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rocksdb/db/compaction_picker.cc

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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.
#include "db/compaction_picker.h"
#define __STDC_FORMAT_MACROS
#include <inttypes.h>
#include <limits>
#include "db/filename.h"
#include "util/log_buffer.h"
#include "util/statistics.h"
namespace rocksdb {
namespace {
// Determine compression type, based on user options, level of the output
// file and whether compression is disabled.
// If enable_compression is false, then compression is always disabled no
// matter what the values of the other two parameters are.
// Otherwise, the compression type is determined based on options and level.
CompressionType GetCompressionType(const Options& options, int level,
const bool enable_compression = true) {
if (!enable_compression) {
// disable compression
return kNoCompression;
}
// If the use has specified a different compression level for each level,
// then pick the compresison for that level.
if (!options.compression_per_level.empty()) {
const int n = options.compression_per_level.size() - 1;
// It is possible for level_ to be -1; in that case, we use level
// 0's compression. This occurs mostly in backwards compatibility
// situations when the builder doesn't know what level the file
// belongs to. Likewise, if level_ is beyond the end of the
// specified compression levels, use the last value.
return options.compression_per_level[std::max(0, std::min(level, n))];
} else {
return options.compression;
}
}
uint64_t TotalCompensatedFileSize(const std::vector<FileMetaData*>& files) {
uint64_t sum = 0;
for (size_t i = 0; i < files.size() && files[i]; i++) {
sum += files[i]->compensated_file_size;
}
return sum;
}
// Multiple two operands. If they overflow, return op1.
uint64_t MultiplyCheckOverflow(uint64_t op1, int op2) {
if (op1 == 0) {
return 0;
}
if (op2 <= 0) {
return op1;
}
uint64_t casted_op2 = (uint64_t) op2;
if (std::numeric_limits<uint64_t>::max() / op1 < casted_op2) {
return op1;
}
return op1 * casted_op2;
}
} // anonymous namespace
CompactionPicker::CompactionPicker(const Options* options,
const InternalKeyComparator* icmp)
: compactions_in_progress_(options->num_levels),
options_(options),
num_levels_(options->num_levels),
icmp_(icmp) {
max_file_size_.reset(new uint64_t[NumberLevels()]);
level_max_bytes_.reset(new uint64_t[NumberLevels()]);
int target_file_size_multiplier = options_->target_file_size_multiplier;
int max_bytes_multiplier = options_->max_bytes_for_level_multiplier;
for (int i = 0; i < NumberLevels(); i++) {
if (i == 0 && options_->compaction_style == kCompactionStyleUniversal) {
max_file_size_[i] = ULLONG_MAX;
level_max_bytes_[i] = options_->max_bytes_for_level_base;
} else if (i > 1) {
max_file_size_[i] = MultiplyCheckOverflow(max_file_size_[i - 1],
target_file_size_multiplier);
level_max_bytes_[i] = MultiplyCheckOverflow(
MultiplyCheckOverflow(level_max_bytes_[i - 1], max_bytes_multiplier),
options_->max_bytes_for_level_multiplier_additional[i - 1]);
} else {
max_file_size_[i] = options_->target_file_size_base;
level_max_bytes_[i] = options_->max_bytes_for_level_base;
}
}
}
CompactionPicker::~CompactionPicker() {}
void CompactionPicker::SizeBeingCompacted(std::vector<uint64_t>& sizes) {
for (int level = 0; level < NumberLevels() - 1; level++) {
uint64_t total = 0;
for (auto c : compactions_in_progress_[level]) {
assert(c->level() == level);
for (int i = 0; i < c->num_input_files(0); i++) {
total += c->input(0, i)->compensated_file_size;
}
}
sizes[level] = total;
}
}
// Clear all files to indicate that they are not being compacted
// Delete this compaction from the list of running compactions.
void CompactionPicker::ReleaseCompactionFiles(Compaction* c, Status status) {
c->MarkFilesBeingCompacted(false);
compactions_in_progress_[c->level()].erase(c);
if (!status.ok()) {
c->ResetNextCompactionIndex();
}
}
uint64_t CompactionPicker::MaxFileSizeForLevel(int level) const {
assert(level >= 0);
assert(level < NumberLevels());
return max_file_size_[level];
}
uint64_t CompactionPicker::MaxGrandParentOverlapBytes(int level) {
uint64_t result = MaxFileSizeForLevel(level);
result *= options_->max_grandparent_overlap_factor;
return result;
}
double CompactionPicker::MaxBytesForLevel(int level) {
// Note: the result for level zero is not really used since we set
// the level-0 compaction threshold based on number of files.
