// Copyright (c) 2013, Facebook, Inc. All rights reserved. // This source code is licensed under the BSD-style license found in the // LICENSE file in the root directory of this source tree. An additional grant // of patent rights can be found in the PATENTS file in the same directory. // // Copyright (c) 2011 The LevelDB Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. See the AUTHORS file for names of contributors. #include "db/compaction_job.h" #ifndef __STDC_FORMAT_MACROS #define __STDC_FORMAT_MACROS #endif #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/merge_helper.h" #include "db/memtable_list.h" #include "db/merge_context.h" #include "db/version_set.h" #include "port/port.h" #include "port/likely.h" #include "rocksdb/db.h" #include "rocksdb/env.h" #include "rocksdb/statistics.h" #include "rocksdb/status.h" #include "rocksdb/table.h" #include "table/block.h" #include "table/block_based_table_factory.h" #include "table/merger.h" #include "table/table_builder.h" #include "table/two_level_iterator.h" #include "util/coding.h" #include "util/logging.h" #include "util/log_buffer.h" #include "util/mutexlock.h" #include "util/perf_context_imp.h" #include "util/iostats_context_imp.h" #include "util/stop_watch.h" #include "util/sync_point.h" namespace rocksdb { struct CompactionJob::CompactionState { Compaction* const compaction; // If there were two snapshots with seq numbers s1 and // s2 and s1 < s2, and if we find two instances of a key k1 then lies // entirely within s1 and s2, then the earlier version of k1 can be safely // deleted because that version is not visible in any snapshot. std::vector existing_snapshots; // Files produced by compaction struct Output { uint64_t number; uint32_t path_id; uint64_t file_size; InternalKey smallest, largest; SequenceNumber smallest_seqno, largest_seqno; }; std::vector outputs; std::list allocated_file_numbers; // State kept for output being generated std::unique_ptr outfile; std::unique_ptr builder; uint64_t total_bytes; Output* current_output() { return &outputs[outputs.size() - 1]; } explicit CompactionState(Compaction* c) : compaction(c), total_bytes(0) {} // Create a client visible context of this compaction CompactionFilter::Context GetFilterContextV1() { CompactionFilter::Context context; context.is_full_compaction = compaction->IsFullCompaction(); context.is_manual_compaction = compaction->IsManualCompaction(); return context; } // Create a client visible context of this compaction CompactionFilterContext GetFilterContext() { CompactionFilterContext context; context.is_full_compaction = compaction->IsFullCompaction(); context.is_manual_compaction = compaction->IsManualCompaction(); return context; } std::vector key_str_buf_; std::vector existing_value_str_buf_; // new_value_buf_ will only be appended if a value changes std::vector new_value_buf_; // if values_changed_buf_[i] is true // new_value_buf_ will add a new entry with the changed value std::vector value_changed_buf_; // to_delete_buf_[i] is true iff key_buf_[i] is deleted std::vector to_delete_buf_; std::vector other_key_str_buf_; std::vector other_value_str_buf_; std::vector combined_key_buf_; std::vector combined_value_buf_; std::string cur_prefix_; // Buffers the kv-pair that will be run through compaction filter V2 // in the future. void BufferKeyValueSlices(const Slice& key, const Slice& value) { key_str_buf_.emplace_back(key.ToString()); existing_value_str_buf_.emplace_back(value.ToString()); } // Buffers the kv-pair that will not be run through compaction filter V2 // in the future. void BufferOtherKeyValueSlices(const Slice& key, const Slice& value) { other_key_str_buf_.emplace_back(key.ToString()); other_value_str_buf_.emplace_back(value.ToString()); } // Add a kv-pair to the combined buffer void AddToCombinedKeyValueSlices(const Slice& key, const Slice& value) { // The real strings are stored in the batch buffers combined_key_buf_.emplace_back(key); combined_value_buf_.emplace_back(value); } // Merging the two buffers void MergeKeyValueSliceBuffer(const InternalKeyComparator* comparator) { size_t i = 0; size_t j = 0; size_t total_size = key_str_buf_.size() + other_key_str_buf_.size(); combined_key_buf_.reserve(total_size); combined_value_buf_.reserve(total_size); while (i + j < total_size) { int comp_res = 0; if (i < key_str_buf_.size() && j < other_key_str_buf_.size()) { comp_res = comparator->Compare(key_str_buf_[i], other_key_str_buf_[j]); } else