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rocksdb/db/compaction_job.cc
Andrew Kryczka 843d2e3137 Shared dictionary compression using reference block 
Summary:
This adds a new metablock containing a shared dictionary that is used
to compress all data blocks in the SST file. The size of the shared dictionary
is configurable in CompressionOptions and defaults to 0. It's currently only
used for zlib/lz4/lz4hc, but the block will be stored in the SST regardless of
the compression type if the user chooses a nonzero dictionary size.

During compaction, computes the dictionary by randomly sampling the first
output file in each subcompaction. It pre-computes the intervals to sample
by assuming the output file will have the maximum allowable length. In case
the file is smaller, some of the pre-computed sampling intervals can be beyond
end-of-file, in which case we skip over those samples and the dictionary will
be a bit smaller. After the dictionary is generated using the first file in a
subcompaction, it is loaded into the compression library before writing each
block in each subsequent file of that subcompaction.

On the read path, gets the dictionary from the metablock, if it exists. Then,
loads that dictionary into the compression library before reading each block.

Test Plan: new unit test

Reviewers: yhchiang, IslamAbdelRahman, cyan, sdong

Reviewed By: sdong

Subscribers: andrewkr, yoshinorim, kradhakrishnan, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D52287
2016-04-27 17:36:03 -07:00

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// Copyright (c) 2011-present, 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_job.h"
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
#include <algorithm>
#include <functional>
#include <list>
#include <memory>
#include <random>
#include <set>
#include <thread>
#include <utility>
#include <vector>
#include "db/builder.h"
#include "db/db_iter.h"
#include "db/dbformat.h"
#include "db/event_helpers.h"
#include "db/filename.h"
#include "db/log_reader.h"
#include "db/log_writer.h"
#include "db/memtable.h"
#include "db/memtable_list.h"
#include "db/merge_context.h"
#include "db/merge_helper.h"
#include "db/version_set.h"
#include "port/likely.h"
#include "port/port.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/statistics.h"
#include "rocksdb/status.h"
#include "rocksdb/table.h"
#include "table/block.h"
#include "table/block_based_table_factory.h"
#include "table/merger.h"
#include "table/table_builder.h"
#include "util/coding.h"
#include "util/file_reader_writer.h"
#include "util/iostats_context_imp.h"
#include "util/log_buffer.h"
#include "util/logging.h"
#include "util/sst_file_manager_impl.h"
#include "util/mutexlock.h"
#include "util/perf_context_imp.h"
#include "util/stop_watch.h"
#include "util/string_util.h"
#include "util/sync_point.h"
#include "util/thread_status_util.h"
namespace rocksdb {
// Maintains state for each sub-compaction
struct CompactionJob::SubcompactionState {
const Compaction* compaction;
std::unique_ptr<CompactionIterator> c_iter;
// The boundaries of the key-range this compaction is interested in. No two
// subcompactions may have overlapping key-ranges.
// 'start' is inclusive, 'end' is exclusive, and nullptr means unbounded
Slice *start, *end;
// The return status of this subcompaction
Status status;
// Files produced by this subcompaction
struct Output {
FileMetaData meta;
bool finished;
std::shared_ptr<const TableProperties> table_properties;
};
// State kept for output being generated
std::vector<Output> outputs;
std::unique_ptr<WritableFileWriter> outfile;
std::unique_ptr<TableBuilder> builder;
Output* current_output() {
if (outputs.empty()) {
// This subcompaction's outptut could be empty if compaction was aborted
// before this subcompaction had a chance to generate any output files.
// When subcompactions are executed sequentially this is more likely and
// will be particulalry likely for the later subcompactions to be empty.
// Once they are run in parallel however it should be much rarer.
return nullptr;
} else {
return &outputs.back();
}
}
// State during the subcompaction
uint64_t total_bytes;
uint64_t num_input_records;
uint64_t num_output_records;
CompactionJobStats compaction_job_stats;
uint64_t approx_size;
// An index that used to speed up ShouldStopBefore().
size_t grandparent_index = 0;
// The number of bytes overlapping between the current output and
// grandparent files used in ShouldStopBefore().
uint64_t overlapped_bytes = 0;
// A flag determine whether the key has been seen in ShouldStopBefore()
bool seen_key = false;
std::string compression_dict;
SubcompactionState(Compaction* c, Slice* _start, Slice* _end,
uint64_t size = 0)
: compaction(c),
start(_start),
end(_end),
outfile(nullptr),
builder(nullptr),
total_bytes(0),
num_input_records(0),
num_output_records(0),
approx_size(size),
grandparent_index(0),
overlapped_bytes(0),
seen_key(false),
compression_dict() {
assert(compaction != nullptr);
}
SubcompactionState(SubcompactionState&& o) { *this = std::move(o); }
SubcompactionState& operator=(SubcompactionState&& o) {
compaction = std::move(o.compaction);
start = std::move(o.start);
end = std::move(o.end);
status = std::move(o.status);
outputs = std::move(o.outputs);
outfile = std::move(o.outfile);
builder = std::move(o.builder);
total_bytes = std::move(o.total_bytes);
num_input_records = std::move(o.num_input_records);
num_output_records = std::move(o.num_output_records);
compaction_job_stats = std::move(o.compaction_job_stats);
approx_size = std::move(o.approx_size);
grandparent_index = std::move(o.grandparent_index);
overlapped_bytes = std::move(o.overlapped_bytes);
seen_key = std::move(o.seen_key);
compression_dict = std::move(o.compression_dict);
return *this;
}
// Because member unique_ptrs do not have these.
