// 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" #include #include #include #include #include #include #include #include "db/builder.h" #include "db/db_iter.h" #include "db/dbformat.h" #include "db/filename.h" #include "db/log_reader.h" #include "db/log_writer.h" #include "db/memtable.h" #include "db/memtablelist.h" #include "db/table_cache.h" #include "db/version_set.h" #include "db/write_batch_internal.h" #include "leveldb/db.h" #include "leveldb/env.h" #include "leveldb/statistics.h" #include "leveldb/status.h" #include "leveldb/table.h" #include "leveldb/table_builder.h" #include "port/port.h" #include "table/block.h" #include "table/merger.h" #include "table/two_level_iterator.h" #include "util/coding.h" #include "util/logging.h" #include "util/mutexlock.h" #include "util/build_version.h" #include "util/auto_split_logger.h" namespace leveldb { void dumpLeveldbBuildVersion(Logger * log); static Status NewLogger(const std::string& dbname, const std::string& db_log_dir, Env* env, size_t max_log_file_size, Logger** logger) { std::string db_absolute_path; env->GetAbsolutePath(dbname, &db_absolute_path); if (max_log_file_size > 0) { // need to auto split the log file? AutoSplitLogger* auto_split_logger = new AutoSplitLogger(env, dbname, db_log_dir, max_log_file_size); Status s = auto_split_logger->GetStatus(); if (!s.ok()) { delete auto_split_logger; } else { *logger = auto_split_logger; } return s; } else { // Open a log file in the same directory as the db env->CreateDir(dbname); // In case it does not exist std::string fname = InfoLogFileName(dbname, db_absolute_path, db_log_dir); env->RenameFile(fname, OldInfoLogFileName(dbname, env->NowMicros(), db_absolute_path, db_log_dir)); return env->NewLogger(fname, logger); } } // Information kept for every waiting writer struct DBImpl::Writer { Status status; WriteBatch* batch; bool sync; bool disableWAL; bool done; port::CondVar cv; explicit Writer(port::Mutex* mu) : cv(mu) { } }; struct DBImpl::CompactionState { Compaction* const compaction; // Sequence numbers < smallest_snapshot are not significant since we // will never have to service a snapshot below smallest_snapshot. // Therefore if we have seen a sequence number S <= smallest_snapshot, // we can drop all entries for the same key with sequence numbers < S. SequenceNumber smallest_snapshot; // Files produced by compaction struct Output { uint64_t number; uint64_t file_size; InternalKey smallest, largest; }; std::vector outputs; std::list allocated_file_numbers; // State kept for output being generated WritableFile* outfile; TableBuilder* builder; uint64_t total_bytes; Output* current_output() { return &outputs[outputs.size()-1]; } explicit CompactionState(Compaction* c) : compaction(c), outfile(NULL), builder(NULL), total_bytes(0) { } }; struct DBImpl::DeletionState { // the set of all live files that cannot be deleted std::set live; // a list of all siles that exists in the db directory std::vector allfiles; // the current filenumber, lognumber and prevlognumber // that corresponds to the set of files in 'live'. uint64_t filenumber, lognumber, prevlognumber; // the list of all files to be evicted from the table cahce std::vector files_to_evict; }; // Fix user-supplied options to be reasonable template static void ClipToRange(T* ptr, V minvalue, V maxvalue) { if (static_cast(*ptr) > maxvalue) *ptr = maxvalue; if (static_cast(*ptr) < minvalue) *ptr = minvalue; } Options SanitizeOptions(const std::string& dbname, const InternalKeyComparator* icmp, const InternalFilterPolicy* ipolicy, const Options& src) { Options result = src; result.comparator = icmp; result.filter_policy = (src.filter_policy != NULL) ? ipolicy : NULL; ClipToRange(&result.max_open_files, 20, 50000); ClipToRange(&result.write_buffer_size, 64<<10, 1<<30); ClipToRange(&result.block_size, 1<<10, 4<<20); if (result.info_log == NULL) { Status s = NewLogger(dbname, result.db_log_dir, src.env, result.max_log_file_size, &result.info_log); if (!s.ok()) { // No place suitable for logging result.info_log = NULL; } } if (result.block_cache == NULL && !result.no_block_cache) { result.block_cache = NewLRUCache(8 << 20); } if (src.compression_per_level != NULL) { result.compression_per_level = new CompressionType[src.num_levels]; for (int i = 0; i < src.num_levels; i++) { result.compression_per_level[i] = src.compression_per_level[i]; } } return result; } DBImpl::DBImpl(const Options& options, const std::string& dbname) : env_(options.env), dbname_(dbname), internal_comparator_(options.comparator), options_(SanitizeOptions( dbname, &internal_comparator_, &internal_filter_policy_, options)), internal_filter_policy_(options.filter_policy), owns_info_log_(options_.info_log != options.info_log), owns_cache_(options_.block_cache != options.block_cache), db_lock_(NULL), shutting_down_(NULL), bg_cv_(&mutex_), mem_(new MemTable(internal_comparator_, NumberLevels())), logfile_(NULL), logfile_number_(0), log_(NULL), tmp_batch_(new WriteBatch), bg_compaction_scheduled_(0), bg_logstats_scheduled_(false), manual_compaction_(NULL), logger_(NULL), disable_delete_obsolete_files_(false), delete_obsolete_files_last_run_(0), stall_level0_slowdown_(0), stall_memtable_compaction_(0), stall_level0_num_files_(0), stall_leveln_slowdown_(0), started_at_(options.env->NowMicros()), flush_on_destroy_(false), delayed_writes_(0) { mem_->Ref(); env_->GetAbsolutePath(dbname, &db_absolute_path_); stats_ = new CompactionStats[options.num_levels]; // Reserve ten files or so for other uses and give the rest to TableCache. const int table_cache_size = options_.max_open_files - 10; table_cache_ = new TableCache(dbname_, &options_, table_cache_size); versions_ = new VersionSet(dbname_, &options_, table_cache_, &internal_comparator_); dumpLeveldbBuildVersion(options_.info_log); options_.Dump(options_.info_log); #ifdef USE_SCRIBE logger_ = new ScribeLogger("localhost", 1456); #endif char name[100]; Status st = env_->GetHostName(name, 100L); if(st.ok()) { host_name_ = name; } else { Log(options_.info_log, "Can't get hostname, use localhost as host name."); host_name_ = "localhost"; } last_log_ts = 0; } DBImpl::~DBImpl() { // Wait for background work to finish if (flush_on_destroy_) { FlushMemTable(FlushOptions()); } mutex_.Lock(); shutting_down_.Release_Store(this); // Any non-NULL value is ok while (bg_compaction_scheduled_ || bg_logstats_scheduled_) { bg_cv_.Wait(); } mutex_.Unlock(); if (db_lock_ != NULL) { env_->UnlockFile(db_lock_); } delete versions_; if (mem_ != NULL) mem_->Unref(); imm_.UnrefAll(); delete tmp_batch_; delete log_; delete logfile_; delete table_cache_; delete[] stats_; if (owns_info_log_) { delete options_.info_log; } if (owns_cache_) { delete options_.block_cache; } if (options_.compression_per_level != NULL) { delete options_.compression_per_level; } delete logger_; } // Do not flush and close database elegantly. Simulate a crash. void DBImpl::TEST_Destroy_DBImpl() { // ensure that no new memtable flushes can occur flush_on_destroy_ = false; // wait till all background compactions are done. mutex_.Lock(); while (bg_compaction_scheduled_ || bg_logstats_scheduled_) { bg_cv_.Wait(); } // Prevent new compactions from occuring. const int LargeNumber = 10000000; bg_compaction_scheduled_ += LargeNumber; mutex_.Unlock(); // force release the lock file. if (db_lock_ != NULL) { env_->UnlockFile(db_lock_); } } Status DBImpl::NewDB() { VersionEdit new_db(NumberLevels()); new_db.SetComparatorName(user_comparator()->Name()); new_db.SetLogNumber(0); new_db.SetNextFile(2); new_db.SetLastSequence(0); const std::string manifest = DescriptorFileName(dbname_, 1); WritableFile* file; Status s = env_->NewWritableFile(manifest, &file); if (!s.ok()) { return s; } { log::Writer log(file); std::string record; new_db.EncodeTo(&record); s = log.AddRecord(record); if (s.ok()) { s = file->Close(); } } delete file; if (s.ok()) { // Make "CURRENT" file that points to the new manifest file. s = SetCurrentFile(env_, dbname_, 1); } else { env_->DeleteFile(manifest); } return s; } void DBImpl::MaybeIgnoreError(Status* s) const { if (s->ok() || options_.paranoid_checks) { // No change needed } else { Log(options_.info_log, "Ignoring error %s", s->ToString().c_str()); *s = Status::OK(); } } // Returns the list of live files in 'live' and the list // of all files in the filesystem in 'allfiles'. void DBImpl::FindObsoleteFiles(DeletionState& deletion_state) { mutex_.AssertHeld(); // if deletion is disabled, do nothing if (disable_delete_obsolete_files_) { return; } // This method is costly when the number of files is large. // Do not allow it to trigger more often than once in // delete_obsolete_files_period_micros. if (options_.delete_obsolete_files_period_micros != 0) { const uint64_t now_micros = env_->NowMicros(); if (delete_obsolete_files_last_run_ + options_.delete_obsolete_files_period_micros > now_micros) { return; } delete_obsolete_files_last_run_ = now_micros; } // Make a set of all of the live files deletion_state.live = pending_outputs_; versions_->AddLiveFiles(&deletion_state.live); // set of all files in the directory env_->GetChildren(dbname_, &deletion_state.allfiles); // Ignore errors // store the current filenum, lognum, etc deletion_state.filenumber = versions_->ManifestFileNumber(); deletion_state.lognumber = versions_->LogNumber(); deletion_state.prevlognumber = versions_->PrevLogNumber(); } // Diffs the files listed in filenames and those that do not // belong to live files are posibly removed. If the removed file // is a sst file, then it returns the file number in files_to_evict. // It is not necesary to hold the mutex when invoking this method. void DBImpl::PurgeObsoleteFiles(DeletionState& state) { uint64_t number; FileType type; std::vector old_log_files; for (size_t i = 0; i < state.allfiles.size(); i++) { if (ParseFileName(state.allfiles[i], &number, &type)) { bool keep = true; switch (type) { case kLogFile: keep = ((number >= state.lognumber) || (number == state.prevlognumber)); break; case kDescriptorFile: // Keep my manifest file, and any newer incarnations' // (in case there is a race that allows other incarnations) keep = (number >= state.filenumber); break; case kTableFile: keep = (state.live.find(number) != state.live.end()); break; case kTempFile: // Any temp files that are currently being written to must // be recorded in pending_outputs_, which is inserted into "live" keep = (state.live.find(number) != state.live.end()); break; case kInfoLogFile: keep = true; if (number != 0) { old_log_files.push_back(state.allfiles[i]); } break; case kCurrentFile: case kDBLockFile: keep = true; break; } if (!keep) { if (type == kTableFile) { // record the files to be evicted from the cache state.files_to_evict.push_back(number); } Log(options_.info_log, "Delete type=%d #%lld\n", int(type), static_cast(number)); Status st = env_->DeleteFile(dbname_ + "/" + state.allfiles[i]); if(!st.ok()) { Log(options_.info_log, "Delete type=%d #%lld FAILED\n", int(type), static_cast(number)); } } } } // Delete old log files. int old_log_file_count = old_log_files.size(); if (old_log_file_count >= KEEP_LOG_FILE_NUM && !options_.db_log_dir.empty()) { std::sort(old_log_files.begin(), old_log_files.end()); for (int i = 0; i >= (old_log_file_count - KEEP_LOG_FILE_NUM); i++) { std::string& to_delete = old_log_files.at(i); // Log(options_.info_log, "Delete type=%d %s\n", // int(kInfoLogFile), to_delete.c_str()); env_->DeleteFile(dbname_ + "/" + to_delete); } } } void DBImpl::EvictObsoleteFiles(DeletionState& state) { for (unsigned int i = 0; i < state.files_to_evict.size(); i++) { table_cache_->Evict(state.files_to_evict[i]); } } void DBImpl::DeleteObsoleteFiles() { mutex_.AssertHeld(); DeletionState deletion_state; std::set live; std::vector allfiles; std::vector files_to_evict; FindObsoleteFiles(deletion_state); PurgeObsoleteFiles(deletion_state); EvictObsoleteFiles(deletion_state); } Status DBImpl::Recover(VersionEdit* edit, bool no_log_recory, bool error_if_log_file_exist) { mutex_.AssertHeld(); // Ignore error from CreateDir since the creation of the DB is // committed only when the descriptor is created, and this directory // may already exist from a previous failed creation attempt. env_->CreateDir(dbname_); assert(db_lock_ == NULL); Status s = env_->LockFile(LockFileName(dbname_), &db_lock_); if (!s.ok()) { return s; } if (!env_->FileExists(CurrentFileName(dbname_))) { if (options_.create_if_missing) { s = NewDB(); if (!s.ok()) { return s; } } else { return Status::InvalidArgument( dbname_, "does not exist (create_if_missing is false)"); } } else { if (options_.error_if_exists) { return Status::InvalidArgument( dbname_, "exists (error_if_exists is true)"); } } s = versions_->Recover(); if (s.ok()) { SequenceNumber max_sequence(0); // Recover from all newer log files than the ones named in the // descriptor (new log files may have been added by the previous // incarnation without registering them in the descriptor). // // Note that PrevLogNumber() is no longer used, but we pay // attention to it in case we are recovering a database // produced by an older version of leveldb. const uint64_t min_log = versions_->LogNumber(); const uint64_t prev_log = versions_->PrevLogNumber(); std::vector filenames; s = env_->GetChildren(dbname_, &filenames); if (!s.ok()) { return s; } uint64_t number; FileType type; std::vector logs; for (size_t i = 0; i < filenames.size(); i++) { if (ParseFileName(filenames[i], &number, &type) && type == kLogFile && ((number >= min_log) || (number == prev_log))) { logs.push_back(number); } } if (logs.size() > 0 && error_if_log_file_exist) { return Status::Corruption("" "The db was opened in readonly mode with error_if_log_file_exist" "flag but a log file already exists"); } if (no_log_recory) { return s; } // Recover in the order in which the logs were generated std::sort(logs.begin(), logs.end()); for (size_t i = 0; i < logs.size(); i++) { s = RecoverLogFile(logs[i], edit, &max_sequence); // The previous incarnation may not have written any MANIFEST // records after allocating this log number. So we manually // update the file number allocation counter in VersionSet. versions_->MarkFileNumberUsed(logs[i]); } if (s.ok()) { if (versions_->LastSequence() < max_sequence) { versions_->SetLastSequence(max_sequence); } } } return s; } Status DBImpl::RecoverLogFile(uint64_t log_number, VersionEdit* edit, SequenceNumber* max_sequence) { struct LogReporter : public log::Reader::Reporter { Env* env; Logger* info_log; const