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rocksdb/db/db_impl_compaction_flush.cc

2731 lines
100 KiB

// 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.
#include "db/db_impl.h"
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
#include "db/builder.h"
#include "db/error_handler.h"
#include "db/event_helpers.h"
#include "monitoring/iostats_context_imp.h"
#include "monitoring/perf_context_imp.h"
#include "monitoring/thread_status_updater.h"
#include "monitoring/thread_status_util.h"
#include "util/sst_file_manager_impl.h"
#include "util/sync_point.h"
namespace rocksdb {
bool DBImpl::EnoughRoomForCompaction(
ColumnFamilyData* cfd, const std::vector<CompactionInputFiles>& inputs,
bool* sfm_reserved_compact_space, LogBuffer* log_buffer) {
// Check if we have enough room to do the compaction
bool enough_room = true;
#ifndef ROCKSDB_LITE
auto sfm = static_cast<SstFileManagerImpl*>(
immutable_db_options_.sst_file_manager.get());
if (sfm) {
// Pass the current bg_error_ to SFM so it can decide what checks to
// perform. If this DB instance hasn't seen any error yet, the SFM can be
// optimistic and not do disk space checks
enough_room =
sfm->EnoughRoomForCompaction(cfd, inputs, error_handler_.GetBGError());
if (enough_room) {
*sfm_reserved_compact_space = true;
}
}
#else
(void)cfd;
(void)inputs;
(void)sfm_reserved_compact_space;
#endif // ROCKSDB_LITE
if (!enough_room) {
// Just in case tests want to change the value of enough_room
TEST_SYNC_POINT_CALLBACK(
"DBImpl::BackgroundCompaction():CancelledCompaction", &enough_room);
ROCKS_LOG_BUFFER(log_buffer,
"Cancelled compaction because not enough room");
RecordTick(stats_, COMPACTION_CANCELLED, 1);
}
return enough_room;
}
Status DBImpl::SyncClosedLogs(JobContext* job_context) {
TEST_SYNC_POINT("DBImpl::SyncClosedLogs:Start");
mutex_.AssertHeld();
autovector<log::Writer*, 1> logs_to_sync;
uint64_t current_log_number = logfile_number_;
while (logs_.front().number < current_log_number &&
logs_.front().getting_synced) {
log_sync_cv_.Wait();
}
for (auto it = logs_.begin();
it != logs_.end() && it->number < current_log_number; ++it) {
auto& log = *it;
assert(!log.getting_synced);
log.getting_synced = true;
logs_to_sync.push_back(log.writer);
}
Status s;
if (!logs_to_sync.empty()) {
mutex_.Unlock();
for (log::Writer* log : logs_to_sync) {
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"[JOB %d] Syncing log #%" PRIu64, job_context->job_id,
log->get_log_number());
s = log->file()->Sync(immutable_db_options_.use_fsync);
if (!s.ok()) {
break;
}
}
if (s.ok()) {
s = directories_.GetWalDir()->Fsync();
}
mutex_.Lock();
// "number <= current_log_number - 1" is equivalent to
// "number < current_log_number".
MarkLogsSynced(current_log_number - 1, true, s);
if (!s.ok()) {
error_handler_.SetBGError(s, BackgroundErrorReason::kFlush);
TEST_SYNC_POINT("DBImpl::SyncClosedLogs:Failed");
return s;
}
}
return s;
}
Status DBImpl::FlushMemTableToOutputFile(
ColumnFamilyData* cfd, const MutableCFOptions& mutable_cf_options,
bool* made_progress, JobContext* job_context,
SuperVersionContext* superversion_context, LogBuffer* log_buffer) {
mutex_.AssertHeld();
assert(cfd->imm()->NumNotFlushed() != 0);
assert(cfd->imm()->IsFlushPending());
SequenceNumber earliest_write_conflict_snapshot;
std::vector<SequenceNumber> snapshot_seqs =
snapshots_.GetAll(&earliest_write_conflict_snapshot);
auto snapshot_checker = snapshot_checker_.get();
if (use_custom_gc_ && snapshot_checker == nullptr) {
snapshot_checker = DisableGCSnapshotChecker::Instance();
}
FlushJob flush_job(
dbname_, cfd, immutable_db_options_, mutable_cf_options,
nullptr /* memtable_id */, env_options_for_compaction_, versions_.get(),
&mutex_, &shutting_down_, snapshot_seqs, earliest_write_conflict_snapshot,
snapshot_checker, job_context, log_buffer, directories_.GetDbDir(),
GetDataDir(cfd, 0U),
GetCompressionFlush(*cfd->ioptions(), mutable_cf_options), stats_,
&event_logger_, mutable_cf_options.report_bg_io_stats,
true /* sync_output_directory */, true /* write_manifest */);
FileMetaData file_meta;
flush_job.PickMemTable();
#ifndef ROCKSDB_LITE
// may temporarily unlock and lock the mutex.
NotifyOnFlushBegin(cfd, &file_meta, mutable_cf_options, job_context->job_id,
flush_job.GetTableProperties());
#endif // ROCKSDB_LITE
Status s;
if (logfile_number_ > 0 &&
versions_->GetColumnFamilySet()->NumberOfColumnFamilies() > 0) {
// If there are more than one column families, we need to make sure that
// all the log files except the most recent one are synced. Otherwise if
// the host crashes after flushing and before WAL is persistent, the
// flushed SST may contain data from write batches whose updates to
// other column families are missing.
// SyncClosedLogs() may unlock and re-lock the db_mutex.
s = SyncClosedLogs(job_context);
}
// Within flush_job.Run, rocksdb may call event listener to notify
// file creation and deletion.
//
// Note that flush_job.Run will unlock and lock the db_mutex,
// and EventListener callback will be called when the db_mutex
// is unlocked by the current thread.
if (s.ok()) {
s = flush_job.Run(&logs_with_prep_tracker_, &file_meta);
} else {
flush_job.Cancel();
}
if (s.ok()) {
InstallSuperVersionAndScheduleWork(cfd, superversion_context,
mutable_cf_options);
if (made_progress) {
*made_progress = true;
}
VersionStorageInfo::LevelSummaryStorage tmp;
ROCKS_LOG_BUFFER(log_buffer, "[%s] Level summary: %s\n",
cfd->GetName().c_str(),
cfd->current()->storage_info()->LevelSummary(&tmp));
}
if (!s.ok() && !s.IsShutdownInProgress()) {
Status new_bg_error = s;
error_handler_.SetBGError(new_bg_error, BackgroundErrorReason::kFlush);
}
if (s.ok()) {
#ifndef ROCKSDB_LITE
// may temporarily unlock and lock the mutex.
NotifyOnFlushCompleted(cfd, &file_meta, mutable_cf_options,
job_context->job_id, flush_job.GetTableProperties());
auto sfm = static_cast<SstFileManagerImpl*>(
immutable_db_options_.sst_file_manager.get());
if (sfm) {
// Notify sst_file_manager that a new file was added
std::string file_path = MakeTableFileName(
cfd->ioptions()->cf_paths[0].path, file_meta.fd.GetNumber());
sfm->OnAddFile(file_path);
if (sfm->IsMaxAllowedSpaceReached()) {
Status new_bg_error = Status::SpaceLimit("Max allowed space was reached");
TEST_SYNC_POINT_CALLBACK(
"DBImpl::FlushMemTableToOutputFile:MaxAllowedSpaceReached",
&new_bg_error);
error_handler_.SetBGError(new_bg_error, BackgroundErrorReason::kFlush);
}
}
#endif // ROCKSDB_LITE
}
return s;
}
Status DBImpl::FlushMemTablesToOutputFiles(
const autovector<BGFlushArg>& bg_flush_args, bool* made_progress,
JobContext* job_context, LogBuffer* log_buffer) {
if (atomic_flush_) {
return AtomicFlushMemTablesToOutputFiles(bg_flush_args, made_progress,
job_context, log_buffer);
}
Status s;
for (auto& arg : bg_flush_args) {
ColumnFamilyData* cfd = arg.cfd_;
const MutableCFOptions& mutable_cf_options =
*cfd->GetLatestMutableCFOptions();
SuperVersionContext* superversion_context = arg.superversion_context_;
s = FlushMemTableToOutputFile(cfd, mutable_cf_options, made_progress,
job_context, superversion_context,
log_buffer);
if (!s.ok()) {
break;
}
}
return s;
}
/*
* Atomically flushes multiple column families.
*
* For each column family, all memtables with ID smaller than or equal to the
* ID specified in bg_flush_args will be flushed. Only after all column
* families finish flush will this function commit to MANIFEST. If any of the
* column families are not flushed successfully, this function does not have
* any side-effect on the state of the database.
*/
Status DBImpl::AtomicFlushMemTablesToOutputFiles(
const autovector<BGFlushArg>& bg_flush_args, bool* made_progress,
JobContext* job_context, LogBuffer* log_buffer) {
mutex_.AssertHeld();
autovector<ColumnFamilyData*> cfds;
for (const auto& arg : bg_flush_args) {
cfds.emplace_back(arg.cfd_);
}
#ifndef NDEBUG
for (const auto cfd : cfds) {
assert(cfd->imm()->NumNotFlushed() != 0);
assert(cfd->imm()->IsFlushPending());
}
#endif /* !NDEBUG */
SequenceNumber earliest_write_conflict_snapshot;
std::vector<SequenceNumber> snapshot_seqs =
snapshots_.GetAll(&earliest_write_conflict_snapshot);
auto snapshot_checker = snapshot_checker_.get();
if (use_custom_gc_ && snapshot_checker == nullptr) {
snapshot_checker = DisableGCSnapshotChecker::Instance();
}
autovector<Directory*> distinct_output_dirs;
std::vector<FlushJob> jobs;
int num_cfs = static_cast<int>(cfds.size());
for (int i = 0; i < num_cfs; ++i) {
auto cfd = cfds[i];
Directory* data_dir = GetDataDir(cfd, 0U);
// Add to distinct output directories if eligible. Use linear search. Since
// the number of elements in the vector is not large, performance should be
// tolerable.
bool found = false;
for (const auto dir : distinct_output_dirs) {
if (dir == data_dir) {
found = true;
break;
}
}
if (!found) {
distinct_output_dirs.emplace_back(data_dir);
}
const MutableCFOptions& mutable_cf_options =
*cfd->GetLatestMutableCFOptions();
const uint64_t* max_memtable_id = &(bg_flush_args[i].max_memtable_id_);
jobs.emplace_back(
dbname_, cfds[i], immutable_db_options_, mutable_cf_options,
max_memtable_id, env_options_for_compaction_, versions_.get(), &mutex_,
&shutting_down_, snapshot_seqs, earliest_write_conflict_snapshot,
snapshot_checker, job_context, log_buffer, directories_.GetDbDir(),
data_dir, GetCompressionFlush(*cfd->ioptions(), mutable_cf_options),
stats_, &event_logger_, mutable_cf_options.report_bg_io_stats,
false /* sync_output_directory */, false /* write_manifest */);
jobs.back().PickMemTable();
}
autovector<FileMetaData> file_meta;
Status s;
assert(num_cfs == static_cast<int>(jobs.size()));
for (int i = 0; i != num_cfs; ++i) {
file_meta.emplace_back(FileMetaData());
#ifndef ROCKSDB_LITE
const MutableCFOptions& mutable_cf_options =
*cfds[i]->GetLatestMutableCFOptions();
// may temporarily unlock and lock the mutex.