SubcompactionState(const SubcompactionState&) = delete;
SubcompactionState& operator=(const SubcompactionState&) = delete;
// Returns true iff we should stop building the current output
// before processing "internal_key".
bool ShouldStopBefore(const Slice& internal_key) {
const InternalKeyComparator* icmp =
&compaction->column_family_data()->internal_comparator();
const std::vector<FileMetaData*>& grandparents = compaction->grandparents();
// Scan to find earliest grandparent file that contains key.
while (grandparent_index < grandparents.size() &&
icmp->Compare(internal_key,
grandparents[grandparent_index]->largest.Encode()) >
0) {
if (seen_key) {
overlapped_bytes += grandparents[grandparent_index]->fd.GetFileSize();
}
assert(grandparent_index + 1 >= grandparents.size() ||
icmp->Compare(
grandparents[grandparent_index]->largest.Encode(),
grandparents[grandparent_index + 1]->smallest.Encode()) <= 0);
grandparent_index++;
}
seen_key = true;
if (overlapped_bytes > compaction->max_grandparent_overlap_bytes()) {
// Too much overlap for current output; start new output
overlapped_bytes = 0;
return true;
}
return false;
}
};
// Maintains state for the entire compaction
struct CompactionJob::CompactionState {
Compaction* const compaction;
// REQUIRED: subcompaction states are stored in order of increasing
// key-range
std::vector<CompactionJob::SubcompactionState> sub_compact_states;
Status status;
uint64_t total_bytes;
uint64_t num_input_records;
uint64_t num_output_records;
explicit CompactionState(Compaction* c)
: compaction(c),
total_bytes(0),
num_input_records(0),
num_output_records(0) {}
size_t NumOutputFiles() {
size_t total = 0;
for (auto& s : sub_compact_states) {
total += s.outputs.size();
}
return total;
}
Slice SmallestUserKey() {
for (const auto& sub_compact_state : sub_compact_states) {
if (!sub_compact_state.outputs.empty() &&
sub_compact_state.outputs[0].finished) {
return sub_compact_state.outputs[0].meta.smallest.user_key();
}
}
// If there is no finished output, return an empty slice.
return Slice(nullptr, 0);
}
Slice LargestUserKey() {
for (auto it = sub_compact_states.rbegin(); it < sub_compact_states.rend();
++it) {
if (!it->outputs.empty() && it->current_output()->finished) {
assert(it->current_output() != nullptr);
return it->current_output()->meta.largest.user_key();
}
}
// If there is no finished output, return an empty slice.
return Slice(nullptr, 0);
}
};
void CompactionJob::AggregateStatistics() {
for (SubcompactionState& sc : compact_->sub_compact_states) {
compact_->total_bytes += sc.total_bytes;
compact_->num_input_records += sc.num_input_records;
compact_->num_output_records += sc.num_output_records;
}
if (compaction_job_stats_) {
for (SubcompactionState& sc : compact_->sub_compact_states) {
compaction_job_stats_->Add(sc.compaction_job_stats);
}
}
}
CompactionJob::CompactionJob(
int job_id, Compaction* compaction, const DBOptions& db_options,
const EnvOptions& env_options, VersionSet* versions,
std::atomic<bool>* shutting_down, LogBuffer* log_buffer,
Directory* db_directory, Directory* output_directory, Statistics* stats,
InstrumentedMutex* db_mutex, Status* db_bg_error,
std::vector<SequenceNumber> existing_snapshots,
SequenceNumber earliest_write_conflict_snapshot,
std::shared_ptr<Cache> table_cache, EventLogger* event_logger,
bool paranoid_file_checks, bool measure_io_stats, const std::string& dbname,
CompactionJobStats* compaction_job_stats)
: job_id_(job_id),
compact_(new CompactionState(compaction)),
compaction_job_stats_(compaction_job_stats),
compaction_stats_(1),
dbname_(dbname),
db_options_(db_options),
env_options_(env_options),
env_(db_options.env),
versions_(versions),
shutting_down_(shutting_down),
log_buffer_(log_buffer),
db_directory_(db_directory),
output_directory_(output_directory),
stats_(stats),
db_mutex_(db_mutex),
db_bg_error_(db_bg_error),
existing_snapshots_(std::move(existing_snapshots)),
earliest_write_conflict_snapshot_(earliest_write_conflict_snapshot),
table_cache_(std::move(table_cache)),
event_logger_(event_logger),
paranoid_file_checks_(paranoid_file_checks),
measure_io_stats_(measure_io_stats) {
assert(log_buffer_ != nullptr);
const auto* cfd = compact_->compaction->column_family_data();
ThreadStatusUtil::SetColumnFamily(cfd, cfd->ioptions()->env,
cfd->options()->enable_thread_tracking);
ThreadStatusUtil::SetThreadOperation(ThreadStatus::OP_COMPACTION);
ReportStartedCompaction(compaction);
}
CompactionJob::~CompactionJob() {
assert(compact_ == nullptr);
ThreadStatusUtil::ResetThreadStatus();
}
void CompactionJob::ReportStartedCompaction(
Compaction* compaction) {
const auto* cfd = compact_->compaction->column_family_data();
ThreadStatusUtil::SetColumnFamily(cfd, cfd->ioptions()->env,
cfd->options()->enable_thread_tracking);
ThreadStatusUtil::SetThreadOperationProperty(
ThreadStatus::COMPACTION_JOB_ID,
job_id_);
ThreadStatusUtil::SetThreadOperationProperty(
ThreadStatus::COMPACTION_INPUT_OUTPUT_LEVEL,
(static_cast<uint64_t>(compact_->compaction->start_level()) << 32) +
compact_->compaction->output_level());
// In the current design, a CompactionJob is always created
// for non-trivial compaction.
assert(compaction->IsTrivialMove() == false ||
compaction->is_manual_compaction() == true);
ThreadStatusUtil::SetThreadOperationProperty(
ThreadStatus::COMPACTION_PROP_FLAGS,
compaction->is_manual_compaction() +
(compaction->deletion_compaction() << 1));
ThreadStatusUtil::SetThreadOperationProperty(
ThreadStatus::COMPACTION_TOTAL_INPUT_BYTES,
compaction->CalculateTotalInputSize());
IOSTATS_RESET(bytes_written);
IOSTATS_RESET(bytes_read);
ThreadStatusUtil::SetThreadOperationProperty(
ThreadStatus::COMPACTION_BYTES_WRITTEN, 0);
ThreadStatusUtil::SetThreadOperationProperty(
ThreadStatus::COMPACTION_BYTES_READ, 0);
// Set the thread operation after operation properties
// to ensure GetThreadList() can always show them all together.