if (i >= key_str_buf_.size() && j < other_key_str_buf_.size()) { comp_res = 1; } else if (j >= other_key_str_buf_.size() && i < key_str_buf_.size()) { comp_res = -1; } if (comp_res > 0) { AddToCombinedKeyValueSlices(other_key_str_buf_[j], other_value_str_buf_[j]); j++; } else if (comp_res < 0) { AddToCombinedKeyValueSlices(key_str_buf_[i], existing_value_str_buf_[i]); i++; } } } void CleanupBatchBuffer() { to_delete_buf_.clear(); key_str_buf_.clear(); existing_value_str_buf_.clear(); new_value_buf_.clear(); value_changed_buf_.clear(); to_delete_buf_.shrink_to_fit(); key_str_buf_.shrink_to_fit(); existing_value_str_buf_.shrink_to_fit(); new_value_buf_.shrink_to_fit(); value_changed_buf_.shrink_to_fit(); other_key_str_buf_.clear(); other_value_str_buf_.clear(); other_key_str_buf_.shrink_to_fit(); other_value_str_buf_.shrink_to_fit(); } void CleanupMergedBuffer() { combined_key_buf_.clear(); combined_value_buf_.clear(); combined_key_buf_.shrink_to_fit(); combined_value_buf_.shrink_to_fit(); } }; CompactionJob::CompactionJob( Compaction* compaction, const DBOptions& db_options, const MutableCFOptions& mutable_cf_options, const EnvOptions& env_options, VersionSet* versions, port::Mutex* db_mutex, std::atomic* shutting_down, FileNumToPathIdMap* pending_outputs, LogBuffer* log_buffer, Directory* db_directory, Statistics* stats, SnapshotList* snapshots, bool is_snapshot_supported, std::shared_ptr table_cache, std::function yield_callback) : compact_(new CompactionState(compaction)), compaction_stats_(1), db_options_(db_options), mutable_cf_options_(mutable_cf_options), env_options_(env_options), env_(db_options.env), versions_(versions), db_mutex_(db_mutex), shutting_down_(shutting_down), pending_outputs_(pending_outputs), log_buffer_(log_buffer), db_directory_(db_directory), stats_(stats), snapshots_(snapshots), is_snapshot_supported_(is_snapshot_supported), table_cache_(std::move(table_cache)), yield_callback_(std::move(yield_callback)) {} void CompactionJob::Prepare() { db_mutex_->AssertHeld(); compact_->CleanupBatchBuffer(); compact_->CleanupMergedBuffer(); // Generate file_levels_ for compaction berfore making Iterator compact_->compaction->GenerateFileLevels(); ColumnFamilyData* cfd = compact_->compaction->column_family_data(); LogToBuffer( log_buffer_, "[%s] Compacting %d@%d + %d@%d files, score %.2f", cfd->GetName().c_str(), compact_->compaction->num_input_files(0), compact_->compaction->level(), compact_->compaction->num_input_files(1), compact_->compaction->output_level(), compact_->compaction->score()); char scratch[2345]; compact_->compaction->Summary(scratch, sizeof(scratch)); LogToBuffer(log_buffer_, "[%s] Compaction start summary: %s\n", cfd->GetName().c_str(), scratch); assert(cfd->current()->storage_info()->NumLevelFiles( compact_->compaction->level()) > 0); assert(compact_->builder == nullptr); assert(!compact_->outfile); visible_at_tip_ = 0; latest_snapshot_ = 0; // TODO(icanadi) move snapshots_ out of CompactionJob snapshots_->getAll(compact_->existing_snapshots); if (compact_->existing_snapshots.size() == 0) { // optimize for fast path if there are no snapshots visible_at_tip_ = versions_->LastSequence(); earliest_snapshot_ = visible_at_tip_; } else { latest_snapshot_ = compact_->existing_snapshots.back(); // Add the current seqno as the 'latest' virtual // snapshot to the end of this list. compact_->existing_snapshots.push_back(versions_->LastSequence()); earliest_snapshot_ = compact_->existing_snapshots[0]; } // Is this compaction producing files at the bottommost level? bottommost_level_ = compact_->compaction->BottomMostLevel(); // Allocate the output file numbers before we release the lock AllocateCompactionOutputFileNumbers(); } Status CompactionJob::Run() { log_buffer_->FlushBufferToLog(); ColumnFamilyData* cfd = compact_->compaction->column_family_data(); int num_output_records = 0; const uint64_t start_micros = env_->NowMicros(); std::unique_ptr input( versions_->MakeInputIterator(compact_->compaction)); input->SeekToFirst(); Status status; ParsedInternalKey ikey; std::unique_ptr compaction_filter_from_factory_v2 = nullptr; auto context = compact_->GetFilterContext(); compaction_filter_from_factory_v2 = cfd->ioptions()->compaction_filter_factory_v2->CreateCompactionFilterV2( context); auto compaction_filter_v2 = compaction_filter_from_factory_v2.get(); int64_t imm_micros = 0; // Micros spent doing imm_ compactions if (!compaction_filter_v2) { status = ProcessKeyValueCompaction(&imm_micros, input.get(), false, &num_output_records); } else { // temp_backup_input always point to the start of the current buffer // temp_backup_input = backup_input; // iterate through input, // 1) buffer ineligible keys and value keys into 2 separate buffers; // 2) send value_buffer to compaction filter and alternate the values; // 3) merge value_buffer with ineligible_value_buffer; // 4) run the modified "compaction" using the old for loop. bool prefix_initialized = false; shared_ptr backup_input( versions_->MakeInputIterator(compact_->compaction)); backup_input->SeekToFirst(); while (backup_input->Valid() && !shutting_down_->load(std::memory_order_acquire) && !cfd->IsDropped()) { // FLUSH preempts compaction // TODO(icanadi) this currently only checks if flush is necessary on // compacting column family. we should also check if flush is necessary on // other column families, too imm_micros += yield_callback_(); Slice key = backup_input->key(); Slice value = backup_input->value(); if (!ParseInternalKey(key, &ikey)) { // log error Log(db_options_.info_log, "[%s] Failed to parse key: %s", cfd->GetName().c_str(), key.ToString().c_str()); continue; } else { const SliceTransform* transformer = cfd->ioptions()->compaction_filter_factory_v2->GetPrefixExtractor(); const auto key_prefix = transformer->Transform(ikey.user_key); if (!prefix_initialized) { compact_->cur_prefix_ = key_prefix.ToString(); prefix_initialized = true; } // If the prefix remains the same, keep buffering if (key_prefix.compare(Slice(compact_->cur_prefix_)) == 0) { // Apply the compaction filter V2 to all the kv pairs sharing // the same prefix if (ikey.type == kTypeValue && (visible_at_tip_ || ikey.sequence > latest_snapshot_)) { // Buffer all keys sharing the same prefix for CompactionFilterV2 // Iterate through keys to check prefix compact_->BufferKeyValueSlices(key, value); } else { // buffer ineligible keys compact_->BufferOtherKeyValueSlices(key, value); } backup_input->Next(); continue; // finish changing values for eligible keys } else { // Now prefix changes, this batch is done. // Call compaction filter on the buffered values to change the value if (compact_->key_str_buf_.size() > 0) { CallCompactionFilterV2(compaction_filter_v2); } compact_->cur_prefix_ = key_prefix.ToString(); } } // Merge this batch of data (values + ineligible keys) compact_->MergeKeyValueSliceBuffer(&cfd->internal_comparator()); // Done buffering for the current prefix. Spit it out to disk // Now just iterate through all the kv-pairs status = ProcessKeyValueCompaction(&imm_micros, input.get(), true, &num_output_records); if (!status.ok()) { break; } // After writing the kv-pairs, we can safely remove the reference // to the string buffer and clean them up compact_->CleanupBatchBuffer(); compact_->CleanupMergedBuffer(); // Buffer the key that triggers the mismatch in prefix if (ikey.type == kTypeValue && (visible_at_tip_ || ikey.sequence > latest_snapshot_)) { compact_->BufferKeyValueSlices(key, value); } else { compact_->BufferOtherKeyValueSlices(key, value); } backup_input->Next(); if (!backup_input->Valid()) { // If this is the single last value, we need to merge it. if (compact_->key_str_buf_.size() > 0) { CallCompactionFilterV2(compaction_filter_v2); } compact_->MergeKeyValueSliceBuffer(&cfd->internal_comparator()); status = ProcessKeyValueCompaction(&imm_micros, input.get(), true, &num_output_records); compact_->CleanupBatchBuffer(); compact_->CleanupMergedBuffer(); } } // done processing all prefix batches // finish the last batch if (compact_->key_str_buf_.size() > 0) { CallCompactionFilterV2(compaction_filter_v2); } compact_->MergeKeyValueSliceBuffer(&cfd->internal_comparator()); status = ProcessKeyValueCompaction(&imm_micros, input.get(), true, &num_output_records); } // checking for compaction filter v2 if (status.ok() && (shutting_down_->load(std::memory_order_acquire) || cfd->IsDropped())) { status = Status::ShutdownInProgress( "Database shutdown or Column family drop during compaction"); } if (status.ok() && compact_->builder != nullptr) { status = FinishCompactionOutputFile(input.get()); } if (status.ok()) { status = input->status(); } input.reset(); if (db_directory_ && !db_options_.disableDataSync) { db_directory_->Fsync(); } compaction_stats_.micros = env_->NowMicros() - start_micros - imm_micros; compaction_stats_.files_in_leveln = compact_->compaction->num_input_files(0); compaction_stats_.files_in_levelnp1 = compact_->compaction->num_input_files(1); MeasureTime(stats_, COMPACTION_TIME, compaction_stats_.micros); int num_output_files = compact_->outputs.size(); if (compact_->builder != nullptr) { // An error occurred so ignore the last output. assert(num_output_files > 0); --num_output_files; } compaction_stats_.files_out_levelnp1 = num_output_files; uint64_t num_input_records = 0; for (int i = 0; i < compact_->compaction->num_input_files(0); i++) { compaction_stats_.bytes_readn += compact_->compaction->input(0, i)->fd.GetFileSize(); compaction_stats_.num_input_records += compact_->compaction->input(0, i)->num_entries; num_input_records += compact_->compaction->input(0, i)->num_entries; } for (int i = 0; i < compact_->compaction->num_input_files(1); i++) { compaction_stats_.bytes_readnp1 += compact_->compaction->input(1, i)->fd.GetFileSize(); num_input_records += compact_->compaction->input(1, i)->num_entries; } for (int i = 0; i < num_output_files; i++) { compaction_stats_.bytes_written += compact_->outputs[i].file_size; } compaction_stats_.num_dropped_records = static_cast(num_input_records) - num_output_records; RecordCompactionIOStats(); LogFlush(db_options_.info_log); return status; } Status CompactionJob::Install(Status status) { db_mutex_->AssertHeld(); ColumnFamilyData* cfd = compact_->compaction->column_family_data(); cfd->internal_stats()->AddCompactionStats( compact_->compaction->output_level(), compaction_stats_); // if there were any unused file number (mostly in case of // compaction error), free up the entry from pending_putputs ReleaseCompactionUnusedFileNumbers(); if (status.ok()) { status = InstallCompactionResults(); } VersionStorageInfo::LevelSummaryStorage tmp; const auto& stats = compaction_stats_; LogToBuffer(log_buffer_, "[%s] compacted to: %s, MB/sec: %.1f rd, %.1f wr, level %d, " "files in(%d, %d) out(%d) " "MB in(%.1f, %.1f) out(%.1f), read-write-amplify(%.1f) " "write-amplify(%.1f) %s, records in: %d, records dropped: %d\n", cfd->GetName().c_str(), cfd->current()->storage_info()->LevelSummary(&tmp), (stats.bytes_readn + stats.bytes_readnp1) / static_cast(stats.micros), stats.bytes_written / static_cast(stats.micros), compact_->compaction->output_level(), 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 + stats.bytes_readn) / static_cast(stats.bytes_readn), stats.bytes_written / static_cast(stats.bytes_readn), status.ToString().c_str(), stats.num_input_records, stats.num_dropped_records); CleanupCompaction(status); return status; } // Allocate the file numbers for the output file. We allocate as // many output file numbers as there are files in level+1 (at least one) // Insert them into pending_outputs so that they do not get deleted. void CompactionJob::AllocateCompactionOutputFileNumbers() { db_mutex_->AssertHeld(); assert(compact_->builder == nullptr); int filesNeeded = compact_->compaction->num_input_files(1); for (int i = 0; i < std::max(filesNeeded, 1); i++) { uint64_t file_number = versions_->NewFileNumber(); pending_outputs_->insert( {file_number, compact_->compaction->GetOutputPathId()}); compact_->allocated_file_numbers.push_back(file_number); } } Status CompactionJob::ProcessKeyValueCompaction(int64_t* imm_micros, Iterator* input, bool is_compaction_v2, int* num_output_records) { assert(num_output_records != nullptr); size_t combined_idx = 0; Status status; std::string compaction_filter_value; ParsedInternalKey ikey; IterKey current_user_key; bool has_current_user_key = false; IterKey delete_key; SequenceNumber last_sequence_for_key __attribute__((unused)) = kMaxSequenceNumber; SequenceNumber visible_in_snapshot = kMaxSequenceNumber; ColumnFamilyData* cfd = compact_->compaction->column_family_data(); MergeHelper merge(cfd->user_comparator(), cfd->ioptions()->merge_operator, db_options_.info_log.get(), cfd->ioptions()->min_partial_merge_operands, false /* internal key corruption is expected */); auto compaction_filter = cfd->ioptions()->compaction_filter; std::unique_ptr compaction_filter_from_factory = nullptr; if (!compaction_filter) { auto context = compact_->GetFilterContextV1(); compaction_filter_from_factory = cfd->ioptions()->compaction_filter_factory->CreateCompactionFilter( context); compaction_filter = compaction_filter_from_factory.get(); } int64_t key_drop_user = 0; int64_t key_drop_newer_entry = 0; int64_t key_drop_obsolete = 