assert(level >= 0);
assert(level < NumberLevels());
return level_max_bytes_[level];
}
void CompactionPicker::GetRange(const std::vector<FileMetaData*>& inputs,
InternalKey* smallest, InternalKey* largest) {
assert(!inputs.empty());
smallest->Clear();
largest->Clear();
for (size_t i = 0; i < inputs.size(); i++) {
FileMetaData* f = inputs[i];
if (i == 0) {
*smallest = f->smallest;
*largest = f->largest;
} else {
if (icmp_->Compare(f->smallest, *smallest) < 0) {
*smallest = f->smallest;
}
if (icmp_->Compare(f->largest, *largest) > 0) {
*largest = f->largest;
}
}
}
}
void CompactionPicker::GetRange(const std::vector<FileMetaData*>& inputs1,
const std::vector<FileMetaData*>& inputs2,
InternalKey* smallest, InternalKey* largest) {
std::vector<FileMetaData*> all = inputs1;
all.insert(all.end(), inputs2.begin(), inputs2.end());
GetRange(all, smallest, largest);
}
bool CompactionPicker::ExpandWhileOverlapping(Compaction* c) {
// If inputs are empty then there is nothing to expand.
if (!c || c->inputs_[0].empty()) {
return true;
}
// GetOverlappingInputs will always do the right thing for level-0.
// So we don't need to do any expansion if level == 0.
if (c->level() == 0) {
return true;
}
const int level = c->level();
InternalKey smallest, largest;
// Keep expanding c->inputs_[0] until we are sure that there is a
// "clean cut" boundary between the files in input and the surrounding files.
// This will ensure that no parts of a key are lost during compaction.
int hint_index = -1;
size_t old_size;
do {
old_size = c->inputs_[0].size();
GetRange(c->inputs_[0].files, &smallest, &largest);
c->inputs_[0].clear();
c->input_version_->GetOverlappingInputs(
level, &smallest, &largest, &c->inputs_[0].files,
hint_index, &hint_index);
} while(c->inputs_[0].size() > old_size);
// Get the new range
GetRange(c->inputs_[0].files, &smallest, &largest);
// If, after the expansion, there are files that are already under
// compaction, then we must drop/cancel this compaction.
int parent_index = -1;
if (c->inputs_[0].empty()) {
Log(options_->info_log,
"[%s] ExpandWhileOverlapping() failure because zero input files",
c->column_family_data()->GetName().c_str());
}
if (c->inputs_[0].empty() || FilesInCompaction(c->inputs_[0].files) ||
(c->level() != c->output_level() &&
ParentRangeInCompaction(c->input_version_, &smallest, &largest, level,
&parent_index))) {
c->inputs_[0].clear();
c->inputs_[1].clear();
return false;
}
return true;
}
uint64_t CompactionPicker::ExpandedCompactionByteSizeLimit(int level) {
uint64_t result = MaxFileSizeForLevel(level);
result *= options_->expanded_compaction_factor;
return result;
}
// Returns true if any one of specified files are being compacted
bool CompactionPicker::FilesInCompaction(std::vector<FileMetaData*>& files) {
for (unsigned int i = 0; i < files.size(); i++) {
if (files[i]->being_compacted) {
return true;
}
}
return false;
}
// Returns true if any one of the parent files are being compacted
bool CompactionPicker::ParentRangeInCompaction(Version* version,
const InternalKey* smallest,
const InternalKey* largest,
int level, int* parent_index) {
std::vector<FileMetaData*> inputs;
assert(level + 1 < NumberLevels());
version->GetOverlappingInputs(level + 1, smallest, largest, &inputs,
*parent_index, parent_index);
return FilesInCompaction(inputs);
}
// Populates the set of inputs from "level+1" that overlap with "level".
// Will also attempt to expand "level" if that doesn't expand "level+1"
// or cause "level" to include a file for compaction that has an overlapping
// user-key with another file.
void CompactionPicker::SetupOtherInputs(Compaction* c) {
// If inputs are empty, then there is nothing to expand.
// If both input and output levels are the same, no need to consider
// files at level "level+1"
if (c->inputs_[0].empty() || c->level() == c->output_level()) {
return;
}
const int level = c->level();
InternalKey smallest, largest;
// Get the range one last time.