ThreadStatusUtil::SetThreadOperation(
ThreadStatus::OP_COMPACTION);
if (compaction_job_stats_) {
compaction_job_stats_->is_manual_compaction =
compaction->is_manual_compaction();
}
}
void CompactionJob::Prepare() {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_COMPACTION_PREPARE);
// Generate file_levels_ for compaction berfore making Iterator
auto* c = compact_->compaction;
assert(c->column_family_data() != nullptr);
assert(c->column_family_data()->current()->storage_info()
->NumLevelFiles(compact_->compaction->level()) > 0);
// Is this compaction producing files at the bottommost level?
bottommost_level_ = c->bottommost_level();
if (c->ShouldFormSubcompactions()) {
const uint64_t start_micros = env_->NowMicros();
GenSubcompactionBoundaries();
MeasureTime(stats_, SUBCOMPACTION_SETUP_TIME,
env_->NowMicros() - start_micros);
assert(sizes_.size() == boundaries_.size() + 1);
for (size_t i = 0; i <= boundaries_.size(); i++) {
Slice* start = i == 0 ? nullptr : &boundaries_[i - 1];
Slice* end = i == boundaries_.size() ? nullptr : &boundaries_[i];
compact_->sub_compact_states.emplace_back(c, start, end, sizes_[i]);
}
MeasureTime(stats_, NUM_SUBCOMPACTIONS_SCHEDULED,
compact_->sub_compact_states.size());
} else {
compact_->sub_compact_states.emplace_back(c, nullptr, nullptr);
}
}
struct RangeWithSize {
Range range;
uint64_t size;
RangeWithSize(const Slice& a, const Slice& b, uint64_t s = 0)
: range(a, b), size(s) {}
};
// Generates a histogram representing potential divisions of key ranges from
// the input. It adds the starting and/or ending keys of certain input files
// to the working set and then finds the approximate size of data in between
// each consecutive pair of slices. Then it divides these ranges into
// consecutive groups such that each group has a similar size.
void CompactionJob::GenSubcompactionBoundaries() {
auto* c = compact_->compaction;
auto* cfd = c->column_family_data();
const Comparator* cfd_comparator = cfd->user_comparator();
std::vector<Slice> bounds;
int start_lvl = c->start_level();
int out_lvl = c->output_level();
// Add the starting and/or ending key of certain input files as a potential
// boundary
for (size_t lvl_idx = 0; lvl_idx < c->num_input_levels(); lvl_idx++) {
int lvl = c->level(lvl_idx);
if (lvl >= start_lvl && lvl <= out_lvl) {
const LevelFilesBrief* flevel = c->input_levels(lvl_idx);
size_t num_files = flevel->num_files;
if (num_files == 0) {
continue;
}
if (lvl == 0) {
// For level 0 add the starting and ending key of each file since the
// files may have greatly differing key ranges (not range-partitioned)
for (size_t i = 0; i < num_files; i++) {
bounds.emplace_back(flevel->files[i].smallest_key);
bounds.emplace_back(flevel->files[i].largest_key);
}
} else {
// For all other levels add the smallest/largest key in the level to
// encompass the range covered by that level
bounds.emplace_back(flevel->files[0].smallest_key);
bounds.emplace_back(flevel->files[num_files - 1].largest_key);
if (lvl == out_lvl) {
// For the last level include the starting keys of all files since
// the last level is the largest and probably has the widest key
// range. Since it's range partitioned, the ending key of one file
// and the starting key of the next are very close (or identical).
for (size_t i = 1; i < num_files; i++) {
bounds.emplace_back(flevel->files[i].smallest_key);
}
}
}
}
}
std::sort(bounds.begin(), bounds.end(),
[cfd_comparator] (const Slice& a, const Slice& b) -> bool {
return cfd_comparator->Compare(ExtractUserKey(a), ExtractUserKey(b)) < 0;
});
// Remove duplicated entries from bounds
bounds.erase(std::unique(bounds.begin(), bounds.end(),
[cfd_comparator] (const Slice& a, const Slice& b) -> bool {
return cfd_comparator->Compare(ExtractUserKey(a), ExtractUserKey(b)) == 0;
}), bounds.end());
// Combine consecutive pairs of boundaries into ranges with an approximate
// size of data covered by keys in that range
uint64_t sum = 0;
std::vector<RangeWithSize> ranges;
auto* v = cfd->current();
for (auto it = bounds.begin();;) {
const Slice a = *it;
it++;
if (it == bounds.end()) {
break;
}
const Slice b = *it;
uint64_t size = versions_->ApproximateSize(v, a, b, start_lvl, out_lvl + 1);
ranges.emplace_back(a, b, size);
sum += size;
}
// Group the ranges into subcompactions
const double min_file_fill_percent = 4.0 / 5;
uint64_t max_output_files = static_cast<uint64_t>(std::ceil(
sum / min_file_fill_percent /
cfd->GetCurrentMutableCFOptions()->MaxFileSizeForLevel(out_lvl)));
uint64_t subcompactions =
std::min({static_cast<uint64_t>(ranges.size()),
static_cast<uint64_t>(db_options_.max_subcompactions),
max_output_files});
double mean = sum * 1.0 / subcompactions;
if (subcompactions > 1) {
// Greedily add ranges to the subcompaction until the sum of the ranges'
// sizes becomes >= the expected mean size of a subcompaction
sum = 0;
for (size_t i = 0; i < ranges.size() - 1; i++) {
sum += ranges[i].size;
if (subcompactions == 1) {
// If there's only one left to schedule then it goes to the end so no
// need to put an end boundary
continue;
}
if (sum >= mean) {
boundaries_.emplace_back(ExtractUserKey(ranges[i].range.limit));
sizes_.emplace_back(sum);
subcompactions--;
sum = 0;
}
}
sizes_.emplace_back(sum + ranges.back().size);
} else {
// Only one range so its size is the total sum of sizes computed above
sizes_.emplace_back(sum);
}
}
Status CompactionJob::Run() {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_COMPACTION_RUN);
TEST_SYNC_POINT("CompactionJob::Run():Start");
log_buffer_->FlushBufferToLog();
LogCompaction();
const size_t num_threads = compact_->sub_compact_states.size();
assert(num_threads > 0);
