i];
}
// Returns the list of file meta data of the specified compaction
// input level.
// REQUIREMENT: "compaction_input_level" must be >= 0 and
// < "input_levels()"
std::vector<FileMetaData*>* const inputs(size_t compaction_input_level) {
assert(compaction_input_level < inputs_.size());
return &inputs_[compaction_input_level].files;
}
// Returns the FileLevel of the specified compaction input level.
FileLevel* input_levels(int compaction_input_level) {
return &input_levels_[compaction_input_level];
}
// Maximum size of files to build during this compaction.
uint64_t MaxOutputFileSize() const { return max_output_file_size_; }
// What compression for output
CompressionType OutputCompressionType() const { return output_compression_; }
// Whether need to write output file to second DB path.
uint32_t GetOutputPathId() const { return output_path_id_; }
// Generate input_levels_ from inputs_
// Should be called when inputs_ is stable
void GenerateFileLevels();
// Is this a trivial compaction that can be implemented by just
// moving a single input file to the next level (no merging or splitting)
bool IsTrivialMove() const;
// If true, then the comaction can be done by simply deleting input files.
bool IsDeletionCompaction() const {
return deletion_compaction_;
}
// Add all inputs to this compaction as delete operations to *edit.
void AddInputDeletions(VersionEdit* edit);
// Returns true if the available information we have guarantees that
// the input "user_key" does not exist in any level beyond "output_level()".
bool KeyNotExistsBeyondOutputLevel(const Slice& user_key);
// Returns true iff we should stop building the current output
// before processing "internal_key".
bool ShouldStopBefore(const Slice& internal_key);
// Release the input version for the compaction, once the compaction
// is successful.
void ReleaseInputs();
// Clear all files to indicate that they are not being compacted
// Delete this compaction from the list of running compactions.
void ReleaseCompactionFiles(Status status);
// Returns the summary of the compaction in "output" with maximum "len"
// in bytes. The caller is responsible for the memory management of
// "output".
void Summary(char* output, int len);
// Return the score that was used to pick this compaction run.
double score() const { return score_; }
// Is this compaction creating a file in the bottom most level?
bool BottomMostLevel() { return bottommost_level_; }
// Does this compaction include all sst files?
bool IsFullCompaction() { return is_full_compaction_; }
// Was this compaction triggered manually by the client?
bool IsManualCompaction() { return is_manual_compaction_; }
// Returns the size in bytes that the output file should be preallocated to.
// In level compaction, that is max_file_size_. In universal compaction, that
// is the sum of all input file sizes.
uint64_t OutputFilePreallocationSize();
private:
friend class CompactionPicker;
friend class UniversalCompactionPicker;
friend class FIFOCompactionPicker;
friend class LevelCompactionPicker;
Compaction(Version* input_version, int start_level, int out_level,
uint64_t target_file_size, uint64_t max_grandparent_overlap_bytes,
uint32_t output_path_id, CompressionType output_compression,
bool seek_compaction = false, bool deletion_compaction = false);
const int start_level_; // the lowest level to be compacted
const int output_level_; // levels to which output files are stored
uint64_t max_output_file_size_;
uint64_t max_grandparent_overlap_bytes_;
Version* input_version_;
VersionEdit* edit_;
int number_levels_;
ColumnFamilyData* cfd_;
Arena arena_; // Arena used to allocate space for file_levels_
uint32_t output_path_id_;
CompressionType output_compression_;
bool seek_compaction_;
// If true, then the comaction can be done by simply deleting input files.
bool deletion_compaction_;
// Compaction input files organized by level.
autovector<CompactionInputFiles> inputs_;
// A copy of inputs_, organized more closely in memory
autovector<FileLevel, 2> input_levels_;
// State used to check for number of of overlapping grandparent files
// (grandparent == "output_level_ + 1")
// This vector is updated by Version::GetOverlappingInputs().
std::vector<FileMetaData*> grandparents_;
size_t grandparent_index_; // Index in grandparent_starts_
bool seen_key_; // Some output key has been seen
uint64_t overlapped_bytes_; // Bytes of overlap between current output
// and grandparent files
int base_index_; // index of the file in files_[start_level_]
int parent_index_; // index of some file with same range in
// files_[start_level_+1]
double score_; // score that was used to pick this compaction.
// Is this compaction creating a file in the bottom most level?
bool bottommost_level_;
// Does this compaction include all sst files?
bool is_full_compaction_;
// Is this compaction requested by the client?
bool is_manual_compaction_;
// "level_ptrs_" holds indices into "input_version_->levels_", where each
// index remembers which file of an associated level we are currently used
// to check KeyNotExistsBeyondOutputLevel() for deletion operation.
// As it is for checking KeyNotExistsBeyondOutputLevel(), it only
// records indices for all levels beyond "output_level_".
std::vector<size_t> level_ptrs_;
// mark (or clear) all files that are being compacted
void MarkFilesBeingCompacted(bool mark_as_compacted);
// Initialize whether the compaction is producing files at the
// bottommost level.
//
// @see BottomMostLevel()
void SetupBottomMostLevel(bool is_manual);
// In case of compaction error, reset the nextIndex that is used
// to pick up the next file to be compacted from files_by_size_
void ResetNextCompactionIndex();
};
} // namespace rocksdb