NotifyOnFlushBegin(cfds[i], &file_meta[i], mutable_cf_options,
job_context->job_id, jobs[i].GetTableProperties());
#endif /* !ROCKSDB_LITE */
}
if (logfile_number_ > 0) {
// TODO (yanqin) investigate whether we should sync the closed logs for
// single column family case.
s = SyncClosedLogs(job_context);
}
// exec_status stores the execution status of flush_jobs as
// <bool /* executed */, Status /* status code */>
autovector<std::pair<bool, Status>> exec_status;
for (int i = 0; i != num_cfs; ++i) {
// Initially all jobs are not executed, with status OK.
std::pair<bool, Status> elem(false, Status::OK());
exec_status.emplace_back(elem);
}
if (s.ok()) {
// TODO (yanqin): parallelize jobs with threads.
for (int i = 0; i != num_cfs; ++i) {
exec_status[i].second =
jobs[i].Run(&logs_with_prep_tracker_, &file_meta[i]);
exec_status[i].first = true;
if (!exec_status[i].second.ok()) {
s = exec_status[i].second;
break;
}
}
}
if (s.ok()) {
// Sync on all distinct output directories.
for (auto dir : distinct_output_dirs) {
if (dir != nullptr) {
s = dir->Fsync();
if (!s.ok()) {
break;
}
}
}
if (s.ok()) {
autovector<const autovector<MemTable*>*> mems_list;
for (int i = 0; i != num_cfs; ++i) {
const auto& mems = jobs[i].GetMemTables();
mems_list.emplace_back(&mems);
}
autovector<ColumnFamilyData*> all_cfds;
autovector<MemTableList*> imm_lists;
autovector<const MutableCFOptions*> mutable_cf_options_list;
for (auto cfd : *versions_->GetColumnFamilySet()) {
all_cfds.emplace_back(cfd);
imm_lists.emplace_back(cfd->imm());
mutable_cf_options_list.emplace_back(cfd->GetLatestMutableCFOptions());
}
s = MemTableList::TryInstallMemtableFlushResults(
imm_lists, all_cfds, mutable_cf_options_list, mems_list,
&atomic_flush_commit_in_progress_, &logs_with_prep_tracker_,
versions_.get(), &mutex_, file_meta, &job_context->memtables_to_free,
directories_.GetDbDir(), log_buffer);
}
}
if (s.ok()) {
assert(num_cfs ==
static_cast<int>(job_context->superversion_contexts.size()));
for (int i = 0; i != num_cfs; ++i) {
InstallSuperVersionAndScheduleWork(cfds[i],
&job_context->superversion_contexts[i],
*cfds[i]->GetLatestMutableCFOptions());
VersionStorageInfo::LevelSummaryStorage tmp;
ROCKS_LOG_BUFFER(log_buffer, "[%s] Level summary: %s\n",
cfds[i]->GetName().c_str(),
cfds[i]->current()->storage_info()->LevelSummary(&tmp));
}
if (made_progress) {
*made_progress = true;
}
#ifndef ROCKSDB_LITE
auto sfm = static_cast<SstFileManagerImpl*>(
immutable_db_options_.sst_file_manager.get());
for (int i = 0; i != num_cfs; ++i) {
NotifyOnFlushCompleted(cfds[i], &file_meta[i],
*cfds[i]->GetLatestMutableCFOptions(),
job_context->job_id, jobs[i].GetTableProperties());
if (sfm) {
std::string file_path = MakeTableFileName(
cfds[i]->ioptions()->cf_paths[0].path, file_meta[i].fd.GetNumber());
sfm->OnAddFile(file_path);
if (sfm->IsMaxAllowedSpaceReached() &&
error_handler_.GetBGError().ok()) {
Status new_bg_error =
Status::SpaceLimit("Max allowed space was reached");
error_handler_.SetBGError(new_bg_error,
BackgroundErrorReason::kFlush);
}
}
}
#endif // ROCKSDB_LITE
}
if (!s.ok()) {
// Have to cancel the flush jobs that have NOT executed because we need to
// unref the versions.
for (int i = 0; i != num_cfs; ++i) {
if (!exec_status[i].first) {
jobs[i].Cancel();
}
}
if (!s.IsShutdownInProgress()) {
for (int i = 0; i != num_cfs; ++i) {
auto& mems = jobs[i].GetMemTables();
cfds[i]->imm()->RollbackMemtableFlush(mems,
file_meta[i].fd.GetNumber());
}
Status new_bg_error = s;
error_handler_.SetBGError(new_bg_error, BackgroundErrorReason::kFlush);
}
}
return s;
}
void DBImpl::NotifyOnFlushBegin(ColumnFamilyData* cfd, FileMetaData* file_meta,
const MutableCFOptions& mutable_cf_options,
int job_id, TableProperties prop) {
#ifndef ROCKSDB_LITE
if (immutable_db_options_.listeners.size() == 0U) {
return;
}
mutex_.AssertHeld();
if (shutting_down_.load(std::memory_order_acquire)) {
return;
}
bool triggered_writes_slowdown =
(cfd->current()->storage_info()->NumLevelFiles(0) >=
mutable_cf_options.level0_slowdown_writes_trigger);
bool triggered_writes_stop =
(cfd->current()->storage_info()->NumLevelFiles(0) >=
mutable_cf_options.level0_stop_writes_trigger);
// release lock while notifying events
mutex_.Unlock();
{
FlushJobInfo info;
info.cf_name = cfd->GetName();
// TODO(yhchiang): make db_paths dynamic in case flush does not
// go to L0 in the future.
info.file_path = MakeTableFileName(cfd->ioptions()->cf_paths[0].path,
file_meta->fd.GetNumber());
info.thread_id = env_->GetThreadID();
info.job_id = job_id;
info.triggered_writes_slowdown = triggered_writes_slowdown;
info.triggered_writes_stop = triggered_writes_stop;
info.smallest_seqno = file_meta->fd.smallest_seqno;
info.largest_seqno = file_meta->fd.largest_seqno;
info.table_properties = prop;
info.flush_reason = cfd->GetFlushReason();
for (auto listener : immutable_db_options_.listeners) {
listener->OnFlushBegin(this, info);
}
}
mutex_.Lock();
// no need to signal bg_cv_ as it will be signaled at the end of the
// flush process.
#else
(void)cfd;
(void)file_meta;
(void)mutable_cf_options;
(void)job_id;
(void)prop;
#endif // ROCKSDB_LITE
}
void DBImpl::NotifyOnFlushCompleted(ColumnFamilyData* cfd,
FileMetaData* file_meta,
const MutableCFOptions& mutable_cf_options,
int job_id, TableProperties prop) {
#ifndef ROCKSDB_LITE
if (immutable_db_options_.listeners.size() == 0U) {
return;
}
mutex_.AssertHeld();
if (shutting_down_.load(std::memory_order_acquire)) {
return;
}
bool triggered_writes_slowdown =
(cfd->current()->storage_info()->NumLevelFiles(0) >=
mutable_cf_options.level0_slowdown_writes_trigger);
bool triggered_writes_stop =
(cfd->current()->storage_info()->NumLevelFiles(0) >=
mutable_cf_options.level0_stop_writes_trigger);
// release lock while notifying events
mutex_.Unlock();
{
FlushJobInfo info;
info.cf_name = cfd->GetName();
// TODO(yhchiang): make db_paths dynamic in case flush does not
// go to L0 in the future.
info.file_path = MakeTableFileName(cfd->ioptions()->cf_paths[0].path,
file_meta->fd.GetNumber());
info.thread_id = env_->GetThreadID();
info.job_id = job_id;
info.triggered_writes_slowdown = triggered_writes_slowdown;
info.triggered_writes_stop = triggered_writes_stop;
info.smallest_seqno = file_meta->fd.smallest_seqno;
info.largest_seqno = file_meta->fd.largest_seqno;
info.table_properties = prop;
info.flush_reason = cfd->GetFlushReason();
for (auto listener : immutable_db_options_.listeners) {
listener->OnFlushCompleted(this, info);
}
}
mutex_.Lock();
// no need to signal bg_cv_ as it will be signaled at the end of the
// flush process.
#else
(void)cfd;
(void)file_meta;
(void)mutable_cf_options;
(void)job_id;
(void)prop;
#endif // ROCKSDB_LITE
}
Status DBImpl::CompactRange(const CompactRangeOptions& options,
ColumnFamilyHandle* column_family,
const Slice* begin, const Slice* end) {
auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family);
auto cfd = cfh->cfd();
if (options.target_path_id >= cfd->ioptions()->cf_paths.size()) {
return Status::InvalidArgument("Invalid target path ID");
}
bool exclusive = options.exclusive_manual_compaction;
bool flush_needed = true;
if (begin != nullptr && end != nullptr) {
// TODO(ajkr): We could also optimize away the flush in certain cases where
// one/both sides of the interval are unbounded. But it requires more
// changes to RangesOverlapWithMemtables.
Range range(*begin, *end);
SuperVersion* super_version = cfd->GetReferencedSuperVersion(&mutex_);
cfd->RangesOverlapWithMemtables({range}, super_version, &flush_needed);
CleanupSuperVersion(super_version);
}
Status s;
if (flush_needed) {
FlushOptions fo;
fo.allow_write_stall = options.allow_write_stall;
if (atomic_flush_) {
autovector<ColumnFamilyData*> cfds;
SelectColumnFamiliesForAtomicFlush(&cfds);
s = AtomicFlushMemTables(cfds, fo, FlushReason::kManualCompaction,
false /* writes_stopped */);
} else {
s = FlushMemTable(cfd, fo, FlushReason::kManualCompaction,
false /* writes_stopped*/);
}
if (!s.ok()) {
LogFlush(immutable_db_options_.info_log);
return s;
}
}
int max_level_with_files = 0;
{
InstrumentedMutexLock l(&mutex_);
Version* base = cfd->current();
for (int level = 1; level < base->storage_info()->num_non_empty_levels();
level++) {
if (base->storage_info()->OverlapInLevel(level, begin, end)) {
max_level_with_files = level;
}
}
}
int final_output_level = 0;
if (cfd->ioptions()->compaction_style == kCompactionStyleUniversal &&
cfd->NumberLevels() > 1) {
// Always compact all files together.
final_output_level = cfd->NumberLevels() - 1;
// if bottom most level is reserved
if (immutable_db_options_.allow_ingest_behind) {
final_output_level--;
}
s = RunManualCompaction(cfd, ColumnFamilyData::kCompactAllLevels,
final_output_level, options.target_path_id,
options.max_subcompactions, begin, end, exclusive);
} else {
for (int level = 0; level <= max_level_with_files; level++) {
int output_level;
// in case the compaction is universal or if we're compacting the
// bottom-most level, the output level will be the same as input one.
// level 0 can never be the bottommost level (i.e. if all files are in
// level 0, we will compact to level 1)
if (cfd->ioptions()->compaction_style == kCompactionStyleUniversal ||
cfd->ioptions()->compaction_style == kCompactionStyleFIFO) {
output_level = level;
} else if (level == max_level_with_files && level > 0) {
if (options.bottommost_level_compaction ==
BottommostLevelCompaction::kSkip) {
// Skip bottommost level compaction
continue;
} else if (options.bottommost_level_compaction ==
BottommostLevelCompaction::kIfHaveCompactionFilter &&
cfd->ioptions()->compaction_filter == nullptr &&
cfd->ioptions()->compaction_filter_factory == nullptr) {
// Skip bottommost level compaction since we don't have a compaction
// filter
continue;
}
output_level = level;
} else {
output_level = level + 1;
if (cfd->ioptions()->compaction_style == kCompactionStyleLevel &&
cfd->ioptions()->level_compaction_dynamic_level_bytes &&
level == 0) {
output_level = ColumnFamilyData::kCompactToBaseLevel;
}
}
s = RunManualCompaction(cfd, level, output_level, options.target_path_id,
options.max_subcompactions, begin, end, exclusive);
if (!s.ok()) {
break;
}
if (output_level == ColumnFamilyData::kCompactToBaseLevel) {
final_output_level = cfd->NumberLevels() - 1;
} else if (output_level > final_output_level) {
final_output_level = output_level;
}
TEST_SYNC_POINT("DBImpl::RunManualCompaction()::1");
TEST_SYNC_POINT("DBImpl::RunManualCompaction()::2");
}
}
if (!s.ok()) {
LogFlush(immutable_db_options_.info_log);
return s;
}
if (options.change_level) {
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"[RefitLevel] waiting for background threads to stop");
s = PauseBackgroundWork();
if (s.ok()) {
s = ReFitLevel(cfd, final_output_level, options.target_level);
}
ContinueBackgroundWork();
}
LogFlush(immutable_db_options_.info_log);
{
InstrumentedMutexLock l(&mutex_);
// an automatic compaction that has been scheduled might have been
// preempted by the manual compactions. Need to schedule it back.
MaybeScheduleFlushOrCompaction();
}
return s;
}
Status DBImpl::CompactFiles(const CompactionOptions& compact_options,
ColumnFamilyHandle* column_family,
const std::vector<std::string>& input_file_names,
const int output_level, const int output_path_id,
std::vector<std::string>* const output_file_names) {
#ifdef ROCKSDB_LITE
(void)compact_options;
(void)column_family;
(void)input_file_names;
(void)output_level;
(void)output_path_id;
(void)output_file_names;
// not supported in lite version
return Status::NotSupported("Not supported in ROCKSDB LITE");
#else
if (column_family == nullptr) {
return Status::InvalidArgument("ColumnFamilyHandle must be non-null.");
}
auto cfd = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family)->cfd();
assert(cfd);
Status s;
JobContext job_context(0, true);
LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL,
immutable_db_options_.info_log.get());
// Perform CompactFiles
SuperVersion* sv = cfd->GetReferencedSuperVersion(&mutex_);
{
InstrumentedMutexLock l(&mutex_);
// This call will unlock/lock the mutex to wait for current running
// IngestExternalFile() calls to finish.