const uint64_t start_micros = env_->NowMicros();
// Launch a thread for each of subcompactions 1...num_threads-1
std::vector<std::thread> thread_pool;
thread_pool.reserve(num_threads - 1);
for (size_t i = 1; i < compact_->sub_compact_states.size(); i++) {
thread_pool.emplace_back(&CompactionJob::ProcessKeyValueCompaction, this,
&compact_->sub_compact_states[i]);
}
// Always schedule the first subcompaction (whether or not there are also
// others) in the current thread to be efficient with resources
ProcessKeyValueCompaction(&compact_->sub_compact_states[0]);
// Wait for all other threads (if there are any) to finish execution
for (auto& thread : thread_pool) {
thread.join();
}
if (output_directory_ && !db_options_.disableDataSync) {
output_directory_->Fsync();
}
compaction_stats_.micros = env_->NowMicros() - start_micros;
MeasureTime(stats_, COMPACTION_TIME, compaction_stats_.micros);
// Check if any thread encountered an error during execution
Status status;
for (const auto& state : compact_->sub_compact_states) {
if (!state.status.ok()) {
status = state.status;
break;
}
}
TablePropertiesCollection tp;
for (const auto& state : compact_->sub_compact_states) {
for (const auto& output : state.outputs) {
auto fn = TableFileName(db_options_.db_paths, output.meta.fd.GetNumber(),
output.meta.fd.GetPathId());
tp[fn] = output.table_properties;
}
}
compact_->compaction->SetOutputTableProperties(std::move(tp));
// Finish up all book-keeping to unify the subcompaction results
AggregateStatistics();
UpdateCompactionStats();
RecordCompactionIOStats();
LogFlush(db_options_.info_log);
TEST_SYNC_POINT("CompactionJob::Run():End");
compact_->status = status;
return status;
}
Status CompactionJob::Install(const MutableCFOptions& mutable_cf_options) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_COMPACTION_INSTALL);
db_mutex_->AssertHeld();
Status status = compact_->status;
ColumnFamilyData* cfd = compact_->compaction->column_family_data();
cfd->internal_stats()->AddCompactionStats(
compact_->compaction->output_level(), compaction_stats_);
if (status.ok()) {
status = InstallCompactionResults(mutable_cf_options);
}
VersionStorageInfo::LevelSummaryStorage tmp;
auto vstorage = cfd->current()->storage_info();
const auto& stats = compaction_stats_;
LogToBuffer(
log_buffer_,
"[%s] compacted to: %s, MB/sec: %.1f rd, %.1f wr, level %d, "
"files in(%d, %d) out(%d) "
"MB in(%.1f, %.1f) out(%.1f), read-write-amplify(%.1f) "
"write-amplify(%.1f) %s, records in: %d, records dropped: %d\n",
cfd->GetName().c_str(), vstorage->LevelSummary(&tmp),
(stats.bytes_read_non_output_levels + stats.bytes_read_output_level) /
static_cast<double>(stats.micros),
stats.bytes_written / static_cast<double>(stats.micros),
compact_->compaction->output_level(),
stats.num_input_files_in_non_output_levels,
stats.num_input_files_in_output_level,
stats.num_output_files,
stats.bytes_read_non_output_levels / 1048576.0,
stats.bytes_read_output_level / 1048576.0,
stats.bytes_written / 1048576.0,
(stats.bytes_written + stats.bytes_read_output_level +
stats.bytes_read_non_output_levels) /
static_cast<double>(stats.bytes_read_non_output_levels),
stats.bytes_written /
static_cast<double>(stats.bytes_read_non_output_levels),
status.ToString().c_str(), stats.num_input_records,
stats.num_dropped_records);
UpdateCompactionJobStats(stats);
auto stream = event_logger_->LogToBuffer(log_buffer_);
stream << "job" << job_id_
<< "event" << "compaction_finished"
<< "compaction_time_micros" << compaction_stats_.micros
<< "output_level" << compact_->compaction->output_level()
<< "num_output_files" << compact_->NumOutputFiles()
<< "total_output_size" << compact_->total_bytes
<< "num_input_records" << compact_->num_input_records
<< "num_output_records" << compact_->num_output_records
<< "num_subcompactions" << compact_->sub_compact_states.size();
if (measure_io_stats_ && compaction_job_stats_ != nullptr) {
stream << "file_write_nanos" << compaction_job_stats_->file_write_nanos;
stream << "file_range_sync_nanos"
<< compaction_job_stats_->file_range_sync_nanos;
stream << "file_fsync_nanos" << compaction_job_stats_->file_fsync_nanos;
stream << "file_prepare_write_nanos"
<< compaction_job_stats_->file_prepare_write_nanos;
}
stream << "lsm_state";
stream.StartArray();
for (int level = 0; level < vstorage->num_levels(); ++level) {
stream << vstorage->NumLevelFiles(level);
}
stream.EndArray();
CleanupCompaction();
return status;
}
void CompactionJob::ProcessKeyValueCompaction(SubcompactionState* sub_compact) {
assert(sub_compact != nullptr);
std::unique_ptr<InternalIterator> input(
versions_->MakeInputIterator(sub_compact->compaction));
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_COMPACTION_PROCESS_KV);
// I/O measurement variables
PerfLevel prev_perf_level = PerfLevel::kEnableTime;
const uint64_t kRecordStatsEvery = 1000;
uint64_t prev_write_nanos = 0;
uint64_t prev_fsync_nanos = 0;
uint64_t prev_range_sync_nanos = 0;
uint64_t prev_prepare_write_nanos = 0;
if (measure_io_stats_) {
prev_perf_level = GetPerfLevel();
SetPerfLevel(PerfLevel::kEnableTime);
prev_write_nanos = IOSTATS(write_nanos);
prev_fsync_nanos = IOSTATS(fsync_nanos);
prev_range_sync_nanos = IOSTATS(range_sync_nanos);
prev_prepare_write_nanos = IOSTATS(prepare_write_nanos);
}
ColumnFamilyData* cfd = sub_compact->compaction->column_family_data();
// To build compression dictionary, we sample the first output file, assuming
// it'll reach the maximum length, and then use the dictionary for compressing
// subsequent output files. The dictionary may be less than max_dict_bytes if
// the first output file's length is less than the maximum.
