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rocksdb/db/compaction/compaction.h

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root 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 "memory/arena.h"
#include "options/cf_options.h"
#include "rocksdb/sst_partitioner.h"
#include "util/autovector.h"
namespace ROCKSDB_NAMESPACE {
// The file contains class Compaction, as well as some helper functions
// and data structures used by the class.
// Utility for comparing sstable boundary keys. Returns -1 if either a or b is
// null which provides the property that a==null indicates a key that is less
// than any key and b==null indicates a key that is greater than any key. Note
// that the comparison is performed primarily on the user-key portion of the
// key. If the user-keys compare equal, an additional test is made to sort
// range tombstone sentinel keys before other keys with the same user-key. The
// result is that 2 user-keys will compare equal if they differ purely on
// their sequence number and value, but the range tombstone sentinel for that
// user-key will compare not equal. This is necessary because the range
// tombstone sentinel key is set as the largest key for an sstable even though
// that key never appears in the database. We don't want adjacent sstables to
// be considered overlapping if they are separated by the range tombstone
// sentinel.
int sstableKeyCompare(const Comparator* user_cmp, const InternalKey& a,
const InternalKey& b);
int sstableKeyCompare(const Comparator* user_cmp, const InternalKey* a,
const InternalKey& b);
int sstableKeyCompare(const Comparator* user_cmp, const InternalKey& a,
const InternalKey* b);
// An AtomicCompactionUnitBoundary represents a range of keys [smallest,
// largest] that exactly spans one ore more neighbouring SSTs on the same
// level. Every pair of SSTs in this range "overlap" (i.e., the largest
// user key of one file is the smallest user key of the next file). These
// boundaries are propagated down to RangeDelAggregator during compaction
// to provide safe truncation boundaries for range tombstones.
struct AtomicCompactionUnitBoundary {
const InternalKey* smallest = nullptr;
const InternalKey* largest = nullptr;
};
// The structure that manages compaction input files associated
// with the same physical level.
struct CompactionInputFiles {
int level;
std::vector<FileMetaData*> files;
std::vector<AtomicCompactionUnitBoundary> atomic_compaction_unit_boundaries;
inline bool empty() const { return files.empty(); }
inline size_t size() const { return files.size(); }
inline void clear() { files.clear(); }
inline FileMetaData* operator[](size_t i) const { return files[i]; }
};
class Version;
class ColumnFamilyData;
class VersionStorageInfo;
class CompactionFilter;
// A Compaction encapsulates metadata about a compaction.
class Compaction {
public:
Compaction(VersionStorageInfo* input_version,
const ImmutableOptions& immutable_options,
const MutableCFOptions& mutable_cf_options,
const MutableDBOptions& mutable_db_options,
std::vector<CompactionInputFiles> inputs, int output_level,
uint64_t target_file_size, uint64_t max_compaction_bytes,
uint32_t output_path_id, CompressionType compression,
CompressionOptions compression_opts,
Temperature output_temperature, uint32_t max_subcompactions,
std::vector<FileMetaData*> grandparents,
bool manual_compaction = false, const std::string& trim_ts = "",
double score = -1, bool deletion_compaction = false,
bool l0_files_might_overlap = true,
CompactionReason compaction_reason = CompactionReason::kUnknown,
BlobGarbageCollectionPolicy blob_garbage_collection_policy =
BlobGarbageCollectionPolicy::kUseDefault,
double blob_garbage_collection_age_cutoff = -1);
// 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(size_t compaction_input_level = 0) const {
return inputs_[compaction_input_level].level;
}
int start_level() const { return start_level_; }
// Outputs will go to this level
int output_level() const { return output_level_; }
// Returns the number of input levels in this compaction.
size_t num_input_levels() const { return inputs_.size(); }
// Return the object that holds the edits to the descriptor done
// by this compaction.