GetRange(c->inputs_[0].files, &smallest, &largest);
// Populate the set of next-level files (inputs_[1]) to include in compaction
c->input_version_->GetOverlappingInputs(
level + 1, &smallest, &largest,
&c->inputs_[1].files, c->parent_index_,
&c->parent_index_);
// Get entire range covered by compaction
InternalKey all_start, all_limit;
GetRange(c->inputs_[0].files, c->inputs_[1].files, &all_start, &all_limit);
// See if we can further grow the number of inputs in "level" without
// changing the number of "level+1" files we pick up. We also choose NOT
// to expand if this would cause "level" to include some entries for some
// user key, while excluding other entries for the same user key. This
// can happen when one user key spans multiple files.
if (!c->inputs_[1].empty()) {
std::vector<FileMetaData*> expanded0;
c->input_version_->GetOverlappingInputs(
level, &all_start, &all_limit, &expanded0, c->base_index_, nullptr);
const uint64_t inputs0_size = TotalCompensatedFileSize(c->inputs_[0].files);
const uint64_t inputs1_size = TotalCompensatedFileSize(c->inputs_[1].files);
const uint64_t expanded0_size = TotalCompensatedFileSize(expanded0);
uint64_t limit = ExpandedCompactionByteSizeLimit(level);
if (expanded0.size() > c->inputs_[0].size() &&
inputs1_size + expanded0_size < limit &&
!FilesInCompaction(expanded0) &&
!c->input_version_->HasOverlappingUserKey(&expanded0, level)) {
InternalKey new_start, new_limit;
GetRange(expanded0, &new_start, &new_limit);
std::vector<FileMetaData*> expanded1;
c->input_version_->GetOverlappingInputs(level + 1, &new_start, &new_limit,
&expanded1, c->parent_index_,
&c->parent_index_);
if (expanded1.size() == c->inputs_[1].size() &&
!FilesInCompaction(expanded1)) {
Log(options_->info_log,
"[%s] Expanding@%d %zu+%zu (%" PRIu64 "+%" PRIu64
" bytes) to %zu+%zu (%" PRIu64 "+%" PRIu64 "bytes)\n",
c->column_family_data()->GetName().c_str(), level,
c->inputs_[0].size(), c->inputs_[1].size(), inputs0_size,
inputs1_size, expanded0.size(), expanded1.size(), expanded0_size,
inputs1_size);
smallest = new_start;
largest = new_limit;
c->inputs_[0].files = expanded0;
c->inputs_[1].files = expanded1;
GetRange(c->inputs_[0].files, c->inputs_[1].files,
&all_start, &all_limit);
}
}
}
// Compute the set of grandparent files that overlap this compaction
// (parent == level+1; grandparent == level+2)
if (level + 2 < NumberLevels()) {
c->input_version_->GetOverlappingInputs(level + 2, &all_start, &all_limit,
&c->grandparents_);
}
}
Compaction* CompactionPicker::CompactRange(Version* version, int input_level,
int output_level,
uint32_t output_path_id,
const InternalKey* begin,
const InternalKey* end,
InternalKey** compaction_end) {
// CompactionPickerFIFO has its own implementation of compact range
assert(options_->compaction_style != kCompactionStyleFIFO);
std::vector<FileMetaData*> inputs;
bool covering_the_whole_range = true;
// All files are 'overlapping' in universal style compaction.
// We have to compact the entire range in one shot.
if (options_->compaction_style == kCompactionStyleUniversal) {
begin = nullptr;
end = nullptr;
}
version->GetOverlappingInputs(input_level, begin, end, &inputs);
if (inputs.empty()) {
return nullptr;
}
// Avoid compacting too much in one shot in case the range is large.
// But we cannot do this for level-0 since level-0 files can overlap
// and we must not pick one file and drop another older file if the
// two files overlap.