const int kSampleLenShift = 6; // 2^6 = 64-byte samples
std::set<size_t> sample_begin_offsets;
if (bottommost_level_ &&
cfd->ioptions()->compression_opts.max_dict_bytes > 0) {
const size_t kMaxSamples =
cfd->ioptions()->compression_opts.max_dict_bytes >> kSampleLenShift;
const size_t kOutFileLen =
cfd->GetCurrentMutableCFOptions()->MaxFileSizeForLevel(
compact_->compaction->output_level());
if (kOutFileLen != port::kMaxSizet) {
const size_t kOutFileNumSamples = kOutFileLen >> kSampleLenShift;
Random64 generator{versions_->NewFileNumber()};
for (size_t i = 0; i < kMaxSamples; ++i) {
sample_begin_offsets.insert(generator.Uniform(kOutFileNumSamples)
<< kSampleLenShift);
}
}
}
auto compaction_filter = cfd->ioptions()->compaction_filter;
std::unique_ptr<CompactionFilter> compaction_filter_from_factory = nullptr;
if (compaction_filter == nullptr) {
compaction_filter_from_factory =
sub_compact->compaction->CreateCompactionFilter();
compaction_filter = compaction_filter_from_factory.get();
}
MergeHelper merge(
env_, cfd->user_comparator(), cfd->ioptions()->merge_operator,
compaction_filter, db_options_.info_log.get(),
cfd->ioptions()->min_partial_merge_operands,
false /* internal key corruption is expected */,
existing_snapshots_.empty() ? 0 : existing_snapshots_.back(),
compact_->compaction->level(), db_options_.statistics.get());
TEST_SYNC_POINT("CompactionJob::Run():Inprogress");
Slice* start = sub_compact->start;
Slice* end = sub_compact->end;
if (start != nullptr) {
IterKey start_iter;
start_iter.SetInternalKey(*start, kMaxSequenceNumber, kValueTypeForSeek);
input->Seek(start_iter.GetKey());
} else {
input->SeekToFirst();
}
Status status;
sub_compact->c_iter.reset(new CompactionIterator(
input.get(), cfd->user_comparator(), &merge, versions_->LastSequence(),
&existing_snapshots_, earliest_write_conflict_snapshot_, env_, false,
sub_compact->compaction, compaction_filter));
auto c_iter = sub_compact->c_iter.get();
c_iter->SeekToFirst();
const auto& c_iter_stats = c_iter->iter_stats();
auto sample_begin_offset_iter = sample_begin_offsets.cbegin();
// data_begin_offset and compression_dict are only valid while generating
// dictionary from the first output file.
size_t data_begin_offset = 0;
std::string compression_dict;
compression_dict.reserve(cfd->ioptions()->compression_opts.max_dict_bytes);
// TODO(noetzli): check whether we could check !shutting_down_->... only
// only occasionally (see diff D42687)
while (status.ok() && !shutting_down_->load(std::memory_order_acquire) &&
!cfd->IsDropped() && c_iter->Valid()) {
// Invariant: c_iter.status() is guaranteed to be OK if c_iter->Valid()
// returns true.
const Slice& key = c_iter->key();
const Slice& value = c_iter->value();
// If an end key (exclusive) is specified, check if the current key is
// >= than it and exit if it is because the iterator is out of its range
if (end != nullptr &&
cfd->user_comparator()->Compare(c_iter->user_key(), *end) >= 0) {
break;
} else if (sub_compact->ShouldStopBefore(key) &&
sub_compact->builder != nullptr) {
status = FinishCompactionOutputFile(input->status(), sub_compact);
if (!status.ok()) {
break;
}
}
if (c_iter_stats.num_input_records % kRecordStatsEvery ==
kRecordStatsEvery - 1) {
RecordDroppedKeys(c_iter_stats, &sub_compact->compaction_job_stats);
c_iter->ResetRecordCounts();
RecordCompactionIOStats();
}
// Open output file if necessary
if (sub_compact->builder == nullptr) {
status = OpenCompactionOutputFile(sub_compact);
if (!status.ok()) {
break;
}
}
assert(sub_compact->builder != nullptr);
assert(sub_compact->current_output() != nullptr);
sub_compact->builder->Add(key, value);
sub_compact->current_output()->meta.UpdateBoundaries(
key, c_iter->ikey().sequence);
sub_compact->num_output_records++;
if (sub_compact->outputs.size() == 1) { // first output file
// Check if this key/value overlaps any sample intervals; if so, appends
// overlapping portions to the dictionary.
for (const auto& data_elmt : {key, value}) {
size_t data_end_offset = data_begin_offset + data_elmt.size();
while (sample_begin_offset_iter != sample_begin_offsets.cend() &&
*sample_begin_offset_iter < data_end_offset) {
size_t sample_end_offset =
*sample_begin_offset_iter + (1 << kSampleLenShift);
// Invariant: Because we advance sample iterator while processing the
// data_elmt containing the sample's last byte, the current sample
// cannot end before the current data_elmt.
assert(data_begin_offset < sample_end_offset);
size_t data_elmt_copy_offset, data_elmt_copy_len;
if (*sample_begin_offset_iter <= data_begin_offset) {
// The sample starts before data_elmt starts, so take bytes starting
// at the beginning of data_elmt.
data_elmt_copy_offset = 0;
} else {
// data_elmt starts before the sample starts, so take bytes starting
// at the below offset into data_elmt.
data_elmt_copy_offset =
*sample_begin_offset_iter - data_begin_offset;
}
if (sample_end_offset <= data_end_offset) {
// The sample ends before data_elmt ends, so take as many bytes as
// needed.
data_elmt_copy_len =
sample_end_offset - (data_begin_offset + data_elmt_copy_offset);
} else {
// data_elmt ends before the sample ends, so take all remaining
// bytes in data_elmt.
