| // 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/version_set.h" |
| |
| #include <algorithm> |
| #include <stdio.h> |
| #include "db/filename.h" |
| #include "db/log_reader.h" |
| #include "db/log_writer.h" |
| #include "db/memtable.h" |
| #include "db/table_cache.h" |
| #include "include/env.h" |
| #include "include/table_builder.h" |
| #include "table/merger.h" |
| #include "table/two_level_iterator.h" |
| #include "util/coding.h" |
| #include "util/logging.h" |
| |
| namespace leveldb { |
| |
| // Maximum number of overlaps in grandparent (i.e., level+2) before we |
| // stop building a single file in a level->level+1 compaction. |
| static const int kMaxGrandParentFiles = 10; |
| |
| static double MaxBytesForLevel(int level) { |
| if (level == 0) { |
| return 4 * 1048576.0; |
| } else { |
| double result = 10 * 1048576.0; |
| while (level > 1) { |
| result *= 10; |
| level--; |
| } |
| return result; |
| } |
| } |
| |
| static uint64_t MaxFileSizeForLevel(int level) { |
| return 2 << 20; // We could vary per level to reduce number of files? |
| } |
| |
| namespace { |
| std::string IntSetToString(const std::set<uint64_t>& s) { |
| std::string result = "{"; |
| for (std::set<uint64_t>::const_iterator it = s.begin(); |
| it != s.end(); |
| ++it) { |
| result += (result.size() > 1) ? "," : ""; |
| result += NumberToString(*it); |
| } |
| result += "}"; |
| return result; |
| } |
| } |
| |
| Version::~Version() { |
| assert(refs_ == 0); |
| for (int level = 0; level < config::kNumLevels; level++) { |
| for (int i = 0; i < files_[level].size(); i++) { |
| FileMetaData* f = files_[level][i]; |
| assert(f->refs >= 0); |
| f->refs--; |
| if (f->refs <= 0) { |
| delete f; |
| } |
| } |
| } |
| delete cleanup_mem_; |
| } |
| |
| // An internal iterator. For a given version/level pair, yields |
| // information about the files in the level. For a given entry, key() |
| // is the largest key that occurs in the file, and value() is an |
| // 8-byte value containing the file number of the file, encoding using |
| // EncodeFixed64. |
| class Version::LevelFileNumIterator : public Iterator { |
| public: |
| LevelFileNumIterator(const Version* version, |
| const std::vector<FileMetaData*>* flist) |
| : icmp_(version->vset_->icmp_.user_comparator()), |
| flist_(flist), |
| index_(flist->size()) { // Marks as invalid |
| } |
| virtual bool Valid() const { |
| return index_ < flist_->size(); |
| } |
| virtual void Seek(const Slice& target) { |
| uint32_t left = 0; |
| uint32_t right = flist_->size() - 1; |
| while (left < right) { |
| uint32_t mid = (left + right) / 2; |
| int cmp = icmp_.Compare((*flist_)[mid]->largest.Encode(), target); |
| if (cmp < 0) { |
| // Key at "mid.largest" is < than "target". Therefore all |
| // files at or before "mid" are uninteresting. |
| left = mid + 1; |
| } else { |
| // Key at "mid.largest" is >= "target". Therefore all files |
| // after "mid" are uninteresting. |
| right = mid; |
| } |
| } |
| index_ = left; |
| } |
| virtual void SeekToFirst() { index_ = 0; } |
| virtual void SeekToLast() { |
| index_ = flist_->empty() ? 0 : flist_->size() - 1; |
| } |
| virtual void Next() { |
| assert(Valid()); |
| index_++; |
| } |
| virtual void Prev() { |
| assert(Valid()); |
| if (index_ == 0) { |
| index_ = flist_->size(); // Marks as invalid |
| } else { |
| index_--; |
| } |
| } |
| Slice key() const { |
| assert(Valid()); |
| return (*flist_)[index_]->largest.Encode(); |
| } |
| Slice value() const { |
| assert(Valid()); |
| EncodeFixed64(value_buf_, (*flist_)[index_]->number); |
| return Slice(value_buf_, sizeof(value_buf_)); |
| } |
| virtual Status status() const { return Status::OK(); } |
| private: |
| const InternalKeyComparator icmp_; |
| const std::vector<FileMetaData*>* const flist_; |
| int index_; |