char* fname; Status* status; // NULL if options_.paranoid_checks==false virtual void Corruption(size_t bytes, const Status& s) { Log(info_log, "%s%s: dropping %d bytes; %s", (this->status == NULL ? "(ignoring error) " : ""), fname, static_cast(bytes), s.ToString().c_str()); if (this->status != NULL && this->status->ok()) *this->status = s; } }; mutex_.AssertHeld(); // Open the log file std::string fname = LogFileName(dbname_, log_number); SequentialFile* file; Status status = env_->NewSequentialFile(fname, &file); if (!status.ok()) { MaybeIgnoreError(&status); return status; } // Create the log reader. LogReporter reporter; reporter.env = env_; reporter.info_log = options_.info_log; reporter.fname = fname.c_str(); reporter.status = (options_.paranoid_checks ? &status : NULL); // We intentially make log::Reader do checksumming even if // paranoid_checks==false so that corruptions cause entire commits // to be skipped instead of propagating bad information (like overly // large sequence numbers). log::Reader reader(file, &reporter, true/*checksum*/, 0/*initial_offset*/); Log(options_.info_log, "Recovering log #%llu", (unsigned long long) log_number); // Read all the records and add to a memtable std::string scratch; Slice record; WriteBatch batch; MemTable* mem = NULL; while (reader.ReadRecord(&record, &scratch) && status.ok()) { if (record.size() < 12) { reporter.Corruption( record.size(), Status::Corruption("log record too small")); continue; } WriteBatchInternal::SetContents(&batch, record); if (mem == NULL) { mem = new MemTable(internal_comparator_, NumberLevels()); mem->Ref(); } status = WriteBatchInternal::InsertInto(&batch, mem); MaybeIgnoreError(&status); if (!status.ok()) { break; } const SequenceNumber last_seq = WriteBatchInternal::Sequence(&batch) + WriteBatchInternal::Count(&batch) - 1; if (last_seq > *max_sequence) { *max_sequence = last_seq; } if (mem->ApproximateMemoryUsage() > options_.write_buffer_size) { status = WriteLevel0TableForRecovery(mem, edit); if (!status.ok()) { // Reflect errors immediately so that conditions like full // file-systems cause the DB::Open() to fail. break; } mem->Unref(); mem = NULL; } } if (status.ok() && mem != NULL) { status = WriteLevel0TableForRecovery(mem, edit); // Reflect errors immediately so that conditions like full // file-systems cause the DB::Open() to fail. } if (mem != NULL) mem->Unref(); delete file; return status; } Status DBImpl::WriteLevel0TableForRecovery(MemTable* mem, VersionEdit* edit) { mutex_.AssertHeld(); const uint64_t start_micros = env_->NowMicros(); FileMetaData meta; meta.number = versions_->NewFileNumber(); pending_outputs_.insert(meta.number); Iterator* iter = mem->NewIterator(); Log(options_.info_log, "Level-0 table #%llu: started", (unsigned long long) meta.number); Status s; { mutex_.Unlock(); s = BuildTable(dbname_, env_, options_, table_cache_, iter, &meta); mutex_.Lock(); } Log(options_.info_log, "Level-0 table #%llu: %lld bytes %s", (unsigned long long) meta.number, (unsigned long long) meta.file_size, s.ToString().c_str()); delete iter; pending_outputs_.erase(meta.number); // Note that if file_size is zero, the file has been deleted and // should not be added to the manifest. int level = 0; if (s.ok() && meta.file_size > 0) { edit->AddFile(level, meta.number, meta.file_size, meta.smallest, meta.largest); } CompactionStats stats; stats.micros = env_->NowMicros() - start_micros; stats.bytes_written = meta.file_size; stats.files_out_levelnp1 = 1; stats_[level].Add(stats); return s; } Status DBImpl::WriteLevel0Table(MemTable* mem, VersionEdit* edit, uint64_t* filenumber) { mutex_.AssertHeld(); const uint64_t start_micros = env_->NowMicros(); FileMetaData meta; meta.number = versions_->NewFileNumber(); *filenumber = meta.number; pending_outputs_.insert(meta.number); Iterator* iter = mem->NewIterator(); Log(options_.info_log, "Level-0 flush table #%llu: started", (unsigned long long) meta.number); Version* base = versions_->current(); base->Ref(); Status s; { mutex_.Unlock(); s = BuildTable(dbname_, env_, options_, table_cache_, iter, &meta); mutex_.Lock(); } base->Unref(); Log(options_.info_log, "Level-0 flush table #%llu: %lld bytes %s", (unsigned long long) meta.number, (unsigned long long) meta.file_size, s.ToString().c_str()); delete iter; // re-acquire the most current version base = versions_->current(); // There could be multiple threads writing to its own level-0 file. // The pending_outputs cannot be cleared here, otherwise this newly // created file might not be considered as a live-file by another // compaction thread that is concurrently deleting obselete files. // The pending_outputs can be cleared only after the new version is // committed so that other threads can recognize this file as a // valid one. // pending_outputs_.erase(meta.number); // Note that if file_size is zero, the file has been deleted and // should not be added to the manifest. int level = 0; if (s.ok() && meta.file_size > 0) { const Slice min_user_key = meta.smallest.user_key(); const Slice max_user_key = meta.largest.user_key(); // if we have more than 1 background thread, then we cannot // insert files directly into higher levels because some other // threads could be concurrently producing compacted files for // that key range. if (base != NULL && options_.max_background_compactions <= 1) { level = base->PickLevelForMemTableOutput(min_user_key, max_user_key); } edit->AddFile(level, meta.number, meta.file_size, meta.smallest, meta.largest); } CompactionStats stats; stats.micros = env_->NowMicros() - start_micros; stats.bytes_written = meta.file_size; stats_[level].Add(stats); return s; } Status DBImpl::CompactMemTable(bool* madeProgress) { mutex_.AssertHeld(); assert(imm_.size() != 0); if (!imm_.IsFlushPending()) { Log(options_.info_log, "Memcompaction already in progress"); Status s = Status::IOError("Memcompaction already in progress"); return s; } // Save the contents of the earliest memtable as a new Table // This will release and re-acquire the mutex. uint64_t file_number; MemTable* m = imm_.PickMemtableToFlush(); if (m == NULL) { Log(options_.info_log, "Nothing in memstore to flush"); Status s = Status::IOError("Nothing in memstore to flush"); return s; } // record the logfile_number_ before we release the mutex VersionEdit* edit = m->GetEdits(); edit->SetPrevLogNumber(0); edit->SetLogNumber(logfile_number_); // Earlier logs no longer needed Status s = WriteLevel0Table(m, edit, &file_number); if (s.ok() && shutting_down_.Acquire_Load()) { s = Status::IOError("Deleting DB during memtable compaction"); } // Replace immutable memtable with the generated Table s = imm_.InstallMemtableFlushResults(m, versions_, s, &mutex_, options_.info_log, file_number, pending_outputs_); if (s.ok()) { if (madeProgress) { *madeProgress = 1; } MaybeScheduleLogDBDeployStats(); // we could have deleted obsolete files here, but it is not // absolutely necessary because it could be also done as part // of other background compaction } return s; } void DBImpl::CompactRange(const Slice* begin, const Slice* end) { int max_level_with_files = 1; { MutexLock l(&mutex_); Version* base = versions_->current(); for (int level = 1; level < NumberLevels(); level++) { if (base->OverlapInLevel(level, begin, end)) { max_level_with_files = level; } } } TEST_CompactMemTable(); // TODO(sanjay): Skip if memtable does not overlap for (int level = 0; level < max_level_with_files; level++) { TEST_CompactRange(level, begin, end); } } int DBImpl::NumberLevels() { return options_.num_levels; } int DBImpl::MaxMemCompactionLevel() { return options_.max_mem_compaction_level; } int DBImpl::Level0StopWriteTrigger() { return options_.level0_stop_writes_trigger; } Status DBImpl::Flush(const FlushOptions& options) { Status status = FlushMemTable(options); return status; } void DBImpl::TEST_CompactRange(int level, const Slice* begin,const Slice* end) { assert(level >= 0); InternalKey begin_storage, end_storage; ManualCompaction manual; manual.level = level; manual.done = false; manual.in_progress = false; if (begin == NULL) { manual.begin = NULL; } else { begin_storage = InternalKey(*begin, kMaxSequenceNumber, kValueTypeForSeek); manual.begin = &begin_storage; } if (end == NULL) { manual.end = NULL; } else { end_storage = InternalKey(*end, 0, static_cast(0)); manual.end = &end_storage; } MutexLock l(&mutex_); // When a manual compaction arrives, temporarily throttle down // the number of background compaction threads to 1. This is // needed to ensure that this manual compaction can compact // any range of keys/files. We artificialy increase // bg_compaction_scheduled_ by a large number, this causes // the system to have a single background thread. Now, // this manual compaction can progress without stomping // on any other concurrent compactions. const int LargeNumber = 10000000; const int newvalue = options_.max_background_compactions-1; bg_compaction_scheduled_ += LargeNumber; while (bg_compaction_scheduled_ > LargeNumber) { Log(options_.info_log, "Manual compaction request waiting for background threads to fall below 1"); bg_cv_.Wait(); } Log(options_.info_log, "Manual compaction starting"); while (!manual.done) { while (manual_compaction_ != NULL) { bg_cv_.Wait(); } manual_compaction_ = &manual; if (bg_compaction_scheduled_ == LargeNumber) { bg_compaction_scheduled_ = newvalue; } MaybeScheduleCompaction(); while (manual_compaction_ == &manual) { bg_cv_.Wait(); } } assert(!manual.in_progress); // wait till there are no background threads scheduled bg_compaction_scheduled_ += LargeNumber; while (bg_compaction_scheduled_ > LargeNumber + newvalue) { Log(options_.info_log, "Manual compaction resetting background threads"); bg_cv_.Wait(); } bg_compaction_scheduled_ = 0; } Status DBImpl::FlushMemTable(const FlushOptions& options) { // NULL batch means just wait for earlier writes to be done Status s = Write(WriteOptions(), NULL); if (s.ok() && options.wait) { // Wait until the compaction completes s = WaitForCompactMemTable(); } return s; } Status DBImpl::WaitForCompactMemTable() { Status s; // Wait until the compaction completes MutexLock l(&mutex_); while (imm_.size() > 0 && bg_error_.ok()) { bg_cv_.Wait(); } if (imm_.size() != 0) { s = bg_error_; } return s; } Status DBImpl::TEST_CompactMemTable() { return FlushMemTable(FlushOptions()); } Status DBImpl::TEST_WaitForCompactMemTable() { return WaitForCompactMemTable(); } Status DBImpl::TEST_WaitForCompact() { // Wait until the compaction completes MutexLock l(&mutex_); while (bg_compaction_scheduled_ && bg_error_.ok()) { bg_cv_.Wait(); } return bg_error_; } void DBImpl::MaybeScheduleCompaction() { mutex_.AssertHeld(); if (bg_compaction_scheduled_ >= options_.max_background_compactions) { // Already scheduled } else if (shutting_down_.Acquire_Load()) { // DB is being deleted; no more background compactions } else if (!imm_.IsFlushPending() && manual_compaction_ == NULL && !versions_->NeedsCompaction()) { // No work to be done } else { bg_compaction_scheduled_++; env_->Schedule(&DBImpl::BGWork, this); } } void DBImpl::BGWork(void* db) { reinterpret_cast(db)->BackgroundCall(); } void DBImpl::BackgroundCall() { bool madeProgress; DeletionState deletion_state; MutexLock l(&mutex_); // Log(options_.info_log, "XXX BG Thread %llx process new work item", pthread_self()); assert(bg_compaction_scheduled_); if (!shutting_down_.Acquire_Load()) { Status s = BackgroundCompaction(&madeProgress, deletion_state); if (!s.ok()) { // 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. bg_cv_.SignalAll(); // In case a waiter can proceed despite the error Log(options_.info_log, "Waiting after background compaction error: %s", s.ToString().c_str()); mutex_.Unlock(); env_->SleepForMicroseconds(1000000); mutex_.Lock(); } } // delete unnecessary files if any, this is done outside the mutex if (!deletion_state.live.empty()) { mutex_.Unlock(); PurgeObsoleteFiles(deletion_state); EvictObsoleteFiles(deletion_state); mutex_.Lock(); } bg_compaction_scheduled_--; MaybeScheduleLogDBDeployStats(); // Previous compaction may have produced too many files in a level, // So reschedule another compaction if we made progress in the // last compaction. if (madeProgress) { MaybeScheduleCompaction(); } bg_cv_.SignalAll(); } Status DBImpl::BackgroundCompaction(bool* madeProgress, DeletionState& deletion_state) { *madeProgress = false; mutex_.AssertHeld(); while (imm_.IsFlushPending()) { Log(options_.info_log, "BackgroundCompaction doing CompactMemTable, compaction slots available %d", options_.max_background_compactions - bg_compaction_scheduled_); Status stat = CompactMemTable(madeProgress); if (!stat.ok()) { return stat; } } Compaction* c = NULL; bool is_manual = (manual_compaction_ != NULL) && (manual_compaction_->in_progress == false); InternalKey manual_end; if (is_manual) { ManualCompaction* m = manual_compaction_; assert(!m->in_progress); m->in_progress = true; // another thread cannot pick up the same work c = versions_->CompactRange(m->level, m->begin, m->end); m->done = (c == NULL); if (c != NULL) { manual_end = c->input(0, c->num_input_files(0) - 1)->largest; } Log(options_.info_log, "Manual compaction at level-%d from %s .. %s; will stop at %s\n", m->level, (m->begin ? m->begin->DebugString().c_str() : "(begin)"), (m->end ? m->end->DebugString().c_str() : "(end)"), (m->done ? "(end)" : manual_end.DebugString().c_str())); } else if (!options_.disable_auto_compactions) { c = versions_->PickCompaction(); } Status status; if (c == NULL) { // Nothing to do Log(options_.info_log, "Compaction nothing to do"); } else if (!is_manual && c->IsTrivialMove()) { // Move file to next level assert(c->num_input_files(0) == 1); FileMetaData* f = c->input(0, 0); c->edit()->DeleteFile(c->level(), f->number); c->edit()->AddFile(c->level() + 1, f->number, f->file_size, f->smallest, f->largest); status = versions_->LogAndApply(c->edit(), &mutex_); VersionSet::LevelSummaryStorage tmp; Log(options_.info_log, "Moved #%lld to level-%d %lld bytes %s: %s\n", static_cast(f->number), c->level() + 1, static_cast(f->file_size), status.ToString().c_str(), versions_->LevelSummary(&tmp)); versions_->ReleaseCompactionFiles(c, status); *madeProgress = true; } else { CompactionState* compact = new CompactionState(c); status = DoCompactionWork(compact); CleanupCompaction(compact); versions_->ReleaseCompactionFiles(c, status); c->ReleaseInputs(); FindObsoleteFiles(deletion_state); *madeProgress = true; } delete c; if (status.ok()) { // Done } else if (shutting_down_.Acquire_Load()) { // Ignore compaction errors found during shutting down } else { Log(options_.info_log, "Compaction error: %s", status.ToString().c_str()); if (options_.paranoid_checks && bg_error_.ok()) { bg_error_ = status; } } if (is_manual) { ManualCompaction* m = manual_compaction_; if (!status.ok()) { 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. m->tmp_storage = manual_end; m->begin = &m->tmp_storage; } m->in_progress = false; // not being processed anymore manual_compaction_ = NULL; } return status; } void DBImpl::CleanupCompaction(CompactionState* compact) { mutex_.AssertHeld(); if (compact->builder != NULL) { // May happen if we get a shutdown call in the middle of compaction compact->builder->Abandon(); delete compact->builder; } else { assert(compact->outfile == NULL); } delete compact->outfile; for (size_t i = 0; i < compact->outputs.size(); i++) { const CompactionState::Output& out = compact->outputs[i]; pending_outputs_.erase(out.number); } delete compact; } // Allocate the file numbers for the output file. We allocate as // many output file numbers as there are files in level+1. // Insert them into pending_outputs so that they do not get deleted. void DBImpl::AllocateCompactionOutputFileNumbers(CompactionState* compact) { mutex_.AssertHeld(); assert(compact != NULL); assert(compact->builder == NULL); int filesNeeded = compact->compaction->num_input_files(1); for (int i = 0; i < filesNeeded; i++) { uint64_t file_number = versions_->NewFileNumber(); pending_outputs_.insert(file_number); compact->allocated_file_numbers.push_back(file_number); } } // Frees up unused file number. void DBImpl::ReleaseCompactionUnusedFileNumbers(CompactionState* compact) { mutex_.AssertHeld(); for (std::list::iterator it = compact->allocated_file_numbers.begin(); it != compact->allocated_file_numbers.end(); ++it) { uint64_t file_number = *it; pending_outputs_.erase(file_number); // Log(options_.info_log, "XXX releasing unused file num %d", file_number); } } Status DBImpl::OpenCompactionOutputFile(CompactionState* compact) { assert(compact != NULL); assert(compact->builder == NULL); uint64_t file_number; // If we have not yet exhausted the pre-allocated file numbers, // then use the one from the front. Otherwise, we have to acquire // the heavyweight lock and allocate a new file number. if (!compact->allocated_file_numbers.empty()) { file_number = compact->allocated_file_numbers.front(); compact->allocated_file_numbers.pop_front(); } else { mutex_.Lock(); file_number = versions_->NewFileNumber(); pending_outputs_.insert(file_number); mutex_.Unlock(); } CompactionState::Output out; out.number = file_number; out.smallest.Clear(); out.largest.Clear(); compact->outputs.push_back(out); // Make the output file std::string fname = TableFileName(dbname_, file_number); Status s = env_->NewWritableFile(fname, &compact->outfile); if (s.ok()) { compact->builder = new TableBuilder(options_, compact->outfile, compact->compaction->level() + 1); } return s; } Status DBImpl::FinishCompactionOutputFile(CompactionState* compact, Iterator* input) { assert(compact != NULL); assert(compact->outfile != NULL); assert(compact->builder != NULL); const uint64_t output_number = compact->current_output()->number; assert(output_number != 0); // Check for iterator errors Status s = input->status(); const uint64_t current_entries = compact->builder->NumEntries(); if (s.ok()) { s = compact->builder->Finish(); } else { compact->builder->Abandon(); } const uint64_t current_bytes = compact->builder->FileSize(); compact->current_output()->file_size = current_bytes; compact->total_bytes += current_bytes; delete compact->builder; compact->builder = NULL; // Finish and check for file errors if (s.ok() && !options_.disableDataSync) { if (options_.use_fsync) { s = compact->outfile->Fsync(); } else { s = compact->outfile->Sync(); } } if (s.ok()) { s = compact->outfile->Close(); } delete compact->outfile; compact->outfile = NULL; if (s.ok() && current_entries > 0) { // Verify that the table is usable Iterator* iter = table_cache_->NewIterator(ReadOptions(), output_number, current_bytes); s = iter->status(); delete iter; if (s.ok()) { Log(options_.info_log, "Generated table #%llu: %lld keys, %lld bytes", (unsigned long long) output_number, (unsigned long long) current_entries, (unsigned long long) current_bytes); } } return s; } Status DBImpl::InstallCompactionResults(CompactionState* compact) { mutex_.AssertHeld(); // 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 (options_.paranoid_checks && !versions_->VerifyCompactionFileConsistency(compact->compaction)) { Log(options_.info_log, "Compaction %d@%d + %d@%d files aborted", compact->compaction->num_input_files(0), compact->compaction->level(), compact->compaction->num_input_files(1), compact->compaction->level() + 1); return Status::IOError("Compaction input files inconsistent"); } Log(options_.info_log, "Compacted %d@%d + %d@%d files => %lld bytes", compact->compaction->num_input_files(0), compact->compaction->level(), compact->compaction->num_input_files(1), compact->compaction->level() + 1, static_cast(compact->total_bytes)); // Add compaction outputs compact->compaction->AddInputDeletions(compact->compaction->edit()); const int level = compact->compaction->level(); for (size_t i = 0; i < compact->outputs.size(); i++) { const CompactionState::Output& out = compact->outputs[i]; compact->compaction->edit()->AddFile( level + 1, out.number, out.file_size, out.smallest, out.largest); } return versions_->LogAndApply(compact->compaction->edit(), &mutex_); } Status DBImpl::DoCompactionWork(CompactionState* compact) { int64_t imm_micros = 0; // Micros spent doing imm_ compactions Log(options_.info_log, "Compacting %d@%d + %d@%d files, compaction slots available %d", compact->compaction->num_input_files(0), compact->compaction->level(), compact->compaction->num_input_files(1), compact->compaction->level() + 1, options_.max_background_compactions - bg_compaction_scheduled_); char scratch[256]; compact->compaction->Summary(scratch, sizeof(scratch)); Log(options_.info_log, "Compaction start summary: %s\n", scratch); assert(versions_->NumLevelFiles(compact->compaction->level()) > 0); assert(compact->builder == NULL); assert(compact->outfile == NULL); if (snapshots_.empty()) { compact->smallest_snapshot = versions_->LastSequence(); } else { compact->smallest_snapshot = snapshots_.oldest()->number_; } // Allocate the output file numbers before we release the lock AllocateCompactionOutputFileNumbers(compact); // Release mutex while we're actually doing the compaction work mutex_.Unlock(); const uint64_t start_micros = env_->NowMicros(); Iterator* input = versions_->MakeInputIterator(compact->compaction); input->SeekToFirst(); Status status; ParsedInternalKey ikey; std::string current_user_key; bool has_current_user_key = false; SequenceNumber last_sequence_for_key = kMaxSequenceNumber; for (; input->Valid() && !shutting_down_.Acquire_Load(); ) { // Prioritize immutable compaction work if (imm_.imm_flush_needed.NoBarrier_Load() != NULL) { const uint64_t imm_start = env_->NowMicros(); mutex_.Lock(); if (imm_.IsFlushPending()) { CompactMemTable(); bg_cv_.SignalAll(); // Wakeup MakeRoomForWrite() if necessary } mutex_.Unlock(); imm_micros += (env_->NowMicros() - imm_start); } Slice key = input->key(); Slice value = input->value(); Slice* compaction_filter_value = NULL; if (compact->compaction->ShouldStopBefore(key) && compact->builder != NULL) { status = FinishCompactionOutputFile(compact, input); if (!status.ok()) { break; } } // Handle key/value, add to state, etc. bool drop = false; if (!ParseInternalKey(key, &ikey)) { // Do not hide error keys current_user_key.clear(); has_current_user_key = false; last_sequence_for_key = kMaxSequenceNumber; } else { if (!has_current_user_key || user_comparator()->Compare(ikey.user_key, Slice(current_user_key)) != 0) { // First occurrence of this user key current_user_key.assign(ikey.user_key.data(), ikey.user_key.size()); has_current_user_key = true; last_sequence_for_key = kMaxSequenceNumber; } if (last_sequence_for_key <= compact->smallest_snapshot) { // Hidden by an newer entry for same user key drop = true; // (A) RecordTick(options_.statistics, COMPACTION_KEY_DROP_NEWER_ENTRY); } else if (ikey.type == kTypeDeletion && ikey.sequence <= compact->smallest_snapshot && compact->compaction->IsBaseLevelForKey(ikey.user_key)) { // For this user key: // (1) there is no data in higher levels // (2) data in lower levels will have larger sequence numbers // (3) data in layers that are being compacted here and have // smaller sequence numbers will be dropped in the next // few iterations of this loop (by rule (A) above). // Therefore this deletion marker is obsolete and can be dropped. drop = true; RecordTick(options_.statistics, COMPACTION_KEY_DROP_OBSOLETE); } else if (options_.CompactionFilter != NULL && ikey.type != kTypeDeletion && ikey.sequence < compact->smallest_snapshot) { // If the user has specified a compaction filter, then invoke // it. If this key is not visible via any snapshot and the // return value of the compaction filter is true and then // drop this key from the output. drop = options_.CompactionFilter(options_.compaction_filter_args, compact->compaction->level(), ikey.user_key, value, &compaction_filter_value); if (drop) { RecordTick(options_.statistics, COMPACTION_KEY_DROP_USER); } // If the application wants to change the value, then do so here. if (compaction_filter_value != NULL) { value = *compaction_filter_value; delete compaction_filter_value; } } last_sequence_for_key = ikey.sequence; } #if 0 Log(options_.info_log, " Compact: %s, seq %d, type: %d %d, drop: %d, is_base: %d, " "%d smallest_snapshot: %d", ikey.user_key.ToString().c_str(), (int)ikey.sequence, ikey.type, kTypeValue, drop, compact->compaction->IsBaseLevelForKey(ikey.user_key), (int)last_sequence_for_key, (int)compact->smallest_snapshot); #endif if (!drop) { // Open output file if necessary if (compact->builder == NULL) { status = OpenCompactionOutputFile(compact); if (!status.ok()) { break; } } if (compact->builder->NumEntries() == 0) { compact->current_output()->smallest.DecodeFrom(key); } compact->current_output()->largest.DecodeFrom(key); compact->builder->Add(key, value); // Close output file if it is big enough if (compact->builder->FileSize() >= compact->compaction->MaxOutputFileSize()) { status = FinishCompactionOutputFile(compact, input); if (!status.ok()) { break; } } } input->Next(); } if (status.ok() && shutting_down_.Acquire_Load()) { status = Status::IOError("Deleting DB during compaction"); } if (status.ok() && compact->builder != NULL) { status = FinishCompactionOutputFile(compact, input); } if (status.ok()) { status = input->status(); } delete input; input = NULL; CompactionStats stats; stats.micros = env_->NowMicros() - start_micros - imm_micros; stats.files_in_leveln = compact->compaction->num_input_files(0); stats.files_in_levelnp1 = compact->compaction->num_input_files(1); stats.files_out_levelnp1 = compact->outputs.size(); for (int i = 0; i < compact->compaction->num_input_files(0); i++) stats.bytes_readn += compact->compaction->input(0, i)->file_size; for (int i = 0; i < compact->compaction->num_input_files(1); i++) stats.bytes_readnp1 += compact->compaction->input(1, i)->file_size; for (size_t i = 0; i < compact->outputs.size(); i++) { stats.bytes_written += compact->outputs[i].file_size; } mutex_.Lock(); stats_[compact->compaction->level() + 1].Add(stats); // if there were any unused file number (mostly in case of // compaction error), free up the entry from pending_putputs ReleaseCompactionUnusedFileNumbers(compact); if (status.ok()) { status = InstallCompactionResults(compact); } VersionSet::LevelSummaryStorage tmp; Log(options_.info_log, "compacted to: %s, %.1f MB/sec, level %d, files in(%d, %d) out(%d) " "MB in(%.1f, %.1f) out(%.1f), amplify(%.1f) %s\n", versions_->LevelSummary(&tmp), (stats.bytes_readn + stats.bytes_readnp1 + stats.bytes_written) / (double) stats.micros, compact->compaction->level() + 1, stats.files_in_leveln, stats.files_in_levelnp1, stats.files_out_levelnp1, stats.bytes_readn / 1048576.0, stats.bytes_readnp1 / 1048576.0, stats.bytes_written / 1048576.0, (stats.bytes_written + stats.bytes_readnp1) / (double) stats.bytes_readn, status.ToString().c_str()); return status; } namespace { struct IterState { port::Mutex* mu; Version* version; std::vector mem; // includes both mem_ and imm_ }; static void CleanupIteratorState(void* arg1, void* arg2) { IterState* state = reinterpret_cast(arg1); state->mu->Lock(); for (unsigned int i = 0; i < state->mem.size(); i++) { state->mem[i]->Unref(); } state->version->Unref(); state->mu->Unlock(); delete state; } } // namespace Iterator* DBImpl::NewInternalIterator(const ReadOptions& options, SequenceNumber* latest_snapshot) { IterState* cleanup = new IterState; mutex_.Lock(); *latest_snapshot = versions_->LastSequence(); // Collect together all needed child iterators for mem std::vector list; mem_->Ref(); list.push_back(mem_->NewIterator()); cleanup->mem.push_back(mem_); // Collect together all needed child iterators for imm_ std::vector immutables; imm_.GetMemTables(&immutables); for (unsigned int i = 0; i < immutables.size(); i++) { MemTable* m = immutables[i]; m->Ref(); list.push_back(m->NewIterator()); cleanup->mem.push_back(m); } // Collect iterators for files in L0 - Ln versions_->current()->AddIterators(options, &list); Iterator* internal_iter = NewMergingIterator(&internal_comparator_, &list[0], list.size()); versions_->current()->Ref(); cleanup->mu = &mutex_; cleanup->version = versions_->current(); internal_iter->RegisterCleanup(CleanupIteratorState, cleanup, NULL); mutex_.Unlock(); return internal_iter; } Iterator* DBImpl::TEST_NewInternalIterator() { SequenceNumber ignored; return NewInternalIterator(ReadOptions(), &ignored); } int64_t DBImpl::TEST_MaxNextLevelOverlappingBytes() { MutexLock l(&mutex_); return versions_->MaxNextLevelOverlappingBytes(); } Status DBImpl::Get(const ReadOptions& options, const Slice& key, std::string* value) { Status s; MutexLock l(&mutex_); SequenceNumber snapshot; if (options.snapshot != NULL) { snapshot = reinterpret_cast(options.snapshot)->number_; } else { snapshot = versions_->LastSequence(); } MemTable* mem = mem_; MemTableList imm = imm_; Version* current = versions_->current(); mem->Ref(); imm.RefAll(); current->Ref(); bool have_stat_update = false; Version::GetStats stats; // Unlock while