WaitForIngestFile();
s = CompactFilesImpl(compact_options, cfd, sv->current, input_file_names,
output_file_names, output_level, output_path_id,
&job_context, &log_buffer);
}
if (sv->Unref()) {
mutex_.Lock();
sv->Cleanup();
mutex_.Unlock();
delete sv;
}
// Find and delete obsolete files
{
InstrumentedMutexLock l(&mutex_);
// If !s.ok(), this means that Compaction failed. In that case, we want
// to delete all obsolete files we might have created and we force
// FindObsoleteFiles(). This is because job_context does not
// catch all created files if compaction failed.
FindObsoleteFiles(&job_context, !s.ok());
} // release the mutex
// delete unnecessary files if any, this is done outside the mutex
if (job_context.HaveSomethingToClean() ||
job_context.HaveSomethingToDelete() || !log_buffer.IsEmpty()) {
// Have to flush the info logs before bg_compaction_scheduled_--
// because if bg_flush_scheduled_ becomes 0 and the lock is
// released, the deconstructor of DB can kick in and destroy all the
// states of DB so info_log might not be available after that point.
// It also applies to access other states that DB owns.
log_buffer.FlushBufferToLog();
if (job_context.HaveSomethingToDelete()) {
// no mutex is locked here. No need to Unlock() and Lock() here.
PurgeObsoleteFiles(job_context);
}
job_context.Clean();
}
return s;
#endif // ROCKSDB_LITE
}
#ifndef ROCKSDB_LITE
Status DBImpl::CompactFilesImpl(
const CompactionOptions& compact_options, ColumnFamilyData* cfd,
Version* version, const std::vector<std::string>& input_file_names,
std::vector<std::string>* const output_file_names, const int output_level,
int output_path_id, JobContext* job_context, LogBuffer* log_buffer) {
mutex_.AssertHeld();
if (shutting_down_.load(std::memory_order_acquire)) {
return Status::ShutdownInProgress();
}
std::unordered_set<uint64_t> input_set;
for (const auto& file_name : input_file_names) {
input_set.insert(TableFileNameToNumber(file_name));
}
ColumnFamilyMetaData cf_meta;
// TODO(yhchiang): can directly use version here if none of the
// following functions call is pluggable to external developers.
version->GetColumnFamilyMetaData(&cf_meta);
if (output_path_id < 0) {
if (cfd->ioptions()->cf_paths.size() == 1U) {
output_path_id = 0;
} else {
return Status::NotSupported(
"Automatic output path selection is not "
"yet supported in CompactFiles()");
}
}
Status s = cfd->compaction_picker()->SanitizeCompactionInputFiles(
&input_set, cf_meta, output_level);
if (!s.ok()) {
return s;
}
std::vector<CompactionInputFiles> input_files;
s = cfd->compaction_picker()->GetCompactionInputsFromFileNumbers(
&input_files, &input_set, version->storage_info(), compact_options);
if (!s.ok()) {
return s;
}
for (const auto& inputs : input_files) {
if (cfd->compaction_picker()->AreFilesInCompaction(inputs.files)) {
return Status::Aborted(
"Some of the necessary compaction input "
"files are already being compacted");
}
}
bool sfm_reserved_compact_space = false;
// First check if we have enough room to do the compaction
bool enough_room = EnoughRoomForCompaction(
cfd, input_files, &sfm_reserved_compact_space, log_buffer);
if (!enough_room) {
// m's vars will get set properly at the end of this function,
// as long as status == CompactionTooLarge
return Status::CompactionTooLarge();
}
// At this point, CompactFiles will be run.
bg_compaction_scheduled_++;
unique_ptr<Compaction> c;
assert(cfd->compaction_picker());
c.reset(cfd->compaction_picker()->CompactFiles(
compact_options, input_files, output_level, version->storage_info(),
*cfd->GetLatestMutableCFOptions(), output_path_id));
// we already sanitized the set of input files and checked for conflicts
// without releasing the lock, so we're guaranteed a compaction can be formed.
assert(c != nullptr);
c->SetInputVersion(version);
// deletion compaction currently not allowed in CompactFiles.
assert(!c->deletion_compaction());
SequenceNumber earliest_write_conflict_snapshot;
std::vector<SequenceNumber> snapshot_seqs =
snapshots_.GetAll(&earliest_write_conflict_snapshot);
auto pending_outputs_inserted_elem =
CaptureCurrentFileNumberInPendingOutputs();
auto snapshot_checker = snapshot_checker_.get();
if (use_custom_gc_ && snapshot_checker == nullptr) {
snapshot_checker = DisableGCSnapshotChecker::Instance();
}
assert(is_snapshot_supported_ || snapshots_.empty());
CompactionJob compaction_job(
job_context->job_id, c.get(), immutable_db_options_,
env_options_for_compaction_, versions_.get(), &shutting_down_,
preserve_deletes_seqnum_.load(), log_buffer, directories_.GetDbDir(),
GetDataDir(c->column_family_data(), c->output_path_id()), stats_, &mutex_,
&error_handler_, snapshot_seqs, earliest_write_conflict_snapshot,
snapshot_checker, table_cache_, &event_logger_,
c->mutable_cf_options()->paranoid_file_checks,
c->mutable_cf_options()->report_bg_io_stats, dbname_,
nullptr); // Here we pass a nullptr for CompactionJobStats because
// CompactFiles does not trigger OnCompactionCompleted(),
// which is the only place where CompactionJobStats is
// returned. The idea of not triggering OnCompationCompleted()
// is that CompactFiles runs in the caller thread, so the user
// should always know when it completes. As a result, it makes
// less sense to notify the users something they should already
// know.
//
// In the future, if we would like to add CompactionJobStats
// support for CompactFiles, we should have CompactFiles API
// pass a pointer of CompactionJobStats as the out-value
// instead of using EventListener.
// Creating a compaction influences the compaction score because the score
// takes running compactions into account (by skipping files that are already
// being compacted). Since we just changed compaction score, we recalculate it
// here.
version->storage_info()->ComputeCompactionScore(*cfd->ioptions(),
*c->mutable_cf_options());
compaction_job.Prepare();
mutex_.Unlock();
TEST_SYNC_POINT("CompactFilesImpl:0");
TEST_SYNC_POINT("CompactFilesImpl:1");
compaction_job.Run();
TEST_SYNC_POINT("CompactFilesImpl:2");
TEST_SYNC_POINT("CompactFilesImpl:3");
mutex_.Lock();
Status status = compaction_job.Install(*c->mutable_cf_options());
if (status.ok()) {
InstallSuperVersionAndScheduleWork(
c->column_family_data(), &job_context->superversion_contexts[0],
*c->mutable_cf_options(), FlushReason::kManualCompaction);
}
c->ReleaseCompactionFiles(s);
#ifndef ROCKSDB_LITE
// Need to make sure SstFileManager does its bookkeeping
auto sfm = static_cast<SstFileManagerImpl*>(
immutable_db_options_.sst_file_manager.get());
if (sfm && sfm_reserved_compact_space) {
sfm->OnCompactionCompletion(c.get());
}
#endif // ROCKSDB_LITE
ReleaseFileNumberFromPendingOutputs(pending_outputs_inserted_elem);
if (status.ok()) {
// Done
} else if (status.IsShutdownInProgress()) {
// Ignore compaction errors found during shutting down
} else {
ROCKS_LOG_WARN(immutable_db_options_.info_log,
"[%s] [JOB %d] Compaction error: %s",
c->column_family_data()->GetName().c_str(),
job_context->job_id, status.ToString().c_str());
error_handler_.SetBGError(status, BackgroundErrorReason::kCompaction);
}
if (output_file_names != nullptr) {
for (const auto newf : c->edit()->GetNewFiles()) {
(*output_file_names)
.push_back(TableFileName(c->immutable_cf_options()->cf_paths,
newf.second.fd.GetNumber(),
newf.second.fd.GetPathId()));
}
}
c.reset();
bg_compaction_scheduled_--;
if (bg_compaction_scheduled_ == 0) {
bg_cv_.SignalAll();
}
TEST_SYNC_POINT("CompactFilesImpl:End");
return status;
}
#endif // ROCKSDB_LITE
Status DBImpl::PauseBackgroundWork() {
InstrumentedMutexLock guard_lock(&mutex_);
bg_compaction_paused_++;
while (bg_bottom_compaction_scheduled_ > 0 || bg_compaction_scheduled_ > 0 ||
bg_flush_scheduled_ > 0) {
bg_cv_.Wait();
}
bg_work_paused_++;
return Status::OK();
}
Status DBImpl::ContinueBackgroundWork() {
InstrumentedMutexLock guard_lock(&mutex_);
if (bg_work_paused_ == 0) {
return Status::InvalidArgument();
}
assert(bg_work_paused_ > 0);
assert(bg_compaction_paused_ > 0);
bg_compaction_paused_--;
bg_work_paused_--;
// It's sufficient to check just bg_work_paused_ here since
// bg_work_paused_ is always no greater than bg_compaction_paused_
if (bg_work_paused_ == 0) {
MaybeScheduleFlushOrCompaction();
}
return Status::OK();
}
void DBImpl::NotifyOnCompactionBegin(ColumnFamilyData* cfd,
Compaction *c, const Status &st,
const CompactionJobStats& job_stats,
int job_id) {
#ifndef ROCKSDB_LITE
if (immutable_db_options_.listeners.empty()) {
return;
}
mutex_.AssertHeld();
if (shutting_down_.load(std::memory_order_acquire)) {
return;
}
Version* current = cfd->current();
current->Ref();
// release lock while notifying events
mutex_.Unlock();
TEST_SYNC_POINT("DBImpl::NotifyOnCompactionBegin::UnlockMutex");
{
CompactionJobInfo info;
info.cf_name = cfd->GetName();
info.status = st;
info.thread_id = env_->GetThreadID();
info.job_id = job_id;
info.base_input_level = c->start_level();
info.output_level = c->output_level();
info.stats = job_stats;
info.table_properties = c->GetOutputTableProperties();
info.compaction_reason = c->compaction_reason();
info.compression = c->output_compression();
for (size_t i = 0; i < c->num_input_levels(); ++i) {
for (const auto fmd : *c->inputs(i)) {
auto fn = TableFileName(c->immutable_cf_options()->cf_paths,
fmd->fd.GetNumber(), fmd->fd.GetPathId());
info.input_files.push_back(fn);
if (info.table_properties.count(fn) == 0) {
std::shared_ptr<const TableProperties> tp;
auto s = current->GetTableProperties(&tp, fmd, &fn);
if (s.ok()) {
info.table_properties[fn] = tp;
}
}
}
}
for (const auto newf : c->edit()->GetNewFiles()) {
info.output_files.push_back(TableFileName(
c->immutable_cf_options()->cf_paths, newf.second.fd.GetNumber(),
newf.second.fd.GetPathId()));
}
for (auto listener : immutable_db_options_.listeners) {
listener->OnCompactionBegin(this, info);
}
}
mutex_.Lock();
current->Unref();
#else
(void)cfd;
(void)c;
(void)st;
(void)job_stats;
(void)job_id;
#endif // ROCKSDB_LITE
}
void DBImpl::NotifyOnCompactionCompleted(
ColumnFamilyData* cfd, Compaction* c, const Status& st,
const CompactionJobStats& compaction_job_stats, const int job_id) {
#ifndef ROCKSDB_LITE
if (immutable_db_options_.listeners.size() == 0U) {
return;
}
mutex_.AssertHeld();
if (shutting_down_.load(std::memory_order_acquire)) {
return;
}
Version* current = cfd->current();
current->Ref();
// release lock while notifying events
mutex_.Unlock();
TEST_SYNC_POINT("DBImpl::NotifyOnCompactionCompleted::UnlockMutex");
{
CompactionJobInfo info;
info.cf_id = cfd->GetID();
info.cf_name = cfd->GetName();
info.status = st;
info.thread_id = env_->GetThreadID();
info.job_id = job_id;
info.base_input_level = c->start_level();
info.output_level = c->output_level();
info.stats = compaction_job_stats;
info.table_properties = c->GetOutputTableProperties();
info.compaction_reason = c->compaction_reason();
info.compression = c->output_compression();
for (size_t i = 0; i < c->num_input_levels(); ++i) {
for (const auto fmd : *c->inputs(i)) {
auto fn = TableFileName(c->immutable_cf_options()->cf_paths,
fmd->fd.GetNumber(), fmd->fd.GetPathId());
info.input_files.push_back(fn);
if (info.table_properties.count(fn) == 0) {
std::shared_ptr<const TableProperties> tp;
auto s = current->GetTableProperties(&tp, fmd, &fn);
if (s.ok()) {
info.table_properties[fn] = tp;
}
}
}
}
for (const auto newf : c->edit()->GetNewFiles()) {
info.output_files.push_back(TableFileName(
c->immutable_cf_options()->cf_paths, newf.second.fd.GetNumber(),
newf.second.fd.GetPathId()));
}
for (auto listener : immutable_db_options_.listeners) {
listener->OnCompactionCompleted(this, info);
}
}
mutex_.Lock();
current->Unref();
// no need to signal bg_cv_ as it will be signaled at the end of the
// flush process.