data_elmt_copy_len =
data_end_offset - (data_begin_offset + data_elmt_copy_offset);
}
compression_dict.append(&data_elmt.data()[data_elmt_copy_offset],
data_elmt_copy_len);
if (sample_end_offset > data_end_offset) {
// Didn't finish sample. Try to finish it with the next data_elmt.
break;
}
// Next sample may require bytes from same data_elmt.
sample_begin_offset_iter++;
}
data_begin_offset = data_end_offset;
}
}
// Close output file if it is big enough
// TODO(aekmekji): determine if file should be closed earlier than this
// during subcompactions (i.e. if output size, estimated by input size, is
// going to be 1.2MB and max_output_file_size = 1MB, prefer to have 0.6MB
// and 0.6MB instead of 1MB and 0.2MB)
if (sub_compact->builder->FileSize() >=
sub_compact->compaction->max_output_file_size()) {
status = FinishCompactionOutputFile(input->status(), sub_compact);
if (sub_compact->outputs.size() == 1) {
// Use dictionary from first output file for compression of subsequent
// files.
sub_compact->compression_dict = std::move(compression_dict);
}
}
c_iter->Next();
}
sub_compact->num_input_records = c_iter_stats.num_input_records;
sub_compact->compaction_job_stats.num_input_deletion_records =
c_iter_stats.num_input_deletion_records;
sub_compact->compaction_job_stats.num_corrupt_keys =
c_iter_stats.num_input_corrupt_records;
sub_compact->compaction_job_stats.total_input_raw_key_bytes +=
c_iter_stats.total_input_raw_key_bytes;
sub_compact->compaction_job_stats.total_input_raw_value_bytes +=
c_iter_stats.total_input_raw_value_bytes;
RecordTick(stats_, FILTER_OPERATION_TOTAL_TIME,
c_iter_stats.total_filter_time);
RecordDroppedKeys(c_iter_stats, &sub_compact->compaction_job_stats);
RecordCompactionIOStats();
if (status.ok() &&
(shutting_down_->load(std::memory_order_acquire) || cfd->IsDropped())) {
status = Status::ShutdownInProgress(
"Database shutdown or Column family drop during compaction");
}
if (status.ok() && sub_compact->builder != nullptr) {
status = FinishCompactionOutputFile(input->status(), sub_compact);
}
if (status.ok()) {
status = input->status();
}
if (measure_io_stats_) {
sub_compact->compaction_job_stats.file_write_nanos +=
IOSTATS(write_nanos) - prev_write_nanos;
sub_compact->compaction_job_stats.file_fsync_nanos +=
IOSTATS(fsync_nanos) - prev_fsync_nanos;
sub_compact->compaction_job_stats.file_range_sync_nanos +=
IOSTATS(range_sync_nanos) - prev_range_sync_nanos;
sub_compact->compaction_job_stats.file_prepare_write_nanos +=
IOSTATS(prepare_write_nanos) - prev_prepare_write_nanos;
if (prev_perf_level != PerfLevel::kEnableTime) {
SetPerfLevel(prev_perf_level);
}
}
sub_compact->c_iter.reset();
input.reset();
sub_compact->status = status;
}
void CompactionJob::RecordDroppedKeys(
const CompactionIteratorStats& c_iter_stats,
CompactionJobStats* compaction_job_stats) {
if (c_iter_stats.num_record_drop_user > 0) {
RecordTick(stats_, COMPACTION_KEY_DROP_USER,
c_iter_stats.num_record_drop_user);
}
if (c_iter_stats.num_record_drop_hidden > 0) {
RecordTick(stats_, COMPACTION_KEY_DROP_NEWER_ENTRY,
c_iter_stats.num_record_drop_hidden);
if (compaction_job_stats) {
compaction_job_stats->num_records_replaced +=
c_iter_stats.num_record_drop_hidden;
}
}
if (c_iter_stats.num_record_drop_obsolete > 0) {
RecordTick(stats_, COMPACTION_KEY_DROP_OBSOLETE,
c_iter_stats.num_record_drop_obsolete);
if (compaction_job_stats) {
compaction_job_stats->num_expired_deletion_records +=
c_iter_stats.num_record_drop_obsolete;
}
}
}
Status CompactionJob::FinishCompactionOutputFile(
const Status& input_status, SubcompactionState* sub_compact) {
AutoThreadOperationStageUpdater stage_updater(
ThreadStatus::STAGE_COMPACTION_SYNC_FILE);
assert(sub_compact != nullptr);
assert(sub_compact->outfile);
assert(sub_compact->builder != nullptr);
assert(sub_compact->current_output() != nullptr);
uint64_t output_number = sub_compact->current_output()->meta.fd.GetNumber();
assert(output_number != 0);
TableProperties table_properties;
// Check for iterator errors
Status s = input_status;
auto meta = &sub_compact->current_output()->meta;
const uint64_t current_entries = sub_compact->builder->NumEntries();
meta->marked_for_compaction = sub_compact->builder->NeedCompact();
if (s.ok()) {
s = sub_compact->builder->Finish();
} else {
sub_compact->builder->Abandon();
}
const uint64_t current_bytes = sub_compact->builder->FileSize();
meta->fd.file_size = current_bytes;
sub_compact->current_output()->finished = true;
sub_compact->total_bytes += current_bytes;
// Finish and check for file errors
if (s.ok() && !db_options_.disableDataSync) {
StopWatch sw(env_, stats_, COMPACTION_OUTFILE_SYNC_MICROS);
s = sub_compact->outfile->Sync(db_options_.use_fsync);
}
if (s.ok()) {
s = sub_compact->outfile->Close();
}
sub_compact->outfile.reset();
if (s.ok() && current_entries > 0) {
// Verify that the table is usable
ColumnFamilyData* cfd = sub_compact->compaction->column_family_data();
InternalIterator* iter = cfd->table_cache()->NewIterator(
ReadOptions(), env_options_, cfd->internal_comparator(), meta->fd,
nullptr, cfd->internal_stats()->GetFileReadHist(
compact_->compaction->output_level()),
false);
s = iter->status();
if (s.ok() && paranoid_file_checks_) {
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {}
s = iter->status();
}
delete iter;
if (s.ok()) {
auto tp = sub_compact->builder->GetTableProperties();
sub_compact->current_output()->table_properties =
std::make_shared<TableProperties>(tp);
TableFileCreationInfo info(std::move(tp));
info.db_name = dbname_;
info.cf_name = cfd->GetName();
info.file_path =
TableFileName(cfd->ioptions()->db_paths, meta->fd.GetNumber(),