reading from files and memtables { mutex_.Unlock(); // First look in the memtable, then in the immutable memtable (if any). LookupKey lkey(key, snapshot); if (mem->Get(lkey, value, &s)) { // Done } else if (imm.Get(lkey, value, &s)) { // Done } else { s = current->Get(options, lkey, value, &stats); have_stat_update = true; } mutex_.Lock(); } if (!options_.disable_seek_compaction && have_stat_update && current->UpdateStats(stats)) { MaybeScheduleCompaction(); } mem->Unref(); imm.UnrefAll(); current->Unref(); return s; } Iterator* DBImpl::NewIterator(const ReadOptions& options) { SequenceNumber latest_snapshot; Iterator* internal_iter = NewInternalIterator(options, &latest_snapshot); return NewDBIterator( &dbname_, env_, user_comparator(), internal_iter, (options.snapshot != NULL ? reinterpret_cast(options.snapshot)->number_ : latest_snapshot)); } const Snapshot* DBImpl::GetSnapshot() { MutexLock l(&mutex_); return snapshots_.New(versions_->LastSequence()); } void DBImpl::ReleaseSnapshot(const Snapshot* s) { MutexLock l(&mutex_); snapshots_.Delete(reinterpret_cast(s)); } // Convenience methods Status DBImpl::Put(const WriteOptions& o, const Slice& key, const Slice& val) { return DB::Put(o, key, val); } Status DBImpl::Delete(const WriteOptions& options, const Slice& key) { return DB::Delete(options, key); } Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) { Writer w(&mutex_); w.batch = my_batch; w.sync = options.sync; w.disableWAL = options.disableWAL; w.done = false; MutexLock l(&mutex_); writers_.push_back(&w); while (!w.done && &w != writers_.front()) { w.cv.Wait(); } if (w.done) { return w.status; } // May temporarily unlock and wait. Status status = MakeRoomForWrite(my_batch == NULL); uint64_t last_sequence = versions_->LastSequence(); Writer* last_writer = &w; if (status.ok() && my_batch != NULL) { // NULL batch is for compactions WriteBatch* updates = BuildBatchGroup(&last_writer); WriteBatchInternal::SetSequence(updates, last_sequence + 1); last_sequence += WriteBatchInternal::Count(updates); // Add to log and apply to memtable. We can release the lock // during this phase since &w is currently responsible for logging // and protects against concurrent loggers and concurrent writes // into mem_. { mutex_.Unlock(); if (options.disableWAL) { flush_on_destroy_ = true; } if (!options.disableWAL) { status = log_->AddRecord(WriteBatchInternal::Contents(updates)); if (status.ok() && options.sync) { if (options_.use_fsync) { status = logfile_->Fsync(); } else { status = logfile_->Sync(); } } } if (status.ok()) { status = WriteBatchInternal::InsertInto(updates, mem_); } mutex_.Lock(); } if (updates == tmp_batch_) tmp_batch_->Clear(); versions_->SetLastSequence(last_sequence); } while (true) { Writer* ready = writers_.front(); writers_.pop_front(); if (ready != &w) { ready->status = status; ready->done = true; ready->cv.Signal(); } if (ready == last_writer) break; } // Notify new head of write queue if (!writers_.empty()) { writers_.front()->cv.Signal(); } return status; } // REQUIRES: Writer list must be non-empty // REQUIRES: First writer must have a non-NULL batch WriteBatch* DBImpl::BuildBatchGroup(Writer** last_writer) { assert(!writers_.empty()); Writer* first = writers_.front(); WriteBatch* result = first->batch; assert(result != NULL); size_t size = WriteBatchInternal::ByteSize(first->batch); // Allow the group to grow up to a maximum size, but if the // original write is small, limit the growth so we do not slow // down the small write too much. size_t max_size = 1 << 20; if (size <= (128<<10)) { max_size = size + (128<<10); } *last_writer = first; std::deque::iterator iter = writers_.begin(); ++iter; // Advance past "first" for (; iter != writers_.end(); ++iter) { Writer* w = *iter; if (w->sync && !first->sync) { // Do not include a sync write into a batch handled by a non-sync write. break; } if (!w->disableWAL && first->disableWAL) { // Do not include a write that needs WAL into a batch that has // WAL disabled. break; } if (w->batch != NULL) { size += WriteBatchInternal::ByteSize(w->batch); if (size > max_size) { // Do not make batch too big break; } // Append to *reuslt if (result == first->batch) { // Switch to temporary batch instead of disturbing caller's batch result = tmp_batch_; assert(WriteBatchInternal::Count(result) == 0); WriteBatchInternal::Append(result, first->batch); } WriteBatchInternal::Append(result, w->batch); } *last_writer = w; } return result; } // REQUIRES: mutex_ is held // REQUIRES: this thread is currently at the front of the writer queue Status DBImpl::MakeRoomForWrite(bool force) { mutex_.AssertHeld(); assert(!writers_.empty()); bool allow_delay = !force; Status s; double score; while (true) { if (!bg_error_.ok()) { // Yield previous error s = bg_error_; break; } else if ( allow_delay && versions_->NumLevelFiles(0) >= options_.level0_slowdown_writes_trigger) { // We are getting close to hitting a hard limit on the number of // L0 files. Rather than delaying a single write by several // seconds when we hit the hard limit, start delaying each // individual write by 1ms to reduce latency variance. Also, // this delay hands over some CPU to the compaction thread in // case it is sharing the same core as the writer. mutex_.Unlock(); uint64_t t1 = env_->NowMicros(); env_->SleepForMicroseconds(1000); uint64_t delayed = env_->NowMicros() - t1; stall_level0_slowdown_ += delayed; allow_delay = false; // Do not delay a single write more than once //Log(options_.info_log, // "delaying write %llu usecs for level0_slowdown_writes_trigger\n", // (long long unsigned int)delayed); mutex_.Lock(); delayed_writes_++; } else if (!force && (mem_->ApproximateMemoryUsage() <= options_.write_buffer_size)) { // There is room in current memtable if (allow_delay) { DelayLoggingAndReset(); } break; } else if (imm_.size() == options_.max_write_buffer_number - 1) { // We have filled up the current memtable, but the previous // ones are still being compacted, so we wait. DelayLoggingAndReset(); Log(options_.info_log, "wait for memtable compaction...\n"); uint64_t t1 = env_->NowMicros(); bg_cv_.Wait(); stall_memtable_compaction_ += env_->NowMicros() - t1; } else if (versions_->NumLevelFiles(0) >= options_.level0_stop_writes_trigger) { // There are too many level-0 files. DelayLoggingAndReset(); uint64_t t1 = env_->NowMicros(); Log(options_.info_log, "wait for fewer level0 files...