| |
| mutable char value_buf_[8]; // Used for encoding the file number for value() |
| }; |
| |
| static Iterator* GetFileIterator(void* arg, |
| const ReadOptions& options, |
| const Slice& file_value) { |
| TableCache* cache = reinterpret_cast<TableCache*>(arg); |
| if (file_value.size() != 8) { |
| return NewErrorIterator( |
| Status::Corruption("FileReader invoked with unexpected value")); |
| } else { |
| return cache->NewIterator(options, DecodeFixed64(file_value.data())); |
| } |
| } |
| |
| Iterator* Version::NewConcatenatingIterator(const ReadOptions& options, |
| int level) const { |
| return NewTwoLevelIterator( |
| new LevelFileNumIterator(this, &files_[level]), |
| &GetFileIterator, vset_->table_cache_, options); |
| } |
| |
| void Version::AddIterators(const ReadOptions& options, |
| std::vector<Iterator*>* iters) { |
| // Merge all level zero files together since they may overlap |
| for (int i = 0; i < files_[0].size(); i++) { |
| iters->push_back( |
| vset_->table_cache_->NewIterator(options, files_[0][i]->number)); |
| } |
| |
| // For levels > 0, we can use a concatenating iterator that sequentially |
| // walks through the non-overlapping files in the level, opening them |
| // lazily. |
| for (int level = 1; level < config::kNumLevels; level++) { |
| if (!files_[level].empty()) { |
| iters->push_back(NewConcatenatingIterator(options, level)); |
| } |
| } |
| } |
| |
| void Version::Ref() { |
| ++refs_; |
| } |
| |
| void Version::Unref() { |
| assert(refs_ >= 1); |
| --refs_; |
| if (refs_ == 0) { |
| vset_->MaybeDeleteOldVersions(); |
| // TODO: try to delete obsolete files |
| } |
| } |
| |
| std::string Version::DebugString() const { |
| std::string r; |
| for (int level = 0; level < config::kNumLevels; level++) { |
| // E.g., level 1: 17:123['a' .. 'd'] 20:43['e' .. 'g'] |
| r.append("level "); |
| AppendNumberTo(&r, level); |
| r.push_back(':'); |
| const std::vector<FileMetaData*>& files = files_[level]; |
| for (int i = 0; i < files.size(); i++) { |
| r.push_back(' '); |
| AppendNumberTo(&r, files[i]->number); |
| r.push_back(':'); |
| AppendNumberTo(&r, files[i]->file_size); |
| r.append("['"); |
| AppendEscapedStringTo(&r, files[i]->smallest.Encode()); |
| r.append("' .. '"); |
| AppendEscapedStringTo(&r, files[i]->largest.Encode()); |
| r.append("']"); |
| } |
| r.push_back('\n'); |
| } |
| return r; |
| } |
| |
| // A helper class so we can efficiently apply a whole sequence |
| // of edits to a particular state without creating intermediate |
| // Versions that contain full copies of the intermediate state. |
| class VersionSet::Builder { |
| private: |
| typedef std::map<uint64_t, FileMetaData*> FileMap; |
| VersionSet* vset_; |
| FileMap files_[config::kNumLevels]; |
| |
| public: |
| // Initialize a builder with the files from *base and other info from *vset |
| Builder(VersionSet* vset, Version* base) |
| : vset_(vset) { |
| for (int level = 0; level < config::kNumLevels; level++) { |
| const std::vector<FileMetaData*>& files = base->files_[level]; |
| for (int i = 0; i < files.size(); i++) { |
| FileMetaData* f = files[i]; |
| f->refs++; |
| files_[level].insert(std::make_pair(f->number, f)); |
| } |
| } |
| } |
| |
| ~Builder() { |
| for (int level = 0; level < config::kNumLevels; level++) { |
| const FileMap& fmap = files_[level]; |
| for (FileMap::const_iterator iter = fmap.begin(); |
| iter != fmap.end(); |
| ++iter) { |
| FileMetaData* f = iter->second; |
| f->refs--; |
| if (f->refs <= 0) { |
| delete f; |
| } |
| } |
| } |
| } |
| |
| // Apply all of the edits in *edit to the current state. |
| void Apply(VersionEdit* edit) { |
| // Update compaction pointers |
| for (int i = 0; i < edit->compact_pointers_.size(); i++) { |
| const int level = edit->compact_pointers_[i].first; |