#else
(void)cfd;
(void)c;
(void)st;
(void)compaction_job_stats;
(void)job_id;
#endif // ROCKSDB_LITE
}
// REQUIREMENT: block all background work by calling PauseBackgroundWork()
// before calling this function
Status DBImpl::ReFitLevel(ColumnFamilyData* cfd, int level, int target_level) {
assert(level < cfd->NumberLevels());
if (target_level >= cfd->NumberLevels()) {
return Status::InvalidArgument("Target level exceeds number of levels");
}
SuperVersionContext sv_context(/* create_superversion */ true);
Status status;
InstrumentedMutexLock guard_lock(&mutex_);
// only allow one thread refitting
if (refitting_level_) {
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"[ReFitLevel] another thread is refitting");
return Status::NotSupported("another thread is refitting");
}
refitting_level_ = true;
const MutableCFOptions mutable_cf_options = *cfd->GetLatestMutableCFOptions();
// move to a smaller level
int to_level = target_level;
if (target_level < 0) {
to_level = FindMinimumEmptyLevelFitting(cfd, mutable_cf_options, level);
}
auto* vstorage = cfd->current()->storage_info();
if (to_level > level) {
if (level == 0) {
return Status::NotSupported(
"Cannot change from level 0 to other levels.");
}
// Check levels are empty for a trivial move
for (int l = level + 1; l <= to_level; l++) {
if (vstorage->NumLevelFiles(l) > 0) {
return Status::NotSupported(
"Levels between source and target are not empty for a move.");
}
}
}
if (to_level != level) {
ROCKS_LOG_DEBUG(immutable_db_options_.info_log,
"[%s] Before refitting:\n%s", cfd->GetName().c_str(),
cfd->current()->DebugString().data());
VersionEdit edit;
edit.SetColumnFamily(cfd->GetID());
for (const auto& f : vstorage->LevelFiles(level)) {
edit.DeleteFile(level, f->fd.GetNumber());
edit.AddFile(to_level, f->fd.GetNumber(), f->fd.GetPathId(),
f->fd.GetFileSize(), f->smallest, f->largest,
f->fd.smallest_seqno, f->fd.largest_seqno,
f->marked_for_compaction);
}
ROCKS_LOG_DEBUG(immutable_db_options_.info_log,
"[%s] Apply version edit:\n%s", cfd->GetName().c_str(),
edit.DebugString().data());
status = versions_->LogAndApply(cfd, mutable_cf_options, &edit, &mutex_,
directories_.GetDbDir());
InstallSuperVersionAndScheduleWork(cfd, &sv_context, mutable_cf_options);
ROCKS_LOG_DEBUG(immutable_db_options_.info_log, "[%s] LogAndApply: %s\n",
cfd->GetName().c_str(), status.ToString().data());
if (status.ok()) {
ROCKS_LOG_DEBUG(immutable_db_options_.info_log,
"[%s] After refitting:\n%s", cfd->GetName().c_str(),
cfd->current()->DebugString().data());
}
}
sv_context.Clean();
refitting_level_ = false;
return status;
}
int DBImpl::NumberLevels(ColumnFamilyHandle* column_family) {
auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family);
return cfh->cfd()->NumberLevels();
}
int DBImpl::MaxMemCompactionLevel(ColumnFamilyHandle* /*column_family*/) {
return 0;
}
int DBImpl::Level0StopWriteTrigger(ColumnFamilyHandle* column_family) {
auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family);
InstrumentedMutexLock l(&mutex_);
return cfh->cfd()
->GetSuperVersion()
->mutable_cf_options.level0_stop_writes_trigger;
}
Status DBImpl::Flush(const FlushOptions& flush_options,
ColumnFamilyHandle* column_family) {
auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family);
ROCKS_LOG_INFO(immutable_db_options_.info_log, "[%s] Manual flush start.",
cfh->GetName().c_str());
Status s;
if (atomic_flush_) {
s = AtomicFlushMemTables({cfh->cfd()}, flush_options,
FlushReason::kManualFlush);
} else {
s = FlushMemTable(cfh->cfd(), flush_options, FlushReason::kManualFlush);
}
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"[%s] Manual flush finished, status: %s\n",
cfh->GetName().c_str(), s.ToString().c_str());
return s;
}
Status DBImpl::Flush(const FlushOptions& flush_options,
const std::vector<ColumnFamilyHandle*>& column_families) {
Status s;
if (!atomic_flush_) {
for (auto cfh : column_families) {
s = Flush(flush_options, cfh);
if (!s.ok()) {
break;
}
}
} else {
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"Manual atomic flush start.\n"
"=====Column families:=====");
for (auto cfh : column_families) {
auto cfhi = static_cast<ColumnFamilyHandleImpl*>(cfh);
ROCKS_LOG_INFO(immutable_db_options_.info_log, "%s",
cfhi->GetName().c_str());
}
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"=====End of column families list=====");
autovector<ColumnFamilyData*> cfds;
std::for_each(column_families.begin(), column_families.end(),
[&cfds](ColumnFamilyHandle* elem) {
auto cfh = static_cast<ColumnFamilyHandleImpl*>(elem);
cfds.emplace_back(cfh->cfd());
});
s = AtomicFlushMemTables(cfds, flush_options, FlushReason::kManualFlush);
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"Manual atomic flush finished, status: %s\n",
"=====Column families:=====", s.ToString().c_str());
for (auto cfh : column_families) {
auto cfhi = static_cast<ColumnFamilyHandleImpl*>(cfh);
ROCKS_LOG_INFO(immutable_db_options_.info_log, "%s",
cfhi->GetName().c_str());
}
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"=====End of column families list=====");
}
return s;
}
Status DBImpl::RunManualCompaction(ColumnFamilyData* cfd, int input_level,
int output_level, uint32_t output_path_id,
uint32_t max_subcompactions,
const Slice* begin, const Slice* end,
bool exclusive, bool disallow_trivial_move) {
assert(input_level == ColumnFamilyData::kCompactAllLevels ||
input_level >= 0);
InternalKey begin_storage, end_storage;
CompactionArg* ca;
bool scheduled = false;
bool manual_conflict = false;
ManualCompactionState manual;
manual.cfd = cfd;
manual.input_level = input_level;
manual.output_level = output_level;
manual.output_path_id = output_path_id;
manual.done = false;
manual.in_progress = false;
manual.incomplete = false;
manual.exclusive = exclusive;
manual.disallow_trivial_move = disallow_trivial_move;
// For universal compaction, we enforce every manual compaction to compact
// all files.
if (begin == nullptr ||
cfd->ioptions()->compaction_style == kCompactionStyleUniversal ||
cfd->ioptions()->compaction_style == kCompactionStyleFIFO) {
manual.begin = nullptr;
} else {
begin_storage.SetMinPossibleForUserKey(*begin);
manual.begin = &begin_storage;
}
if (end == nullptr ||
cfd->ioptions()->compaction_style == kCompactionStyleUniversal ||
cfd->ioptions()->compaction_style == kCompactionStyleFIFO) {
manual.end = nullptr;
} else {
end_storage.SetMaxPossibleForUserKey(*end);
manual.end = &end_storage;
}
TEST_SYNC_POINT("DBImpl::RunManualCompaction:0");
TEST_SYNC_POINT("DBImpl::RunManualCompaction:1");
InstrumentedMutexLock l(&mutex_);
// When a manual compaction arrives, temporarily disable scheduling of
// non-manual compactions and wait until the number of scheduled compaction
// jobs drops to zero. This is needed to ensure that this manual compaction
// can compact any range of keys/files.
//
// HasPendingManualCompaction() is true when at least one thread is inside
// RunManualCompaction(), i.e. during that time no other compaction will
// get scheduled (see MaybeScheduleFlushOrCompaction).
//
// Note that the following loop doesn't stop more that one thread calling
// RunManualCompaction() from getting to the second while loop below.
// However, only one of them will actually schedule compaction, while
// others will wait on a condition variable until it completes.
AddManualCompaction(&manual);
TEST_SYNC_POINT_CALLBACK("DBImpl::RunManualCompaction:NotScheduled", &mutex_);
if (exclusive) {
while (bg_bottom_compaction_scheduled_ > 0 ||
bg_compaction_scheduled_ > 0) {
TEST_SYNC_POINT("DBImpl::RunManualCompaction:WaitScheduled");
ROCKS_LOG_INFO(
immutable_db_options_.info_log,
"[%s] Manual compaction waiting for all other scheduled background "
"compactions to finish",
cfd->GetName().c_str());
bg_cv_.Wait();
}
}
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"[%s] Manual compaction starting", cfd->GetName().c_str());
// We don't check bg_error_ here, because if we get the error in compaction,
// the compaction will set manual.status to bg_error_ and set manual.done to
// true.
while (!manual.done) {
assert(HasPendingManualCompaction());
manual_conflict = false;
Compaction* compaction = nullptr;
if (ShouldntRunManualCompaction(&manual) || (manual.in_progress == true) ||
scheduled ||
(((manual.manual_end = &manual.tmp_storage1) != nullptr) &&
((compaction = manual.cfd->CompactRange(
*manual.cfd->GetLatestMutableCFOptions(), manual.input_level,
manual.output_level, manual.output_path_id, max_subcompactions,
manual.begin, manual.end, &manual.manual_end,
&manual_conflict)) == nullptr &&
manual_conflict))) {
// exclusive manual compactions should not see a conflict during
// CompactRange
assert(!exclusive || !manual_conflict);
// Running either this or some other manual compaction
bg_cv_.Wait();
if (scheduled && manual.incomplete == true) {
assert(!manual.in_progress);
scheduled = false;
manual.incomplete = false;
}
} else if (!scheduled) {
if (compaction == nullptr) {
manual.done = true;
bg_cv_.SignalAll();
continue;
}
ca = new CompactionArg;
ca->db = this;
ca->prepicked_compaction = new PrepickedCompaction;
ca->prepicked_compaction->manual_compaction_state = &manual;
ca->prepicked_compaction->compaction = compaction;
manual.incomplete = false;
bg_compaction_scheduled_++;
env_->Schedule(&DBImpl::BGWorkCompaction, ca, Env::Priority::LOW, this,
&DBImpl::UnscheduleCallback);
scheduled = true;
}
}
assert(!manual.in_progress);
assert(HasPendingManualCompaction());
RemoveManualCompaction(&manual);
bg_cv_.SignalAll();
return manual.status;
}
void DBImpl::GenerateFlushRequest(const autovector<ColumnFamilyData*>& cfds,
FlushRequest* req) {
assert(req != nullptr);
for (const auto cfd : cfds) {
if (nullptr == cfd) {
// cfd may be null, see DBImpl::ScheduleFlushes
continue;
}
uint64_t max_memtable_id = cfd->imm()->GetLatestMemTableID();
req->emplace_back(cfd, max_memtable_id);
}
}
Status DBImpl::FlushMemTable(ColumnFamilyData* cfd,
const FlushOptions& flush_options,
FlushReason flush_reason, bool writes_stopped) {
Status s;
uint64_t flush_memtable_id = 0;
if (!flush_options.allow_write_stall) {
bool flush_needed = true;
s = WaitUntilFlushWouldNotStallWrites(cfd, &flush_needed);
TEST_SYNC_POINT("DBImpl::FlushMemTable:StallWaitDone");
if (!s.ok() || !flush_needed) {
return s;
}
}
FlushRequest flush_req;
{
WriteContext context;
InstrumentedMutexLock guard_lock(&mutex_);
WriteThread::Writer w;
if (!writes_stopped) {
write_thread_.EnterUnbatched(&w, &mutex_);
}
if (cfd->imm()->NumNotFlushed() != 0 || !cfd->mem()->IsEmpty() ||
!cached_recoverable_state_empty_.load()) {
s = SwitchMemtable(cfd, &context);
flush_memtable_id = cfd->imm()->GetLatestMemTableID();
flush_req.emplace_back(cfd, flush_memtable_id);
}
if (s.ok() && !flush_req.empty()) {
for (auto& elem : flush_req) {
ColumnFamilyData* loop_cfd = elem.first;
loop_cfd->imm()->FlushRequested();
}
SchedulePendingFlush(flush_req, flush_reason);
MaybeScheduleFlushOrCompaction();
}
if (!writes_stopped) {
write_thread_.ExitUnbatched(&w);
}
}
if (s.ok() && flush_options.wait) {
autovector<ColumnFamilyData*> cfds;
autovector<const uint64_t*> flush_memtable_ids;
for (auto& iter : flush_req) {
cfds.push_back(iter.first);
flush_memtable_ids.push_back(&(iter.second));
}
s = WaitForFlushMemTables(cfds, flush_memtable_ids,
(flush_reason == FlushReason::kErrorRecovery));
}
TEST_SYNC_POINT("FlushMemTableFinished");
return s;
}
// Flush all elments in 'column_family_datas'
// and atomically record the result to the MANIFEST.