if (input_level > 0) {
const uint64_t limit =
MaxFileSizeForLevel(input_level) * options_->source_compaction_factor;
uint64_t total = 0;
for (size_t i = 0; i + 1 < inputs.size(); ++i) {
uint64_t s = inputs[i]->compensated_file_size;
total += s;
if (total >= limit) {
**compaction_end = inputs[i + 1]->smallest;
covering_the_whole_range = false;
inputs.resize(i + 1);
break;
}
}
}
assert(output_path_id < static_cast<uint32_t>(options_->db_paths.size()));
Compaction* c = new Compaction(
version, input_level, output_level, MaxFileSizeForLevel(output_level),
MaxGrandParentOverlapBytes(input_level), output_path_id,
GetCompressionType(*options_, output_level));
c->inputs_[0].files = inputs;
if (ExpandWhileOverlapping(c) == false) {
delete c;
Log(options_->info_log,
"[%s] Could not compact due to expansion failure.\n",
version->cfd_->GetName().c_str());
return nullptr;
}
SetupOtherInputs(c);
if (covering_the_whole_range) {
*compaction_end = nullptr;
}
// These files that are to be manaully compacted do not trample
// upon other files because manual compactions are processed when
// the system has a max of 1 background compaction thread.
c->MarkFilesBeingCompacted(true);
// Is this compaction creating a file at the bottommost level
c->SetupBottomMostLevel(true);
c->is_manual_compaction_ = true;
return c;
}
Compaction* LevelCompactionPicker::PickCompaction(Version* version,
LogBuffer* log_buffer) {
Compaction* c = nullptr;
int level = -1;
// Compute the compactions needed. It is better to do it here
// and also in LogAndApply(), otherwise the values could be stale.
std::vector<uint64_t> size_being_compacted(NumberLevels() - 1);
SizeBeingCompacted(size_being_compacted);
version->ComputeCompactionScore(size_being_compacted);
// We prefer compactions triggered by too much data in a level over
// the compactions triggered by seeks.
//
// Find the compactions by size on all levels.
for (int i = 0; i < NumberLevels() - 1; i++) {
assert(i == 0 ||
version->compaction_score_[i] <= version->compaction_score_[i - 1]);
level = version->compaction_level_[i];
if ((version->compaction_score_[i] >= 1)) {
c = PickCompactionBySize(version, level, version->compaction_score_[i]);
if (ExpandWhileOverlapping(c) == false) {
delete c;
c = nullptr;
} else {
break;
}
}
}
if (c == nullptr) {
return nullptr;
}
// Two level 0 compaction won't run at the same time, so don't need to worry
// about files on level 0 being compacted.
if (level == 0) {
assert(compactions_in_progress_[0].empty());
InternalKey smallest, largest;
GetRange(c->inputs_[0].files, &smallest, &largest);
// Note that the next call will discard the file we placed in
// c->inputs_[0] earlier and replace it with an overlapping set
// which will include the picked file.
c->inputs_[0].clear();
c->input_version_->GetOverlappingInputs(0, &smallest, &largest,
&c->inputs_[0].files);
// If we include more L0 files in the same compaction run it can
// cause the 'smallest' and 'largest' key to get extended to a
// larger range. So, re-invoke GetRange to get the new key range
GetRange(c->inputs_[0].files, &smallest, &largest);
if (ParentRangeInCompaction(c->input_version_, &smallest, &largest, level,
&c->parent_index_)) {
delete c;
return nullptr;
}
assert(!c->inputs_[0].empty());
}
// Setup "level+1" files (inputs_[1])
SetupOtherInputs(c);
// mark all the files that are being compacted
c->MarkFilesBeingCompacted(true);
// Is this compaction creating a file at the bottommost level
c->SetupBottomMostLevel(false);
// remember this currently undergoing compaction
compactions_in_progress_[level].insert(c);
return c;
}
Compaction* LevelCompactionPicker::PickCompactionBySize(Version* version,
int level,
double score) {
Compaction* c = nullptr;
// level 0 files are overlapping. So we cannot pick more
// than one concurrent compactions at this level. This
// could be made better by looking at key-ranges that are
// being compacted at level 0.
if (level == 0 && compactions_in_progress_[level].size() == 1) {
return nullptr;
}
assert(level >= 0);
assert(level + 1 < NumberLevels());
c = new Compaction(version, level, level + 1, MaxFileSizeForLevel(level + 1),
MaxGrandParentOverlapBytes(level), 0,
GetCompressionType(*options_, level + 1));
c->score_ = score;
// Pick the largest file in this level that is not already
// being compacted
std::vector<int>& file_size = c->input_version_->files_by_size_[level];
// record the first file that is not yet compacted
int nextIndex = -1;
for (unsigned int i = c->input_version_->next_file_to_compact_by_size_[level];
i < file_size.size(); i++) {
int index = file_size[i];
FileMetaData* f = c->input_version_->files_[level][index];
// Check to verify files are arranged in descending compensated size.
assert((i == file_size.size() - 1) ||
(i >= Version::number_of_files_to_sort_ - 1) ||
(f->compensated_file_size >=
c->input_version_->files_[level][file_size[i + 1]]->
compensated_file_size));
// do not pick a file to compact if it is being compacted
// from n-1 level.
if (f->being_compacted) {
continue;
}
// remember the startIndex for the next call to PickCompaction
if (nextIndex == -1) {
nextIndex = i;
}
// Do not pick this file if its parents at level+1 are being compacted.