VersionEdit* edit() { 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()".
size_t 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, size_t i) const {
assert(compaction_input_level < inputs_.size());
return inputs_[compaction_input_level][i];
}
const std::vector<AtomicCompactionUnitBoundary>* boundaries(
size_t compaction_input_level) const {
assert(compaction_input_level < inputs_.size());
return &inputs_[compaction_input_level].atomic_compaction_unit_boundaries;
}
// Returns the list of file meta data of the specified compaction
// input level.
// REQUIREMENT: "compaction_input_level" must be >= 0 and
// < "input_levels()"
const std::vector<FileMetaData*>* inputs(
size_t compaction_input_level) const {
assert(compaction_input_level < inputs_.size());
return &inputs_[compaction_input_level].files;
}
const std::vector<CompactionInputFiles>* inputs() { return &inputs_; }
// Returns the LevelFilesBrief of the specified compaction input level.
const LevelFilesBrief* input_levels(size_t compaction_input_level) const {
return &input_levels_[compaction_input_level];
}
// Maximum size of files to build during this compaction.
uint64_t max_output_file_size() const { return max_output_file_size_; }
// What compression for output
CompressionType output_compression() const { return output_compression_; }
// What compression options for output
const CompressionOptions& output_compression_opts() const {
return output_compression_opts_;
}
// Whether need to write output file to second DB path.
uint32_t output_path_id() const { return output_path_id_; }
// 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;
// The split user key in the output level if this compaction is required to
// split the output files according to the existing cursor in the output
// level under round-robin compaction policy. Empty indicates no required
// splitting key
const InternalKey* GetOutputSplitKey() const { return output_split_key_; }
// If true, then the compaction can be done by simply deleting input files.
bool deletion_compaction() 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,
std::vector<size_t>* level_ptrs) const;
// Clear all files to indicate that they are not being compacted
// Delete this compaction from the list of running compactions.
//
// Requirement: DB mutex held
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 bottommost_level() const { return bottommost_level_; }
// Does this compaction include all sst files?
bool is_full_compaction() const { return is_full_compaction_; }
// Was this compaction triggered manually by the client?
bool is_manual_compaction() const { return is_manual_compaction_; }
std::string trim_ts() const { return trim_ts_; }
// Used when allow_trivial_move option is set in
// Universal compaction. If all the input files are
// non overlapping, then is_trivial_move_ variable
// will be set true, else false
void set_is_trivial_move(bool trivial_move) {
is_trivial_move_ = trivial_move;
}
// Used when allow_trivial_move option is set in
// Universal compaction. Returns true, if the input files
// are non-overlapping and can be trivially moved.
bool is_trivial_move() const { return is_trivial_move_; }
// How many total levels are there?
int number_levels() const { return number_levels_; }
// Return the ImmutableOptions that should be used throughout the compaction
// procedure
const ImmutableOptions* immutable_options() const {
return &immutable_options_;
}
// Return the MutableCFOptions that should be used throughout the compaction
// procedure
const MutableCFOptions* mutable_cf_options() const {
return &mutable_cf_options_;
}
// 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() const;
void SetInputVersion(Version* input_version);
struct InputLevelSummaryBuffer {
char buffer[128];
};
const char* InputLevelSummary(InputLevelSummaryBuffer* scratch) const;
uint64_t CalculateTotalInputSize() const;
// 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();
// Create a CompactionFilter from compaction_filter_factory
std::unique_ptr<CompactionFilter> CreateCompactionFilter() const;
// Create a SstPartitioner from sst_partitioner_factory
std::unique_ptr<SstPartitioner> CreateSstPartitioner() const;
// Is the input level corresponding to output_level_ empty?
bool IsOutputLevelEmpty() const;
// Should this compaction be broken up into smaller ones run in parallel?
bool ShouldFormSubcompactions() const;
// Returns true iff at least one input file references a blob file.