Status DBImpl::AtomicFlushMemTables(
const autovector<ColumnFamilyData*>& column_family_datas,
const FlushOptions& flush_options, FlushReason flush_reason,
bool writes_stopped) {
Status s;
if (!flush_options.allow_write_stall) {
int num_cfs_to_flush = 0;
for (auto cfd : column_family_datas) {
bool flush_needed = true;
s = WaitUntilFlushWouldNotStallWrites(cfd, &flush_needed);
if (!s.ok()) {
return s;
} else if (flush_needed) {
++num_cfs_to_flush;
}
}
if (0 == num_cfs_to_flush) {
return s;
}
}
FlushRequest flush_req;
autovector<ColumnFamilyData*> cfds;
{
WriteContext context;
InstrumentedMutexLock guard_lock(&mutex_);
WriteThread::Writer w;
if (!writes_stopped) {
write_thread_.EnterUnbatched(&w, &mutex_);
}
for (auto cfd : column_family_datas) {
if (cfd->IsDropped()) {
continue;
}
if (cfd->imm()->NumNotFlushed() != 0 || !cfd->mem()->IsEmpty() ||
!cached_recoverable_state_empty_.load()) {
cfds.emplace_back(cfd);
}
}
for (auto cfd : cfds) {
cfd->Ref();
s = SwitchMemtable(cfd, &context);
cfd->Unref();
if (!s.ok()) {
break;
}
}
if (s.ok()) {
AssignAtomicFlushSeq(cfds);
for (auto cfd : cfds) {
cfd->imm()->FlushRequested();
}
GenerateFlushRequest(cfds, &flush_req);
SchedulePendingFlush(flush_req, flush_reason);
MaybeScheduleFlushOrCompaction();
}
if (!writes_stopped) {
write_thread_.ExitUnbatched(&w);
}
}
if (s.ok() && flush_options.wait) {
autovector<const uint64_t*> flush_memtable_ids;
for (auto& iter : flush_req) {
flush_memtable_ids.push_back(&(iter.second));
}
s = WaitForFlushMemTables(cfds, flush_memtable_ids,
(flush_reason == FlushReason::kErrorRecovery));
}
return s;
}
// Calling FlushMemTable(), whether from DB::Flush() or from Backup Engine, can
// cause write stall, for example if one memtable is being flushed already.
// This method tries to avoid write stall (similar to CompactRange() behavior)
// it emulates how the SuperVersion / LSM would change if flush happens, checks
// it against various constrains and delays flush if it'd cause write stall.
// Called should check status and flush_needed to see if flush already happened.
Status DBImpl::WaitUntilFlushWouldNotStallWrites(ColumnFamilyData* cfd,
bool* flush_needed) {
{
*flush_needed = true;
InstrumentedMutexLock l(&mutex_);
uint64_t orig_active_memtable_id = cfd->mem()->GetID();
WriteStallCondition write_stall_condition = WriteStallCondition::kNormal;
do {
if (write_stall_condition != WriteStallCondition::kNormal) {
TEST_SYNC_POINT("DBImpl::WaitUntilFlushWouldNotStallWrites:StallWait");
ROCKS_LOG_INFO(immutable_db_options_.info_log,
"[%s] WaitUntilFlushWouldNotStallWrites"
" waiting on stall conditions to clear",
cfd->GetName().c_str());
bg_cv_.Wait();
}
if (cfd->IsDropped() || shutting_down_.load(std::memory_order_acquire)) {
return Status::ShutdownInProgress();
}
uint64_t earliest_memtable_id =
std::min(cfd->mem()->GetID(), cfd->imm()->GetEarliestMemTableID());
if (earliest_memtable_id > orig_active_memtable_id) {
// We waited so long that the memtable we were originally waiting on was
// flushed.
*flush_needed = false;
return Status::OK();
}
const auto& mutable_cf_options = *cfd->GetLatestMutableCFOptions();
const auto* vstorage = cfd->current()->storage_info();
// Skip stalling check if we're below auto-flush and auto-compaction
// triggers. If it stalled in these conditions, that'd mean the stall
// triggers are so low that stalling is needed for any background work. In
// that case we shouldn't wait since background work won't be scheduled.
if (cfd->imm()->NumNotFlushed() <
cfd->ioptions()->min_write_buffer_number_to_merge &&
vstorage->l0_delay_trigger_count() <
mutable_cf_options.level0_file_num_compaction_trigger) {
break;
}
// check whether one extra immutable memtable or an extra L0 file would
// cause write stalling mode to be entered. It could still enter stall
// mode due to pending compaction bytes, but that's less common
write_stall_condition =
ColumnFamilyData::GetWriteStallConditionAndCause(
cfd->imm()->NumNotFlushed() + 1,
vstorage->l0_delay_trigger_count() + 1,
vstorage->estimated_compaction_needed_bytes(), mutable_cf_options)
.first;
} while (write_stall_condition != WriteStallCondition::kNormal);
}
return Status::OK();
}
// Wait for memtables to be flushed for multiple column families.
// let N = cfds.size()
// for i in [0, N),
// 1) if flush_memtable_ids[i] is not null, then the memtables with lower IDs
// have to be flushed for THIS column family;
// 2) if flush_memtable_ids[i] is null, then all memtables in THIS column
// family have to be flushed.
// Finish waiting when ALL column families finish flushing memtables.
// resuming_from_bg_err indicates whether the caller is trying to resume from
// background error or in normal processing.
Status DBImpl::WaitForFlushMemTables(
const autovector<ColumnFamilyData*>& cfds,
const autovector<const uint64_t*>& flush_memtable_ids,
bool resuming_from_bg_err) {
int num = static_cast<int>(cfds.size());
// Wait until the compaction completes
InstrumentedMutexLock l(&mutex_);
// If the caller is trying to resume from bg error, then
// error_handler_.IsDBStopped() is true.
while (resuming_from_bg_err || !error_handler_.IsDBStopped()) {
if (shutting_down_.load(std::memory_order_acquire)) {
return Status::ShutdownInProgress();
}
// If an error has occurred during resumption, then no need to wait.
if (!error_handler_.GetRecoveryError().ok()) {
break;
}
// Number of column families that have been dropped.
int num_dropped = 0;
// Number of column families that have finished flush.
int num_finished = 0;
for (int i = 0; i < num; ++i) {
if (cfds[i]->IsDropped()) {
++num_dropped;
} else if (cfds[i]->imm()->NumNotFlushed() == 0 ||
(flush_memtable_ids[i] != nullptr &&
cfds[i]->imm()->GetEarliestMemTableID() >
*flush_memtable_ids[i])) {
++num_finished;
}
}
if (1 == num_dropped && 1 == num) {
return Status::InvalidArgument("Cannot flush a dropped CF");
}
// Column families involved in this flush request have either been dropped
// or finished flush. Then it's time to finish waiting.
if (num_dropped + num_finished == num) {
break;
}
bg_cv_.Wait();
}
Status s;
// If not resuming from bg error, and an error has caused the DB to stop,
// then report the bg error to caller.
if (!resuming_from_bg_err && error_handler_.IsDBStopped()) {
s = error_handler_.GetBGError();
}
return s;
}
Status DBImpl::EnableAutoCompaction(
const std::vector<ColumnFamilyHandle*>& column_family_handles) {
Status s;
for (auto cf_ptr : column_family_handles) {
Status status =
this->SetOptions(cf_ptr, {{"disable_auto_compactions", "false"}});
if (!status.ok()) {
s = status;
}
}
return s;
}
void DBImpl::MaybeScheduleFlushOrCompaction() {
mutex_.AssertHeld();
if (!opened_successfully_) {
// Compaction may introduce data race to DB open
return;
}
if (bg_work_paused_ > 0) {
// we paused the background work
return;
} else if (error_handler_.IsBGWorkStopped() &&
!error_handler_.IsRecoveryInProgress()) {
// There has been a hard error and this call is not part of the recovery
// sequence. Bail out here so we don't get into an endless loop of
// scheduling BG work which will again call this function
return;
} else if (shutting_down_.load(std::memory_order_acquire)) {
// DB is being deleted; no more background compactions
return;
}
auto bg_job_limits = GetBGJobLimits();
bool is_flush_pool_empty =
env_->GetBackgroundThreads(Env::Priority::HIGH) == 0;
while (!is_flush_pool_empty && unscheduled_flushes_ > 0 &&
bg_flush_scheduled_ < bg_job_limits.max_flushes) {
bg_flush_scheduled_++;
env_->Schedule(&DBImpl::BGWorkFlush, this, Env::Priority::HIGH, this);
}
// special case -- if high-pri (flush) thread pool is empty, then schedule
// flushes in low-pri (compaction) thread pool.
if (is_flush_pool_empty) {
while (unscheduled_flushes_ > 0 &&
bg_flush_scheduled_ + bg_compaction_scheduled_ <
bg_job_limits.max_flushes) {
bg_flush_scheduled_++;
env_->Schedule(&DBImpl::BGWorkFlush, this, Env::Priority::LOW, this);
}
}
if (bg_compaction_paused_ > 0) {
// we paused the background compaction
return;
} else if (error_handler_.IsBGWorkStopped()) {
// Compaction is not part of the recovery sequence from a hard error. We
// might get here because recovery might do a flush and install a new
// super version, which will try to schedule pending compactions. Bail
// out here and let the higher level recovery handle compactions
return;
}
if (HasExclusiveManualCompaction()) {
// only manual compactions are allowed to run. don't schedule automatic
// compactions
TEST_SYNC_POINT("DBImpl::MaybeScheduleFlushOrCompaction:Conflict");
return;
}
while (bg_compaction_scheduled_ < bg_job_limits.max_compactions &&
unscheduled_compactions_ > 0) {
CompactionArg* ca = new CompactionArg;
ca->db = this;
ca->prepicked_compaction = nullptr;
bg_compaction_scheduled_++;
unscheduled_compactions_--;
env_->Schedule(&DBImpl::BGWorkCompaction, ca, Env::Priority::LOW, this,
&DBImpl::UnscheduleCallback);
}
}
DBImpl::BGJobLimits DBImpl::GetBGJobLimits() const {
mutex_.AssertHeld();
return GetBGJobLimits(immutable_db_options_.max_background_flushes,
mutable_db_options_.max_background_compactions,
mutable_db_options_.max_background_jobs,
write_controller_.NeedSpeedupCompaction());
}
DBImpl::BGJobLimits DBImpl::GetBGJobLimits(int max_background_flushes,
int max_background_compactions,
int max_background_jobs,
bool parallelize_compactions) {
BGJobLimits res;
if (max_background_flushes == -1 && max_background_compactions == -1) {
// for our first stab implementing max_background_jobs, simply allocate a
// quarter of the threads to flushes.