0; int64_t loop_cnt = 0; while (input->Valid() && !shutting_down_->load(std::memory_order_acquire) && !cfd->IsDropped() && status.ok()) { if (++loop_cnt > 1000) { if (key_drop_user > 0) { RecordTick(stats_, COMPACTION_KEY_DROP_USER, key_drop_user); key_drop_user = 0; } if (key_drop_newer_entry > 0) { RecordTick(stats_, COMPACTION_KEY_DROP_NEWER_ENTRY, key_drop_newer_entry); key_drop_newer_entry = 0; } if (key_drop_obsolete > 0) { RecordTick(stats_, COMPACTION_KEY_DROP_OBSOLETE, key_drop_obsolete); key_drop_obsolete = 0; } RecordCompactionIOStats(); loop_cnt = 0; } // FLUSH preempts compaction // TODO(icanadi) this currently only checks if flush is necessary on // compacting column family. we should also check if flush is necessary on // other column families, too (*imm_micros) += yield_callback_(); Slice key; Slice value; // If is_compaction_v2 is on, kv-pairs are reset to the prefix batch. // This prefix batch should contain results after calling // compaction_filter_v2. // // If is_compaction_v2 is off, this function will go through all the // kv-pairs in input. if (!is_compaction_v2) { key = input->key(); value = input->value(); } else { if (combined_idx >= compact_->combined_key_buf_.size()) { break; } assert(combined_idx < compact_->combined_key_buf_.size()); key = compact_->combined_key_buf_[combined_idx]; value = compact_->combined_value_buf_[combined_idx]; ++combined_idx; } if (compact_->compaction->ShouldStopBefore(key) && compact_->builder != nullptr) { status = FinishCompactionOutputFile(input); if (!status.ok()) { break; } } // Handle key/value, add to state, etc. bool drop = false; bool current_entry_is_merging = false; if (!ParseInternalKey(key, &ikey)) { // Do not hide error keys // TODO: error key stays in db forever? Figure out the intention/rationale // v10 error v8 : we cannot hide v8 even though it's pretty obvious. current_user_key.Clear(); has_current_user_key = false; last_sequence_for_key = kMaxSequenceNumber; visible_in_snapshot = kMaxSequenceNumber; } else { if (!has_current_user_key || cfd->user_comparator()->Compare(ikey.user_key, current_user_key.GetKey()) != 0) { // First occurrence of this user key current_user_key.SetKey(ikey.user_key); has_current_user_key = true; last_sequence_for_key = kMaxSequenceNumber; visible_in_snapshot = kMaxSequenceNumber; // apply the compaction filter to the first occurrence of the user key if (compaction_filter && !is_compaction_v2 && ikey.type == kTypeValue && (visible_at_tip_ || ikey.sequence > latest_snapshot_)) { // If the user has specified a compaction filter and the sequence // number is greater than any external snapshot, then invoke the // filter. // If the return value of the compaction filter is true, replace // the entry with a delete marker. bool value_changed = false; compaction_filter_value.clear(); bool to_delete = compaction_filter->Filter( compact_->compaction->level(), ikey.user_key, value, &compaction_filter_value, &value_changed); if (to_delete) { // make a copy of the original key and convert it to a delete delete_key.SetInternalKey(ExtractUserKey(key), ikey.sequence, kTypeDeletion); // anchor the key again key = delete_key.GetKey(); // needed because ikey is backed by key ParseInternalKey(key, &ikey); // no value associated with delete value.clear(); ++key_drop_user; } else if (value_changed) { value = compaction_filter_value; } } } // If there are no snapshots, then this kv affect visibility at tip. // Otherwise, search though all existing snapshots to find // the earlist snapshot that is affected by this kv. SequenceNumber prev_snapshot = 0; // 0 means no previous snapshot SequenceNumber visible = visible_at_tip_ ? visible_at_tip_ : is_snapshot_supported_ ? findEarliestVisibleSnapshot(ikey.sequence, compact_->existing_snapshots, &prev_snapshot) : 0; if (visible_in_snapshot == visible) { // If the earliest snapshot is which this key is visible in // is the same as the visibily of a previous instance of the // same key, then this kv is not visible in any snapshot. // Hidden by an newer entry for same user key // TODO: why not > ? assert(last_sequence_for_key >= ikey.sequence); drop = true; // (A) ++key_drop_newer_entry; } else if (ikey.type == kTypeDeletion && ikey.sequence <= earliest_snapshot_ && compact_->compaction->KeyNotExistsBeyondOutputLevel( 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; ++key_drop_obsolete; } else if (ikey.type == kTypeMerge) { if (!merge.HasOperator()) { LogToBuffer(log_buffer_, "Options::merge_operator is null."); status = Status::InvalidArgument( "merge_operator is not properly initialized."); break; } // We know the merge type entry is not hidden, otherwise we would // have hit (A) // We encapsulate the merge related state machine in a different // object to minimize change to the existing flow. Turn out this // logic could also be nicely re-used for memtable flush purge // optimization in BuildTable. int steps = 0; merge.MergeUntil(input, prev_snapshot, bottommost_level_, db_options_.statistics.get(), &steps); // Skip the Merge ops combined_idx = combined_idx - 1 + steps; current_entry_is_merging = true; if (merge.IsSuccess()) { // Successfully found Put/Delete/(end-of-key-range) while merging // Get the merge result key = merge.key(); ParseInternalKey(key, &ikey); value = merge.value(); } else { // Did not find a Put/Delete/(end-of-key-range) while merging // We now have some stack of merge operands to write out. // NOTE: key,value, and ikey are now referring to old entries. // These will be correctly set below. assert(!merge.keys().empty()); assert(merge.keys().size() == merge.values().size()); // Hack to make sure last_sequence_for_key is correct ParseInternalKey(merge.keys().front(), &ikey); } } last_sequence_for_key = ikey.sequence; visible_in_snapshot = visible; } if (!drop) { // We may write a single key (e.g.: for Put/Delete or successful merge). // Or we may instead have to write a sequence/list of keys. // We have to write a sequence iff we have an unsuccessful merge bool has_merge_list = current_entry_is_merging && !merge.IsSuccess(); const std::deque* keys = nullptr; const std::deque* values = nullptr; std::deque::const_reverse_iterator key_iter; std::deque::const_reverse_iterator value_iter; if (has_merge_list) { keys = &merge.keys(); values = &merge.values(); key_iter = keys->rbegin(); // The back (*rbegin()) is the first key value_iter = values->rbegin(); key = Slice(*key_iter); value = Slice(*value_iter); } // If we have a list of keys to write, traverse the list. // If we have a single key to write, simply write that key. while (true) { // Invariant: key,value,ikey will always be the next entry to write char* kptr = (char*)key.data(); std::string kstr; // Zeroing out the sequence number leads to better compression. // If this is the bottommost level (no files in lower levels) // and the earliest snapshot is larger than this seqno // then we can squash the seqno to zero. if (bottommost_level_ && ikey.sequence < earliest_snapshot_ && ikey.type != kTypeMerge) { assert(ikey.type != kTypeDeletion); // make a copy because updating in place would cause problems // with the priority queue that is managing the input key iterator kstr.assign(key.data(), key.size()); kptr = (char*)kstr.c_str(); UpdateInternalKey(kptr, key.size(), (uint64_t)0, ikey.type); } Slice newkey(kptr, key.size()); assert((key.clear(), 1)); // we do not need 'key' anymore // Open output file if necessary if (compact_->builder == nullptr) { status = OpenCompactionOutputFile(); if (!status.ok()) { break; } } SequenceNumber seqno = GetInternalKeySeqno(newkey); if (compact_->builder->NumEntries() == 0) { compact_->current_output()->smallest.DecodeFrom(newkey); compact_->current_output()->smallest_seqno = seqno; } else { compact_->current_output()->smallest_seqno = std::min(compact_->current_output()->smallest_seqno, seqno); } compact_->current_output()->largest.DecodeFrom(newkey); compact_->builder->Add(newkey, value); (*num_output_records)++, compact_->current_output()->largest_seqno = std::max(compact_->current_output()->largest_seqno, seqno); // Close output file if it is big enough if (compact_->builder->FileSize() >= compact_->compaction->MaxOutputFileSize()) { status = FinishCompactionOutputFile(input); if (!status.ok()) { break; } } // If we have a list of entries, move to next element // If we only had one entry, then break the loop. if (has_merge_list) { ++key_iter; ++value_iter; // If at end of list if (key_iter == keys->rend() || value_iter == values->rend()) { // Sanity Check: if one ends, then both end assert(key_iter == keys->rend() && value_iter == values->rend()); break; } // Otherwise not at end of list. Update key, value, and ikey. key = Slice(*key_iter); value = Slice(*value_iter); ParseInternalKey(key, &ikey); } else { // Only had one item to begin with (Put/Delete) break; } } // while (true) } // if (!drop) // MergeUntil has moved input to the next entry if (!current_entry_is_merging) { input->Next(); } } if (key_drop_user > 0) { RecordTick(stats_, COMPACTION_KEY_DROP_USER, key_drop_user); } if (key_drop_newer_entry > 0) { RecordTick(stats_, COMPACTION_KEY_DROP_NEWER_ENTRY, key_drop_newer_entry); } if (key_drop_obsolete > 0) { RecordTick(stats_, COMPACTION_KEY_DROP_OBSOLETE, key_drop_obsolete); } RecordCompactionIOStats(); return status; } void CompactionJob::CallCompactionFilterV2( CompactionFilterV2* compaction_filter_v2) { if (compact_ == nullptr || compaction_filter_v2 == nullptr) { return; } // Assemble slice vectors for user keys and existing values. // We also keep track of our parsed internal key structs because // we may need to access the sequence number in the event that // keys are garbage collected during the filter process. std::vector ikey_buf; std::vector user_key_buf; std::vector existing_value_buf; for (const auto& key : compact_->key_str_buf_) { ParsedInternalKey ikey; ParseInternalKey(Slice(key), &ikey); ikey_buf.emplace_back(ikey); user_key_buf.emplace_back(ikey.user_key); } for (const auto& value : compact_->existing_value_str_buf_) { existing_value_buf.emplace_back(Slice(value)); } // If the user has specified a compaction filter and the sequence // number is greater than any external snapshot, then invoke the // filter. // If the return value of the compaction filter is true, replace // the entry with a delete marker. compact_->to_delete_buf_ = compaction_filter_v2->Filter( compact_->compaction->level(), user_key_buf, existing_value_buf, &compact_->new_value_buf_, &compact_->value_changed_buf_); // new_value_buf_.size() <= to_delete__buf_.size(). "=" iff all // kv-pairs in this compaction run needs to be deleted. assert(compact_->to_delete_buf_.size() == compact_->key_str_buf_.size()); assert(compact_->to_delete_buf_.size() == compact_->existing_value_str_buf_.size()); assert(compact_->to_delete_buf_.size() == compact_->value_changed_buf_.size()); int new_value_idx = 0; for (unsigned int i = 0; i < compact_->to_delete_buf_.size(); ++i) { if (compact_->to_delete_buf_[i]) { // update the string buffer directly // the Slice buffer points to the updated buffer UpdateInternalKey(&compact_->key_str_buf_[i][0], compact_->key_str_buf_[i].size(), ikey_buf[i].sequence, kTypeDeletion); // no value associated with delete compact_->existing_value_str_buf_[i].clear(); RecordTick(stats_, COMPACTION_KEY_DROP_USER); } else if (compact_->value_changed_buf_[i]) { compact_->existing_value_str_buf_[i] = compact_->new_value_buf_[new_value_idx++]; } } // for } Status CompactionJob::FinishCompactionOutputFile(Iterator* input) { assert(compact_ != nullptr); assert(compact_->outfile); assert(compact_->builder != nullptr); const uint64_t output_number = compact_->current_output()->number; const uint32_t output_path_id = compact_->current_output()->path_id; 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; compact_->builder.reset(); // Finish and check for file errors if (s.ok() && !db_options_.disableDataSync) { if (db_options_.use_fsync) { StopWatch sw(env_, stats_, COMPACTION_OUTFILE_SYNC_MICROS); s = compact_->outfile->Fsync(); } else { StopWatch sw(env_, stats_, COMPACTION_OUTFILE_SYNC_MICROS); s = compact_->outfile->Sync(); } } if (s.ok()) { s = compact_->outfile->Close(); } compact_->outfile.reset(); if (s.ok() && current_entries > 0) { // Verify that the table is usable ColumnFamilyData* cfd = compact_->compaction->column_family_data(); FileDescriptor fd(output_number, output_path_id, current_bytes); Iterator* iter = cfd->table_cache()->NewIterator( ReadOptions(), env_options_, cfd->internal_comparator(), fd); s = iter->status(); delete iter; if (s.ok()) { Log(db_options_.info_log, "[%s] Generated table #%" PRIu64 ": %" PRIu64 " keys, %" PRIu64 " bytes", cfd->GetName().c_str(), output_number, current_entries, current_bytes); } } return s; } Status CompactionJob::InstallCompactionResults() { db_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 (!versions_->VerifyCompactionFileConsistency(compact_->compaction)) { Log(db_options_.info_log, "[%s] Compaction %d@%d + %d@%d files aborted", compact_->compaction->column_family_data()->GetName().c_str(), compact_->compaction->num_input_files(0), compact_->compaction->level(), compact_->compaction->num_input_files(1), compact_->compaction->output_level()); return Status::Corruption("Compaction input