meta->fd.GetPathId());
info.file_size = meta->fd.GetFileSize();
info.job_id = job_id_;
Log(InfoLogLevel::INFO_LEVEL, db_options_.info_log,
"[%s] [JOB %d] Generated table #%" PRIu64 ": %" PRIu64
" keys, %" PRIu64 " bytes%s",
cfd->GetName().c_str(), job_id_, output_number, current_entries,
current_bytes,
meta->marked_for_compaction ? " (need compaction)" : "");
EventHelpers::LogAndNotifyTableFileCreation(
event_logger_, cfd->ioptions()->listeners, meta->fd, info);
}
}
// Report new file to SstFileManagerImpl
auto sfm =
static_cast<SstFileManagerImpl*>(db_options_.sst_file_manager.get());
if (sfm && meta->fd.GetPathId() == 0) {
ColumnFamilyData* cfd = sub_compact->compaction->column_family_data();
auto fn = TableFileName(cfd->ioptions()->db_paths, meta->fd.GetNumber(),
meta->fd.GetPathId());
sfm->OnAddFile(fn);
if (sfm->IsMaxAllowedSpaceReached()) {
InstrumentedMutexLock l(db_mutex_);
if (db_bg_error_->ok()) {
s = Status::IOError("Max allowed space was reached");
*db_bg_error_ = s;
TEST_SYNC_POINT(
"CompactionJob::FinishCompactionOutputFile:MaxAllowedSpaceReached");
}
}
}
sub_compact->builder.reset();
return s;
}
Status CompactionJob::InstallCompactionResults(
const MutableCFOptions& mutable_cf_options) {
db_mutex_->AssertHeld();
auto* compaction = compact_->compaction;
// paranoia: verify that the files that we started with
// still exist in the current version and in the same original level.
// This ensures that a concurrent compaction did not erroneously
// pick the same files to compact_.
if (!versions_->VerifyCompactionFileConsistency(compaction)) {
Compaction::InputLevelSummaryBuffer inputs_summary;
Log(InfoLogLevel::ERROR_LEVEL, db_options_.info_log,
"[%s] [JOB %d] Compaction %s aborted",
compaction->column_family_data()->GetName().c_str(), job_id_,
compaction->InputLevelSummary(&inputs_summary));
return Status::Corruption("Compaction input files inconsistent");
}
{
Compaction::InputLevelSummaryBuffer inputs_summary;
Log(InfoLogLevel::INFO_LEVEL, db_options_.info_log,
"[%s] [JOB %d] Compacted %s => %" PRIu64 " bytes",
compaction->column_family_data()->GetName().c_str(), job_id_,
compaction->InputLevelSummary(&inputs_summary), compact_->total_bytes);
}
// Add compaction outputs
compaction->AddInputDeletions(compact_->compaction->edit());
for (const auto& sub_compact : compact_->sub_compact_states) {
for (const auto& out : sub_compact.outputs) {
compaction->edit()->AddFile(compaction->output_level(), out.meta);
}
}
return versions_->LogAndApply(compaction->column_family_data(),
mutable_cf_options, compaction->edit(),
db_mutex_, db_directory_);
}
void CompactionJob::RecordCompactionIOStats() {
RecordTick(stats_, COMPACT_READ_BYTES, IOSTATS(bytes_read));
ThreadStatusUtil::IncreaseThreadOperationProperty(
ThreadStatus::COMPACTION_BYTES_READ, IOSTATS(bytes_read));
IOSTATS_RESET(bytes_read);
RecordTick(stats_, COMPACT_WRITE_BYTES, IOSTATS(bytes_written));
ThreadStatusUtil::IncreaseThreadOperationProperty(
ThreadStatus::COMPACTION_BYTES_WRITTEN, IOSTATS(bytes_written));
IOSTATS_RESET(bytes_written);
}
Status CompactionJob::OpenCompactionOutputFile(
SubcompactionState* sub_compact) {
assert(sub_compact != nullptr);
assert(sub_compact->builder == nullptr);
// no need to lock because VersionSet::next_file_number_ is atomic
uint64_t file_number = versions_->NewFileNumber();
// Make the output file
unique_ptr<WritableFile> writable_file;
std::string fname = TableFileName(db_options_.db_paths, file_number,
sub_compact->compaction->output_path_id());
Status s = NewWritableFile(env_, fname, &writable_file, env_options_);
if (!s.ok()) {
Log(InfoLogLevel::ERROR_LEVEL, db_options_.info_log,
"[%s] [JOB %d] OpenCompactionOutputFiles for table #%" PRIu64
" fails at NewWritableFile with status %s",
sub_compact->compaction->column_family_data()->GetName().c_str(),
job_id_, file_number, s.ToString().c_str());
LogFlush(db_options_.info_log);
return s;
}
SubcompactionState::Output out;
out.meta.fd =
FileDescriptor(file_number, sub_compact->compaction->output_path_id(), 0);
out.finished = false;
sub_compact->outputs.push_back(out);
writable_file->SetIOPriority(Env::IO_LOW);
writable_file->SetPreallocationBlockSize(static_cast<size_t>(
sub_compact->compaction->OutputFilePreallocationSize()));
sub_compact->outfile.reset(
new WritableFileWriter(std::move(writable_file), env_options_));
ColumnFamilyData* cfd = sub_compact->compaction->column_family_data();
// If the Column family flag is to only optimize filters for hits,
// we can skip creating filters if this is the bottommost_level where
// data is going to be found
bool skip_filters =
cfd->ioptions()->optimize_filters_for_hits && bottommost_level_;
sub_compact->builder.reset(NewTableBuilder(
*cfd->ioptions(), cfd->internal_comparator(),
cfd->int_tbl_prop_collector_factories(), cfd->GetID(), cfd->GetName(),
sub_compact->outfile.get(), sub_compact->compaction->output_compression(),
cfd->ioptions()->compression_opts, &sub_compact->compression_dict,
skip_filters));
LogFlush(db_options_.info_log);
return s;
}
void CompactionJob::CleanupCompaction() {
for (SubcompactionState& sub_compact : compact_->sub_compact_states) {
const auto& sub_status = sub_compact.status;
if (sub_compact.builder != nullptr) {
// May happen if we get a shutdown call in the middle of compaction
sub_compact.builder->Abandon();
sub_compact.builder.reset();
} else {
assert(!sub_status.ok() || sub_compact.outfile == nullptr);
}
for (const auto& out : sub_compact.outputs) {
// If this file was inserted into the table cache then remove
// them here because this compaction was not committed.