res.max_flushes = std::max(1, max_background_jobs / 4);
res.max_compactions = std::max(1, max_background_jobs - res.max_flushes);
} else {
// compatibility code in case users haven't migrated to max_background_jobs,
// which automatically computes flush/compaction limits
res.max_flushes = std::max(1, max_background_flushes);
res.max_compactions = std::max(1, max_background_compactions);
}
if (!parallelize_compactions) {
// throttle background compactions until we deem necessary
res.max_compactions = 1;
}
return res;
}
void DBImpl::AddToCompactionQueue(ColumnFamilyData* cfd) {
assert(!cfd->queued_for_compaction());
cfd->Ref();
compaction_queue_.push_back(cfd);
cfd->set_queued_for_compaction(true);
}
ColumnFamilyData* DBImpl::PopFirstFromCompactionQueue() {
assert(!compaction_queue_.empty());
auto cfd = *compaction_queue_.begin();
compaction_queue_.pop_front();
assert(cfd->queued_for_compaction());
cfd->set_queued_for_compaction(false);
return cfd;
}
DBImpl::FlushRequest DBImpl::PopFirstFromFlushQueue() {
assert(!flush_queue_.empty());
FlushRequest flush_req = flush_queue_.front();
assert(unscheduled_flushes_ >= static_cast<int>(flush_req.size()));
unscheduled_flushes_ -= static_cast<int>(flush_req.size());
flush_queue_.pop_front();
// TODO: need to unset flush reason?
return flush_req;
}
void DBImpl::SchedulePendingFlush(const FlushRequest& flush_req,
FlushReason flush_reason) {
if (flush_req.empty()) {
return;
}
for (auto& iter : flush_req) {
ColumnFamilyData* cfd = iter.first;
cfd->Ref();
cfd->SetFlushReason(flush_reason);
}
unscheduled_flushes_ += static_cast<int>(flush_req.size());
flush_queue_.push_back(flush_req);
}
void DBImpl::SchedulePendingCompaction(ColumnFamilyData* cfd) {
if (!cfd->queued_for_compaction() && cfd->NeedsCompaction()) {
AddToCompactionQueue(cfd);
++unscheduled_compactions_;
}
}
void DBImpl::SchedulePendingPurge(std::string fname, std::string dir_to_sync,
FileType type, uint64_t number, int job_id) {
mutex_.AssertHeld();
PurgeFileInfo file_info(fname, dir_to_sync, type, number, job_id);
purge_queue_.push_back(std::move(file_info));
}
void DBImpl::BGWorkFlush(void* db) {
IOSTATS_SET_THREAD_POOL_ID(Env::Priority::HIGH);
TEST_SYNC_POINT("DBImpl::BGWorkFlush");
reinterpret_cast<DBImpl*>(db)->BackgroundCallFlush();
TEST_SYNC_POINT("DBImpl::BGWorkFlush:done");
}
void DBImpl::BGWorkCompaction(void* arg) {
CompactionArg ca = *(reinterpret_cast<CompactionArg*>(arg));
delete reinterpret_cast<CompactionArg*>(arg);
IOSTATS_SET_THREAD_POOL_ID(Env::Priority::LOW);
TEST_SYNC_POINT("DBImpl::BGWorkCompaction");
auto prepicked_compaction =
static_cast<PrepickedCompaction*>(ca.prepicked_compaction);
reinterpret_cast<DBImpl*>(ca.db)->BackgroundCallCompaction(
prepicked_compaction, Env::Priority::LOW);
delete prepicked_compaction;
}
void DBImpl::BGWorkBottomCompaction(void* arg) {
CompactionArg ca = *(static_cast<CompactionArg*>(arg));
delete static_cast<CompactionArg*>(arg);
IOSTATS_SET_THREAD_POOL_ID(Env::Priority::BOTTOM);
TEST_SYNC_POINT("DBImpl::BGWorkBottomCompaction");
auto* prepicked_compaction = ca.prepicked_compaction;
assert(prepicked_compaction && prepicked_compaction->compaction &&
!prepicked_compaction->manual_compaction_state);
ca.db->BackgroundCallCompaction(prepicked_compaction, Env::Priority::BOTTOM);
delete prepicked_compaction;
}
void DBImpl::BGWorkPurge(void* db) {
IOSTATS_SET_THREAD_POOL_ID(Env::Priority::HIGH);
TEST_SYNC_POINT("DBImpl::BGWorkPurge:start");
reinterpret_cast<DBImpl*>(db)->BackgroundCallPurge();
TEST_SYNC_POINT("DBImpl::BGWorkPurge:end");
}
void DBImpl::UnscheduleCallback(void* arg) {
CompactionArg ca = *(reinterpret_cast<CompactionArg*>(arg));
delete reinterpret_cast<CompactionArg*>(arg);
if (ca.prepicked_compaction != nullptr) {
if (ca.prepicked_compaction->compaction != nullptr) {
delete ca.prepicked_compaction->compaction;
}
delete ca.prepicked_compaction;
}
TEST_SYNC_POINT("DBImpl::UnscheduleCallback");
}
Status DBImpl::BackgroundFlush(bool* made_progress, JobContext* job_context,
LogBuffer* log_buffer, FlushReason* reason) {
mutex_.AssertHeld();
Status status;
*reason = FlushReason::kOthers;
// If BG work is stopped due to an error, but a recovery is in progress,
// that means this flush is part of the recovery. So allow it to go through
if (!error_handler_.IsBGWorkStopped()) {
if (shutting_down_.load(std::memory_order_acquire)) {
status = Status::ShutdownInProgress();
}
} else if (!error_handler_.IsRecoveryInProgress()) {
status = error_handler_.GetBGError();
}
if (!status.ok()) {
return status;
}
autovector<BGFlushArg> bg_flush_args;
std::vector<SuperVersionContext>& superversion_contexts =
job_context->superversion_contexts;
while (!flush_queue_.empty()) {
// This cfd is already referenced
const FlushRequest& flush_req = PopFirstFromFlushQueue();
superversion_contexts.clear();
superversion_contexts.reserve(flush_req.size());
for (const auto& iter : flush_req) {
ColumnFamilyData* cfd = iter.first;
if (cfd->IsDropped() || !cfd->imm()->IsFlushPending()) {
// can't flush this CF, try next one
if (cfd->Unref()) {
delete cfd;
}
continue;
}
superversion_contexts.emplace_back(SuperVersionContext(true));
bg_flush_args.emplace_back(cfd, iter.second,
&(superversion_contexts.back()));
}
if (!bg_flush_args.empty()) {
break;
}
}
if (!bg_flush_args.empty()) {
auto bg_job_limits = GetBGJobLimits();
for (const auto& arg : bg_flush_args) {
ColumnFamilyData* cfd = arg.cfd_;
ROCKS_LOG_BUFFER(
log_buffer,
"Calling FlushMemTableToOutputFile with column "
"family [%s], flush slots available %d, compaction slots available "
"%d, "
"flush slots scheduled %d, compaction slots scheduled %d",
cfd->GetName().c_str(), bg_job_limits.max_flushes,
bg_job_limits.max_compactions, bg_flush_scheduled_,
bg_compaction_scheduled_);
}
status = FlushMemTablesToOutputFiles(bg_flush_args, made_progress,
job_context, log_buffer);
// All the CFDs in the FlushReq must have the same flush reason, so just
// grab the first one
*reason = bg_flush_args[0].cfd_->GetFlushReason();
for (auto& arg : bg_flush_args) {
ColumnFamilyData* cfd = arg.cfd_;
if (cfd->Unref()) {
delete cfd;
arg.cfd_ = nullptr;
}
}
}
return status;
}
void DBImpl::BackgroundCallFlush() {
bool made_progress = false;
JobContext job_context(next_job_id_.fetch_add(1), true);
TEST_SYNC_POINT("DBImpl::BackgroundCallFlush:start");
LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL,
immutable_db_options_.info_log.get());
{
InstrumentedMutexLock l(&mutex_);
assert(bg_flush_scheduled_);
num_running_flushes_++;
auto pending_outputs_inserted_elem =
CaptureCurrentFileNumberInPendingOutputs();
FlushReason reason;
Status s =
BackgroundFlush(&made_progress, &job_context, &log_buffer, &reason);
if (!s.ok() && !s.IsShutdownInProgress() &&
reason != FlushReason::kErrorRecovery) {
// Wait a little bit before retrying background flush in
// case this is an environmental problem and we do not want to
// chew up resources for failed flushes for the duration of
// the problem.
uint64_t error_cnt =
default_cf_internal_stats_->BumpAndGetBackgroundErrorCount();
bg_cv_.SignalAll(); // In case a waiter can proceed despite the error
mutex_.Unlock();
ROCKS_LOG_ERROR(immutable_db_options_.info_log,
"Waiting after background flush error: %s"
"Accumulated background error counts: %" PRIu64,
s.ToString().c_str(), error_cnt);
log_buffer.FlushBufferToLog();
LogFlush(immutable_db_options_.info_log);
env_->SleepForMicroseconds(1000000);
mutex_.Lock();
}
TEST_SYNC_POINT("DBImpl::BackgroundCallFlush:FlushFinish:0");
ReleaseFileNumberFromPendingOutputs(pending_outputs_inserted_elem);
// If flush failed, we want to delete all temporary files that we might have
// created. Thus, we force full scan in FindObsoleteFiles()
FindObsoleteFiles(&job_context, !s.ok() && !s.IsShutdownInProgress());
// delete unnecessary files if any, this is done outside the mutex
if (job_context.HaveSomethingToClean() ||
job_context.HaveSomethingToDelete() || !log_buffer.IsEmpty()) {
mutex_.Unlock();
TEST_SYNC_POINT("DBImpl::BackgroundCallFlush:FilesFound");
// Have to flush the info logs before bg_flush_scheduled_--
// because if bg_flush_scheduled_ becomes 0 and the lock is
// released, the deconstructor of DB can kick in and destroy all the
// states of DB so info_log might not be available after that point.
// It also applies to access other states that DB owns.
log_buffer.FlushBufferToLog();
if (job_context.HaveSomethingToDelete()) {
PurgeObsoleteFiles(job_context);
}
job_context.Clean();
mutex_.Lock();
}
assert(num_running_flushes_ > 0);
num_running_flushes_--;
bg_flush_scheduled_--;
// See if there's more work to be done
MaybeScheduleFlushOrCompaction();
bg_cv_.SignalAll();
// IMPORTANT: there should be no code after calling SignalAll. This call may
// signal the DB destructor that it's OK to proceed with destruction. In
// that case, all DB variables will be dealloacated and referencing them
// will cause trouble.
}
}
void DBImpl::BackgroundCallCompaction(PrepickedCompaction* prepicked_compaction,
Env::Priority bg_thread_pri) {
bool made_progress = false;
JobContext job_context(next_job_id_.fetch_add(1), true);
TEST_SYNC_POINT("BackgroundCallCompaction:0");
LogBuffer log_buffer(InfoLogLevel::INFO_LEVEL,
immutable_db_options_.info_log.get());
{
InstrumentedMutexLock l(&mutex_);
// This call will unlock/lock the mutex to wait for current running
// IngestExternalFile() calls to finish.
WaitForIngestFile();
num_running_compactions_++;
auto pending_outputs_inserted_elem =
CaptureCurrentFileNumberInPendingOutputs();
assert((bg_thread_pri == Env::Priority::BOTTOM &&
bg_bottom_compaction_scheduled_) ||
(bg_thread_pri == Env::Priority::LOW && bg_compaction_scheduled_));
Status s = BackgroundCompaction(&made_progress, &job_context, &log_buffer,
prepicked_compaction);
TEST_SYNC_POINT("BackgroundCallCompaction:1");
if (!s.ok() && !s.IsShutdownInProgress()) {
// Wait a little bit before retrying background compaction in
// case this is an environmental problem and we do not want to
// chew up resources for failed compactions for the duration of
// the problem.
uint64_t error_cnt =
default_cf_internal_stats_->BumpAndGetBackgroundErrorCount();
bg_cv_.SignalAll(); // In case a waiter can proceed despite the error
mutex_.Unlock();
log_buffer.FlushBufferToLog();
ROCKS_LOG_ERROR(immutable_db_options_.info_log,
"Waiting after background compaction error: %s, "
"Accumulated background error counts: %" PRIu64,
s.ToString().c_str(), error_cnt);
LogFlush(immutable_db_options_.info_log);
env_->SleepForMicroseconds(1000000);
mutex_.Lock();
}
ReleaseFileNumberFromPendingOutputs(pending_outputs_inserted_elem);
// If compaction failed, we want to delete all temporary files that we might
// have created (they might not be all recorded in job_context in case of a
// failure). Thus, we force full scan in FindObsoleteFiles()
FindObsoleteFiles(&job_context, !s.ok() && !s.IsShutdownInProgress());
TEST_SYNC_POINT("DBImpl::BackgroundCallCompaction:FoundObsoleteFiles");
// delete unnecessary files if any, this is done outside the mutex
if (job_context.HaveSomethingToClean() ||
job_context.HaveSomethingToDelete() || !log_buffer.IsEmpty()) {
mutex_.Unlock();
// Have to flush the info logs before bg_compaction_scheduled_--
// because if bg_flush_scheduled_ becomes 0 and the lock is
// released, the deconstructor of DB can kick in and destroy all the
// states of DB so info_log might not be available after that point.