// Maybe we can avoid redoing this work in SetupOtherInputs
int parent_index = -1;
if (ParentRangeInCompaction(c->input_version_, &f->smallest, &f->largest,
level, &parent_index)) {
continue;
}
c->inputs_[0].files.push_back(f);
c->base_index_ = index;
c->parent_index_ = parent_index;
break;
}
if (c->inputs_[0].empty()) {
delete c;
c = nullptr;
}
// store where to start the iteration in the next call to PickCompaction
version->next_file_to_compact_by_size_[level] = nextIndex;
return c;
}
// Universal style of compaction. Pick files that are contiguous in
// time-range to compact.
//
Compaction* UniversalCompactionPicker::PickCompaction(Version* version,
LogBuffer* log_buffer) {
int level = 0;
double score = version->compaction_score_[0];
if ((version->files_[level].size() <
(unsigned int)options_->level0_file_num_compaction_trigger)) {
LogToBuffer(log_buffer, "[%s] Universal: nothing to do\n",
version->cfd_->GetName().c_str());
return nullptr;
}
Version::FileSummaryStorage tmp;
LogToBuffer(log_buffer, "[%s] Universal: candidate files(%zu): %s\n",
version->cfd_->GetName().c_str(), version->files_[level].size(),
version->LevelFileSummary(&tmp, 0));
// Check for size amplification first.
Compaction* c;
if ((c = PickCompactionUniversalSizeAmp(version, score, log_buffer)) !=
nullptr) {
LogToBuffer(log_buffer, "[%s] Universal: compacting for size amp\n",
version->cfd_->GetName().c_str());
} else {
// Size amplification is within limits. Try reducing read
// amplification while maintaining file size ratios.
unsigned int ratio = options_->compaction_options_universal.size_ratio;
if ((c = PickCompactionUniversalReadAmp(version, score, ratio, UINT_MAX,
log_buffer)) != nullptr) {
LogToBuffer(log_buffer, "[%s] Universal: compacting for size ratio\n",
version->cfd_->GetName().c_str());
} else {
// Size amplification and file size ratios are within configured limits.
// If max read amplification is exceeding configured limits, then force
// compaction without looking at filesize ratios and try to reduce
// the number of files to fewer than level0_file_num_compaction_trigger.
unsigned int num_files = version->files_[level].size() -
options_->level0_file_num_compaction_trigger;
if ((c = PickCompactionUniversalReadAmp(
version, score, UINT_MAX, num_files, log_buffer)) != nullptr) {
LogToBuffer(log_buffer, "[%s] Universal: compacting for file num\n",
version->cfd_->GetName().c_str());
}
}
}
if (c == nullptr) {
return nullptr;
}
assert(c->inputs_[0].size() > 1);
// validate that all the chosen files are non overlapping in time
FileMetaData* newerfile __attribute__((unused)) = nullptr;
for (unsigned int i = 0; i < c->inputs_[0].size(); i++) {
FileMetaData* f = c->inputs_[0][i];
assert (f->smallest_seqno <= f->largest_seqno);
assert(newerfile == nullptr ||
newerfile->smallest_seqno > f->largest_seqno);
newerfile = f;
}
// Is the earliest file part of this compaction?
FileMetaData* last_file = c->input_version_->files_[level].back();
c->bottommost_level_ = c->inputs_[0].files.back() == last_file;
// update statistics
MeasureTime(options_->statistics.get(),
NUM_FILES_IN_SINGLE_COMPACTION, c->inputs_[0].size());
// mark all the files that are being compacted
c->MarkFilesBeingCompacted(true);
// remember this currently undergoing compaction
compactions_in_progress_[level].insert(c);
// Record whether this compaction includes all sst files.