if (!sub_status.ok()) {
TableCache::Evict(table_cache_.get(), out.meta.fd.GetNumber());
}
}
}
delete compact_;
compact_ = nullptr;
}
#ifndef ROCKSDB_LITE
namespace {
void CopyPrefix(
const Slice& src, size_t prefix_length, std::string* dst) {
assert(prefix_length > 0);
size_t length = src.size() > prefix_length ? prefix_length : src.size();
dst->assign(src.data(), length);
}
} // namespace
#endif // !ROCKSDB_LITE
void CompactionJob::UpdateCompactionStats() {
Compaction* compaction = compact_->compaction;
compaction_stats_.num_input_files_in_non_output_levels = 0;
compaction_stats_.num_input_files_in_output_level = 0;
for (int input_level = 0;
input_level < static_cast<int>(compaction->num_input_levels());
++input_level) {
if (compaction->start_level() + input_level
!= compaction->output_level()) {
UpdateCompactionInputStatsHelper(
&compaction_stats_.num_input_files_in_non_output_levels,
&compaction_stats_.bytes_read_non_output_levels,
input_level);
} else {
UpdateCompactionInputStatsHelper(
&compaction_stats_.num_input_files_in_output_level,
&compaction_stats_.bytes_read_output_level,
input_level);
}
}
for (const auto& sub_compact : compact_->sub_compact_states) {
size_t num_output_files = sub_compact.outputs.size();
if (sub_compact.builder != nullptr) {
// An error occurred so ignore the last output.
assert(num_output_files > 0);
--num_output_files;
}
compaction_stats_.num_output_files += static_cast<int>(num_output_files);
for (const auto& out : sub_compact.outputs) {
compaction_stats_.bytes_written += out.meta.fd.file_size;
}
if (sub_compact.num_input_records > sub_compact.num_output_records) {
compaction_stats_.num_dropped_records +=
sub_compact.num_input_records - sub_compact.num_output_records;
}
}
}
void CompactionJob::UpdateCompactionInputStatsHelper(
int* num_files, uint64_t* bytes_read, int input_level) {
const Compaction* compaction = compact_->compaction;
auto num_input_files = compaction->num_input_files(input_level);
*num_files += static_cast<int>(num_input_files);
for (size_t i = 0; i < num_input_files; ++i) {
const auto* file_meta = compaction->input(input_level, i);
*bytes_read += file_meta->fd.GetFileSize();
compaction_stats_.num_input_records +=
static_cast<uint64_t>(file_meta->num_entries);
}
}
void CompactionJob::UpdateCompactionJobStats(
const InternalStats::CompactionStats& stats) const {
#ifndef ROCKSDB_LITE
if (compaction_job_stats_) {
compaction_job_stats_->elapsed_micros = stats.micros;
// input information
compaction_job_stats_->total_input_bytes =
stats.bytes_read_non_output_levels +
stats.bytes_read_output_level;
compaction_job_stats_->num_input_records =
compact_->num_input_records;
compaction_job_stats_->num_input_files =
stats.num_input_files_in_non_output_levels +
stats.num_input_files_in_output_level;
compaction_job_stats_->num_input_files_at_output_level =
stats.num_input_files_in_output_level;
// output information
compaction_job_stats_->total_output_bytes = stats.bytes_written;
compaction_job_stats_->num_output_records =
compact_->num_output_records;
compaction_job_stats_->num_output_files = stats.num_output_files;
if (compact_->NumOutputFiles() > 0U) {
CopyPrefix(
compact_->SmallestUserKey(),
CompactionJobStats::kMaxPrefixLength,
&compaction_job_stats_->smallest_output_key_prefix);
CopyPrefix(
compact_->LargestUserKey(),
CompactionJobStats::kMaxPrefixLength,
&compaction_job_stats_->largest_output_key_prefix);
}
}
#endif // !ROCKSDB_LITE
}
void CompactionJob::LogCompaction() {
Compaction* compaction = compact_->compaction;
ColumnFamilyData* cfd = compaction->column_family_data();
// Let's check if anything will get logged. Don't prepare all the info if
// we're not logging
if (db_options_.info_log_level <= InfoLogLevel::INFO_LEVEL) {
Compaction::InputLevelSummaryBuffer inputs_summary;
Log(InfoLogLevel::INFO_LEVEL, db_options_.info_log,
"[%s] [JOB %d] Compacting %s, score %.2f", cfd->GetName().c_str(),
job_id_, compaction->InputLevelSummary(&inputs_summary),
compaction->score());
char scratch[2345];
compaction->Summary(scratch, sizeof(scratch));
Log(InfoLogLevel::INFO_LEVEL, db_options_.info_log,
"[%s] Compaction start summary: %s\n", cfd->GetName().c_str(), scratch);
// build event logger report
auto stream = event_logger_->Log();
stream << "job" << job_id_ << "event"
<< "compaction_started";
for (size_t i = 0; i < compaction->num_input_levels(); ++i) {
stream << ("files_L" + ToString(compaction->level(i)));
stream.StartArray();
for (auto f : *compaction->inputs(i)) {
stream << f->fd.GetNumber();
}
stream.EndArray();
}
stream << "score" << compaction->score() << "input_data_size"
<< compaction->CalculateTotalInputSize();
}
}
} // namespace rocksdb
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