\n"); bg_cv_.Wait(); stall_level0_num_files_ += env_->NowMicros() - t1; } else if ( allow_delay && options_.rate_limit > 1.0 && (score = versions_->MaxCompactionScore()) > options_.rate_limit) { // Delay a write when the compaction score for any level is too large. mutex_.Unlock(); uint64_t t1 = env_->NowMicros(); env_->SleepForMicroseconds(1000); uint64_t delayed = env_->NowMicros() - t1; stall_leveln_slowdown_ += delayed; allow_delay = false; // Do not delay a single write more than once Log(options_.info_log, "delaying write %llu usecs for rate limits with max score %.2f\n", (long long unsigned int)delayed, score); mutex_.Lock(); } else { // Attempt to switch to a new memtable and trigger compaction of old DelayLoggingAndReset(); assert(versions_->PrevLogNumber() == 0); uint64_t new_log_number = versions_->NewFileNumber(); WritableFile* lfile = NULL; s = env_->NewWritableFile(LogFileName(dbname_, new_log_number), &lfile); if (!s.ok()) { // Avoid chewing through file number space in a tight loop. versions_->ReuseFileNumber(new_log_number); break; } delete log_; delete logfile_; logfile_ = lfile; logfile_number_ = new_log_number; log_ = new log::Writer(lfile); imm_.Add(mem_); mem_ = new MemTable(internal_comparator_, NumberLevels()); mem_->Ref(); force = false; // Do not force another compaction if have room MaybeScheduleCompaction(); } } return s; } bool DBImpl::GetProperty(const Slice& property, std::string* value) { value->clear(); MutexLock l(&mutex_); Slice in = property; Slice prefix("leveldb."); if (!in.starts_with(prefix)) return false; in.remove_prefix(prefix.size()); if (in.starts_with("num-files-at-level")) { in.remove_prefix(strlen("num-files-at-level")); uint64_t level; bool ok = ConsumeDecimalNumber(&in, &level) && in.empty(); if (!ok || (int)level >= NumberLevels()) { return false; } else { char buf[100]; snprintf(buf, sizeof(buf), "%d", versions_->NumLevelFiles(static_cast(level))); *value = buf; return true; } } else if (in == "stats") { char buf[1000]; uint64_t total_bytes = 0; uint64_t micros_up = env_->NowMicros() - started_at_; double seconds_up = micros_up / 1000000.0; // Pardon the long line but I think it is easier to read this way. snprintf(buf, sizeof(buf), " Compactions\n" "Level Files Size(MB) Time(sec) Read(MB) Write(MB) Rn(MB) Rnp1(MB) Wnew(MB) Amplify Read(MB/s) Write(MB/s) Rn Rnp1 Wnp1 NewW Count\n" "------------------------------------------------------------------------------------------------------------------------------------------------------------\n" ); value->append(buf); for (int level = 0; level < NumberLevels(); level++) { int files = versions_->NumLevelFiles(level); if (stats_[level].micros > 0 || files > 0) { int64_t bytes_read = stats_[level].bytes_readn + stats_[level].bytes_readnp1; int64_t bytes_new = stats_[level].bytes_written - stats_[level].bytes_readnp1; double amplify = (stats_[level].bytes_readn == 0) ? 0.0 : (stats_[level].bytes_written + stats_[level].bytes_readnp1) / (double) stats_[level].bytes_readn; total_bytes += bytes_read + stats_[level].bytes_written; snprintf( buf, sizeof(buf), "%3d %8d %8.0f %9.0f %9.0f %9.0f %9.0f %9.0f %9.0f %7.1f %9.1f %11.1f %8d %8d %8d %8d %8d\n", level, files, versions_->NumLevelBytes(level) / 1048576.0, stats_[level].micros / 1e6, bytes_read / 1048576.0, stats_[level].bytes_written / 1048576.0, stats_[level].bytes_readn / 1048576.0, stats_[level].bytes_readnp1 / 1048576.0, bytes_new / 1048576.0, amplify, (bytes_read / 1048576.0) / (stats_[level].micros / 1000000.0), (stats_[level].bytes_written / 1048576.0) / (stats_[level].micros / 1000000.0), stats_[level].files_in_leveln, stats_[level].files_in_levelnp1, stats_[level].files_out_levelnp1, stats_[level].files_out_levelnp1 - stats_[level].files_in_levelnp1, stats_[level].count); value->append(buf); } } snprintf(buf, sizeof(buf), "Amplification: %.1f rate, %.2f GB in, %.2f GB out, %.2f MB/sec in, %.2f MB/sec out\n", (double) total_bytes / stats_[0].bytes_written, stats_[0].bytes_written / (1048576.0 * 1024), total_bytes / (1048576.0 * 1024), stats_[0].bytes_written / 1048576.0 / seconds_up, total_bytes / 1048576.0 / seconds_up); value->append(buf); snprintf(buf, sizeof(buf), "Uptime(secs): %.1f\n", seconds_up); value->append(buf); snprintf(buf, sizeof(buf), "Stalls(secs): %.3f level0_slowdown, %.3f level0_numfiles, " "%.3f memtable_compaction, %.3f leveln_slowdown\n", stall_level0_slowdown_ / 1000000.0, stall_level0_num_files_ / 1000000.0, stall_memtable_compaction_ / 1000000.0, stall_leveln_slowdown_ / 1000000.0); value->append(buf); return true; } else if (in == "sstables") { *value = versions_->current()->DebugString(); return true; } return false; } void DBImpl::GetApproximateSizes( const Range* range, int n, uint64_t* sizes) { // TODO(opt): better implementation Version* v; { MutexLock l(&mutex_); versions_->current()->Ref(); v = versions_->current(); } for (int i = 0; i < n; i++) { // Convert user_key into a corresponding internal key. InternalKey k1(range[i].start, kMaxSequenceNumber, kValueTypeForSeek); InternalKey k2(range[i].limit, kMaxSequenceNumber, kValueTypeForSeek); uint64_t start = versions_->ApproximateOffsetOf(v, k1); uint64_t limit = versions_->ApproximateOffsetOf(v, k2); sizes[i] = (limit >= start ? limit - start : 0); } { MutexLock l(&mutex_); v->Unref(); } } inline void DBImpl::DelayLoggingAndReset() { if (delayed_writes_ > 0) { Log(options_.info_log, "delayed %d write...\n", delayed_writes_ ); delayed_writes_ = 0; } } // Default implementations of convenience methods that subclasses of DB // can call if they wish Status DB::Put(const WriteOptions& opt, const Slice& key, const Slice& value) { WriteBatch batch; batch.Put(key, value); return Write(opt, &batch); } Status DB::Delete(const WriteOptions& opt, const Slice& key) { WriteBatch batch; batch.Delete(key); return Write(opt, &batch); } DB::~DB() { } Status DB::Open(const Options& options, const std::string& dbname, DB** dbptr) { *dbptr = NULL; if (options.block_cache != NULL && options.no_block_cache) { return Status::InvalidArgument( "no_block_cache is true while block_cache is not NULL"); } DBImpl* impl = new DBImpl(options, dbname); impl->mutex_.Lock(); VersionEdit edit(impl->NumberLevels()); Status s = impl->Recover(&edit); // Handles create_if_missing, error_if_exists if (s.ok()) { uint64_t new_log_number = impl->versions_->NewFileNumber(); WritableFile* lfile; s = options.env->NewWritableFile(LogFileName(dbname, new_log_number), &lfile); if (s.ok()) { edit.SetLogNumber(new_log_number); impl->logfile_ = lfile; impl->logfile_number_ = new_log_number; impl->log_ = new log::Writer(lfile); s = impl->versions_->LogAndApply(&edit, &impl->mutex_); } if (s.ok()) { impl->DeleteObsoleteFiles(); impl->MaybeScheduleCompaction(); impl->MaybeScheduleLogDBDeployStats(); } } impl->mutex_.Unlock(); if (s.ok()) { *dbptr = impl; } else { delete impl; } return s; } Snapshot::~Snapshot() { } Status DestroyDB(const std::string& dbname, const Options& options) { Env* env = options.env; std::vector filenames; // Ignore error in case directory does not exist env->GetChildren(dbname, &filenames); if (filenames.empty()) { return Status::OK(); } FileLock* lock; const std::string lockname = LockFileName(dbname); Status result = env->LockFile(lockname, &lock); if (result.ok()) { uint64_t number; FileType type; for (size_t i = 0; i < filenames.size(); i++) { if (ParseFileName(filenames[i], &number, &type) && type != kDBLockFile) { // Lock file will be deleted at end Status del = env->DeleteFile(dbname + "/" + filenames[i]); if (result.ok() && !del.ok()) { result = del; } } } env->UnlockFile(lock); // Ignore error since state is already gone env->DeleteFile(lockname); env->DeleteDir(dbname); // Ignore error in case dir contains other files } return result; } // // A global method that can dump out the build version void dumpLeveldbBuildVersion(Logger * log) { Log(log, "Git sha %s", leveldb_build_git_sha); Log(log, "Git datetime %s", leveldb_build_git_datetime); Log(log, "Compile time %s %s", leveldb_build_compile_time, leveldb_build_compile_date); } } // namespace leveldb