// For now, it is only relevant in universal compaction mode.
c->is_full_compaction_ =
(c->inputs_[0].size() == c->input_version_->files_[0].size());
return c;
}
uint32_t UniversalCompactionPicker::GetPathId(const Options& options,
uint64_t file_size) {
// Two conditions need to be satisfied:
// (1) the target path needs to be able to hold the file's size
// (2) Total size left in this and previous paths need to be not
// smaller than expected future file size before this new file is
// compacted, which is estimated based on size_ratio.
// For example, if now we are compacting files of size (1, 1, 2, 4, 8),
// we will make sure the target file, probably with size of 16, will be
// placed in a path so that eventually when new files are generated and
// compacted to (1, 1, 2, 4, 8, 16), all those files can be stored in or
// before the path we chose.
//
// TODO(sdong): now the case of multiple column families is not
// considered in this algorithm. So the target size can be violated in
// that case. We need to improve it.
uint64_t accumulated_size = 0;
uint64_t future_size =
file_size * (100 - options.compaction_options_universal.size_ratio) / 100;
uint32_t p = 0;
for (; p < options.db_paths.size() - 1; p++) {
uint64_t target_size = options.db_paths[p].target_size;
if (target_size > file_size &&
accumulated_size + (target_size - file_size) > future_size) {
return p;
}
accumulated_size += target_size;
}
return p;
}
//
// Consider compaction files based on their size differences with
// the next file in time order.
//
Compaction* UniversalCompactionPicker::PickCompactionUniversalReadAmp(
Version* version, double score, unsigned int ratio,
unsigned int max_number_of_files_to_compact, LogBuffer* log_buffer) {
int level = 0;
unsigned int min_merge_width =
options_->compaction_options_universal.min_merge_width;
unsigned int max_merge_width =
options_->compaction_options_universal.max_merge_width;
// The files are sorted from newest first to oldest last.
const auto& files = version->files_[level];
FileMetaData* f = nullptr;
bool done = false;
int start_index = 0;
unsigned int candidate_count = 0;
unsigned int max_files_to_compact = std::min(max_merge_width,
max_number_of_files_to_compact);
min_merge_width = std::max(min_merge_width, 2U);
// Considers a candidate file only if it is smaller than the
// total size accumulated so far.
for (unsigned int loop = 0; loop < files.size(); loop++) {
candidate_count = 0;
// Skip files that are already being compacted
for (f = nullptr; loop < files.size(); loop++) {
f = files[loop];
if (!f->being_compacted) {
candidate_count = 1;
break;
}
LogToBuffer(log_buffer, "[%s] Universal: file %" PRIu64
"[%d] being compacted, skipping",
version->cfd_->GetName().c_str(), f->fd.GetNumber(), loop);
f = nullptr;
}
// This file is not being compacted. Consider it as the
// first candidate to be compacted.
uint64_t candidate_size = f != nullptr? f->compensated_file_size : 0;
if (f != nullptr) {
LogToBuffer(
log_buffer, "[%s] Universal: Possible candidate file %s[%d].",
version->cfd_->GetName().c_str(),
FormatFileNumber(f->fd.GetNumber(), f->fd.GetPathId()).c_str(), loop);
}
// Check if the suceeding files need compaction.
for (unsigned int i = loop + 1;
candidate_count < max_files_to_compact && i < files.size(); i++) {
FileMetaData* f = files[i];
if (f->being_compacted) {
break;
}
// Pick files if the total/last candidate file size (increased by the
// specified ratio) is still larger than the next candidate file.
// candidate_size is the total size of files picked so far with the
// default kCompactionStopStyleTotalSize; with
// kCompactionStopStyleSimilarSize, it's simply the size of the last
// picked file.
uint64_t sz = (candidate_size * (100L + ratio)) /100;
if (sz < f->fd.GetFileSize()) {
break;
}
if (options_->compaction_options_universal.stop_style == kCompactionStopStyleSimilarSize) {
// Similar-size stopping rule: also check the last picked file isn't
// far larger than the next candidate file.
sz = (f->fd.GetFileSize() * (100L + ratio)) / 100;
if (sz < candidate_size) {
// If the small file we've encountered begins a run of similar-size
// files, we'll pick them up on a future iteration of the outer
// loop. If it's some lonely straggler, it'll eventually get picked
// by the last-resort read amp strategy which disregards size ratios.
break;
}
candidate_size = f->compensated_file_size;
} else { // default kCompactionStopStyleTotalSize
candidate_size += f->compensated_file_size;
}
candidate_count++;
}
// Found a series of consecutive files that need compaction.