// It also applies to access other states that DB owns.
log_buffer.FlushBufferToLog();
if (job_context.HaveSomethingToDelete()) {
PurgeObsoleteFiles(job_context);
TEST_SYNC_POINT("DBImpl::BackgroundCallCompaction:PurgedObsoleteFiles");
}
job_context.Clean();
mutex_.Lock();
}
assert(num_running_compactions_ > 0);
num_running_compactions_--;
if (bg_thread_pri == Env::Priority::LOW) {
bg_compaction_scheduled_--;
} else {
assert(bg_thread_pri == Env::Priority::BOTTOM);
bg_bottom_compaction_scheduled_--;
}
versions_->GetColumnFamilySet()->FreeDeadColumnFamilies();
// See if there's more work to be done
MaybeScheduleFlushOrCompaction();
if (made_progress ||
(bg_compaction_scheduled_ == 0 &&
bg_bottom_compaction_scheduled_ == 0) ||
HasPendingManualCompaction() || unscheduled_compactions_ == 0) {
// signal if
// * made_progress -- need to wakeup DelayWrite
// * bg_{bottom,}_compaction_scheduled_ == 0 -- need to wakeup ~DBImpl
// * HasPendingManualCompaction -- need to wakeup RunManualCompaction
// If none of this is true, there is no need to signal since nobody is
// waiting for it
bg_cv_.SignalAll();
}
// IMPORTANT: there should be no code after calling SignalAll. This call may
// signal the DB destructor that it's OK to proceed with destruction. In
// that case, all DB variables will be dealloacated and referencing them
// will cause trouble.
}
}
Status DBImpl::BackgroundCompaction(bool* made_progress,
JobContext* job_context,
LogBuffer* log_buffer,
PrepickedCompaction* prepicked_compaction) {
ManualCompactionState* manual_compaction =
prepicked_compaction == nullptr
? nullptr
: prepicked_compaction->manual_compaction_state;
*made_progress = false;
mutex_.AssertHeld();
TEST_SYNC_POINT("DBImpl::BackgroundCompaction:Start");
bool is_manual = (manual_compaction != nullptr);
unique_ptr<Compaction> c;
if (prepicked_compaction != nullptr &&
prepicked_compaction->compaction != nullptr) {
c.reset(prepicked_compaction->compaction);
}
bool is_prepicked = is_manual || c;
// (manual_compaction->in_progress == false);
bool trivial_move_disallowed =
is_manual && manual_compaction->disallow_trivial_move;
CompactionJobStats compaction_job_stats;
Status status;
if (!error_handler_.IsBGWorkStopped()) {
if (shutting_down_.load(std::memory_order_acquire)) {
status = Status::ShutdownInProgress();
}
} else {
status = error_handler_.GetBGError();
// If we get here, it means a hard error happened after this compaction
// was scheduled by MaybeScheduleFlushOrCompaction(), but before it got
// a chance to execute. Since we didn't pop a cfd from the compaction
// queue, increment unscheduled_compactions_
unscheduled_compactions_++;
}
if (!status.ok()) {
if (is_manual) {
manual_compaction->status = status;
manual_compaction->done = true;
manual_compaction->in_progress = false;
manual_compaction = nullptr;
}
if (c) {
c->ReleaseCompactionFiles(status);
c.reset();
}
return status;
}
if (is_manual) {
// another thread cannot pick up the same work
manual_compaction->in_progress = true;
}
// InternalKey manual_end_storage;
// InternalKey* manual_end = &manual_end_storage;
bool sfm_reserved_compact_space = false;
if (is_manual) {
ManualCompactionState* m = manual_compaction;
assert(m->in_progress);
if (!c) {
m->done = true;
m->manual_end = nullptr;
ROCKS_LOG_BUFFER(log_buffer,
"[%s] Manual compaction from level-%d from %s .. "
"%s; nothing to do\n",
m->cfd->GetName().c_str(), m->input_level,
(m->begin ? m->begin->DebugString().c_str() : "(begin)"),
(m->end ? m->end->DebugString().c_str() : "(end)"));
} else {
// First check if we have enough room to do the compaction
bool enough_room = EnoughRoomForCompaction(
m->cfd, *(c->inputs()), &sfm_reserved_compact_space, log_buffer);
if (!enough_room) {
// Then don't do the compaction
c->ReleaseCompactionFiles(status);
c.reset();
// m's vars will get set properly at the end of this function,
// as long as status == CompactionTooLarge
status = Status::CompactionTooLarge();
} else {
ROCKS_LOG_BUFFER(
log_buffer,
"[%s] Manual compaction from level-%d to level-%d from %s .. "
"%s; will stop at %s\n",
m->cfd->GetName().c_str(), m->input_level, c->output_level(),
(m->begin ? m->begin->DebugString().c_str() : "(begin)"),
(m->end ? m->end->DebugString().c_str() : "(end)"),
((m->done || m->manual_end == nullptr)
? "(end)"
: m->manual_end->DebugString().c_str()));
}
}
} else if (!is_prepicked && !compaction_queue_.empty()) {
if (HasExclusiveManualCompaction()) {
// Can't compact right now, but try again later
TEST_SYNC_POINT("DBImpl::BackgroundCompaction()::Conflict");
// Stay in the compaction queue.
unscheduled_compactions_++;
return Status::OK();
}
// cfd is referenced here
auto cfd = PopFirstFromCompactionQueue();
// We unreference here because the following code will take a Ref() on
// this cfd if it is going to use it (Compaction class holds a
// reference).
// This will all happen under a mutex so we don't have to be afraid of
// somebody else deleting it.
if (cfd->Unref()) {
delete cfd;
// This was the last reference of the column family, so no need to
// compact.
return Status::OK();
}
// Pick up latest mutable CF Options and use it throughout the
// compaction job
// Compaction makes a copy of the latest MutableCFOptions. It should be used
// throughout the compaction procedure to make sure consistency. It will
// eventually be installed into SuperVersion
auto* mutable_cf_options = cfd->GetLatestMutableCFOptions();
if (!mutable_cf_options->disable_auto_compactions && !cfd->IsDropped()) {
// NOTE: try to avoid unnecessary copy of MutableCFOptions if
// compaction is not necessary. Need to make sure mutex is held
// until we make a copy in the following code
TEST_SYNC_POINT("DBImpl::BackgroundCompaction():BeforePickCompaction");
c.reset(cfd->PickCompaction(*mutable_cf_options, log_buffer));
TEST_SYNC_POINT("DBImpl::BackgroundCompaction():AfterPickCompaction");
if (c != nullptr) {
bool enough_room = EnoughRoomForCompaction(
cfd, *(c->inputs()), &sfm_reserved_compact_space, log_buffer);
if (!enough_room) {
// Then don't do the compaction
c->ReleaseCompactionFiles(status);
c->column_family_data()
->current()
->storage_info()
->ComputeCompactionScore(*(c->immutable_cf_options()),
*(c->mutable_cf_options()));
AddToCompactionQueue(cfd);
++unscheduled_compactions_;
c.reset();
// Don't need to sleep here, because BackgroundCallCompaction
// will sleep if !s.ok()
status = Status::CompactionTooLarge();
} else {
// update statistics
MeasureTime(stats_, NUM_FILES_IN_SINGLE_COMPACTION,
c->inputs(0)->size());
// There are three things that can change compaction score:
// 1) When flush or compaction finish. This case is covered by
// InstallSuperVersionAndScheduleWork
// 2) When MutableCFOptions changes. This case is also covered by
// InstallSuperVersionAndScheduleWork, because this is when the new
// options take effect.
// 3) When we Pick a new compaction, we "remove" those files being
// compacted from the calculation, which then influences compaction
// score. Here we check if we need the new compaction even without the
// files that are currently being compacted. If we need another
// compaction, we might be able to execute it in parallel, so we add
// it to the queue and schedule a new thread.
if (cfd->NeedsCompaction()) {
// Yes, we need more compactions!
AddToCompactionQueue(cfd);
++unscheduled_compactions_;
MaybeScheduleFlushOrCompaction();
}
}
}
}
}
if (!c) {
// Nothing to do
ROCKS_LOG_BUFFER(log_buffer, "Compaction nothing to do");
} else if (c->deletion_compaction()) {
// TODO(icanadi) Do we want to honor snapshots here? i.e. not delete old
// file if there is alive snapshot pointing to it
assert(c->num_input_files(1) == 0);
assert(c->level() == 0);
assert(c->column_family_data()->ioptions()->compaction_style ==
kCompactionStyleFIFO);
compaction_job_stats.num_input_files = c->num_input_files(0);
NotifyOnCompactionBegin(c->column_family_data(), c.get(), status,
compaction_job_stats, job_context->job_id);
for (const auto& f : *c->inputs(0)) {
c->edit()->DeleteFile(c->level(), f->fd.GetNumber());
}
status = versions_->LogAndApply(c->column_family_data(),
*c->mutable_cf_options(), c->edit(),
&mutex_, directories_.GetDbDir());
InstallSuperVersionAndScheduleWork(
c->column_family_data(), &job_context->superversion_contexts[0],
*c->mutable_cf_options(), FlushReason::kAutoCompaction);
ROCKS_LOG_BUFFER(log_buffer, "[%s] Deleted %d files\n",
c->column_family_data()->GetName().c_str(),
c->num_input_files(0));
*made_progress = true;
} else if (!trivial_move_disallowed && c->IsTrivialMove()) {
TEST_SYNC_POINT("DBImpl::BackgroundCompaction:TrivialMove");
// Instrument for event update
// TODO(yhchiang): add op details for showing trivial-move.
ThreadStatusUtil::SetColumnFamily(
c->column_family_data(), c->column_family_data()->ioptions()->env,
immutable_db_options_.enable_thread_tracking);
ThreadStatusUtil::SetThreadOperation(ThreadStatus::OP_COMPACTION);
compaction_job_stats.num_input_files = c->num_input_files(0);
NotifyOnCompactionBegin(c->column_family_data(), c.get(), status,
compaction_job_stats, job_context->job_id);
// Move files to next level
int32_t moved_files = 0;
int64_t moved_bytes = 0;
for (unsigned int l = 0; l < c->num_input_levels(); l++) {
if (c->level(l) == c->output_level()) {
continue;
}
for (size_t i = 0; i < c->num_input_files(l); i++) {
FileMetaData* f = c->input(l, i);
c->edit()->DeleteFile(c->level(l), f->fd.GetNumber());
c->edit()->AddFile(c->output_level(), f->fd.GetNumber(),
f->fd.GetPathId(), f->fd.GetFileSize(), f->smallest,
f->largest, f->fd.smallest_seqno,
f->fd.largest_seqno, f->marked_for_compaction);
ROCKS_LOG_BUFFER(
log_buffer,
"[%s] Moving #%" PRIu64 " to level-%d %" PRIu64 " bytes\n",
c->column_family_data()->GetName().c_str(), f->fd.GetNumber(),
c->output_level(), f->fd.GetFileSize());
++moved_files;
moved_bytes += f->fd.GetFileSize();
}
}
status = versions_->LogAndApply(c->column_family_data(),
*c->mutable_cf_options(), c->edit(),
&mutex_, directories_.GetDbDir());
// Use latest MutableCFOptions
InstallSuperVersionAndScheduleWork(
c->column_family_data(), &job_context->superversion_contexts[0],
*c->mutable_cf_options(), FlushReason::kAutoCompaction);
VersionStorageInfo::LevelSummaryStorage tmp;
c->column_family_data()->internal_stats()->IncBytesMoved(c->output_level(),
moved_bytes);
{
event_logger_.LogToBuffer(log_buffer)
<< "job" << job_context->job_id << "event"
<< "trivial_move"
<< "destination_level" << c->output_level() << "files" << moved_files
<< "total_files_size" << moved_bytes;
}
ROCKS_LOG_BUFFER(
log_buffer,
"[%s] Moved #%d files to level-%d %" PRIu64 " bytes %s: %s\n",
c->column_family_data()->GetName().c_str(), moved_files,
c->output_level(), moved_bytes, status.ToString().c_str(),
c->column_family_data()->current()->storage_info()->LevelSummary(&tmp));
*made_progress = true;
// Clear Instrument
ThreadStatusUtil::ResetThreadStatus();
} else if (!is_prepicked && c->output_level() > 0 &&
c->output_level() ==
c->column_family_data()
->current()
->storage_info()
->MaxOutputLevel(
immutable_db_options_.allow_ingest_behind) &&
env_->GetBackgroundThreads(Env::Priority::BOTTOM) > 0) {
// Forward compactions involving last level to the bottom pool if it exists,
// such that compactions unlikely to contribute to write stalls can be
// delayed or deprioritized.