files inconsistent"); } LogToBuffer(log_buffer_, "[%s] Compacted %d@%d + %d@%d files => %lld bytes", compact_->compaction->column_family_data()->GetName().c_str(), compact_->compaction->num_input_files(0), compact_->compaction->level(), compact_->compaction->num_input_files(1), compact_->compaction->output_level(), static_cast(compact_->total_bytes)); // Add compaction outputs compact_->compaction->AddInputDeletions(compact_->compaction->edit()); for (size_t i = 0; i < compact_->outputs.size(); i++) { const CompactionState::Output& out = compact_->outputs[i]; compact_->compaction->edit()->AddFile( compact_->compaction->output_level(), out.number, out.path_id, out.file_size, out.smallest, out.largest, out.smallest_seqno, out.largest_seqno); } return versions_->LogAndApply( compact_->compaction->column_family_data(), mutable_cf_options_, compact_->compaction->edit(), db_mutex_, db_directory_); } // Given a sequence number, return the sequence number of the // earliest snapshot that this sequence number is visible in. // The snapshots themselves are arranged in ascending order of // sequence numbers. // Employ a sequential search because the total number of // snapshots are typically small. inline SequenceNumber CompactionJob::findEarliestVisibleSnapshot( SequenceNumber in, const std::vector& snapshots, SequenceNumber* prev_snapshot) { SequenceNumber prev __attribute__((unused)) = 0; for (const auto cur : snapshots) { assert(prev <= cur); if (cur >= in) { *prev_snapshot = prev; return cur; } prev = cur; // assignment assert(prev); } Log(db_options_.info_log, "Looking for seqid %" PRIu64 " but maxseqid is %" PRIu64 "", in, snapshots[snapshots.size() - 1]); assert(0); return 0; } void CompactionJob::RecordCompactionIOStats() { RecordTick(stats_, COMPACT_READ_BYTES, IOSTATS(bytes_read)); IOSTATS_RESET(bytes_read); RecordTick(stats_, COMPACT_WRITE_BYTES, IOSTATS(bytes_written)); IOSTATS_RESET(bytes_written); } // Frees up unused file number. void CompactionJob::ReleaseCompactionUnusedFileNumbers() { db_mutex_->AssertHeld(); for (const auto file_number : compact_->allocated_file_numbers) { pending_outputs_->erase(file_number); } } Status CompactionJob::OpenCompactionOutputFile() { assert(compact_ != nullptr); assert(compact_->builder == nullptr); 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 { db_mutex_->Lock(); file_number = versions_->NewFileNumber(); pending_outputs_->insert( {file_number, compact_->compaction->GetOutputPathId()}); db_mutex_->Unlock(); } // Make the output file std::string fname = TableFileName(db_options_.db_paths, file_number, compact_->compaction->GetOutputPathId()); Status s = env_->NewWritableFile(fname, &compact_->outfile, env_options_); if (!s.ok()) { Log(InfoLogLevel::ERROR_LEVEL, db_options_.info_log, "[%s] OpenCompactionOutputFiles for table #%" PRIu64 " " "fails at NewWritableFile with status %s", compact_->compaction->column_family_data()->GetName().c_str(), file_number, s.ToString().c_str()); LogFlush(db_options_.info_log); return s; } CompactionState::Output out; out.number = file_number; out.path_id = compact_->compaction->GetOutputPathId(); out.smallest.Clear(); out.largest.Clear(); out.smallest_seqno = out.largest_seqno = 0; compact_->outputs.push_back(out); compact_->outfile->SetIOPriority(Env::IO_LOW); compact_->outfile->SetPreallocationBlockSize( compact_->compaction->OutputFilePreallocationSize(mutable_cf_options_)); ColumnFamilyData* cfd = compact_->compaction->column_family_data(); compact_->builder.reset(NewTableBuilder( *cfd->ioptions(), cfd->internal_comparator(), compact_->outfile.get(), compact_->compaction->OutputCompressionType(), cfd->ioptions()->compression_opts)); LogFlush(db_options_.info_log); return s; } void CompactionJob::CleanupCompaction(Status status) { db_mutex_->AssertHeld(); if (compact_->builder != nullptr) { // May happen if we get a shutdown call in the middle of compaction compact_->builder->Abandon(); compact_->builder.reset(); } else { assert(!status.ok() || compact_->outfile == nullptr); } for (size_t i = 0; i < compact_->outputs.size(); i++) { const CompactionState::Output& out = compact_->outputs[i]; pending_outputs_->erase(out.number); // If this file was inserted into the table cache then remove // them here because this compaction was not committed. if (!status.ok()) { TableCache::Evict(table_cache_.get(), out.number); } } delete compact_; compact_ = nullptr; } } // namespace rocksdb