if (candidate_count >= (unsigned int)min_merge_width) {
start_index = loop;
done = true;
break;
} else {
for (unsigned int i = loop;
i < loop + candidate_count && i < files.size(); i++) {
FileMetaData* f = files[i];
LogToBuffer(log_buffer, "[%s] Universal: Skipping file %" PRIu64
"[%d] with size %" PRIu64
" (compensated size %" PRIu64 ") %d\n",
version->cfd_->GetName().c_str(), f->fd.GetNumber(), i,
f->fd.GetFileSize(), f->compensated_file_size,
f->being_compacted);
}
}
}
if (!done || candidate_count <= 1) {
return nullptr;
}
unsigned int first_index_after = start_index + candidate_count;
// Compression is enabled if files compacted earlier already reached
// size ratio of compression.
bool enable_compression = true;
int ratio_to_compress =
options_->compaction_options_universal.compression_size_percent;
if (ratio_to_compress >= 0) {
uint64_t total_size = version->NumLevelBytes(level);
uint64_t older_file_size = 0;
for (unsigned int i = files.size() - 1;
i >= first_index_after; i--) {
older_file_size += files[i]->fd.GetFileSize();
if (older_file_size * 100L >= total_size * (long) ratio_to_compress) {
enable_compression = false;
break;
}
}
}
uint64_t estimated_total_size = 0;
for (unsigned int i = 0; i < first_index_after; i++) {
estimated_total_size += files[i]->fd.GetFileSize();
}
uint32_t path_id = GetPathId(*options_, estimated_total_size);
Compaction* c = new Compaction(
version, level, level, MaxFileSizeForLevel(level), LLONG_MAX, path_id,
GetCompressionType(*options_, level, enable_compression));
c->score_ = score;
for (unsigned int i = start_index; i < first_index_after; i++) {
FileMetaData* f = c->input_version_->files_[level][i];
c->inputs_[0].files.push_back(f);
LogToBuffer(log_buffer,
"[%s] Universal: Picking file %s[%d] "
"with size %" PRIu64 " (compensated size %" PRIu64 ")\n",
version->cfd_->GetName().c_str(),
FormatFileNumber(f->fd.GetNumber(), f->fd.GetPathId()).c_str(),
i, f->fd.GetFileSize(), f->compensated_file_size);
}
return c;
}
// Look at overall size amplification. If size amplification
// exceeeds the configured value, then do a compaction
// of the candidate files all the way upto the earliest
// base file (overrides configured values of file-size ratios,
// min_merge_width and max_merge_width).
//
Compaction* UniversalCompactionPicker::PickCompactionUniversalSizeAmp(
Version* version, double score, LogBuffer* log_buffer) {
int level = 0;
// percentage flexibilty while reducing size amplification
uint64_t ratio = options_->compaction_options_universal.
max_size_amplification_percent;
// The files are sorted from newest first to oldest last.
const auto& files = version->files_[level];
unsigned int candidate_count = 0;
uint64_t candidate_size = 0;
unsigned int start_index = 0;
FileMetaData* f = nullptr;
// Skip files that are already being compacted
for (unsigned int loop = 0; loop < files.size() - 1; loop++) {
f = files[loop];
if (!f->being_compacted) {
start_index = loop; // Consider this as the first candidate.
break;
}
LogToBuffer(log_buffer, "[%s] Universal: skipping file %s[%d] compacted %s",
version->cfd_->GetName().c_str(),
FormatFileNumber(f->fd.GetNumber(), f->fd.GetPathId()).c_str(),
loop, " cannot be a candidate to reduce size amp.\n");
f = nullptr;
}
if (f == nullptr) {
return nullptr; // no candidate files
}
LogToBuffer(log_buffer, "[%s] Universal: First candidate file %s[%d] %s",
version->cfd_->GetName().c_str(),
FormatFileNumber(f->fd.GetNumber(), f->fd.GetPathId()).c_str(),
start_index, " to reduce size amp.\n");
// keep adding up all the remaining files
for (unsigned int loop = start_index; loop < files.size() - 1; loop++) {
f = files[loop];
if (f->being_compacted) {
LogToBuffer(
log_buffer, "[%s] Universal: Possible candidate file %s[%d] %s.",
version->cfd_->GetName().c_str(),
FormatFileNumber(f->fd.GetNumber(), f->fd.GetPathId()).c_str(), loop,
" is already being compacted. No size amp reduction possible.\n");
return nullptr;
}
candidate_size += f->compensated_file_size;
candidate_count++;
}
if (candidate_count == 0) {
return nullptr;
}
// size of earliest file
uint64_t earliest_file_size = files.back()->fd.GetFileSize();
// size amplification = percentage of additional size
if (candidate_size * 100 < ratio * earliest_file_size) {
LogToBuffer(
log_buffer,
"[%s] Universal: size amp not needed. newer-files-total-size %" PRIu64
"earliest-file-size %" PRIu64,
version->cfd_->GetName().c_str(), candidate_size, earliest_file_size);
return nullptr;
} else {
LogToBuffer(
log_buffer,
"[%s] Universal: size amp needed. newer-files-total-size %" PRIu64
"earliest-file-size %" PRIu64,
version->cfd_->GetName().c_str(), candidate_size, earliest_file_size);
}
assert(start_index >= 0 && start_index < files.size() - 1);
// Estimate total file size
uint64_t estimated_total_size = 0;
for (unsigned int loop = start_index; loop < files.size(); loop++) {
estimated_total_size += files[loop]->fd.GetFileSize();
}
uint32_t path_id = GetPathId(*options_, estimated_total_size);
// create a compaction request
// We always compact all the files, so always compress.