//
// PRE: input version has been set.
bool DoesInputReferenceBlobFiles() const;
// test function to validate the functionality of IsBottommostLevel()
// function -- determines if compaction with inputs and storage is bottommost
static bool TEST_IsBottommostLevel(
int output_level, VersionStorageInfo* vstorage,
const std::vector<CompactionInputFiles>& inputs);
TablePropertiesCollection GetOutputTableProperties() const {
return output_table_properties_;
}
void SetOutputTableProperties(TablePropertiesCollection tp) {
output_table_properties_ = std::move(tp);
}
Slice GetSmallestUserKey() const { return smallest_user_key_; }
Slice GetLargestUserKey() const { return largest_user_key_; }
// Return true if the compaction supports per_key_placement
bool SupportsPerKeyPlacement() const;
// Get per_key_placement penultimate output level, which is `last_level - 1`
// if per_key_placement feature is supported. Otherwise, return -1.
int GetPenultimateLevel() const;
// Return true if the given range is overlap with penultimate level output
// range.
bool OverlapPenultimateLevelOutputRange(const Slice& smallest_key,
const Slice& largest_key) const;
// Return true if the key is within penultimate level output range for
// per_key_placement feature, which is safe to place the key to the
// penultimate level. different compaction strategy has different rules.
// If per_key_placement is not supported, always return false.
// TODO: currently it doesn't support moving data from the last level to the
// penultimate level
bool WithinPenultimateLevelOutputRange(const Slice& key) const;
CompactionReason compaction_reason() const { return compaction_reason_; }
const std::vector<FileMetaData*>& grandparents() const {
return grandparents_;
}
uint64_t max_compaction_bytes() const { return max_compaction_bytes_; }
Temperature output_temperature() const { return output_temperature_; }
uint32_t max_subcompactions() const { return max_subcompactions_; }
bool enable_blob_garbage_collection() const {
return enable_blob_garbage_collection_;
}
double blob_garbage_collection_age_cutoff() const {
return blob_garbage_collection_age_cutoff_;
}
// start and end are sub compact range. Null if no boundary.
// This is used to filter out some input files' ancester's time range.
uint64_t MinInputFileOldestAncesterTime(const InternalKey* start,
const InternalKey* end) const;
// Called by DBImpl::NotifyOnCompactionCompleted to make sure number of
// compaction begin and compaction completion callbacks match.
void SetNotifyOnCompactionCompleted() {
notify_on_compaction_completion_ = true;
}
bool ShouldNotifyOnCompactionCompleted() const {
return notify_on_compaction_completion_;
}
static constexpr int kInvalidLevel = -1;
// Evaluate penultimate output level. If the compaction supports
// per_key_placement feature, it returns the penultimate level number.
// Otherwise, it's set to kInvalidLevel (-1), which means
// output_to_penultimate_level is not supported.
static int EvaluatePenultimateLevel(const ImmutableOptions& immutable_options,
const int start_level,
const int output_level);
private:
// mark (or clear) all files that are being compacted
void MarkFilesBeingCompacted(bool mark_as_compacted);
// get the smallest and largest key present in files to be compacted
static void GetBoundaryKeys(VersionStorageInfo* vstorage,
const std::vector<CompactionInputFiles>& inputs,
Slice* smallest_key, Slice* largest_key,
int exclude_level = -1);
// populate penultimate level output range, which will be used to determine if
// a key is safe to output to the penultimate level (details see
// `Compaction::WithinPenultimateLevelOutputRange()`.