TEST_SYNC_POINT("DBImpl::BackgroundCompaction:ForwardToBottomPriPool");
CompactionArg* ca = new CompactionArg;
ca->db = this;
ca->prepicked_compaction = new PrepickedCompaction;
ca->prepicked_compaction->compaction = c.release();
ca->prepicked_compaction->manual_compaction_state = nullptr;
++bg_bottom_compaction_scheduled_;
env_->Schedule(&DBImpl::BGWorkBottomCompaction, ca, Env::Priority::BOTTOM,
this, &DBImpl::UnscheduleCallback);
} else {
int output_level __attribute__((__unused__));
output_level = c->output_level();
TEST_SYNC_POINT_CALLBACK("DBImpl::BackgroundCompaction:NonTrivial",
&output_level);
SequenceNumber earliest_write_conflict_snapshot;
std::vector<SequenceNumber> snapshot_seqs =
snapshots_.GetAll(&earliest_write_conflict_snapshot);
auto snapshot_checker = snapshot_checker_.get();
if (use_custom_gc_ && snapshot_checker == nullptr) {
snapshot_checker = DisableGCSnapshotChecker::Instance();
}
assert(is_snapshot_supported_ || snapshots_.empty());
CompactionJob compaction_job(
job_context->job_id, c.get(), immutable_db_options_,
env_options_for_compaction_, versions_.get(), &shutting_down_,
preserve_deletes_seqnum_.load(), log_buffer, directories_.GetDbDir(),
GetDataDir(c->column_family_data(), c->output_path_id()), stats_,
&mutex_, &error_handler_, snapshot_seqs, earliest_write_conflict_snapshot,
snapshot_checker, table_cache_, &event_logger_,
c->mutable_cf_options()->paranoid_file_checks,
c->mutable_cf_options()->report_bg_io_stats, dbname_,
&compaction_job_stats);
compaction_job.Prepare();
NotifyOnCompactionBegin(c->column_family_data(), c.get(), status,
compaction_job_stats, job_context->job_id);
mutex_.Unlock();
compaction_job.Run();
TEST_SYNC_POINT("DBImpl::BackgroundCompaction:NonTrivial:AfterRun");
mutex_.Lock();
status = compaction_job.Install(*c->mutable_cf_options());
if (status.ok()) {
InstallSuperVersionAndScheduleWork(
c->column_family_data(), &job_context->superversion_contexts[0],
*c->mutable_cf_options(), FlushReason::kAutoCompaction);
}
*made_progress = true;
}
if (c != nullptr) {
c->ReleaseCompactionFiles(status);
*made_progress = true;
#ifndef ROCKSDB_LITE
// Need to make sure SstFileManager does its bookkeeping
auto sfm = static_cast<SstFileManagerImpl*>(
immutable_db_options_.sst_file_manager.get());
if (sfm && sfm_reserved_compact_space) {
sfm->OnCompactionCompletion(c.get());
}
#endif // ROCKSDB_LITE
NotifyOnCompactionCompleted(c->column_family_data(), c.get(), status,
compaction_job_stats, job_context->job_id);
}
if (status.ok() || status.IsCompactionTooLarge()) {
// Done
} else if (status.IsShutdownInProgress()) {
// Ignore compaction errors found during shutting down
} else {
ROCKS_LOG_WARN(immutable_db_options_.info_log, "Compaction error: %s",
status.ToString().c_str());
error_handler_.SetBGError(status, BackgroundErrorReason::kCompaction);
if (c != nullptr && !is_manual && !error_handler_.IsBGWorkStopped()) {
// Put this cfd back in the compaction queue so we can retry after some
// time
auto cfd = c->column_family_data();
assert(cfd != nullptr);
// Since this compaction failed, we need to recompute the score so it
// takes the original input files into account
c->column_family_data()
->current()
->storage_info()
->ComputeCompactionScore(*(c->immutable_cf_options()),
*(c->mutable_cf_options()));
if (!cfd->queued_for_compaction()) {
AddToCompactionQueue(cfd);
++unscheduled_compactions_;
}
}
}
// this will unref its input_version and column_family_data
c.reset();
if (is_manual) {
ManualCompactionState* m = manual_compaction;
if (!status.ok()) {
m->status = status;
m->done = true;
}
// For universal compaction:
// Because universal compaction always happens at level 0, so one
// compaction will pick up all overlapped files. No files will be
// filtered out due to size limit and left for a successive compaction.
// So we can safely conclude the current compaction.
//
// Also note that, if we don't stop here, then the current compaction
// writes a new file back to level 0, which will be used in successive
// compaction. Hence the manual compaction will never finish.
//
// Stop the compaction if manual_end points to nullptr -- this means
// that we compacted the whole range. manual_end should always point
// to nullptr in case of universal compaction
if (m->manual_end == nullptr) {
m->done = true;
}
if (!m->done) {
// We only compacted part of the requested range. Update *m
// to the range that is left to be compacted.
// Universal and FIFO compactions should always compact the whole range
assert(m->cfd->ioptions()->compaction_style !=
kCompactionStyleUniversal ||
m->cfd->ioptions()->num_levels > 1);
assert(m->cfd->ioptions()->compaction_style != kCompactionStyleFIFO);
m->tmp_storage = *m->manual_end;
m->begin = &m->tmp_storage;
m->incomplete = true;
}
m->in_progress = false; // not being processed anymore
}
TEST_SYNC_POINT("DBImpl::BackgroundCompaction:Finish");
return status;
}
bool DBImpl::HasPendingManualCompaction() {
return (!manual_compaction_dequeue_.empty());
}
void DBImpl::AddManualCompaction(DBImpl::ManualCompactionState* m) {
manual_compaction_dequeue_.push_back(m);
}
void DBImpl::RemoveManualCompaction(DBImpl::ManualCompactionState* m) {
// Remove from queue
std::deque<ManualCompactionState*>::iterator it =
manual_compaction_dequeue_.begin();
while (it != manual_compaction_dequeue_.end()) {
if (m == (*it)) {
it = manual_compaction_dequeue_.erase(it);
return;
}
it++;
}
assert(false);
return;
}
bool DBImpl::ShouldntRunManualCompaction(ManualCompactionState* m) {
if (num_running_ingest_file_ > 0) {
// We need to wait for other IngestExternalFile() calls to finish
// before running a manual compaction.
return true;
}
if (m->exclusive) {
return (bg_bottom_compaction_scheduled_ > 0 ||
bg_compaction_scheduled_ > 0);
}
std::deque<ManualCompactionState*>::iterator it =
manual_compaction_dequeue_.begin();
bool seen = false;
while (it != manual_compaction_dequeue_.end()) {
if (m == (*it)) {
it++;
seen = true;
continue;
} else if (MCOverlap(m, (*it)) && (!seen && !(*it)->in_progress)) {
// Consider the other manual compaction *it, conflicts if:
// overlaps with m
// and (*it) is ahead in the queue and is not yet in progress
return true;
}
it++;
}
return false;
}
bool DBImpl::HaveManualCompaction(ColumnFamilyData* cfd) {
// Remove from priority queue
std::deque<ManualCompactionState*>::iterator it =
manual_compaction_dequeue_.begin();
while (it != manual_compaction_dequeue_.end()) {
if ((*it)->exclusive) {
return true;
}
if ((cfd == (*it)->cfd) && (!((*it)->in_progress || (*it)->done))) {
// Allow automatic compaction if manual compaction is
// in progress
return true;
}
it++;
}
return false;
}
bool DBImpl::HasExclusiveManualCompaction() {
// Remove from priority queue
std::deque<ManualCompactionState*>::iterator it =
manual_compaction_dequeue_.begin();
while (it != manual_compaction_dequeue_.end()) {
if ((*it)->exclusive) {
return true;
}
it++;
}
return false;
}
bool DBImpl::MCOverlap(ManualCompactionState* m, ManualCompactionState* m1) {
if ((m->exclusive) || (m1->exclusive)) {
return true;
}
if (m->cfd != m1->cfd) {
return false;
}
return true;
}
// SuperVersionContext gets created and destructed outside of the lock --
// we use this conveniently to:
// * malloc one SuperVersion() outside of the lock -- new_superversion
// * delete SuperVersion()s outside of the lock -- superversions_to_free
//
// However, if InstallSuperVersionAndScheduleWork() gets called twice with the
// same sv_context, we can't reuse the SuperVersion() that got
// malloced because
// first call already used it. In that rare case, we take a hit and create a
// new SuperVersion() inside of the mutex. We do similar thing
// for superversion_to_free
void DBImpl::InstallSuperVersionAndScheduleWork(
ColumnFamilyData* cfd, SuperVersionContext* sv_context,
const MutableCFOptions& mutable_cf_options,
FlushReason /* flush_reason */) {
// TODO(yanqin) investigate if 'flush_reason' can be removed since it's not
// used.
mutex_.AssertHeld();
// Update max_total_in_memory_state_
size_t old_memtable_size = 0;
auto* old_sv = cfd->GetSuperVersion();
if (old_sv) {
old_memtable_size = old_sv->mutable_cf_options.write_buffer_size *
old_sv->mutable_cf_options.max_write_buffer_number;
}
// this branch is unlikely to step in
if (UNLIKELY(sv_context->new_superversion == nullptr)) {
sv_context->NewSuperVersion();
}
cfd->InstallSuperVersion(sv_context, &mutex_, mutable_cf_options);
// Whenever we install new SuperVersion, we might need to issue new flushes or
// compactions.
SchedulePendingCompaction(cfd);
MaybeScheduleFlushOrCompaction();
// Update max_total_in_memory_state_
max_total_in_memory_state_ = max_total_in_memory_state_ - old_memtable_size +
mutable_cf_options.write_buffer_size *
mutable_cf_options.max_write_buffer_number;
}
// ShouldPurge is called by FindObsoleteFiles when doing a full scan,
// and db mutex (mutex_) should already be held. This function performs a
// linear scan of an vector (files_grabbed_for_purge_) in search of a
// certain element. We expect FindObsoleteFiles with full scan to occur once
// every 10 hours by default, and the size of the vector is small.
// Therefore, the cost is affordable even if the mutex is held.
// Actually, the current implementation of FindObsoleteFiles with
// full_scan=true can issue I/O requests to obtain list of files in
// directories, e.g. env_->getChildren while holding db mutex.
// In the future, if we want to reduce the cost of search, we may try to keep
// the vector sorted.
bool DBImpl::ShouldPurge(uint64_t file_number) const {
for (auto fn : files_grabbed_for_purge_) {
if (file_number == fn) {
return false;
}
}
for (const auto& purge_file_info : purge_queue_) {
if (purge_file_info.number == file_number) {
return false;
}
}
return true;
}
// MarkAsGrabbedForPurge is called by FindObsoleteFiles, and db mutex
// (mutex_) should already be held.
void DBImpl::MarkAsGrabbedForPurge(uint64_t file_number) {
files_grabbed_for_purge_.emplace_back(file_number);
}
void DBImpl::SetSnapshotChecker(SnapshotChecker* snapshot_checker) {
InstrumentedMutexLock l(&mutex_);
// snapshot_checker_ should only set once. If we need to set it multiple
// times, we need to make sure the old one is not deleted while it is still
// using by a compaction job.
assert(!snapshot_checker_);
snapshot_checker_.reset(snapshot_checker);
}
} // namespace rocksdb