Compaction* c =
new Compaction(version, level, level, MaxFileSizeForLevel(level),
LLONG_MAX, path_id, GetCompressionType(*options_, level));
c->score_ = score;
for (unsigned int loop = start_index; loop < files.size(); loop++) {
f = c->input_version_->files_[level][loop];
c->inputs_[0].files.push_back(f);
LogToBuffer(log_buffer,
"[%s] Universal: size amp picking file %" PRIu64 "[%d] "
"with size %" PRIu64 " (compensated size %" PRIu64 ")",
version->cfd_->GetName().c_str(),
f->fd.GetNumber(), loop,
f->fd.GetFileSize(), f->compensated_file_size);
}
return c;
}
Compaction* FIFOCompactionPicker::PickCompaction(Version* version,
LogBuffer* log_buffer) {
assert(version->NumberLevels() == 1);
uint64_t total_size = 0;
for (const auto& file : version->files_[0]) {
total_size += file->compensated_file_size;
}
if (total_size <= options_->compaction_options_fifo.max_table_files_size ||
version->files_[0].size() == 0) {
// total size not exceeded
LogToBuffer(log_buffer,
"[%s] FIFO compaction: nothing to do. Total size %" PRIu64
", max size %" PRIu64 "\n",
version->cfd_->GetName().c_str(), total_size,
options_->compaction_options_fifo.max_table_files_size);
return nullptr;
}
if (compactions_in_progress_[0].size() > 0) {
LogToBuffer(log_buffer,
"[%s] FIFO compaction: Already executing compaction. No need "
"to run parallel compactions since compactions are very fast",
version->cfd_->GetName().c_str());
return nullptr;
}
Compaction* c = new Compaction(version, 0, 0, 0, 0, 0, kNoCompression, false,
true /* is deletion compaction */);
// delete old files (FIFO)
for (auto ritr = version->files_[0].rbegin();
ritr != version->files_[0].rend(); ++ritr) {
auto f = *ritr;
total_size -= f->compensated_file_size;
c->inputs_[0].files.push_back(f);
char tmp_fsize[16];
AppendHumanBytes(f->fd.GetFileSize(), tmp_fsize, sizeof(tmp_fsize));
LogToBuffer(log_buffer, "[%s] FIFO compaction: picking file %" PRIu64
" with size %s for deletion",
version->cfd_->GetName().c_str(), f->fd.GetNumber(), tmp_fsize);
if (total_size <= options_->compaction_options_fifo.max_table_files_size) {
break;
}
}
c->MarkFilesBeingCompacted(true);
compactions_in_progress_[0].insert(c);
return c;
}
Compaction* FIFOCompactionPicker::CompactRange(
Version* version, int input_level, int output_level,
uint32_t output_path_id, const InternalKey* begin, const InternalKey* end,
InternalKey** compaction_end) {
assert(input_level == 0);
assert(output_level == 0);
*compaction_end = nullptr;
LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL, options_->info_log.get());
Compaction* c = PickCompaction(version, &log_buffer);
if (c != nullptr) {
assert(output_path_id < static_cast<uint32_t>(options_->db_paths.size()));
c->output_path_id_ = output_path_id;
}
log_buffer.FlushBufferToLog();
return c;
}
} // namespace rocksdb