// TODO: Currently the penultimate level output range is the min/max keys of
// non-last-level input files. Which is only good if there's no key moved
// from the last level to the penultimate level. For a more complicated per
// key placement which may move data from the last level to the penultimate
// level, it needs extra check.
void PopulatePenultimateLevelOutputRange();
// Get the atomic file boundaries for all files in the compaction. Necessary
// in order to avoid the scenario described in
// https://github.com/facebook/rocksdb/pull/4432#discussion_r221072219 and
// plumb down appropriate key boundaries to RangeDelAggregator during
// compaction.
static std::vector<CompactionInputFiles> PopulateWithAtomicBoundaries(
VersionStorageInfo* vstorage, std::vector<CompactionInputFiles> inputs);
// helper function to determine if compaction with inputs and storage is
// bottommost
static bool IsBottommostLevel(
int output_level, VersionStorageInfo* vstorage,
const std::vector<CompactionInputFiles>& inputs);
static bool IsFullCompaction(VersionStorageInfo* vstorage,
const std::vector<CompactionInputFiles>& inputs);
VersionStorageInfo* input_vstorage_;
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_compaction_bytes_;
uint32_t max_subcompactions_;
const ImmutableOptions immutable_options_;
const MutableCFOptions mutable_cf_options_;
Version* input_version_;
VersionEdit edit_;
const int number_levels_;
ColumnFamilyData* cfd_;
Arena arena_; // Arena used to allocate space for file_levels_
const uint32_t output_path_id_;
CompressionType output_compression_;
CompressionOptions output_compression_opts_;
Temperature output_temperature_;
// If true, then the compaction can be done by simply deleting input files.
const bool deletion_compaction_;
// should it split the output file using the compact cursor?
const InternalKey* output_split_key_;
// L0 files in LSM-tree might be overlapping. But the compaction picking
// logic might pick a subset of the files that aren't overlapping. if
// that is the case, set the value to false. Otherwise, set it true.
bool l0_files_might_overlap_;
// Compaction input files organized by level. Constant after construction
const std::vector<CompactionInputFiles> inputs_;
// A copy of inputs_, organized more closely in memory
autovector<LevelFilesBrief, 2> input_levels_;
// State used to check for number of overlapping grandparent files
// (grandparent == "output_level_ + 1")
std::vector<FileMetaData*> grandparents_;
const double score_; // score that was used to pick this compaction.
// Is this compaction creating a file in the bottom most level?
const bool bottommost_level_;
// Does this compaction include all sst files?
const bool is_full_compaction_;
// Is this compaction requested by the client?
const bool is_manual_compaction_;
// The data with timestamp > trim_ts_ will be removed
const std::string trim_ts_;
// True if we can do trivial move in Universal multi level
// compaction
bool is_trivial_move_;
// Does input compression match the output compression?
bool InputCompressionMatchesOutput() const;
// table properties of output files
TablePropertiesCollection output_table_properties_;
// smallest user keys in compaction
Slice smallest_user_key_;
// largest user keys in compaction
Slice largest_user_key_;
// Reason for compaction
CompactionReason compaction_reason_;
// Notify on compaction completion only if listener was notified on compaction
// begin.
bool notify_on_compaction_completion_;
// Enable/disable GC collection for blobs during compaction.
bool enable_blob_garbage_collection_;
// Blob garbage collection age cutoff.
double blob_garbage_collection_age_cutoff_;
// only set when per_key_placement feature is enabled, -1 (kInvalidLevel)
// means not supported.
const int penultimate_level_;
// Key range for penultimate level output
Slice penultimate_level_smallest_user_key_;
Slice penultimate_level_largest_user_key_;
};
#ifndef NDEBUG
// Helper struct only for tests, which contains the data to decide if a key
// should be output to the penultimate level.
// TODO: remove this when the public feature knob is available
struct PerKeyPlacementContext {
const int level;
const Slice key;
const Slice value;
const SequenceNumber seq_num;
bool output_to_penultimate_level;
PerKeyPlacementContext(int _level, Slice _key, Slice _value,
SequenceNumber _seq_num)
: level(_level), key(_key), value(_value), seq_num(_seq_num) {
output_to_penultimate_level = false;
}
};
#endif /* !NDEBUG */
// Return sum of sizes of all files in `files`.
extern uint64_t TotalFileSize(const std::vector<FileMetaData*>& files);
} // namespace ROCKSDB_NAMESPACE