| vset_->compact_pointer_[level] = |
| edit->compact_pointers_[i].second.Encode().ToString(); |
| } |
| |
| // Delete files |
| const VersionEdit::DeletedFileSet& del = edit->deleted_files_; |
| for (VersionEdit::DeletedFileSet::const_iterator iter = del.begin(); |
| iter != del.end(); |
| ++iter) { |
| const int level = iter->first; |
| const uint64_t number = iter->second; |
| FileMap::iterator fiter = files_[level].find(number); |
| assert(fiter != files_[level].end()); // Sanity check for debug mode |
| if (fiter != files_[level].end()) { |
| FileMetaData* f = fiter->second; |
| f->refs--; |
| if (f->refs <= 0) { |
| delete f; |
| } |
| files_[level].erase(fiter); |
| } |
| } |
| |
| // Add new files |
| for (int i = 0; i < edit->new_files_.size(); i++) { |
| const int level = edit->new_files_[i].first; |
| FileMetaData* f = new FileMetaData(edit->new_files_[i].second); |
| f->refs = 1; |
| assert(files_[level].count(f->number) == 0); |
| files_[level].insert(std::make_pair(f->number, f)); |
| } |
| |
| // Add large value refs |
| for (int i = 0; i < edit->large_refs_added_.size(); i++) { |
| const VersionEdit::Large& l = edit->large_refs_added_[i]; |
| vset_->RegisterLargeValueRef(l.large_ref, l.fnum, l.internal_key); |
| } |
| } |
| |
| // Save the current state in *v. |
| void SaveTo(Version* v) { |
| for (int level = 0; level < config::kNumLevels; level++) { |
| const FileMap& fmap = files_[level]; |
| for (FileMap::const_iterator iter = fmap.begin(); |
| iter != fmap.end(); |
| ++iter) { |
| FileMetaData* f = iter->second; |
| f->refs++; |
| v->files_[level].push_back(f); |
| } |
| } |
| } |
| }; |
| |
| VersionSet::VersionSet(const std::string& dbname, |
| const Options* options, |
| TableCache* table_cache, |
| const InternalKeyComparator* cmp) |
| : env_(options->env), |
| dbname_(dbname), |
| options_(options), |
| table_cache_(table_cache), |
| icmp_(*cmp), |
| next_file_number_(2), |
| manifest_file_number_(0), // Filled by Recover() |
| descriptor_file_(NULL), |
| descriptor_log_(NULL), |
| current_(new Version(this)), |
| oldest_(current_) { |
| } |
| |
| VersionSet::~VersionSet() { |
| for (Version* v = oldest_; v != NULL; ) { |
| Version* next = v->next_; |
| assert(v->refs_ == 0); |
| delete v; |
| v = next; |
| } |
| delete descriptor_log_; |
| delete descriptor_file_; |
| } |
| |
| Status VersionSet::LogAndApply(VersionEdit* edit, MemTable* cleanup_mem) { |
| edit->SetNextFile(next_file_number_); |
| |
| Version* v = new Version(this); |
| { |
| Builder builder(this, current_); |
| builder.Apply(edit); |
| builder.SaveTo(v); |
| } |
| |
| std::string new_manifest_file; |
| Status s = Finalize(v); |
| |
| // Initialize new descriptor log file if necessary by creating |
| // a temporary file that contains a snapshot of the current version. |
| if (s.ok()) { |
| if (descriptor_log_ == NULL) { |
| assert(descriptor_file_ == NULL); |
| new_manifest_file = DescriptorFileName(dbname_, manifest_file_number_); |
| edit->SetNextFile(next_file_number_); |
| s = env_->NewWritableFile(new_manifest_file, &descriptor_file_); |
| if (s.ok()) { |
| descriptor_log_ = new log::Writer(descriptor_file_); |
| s = WriteSnapshot(descriptor_log_); |
| } |
| } |
| } |
| |
| // Write new record to log file |
| if (s.ok()) { |
| std::string record; |
| edit->EncodeTo(&record); |
| s = descriptor_log_->AddRecord(record); |
| if (s.ok()) { |
| s = descriptor_file_->Sync(); |
| } |
| } |
| |
| // If we just created a new descriptor file, install it by writing a |
| // new CURRENT file that points to it. |
| if (s.ok() && !new_manifest_file.empty()) { |
| s = SetCurrentFile(env_, dbname_, manifest_file_number_); |
| } |
| |
| // Install the new version |
| if (s.ok()) { |
| assert(current_->next_ == NULL); |
| assert(current_->cleanup_mem_ == NULL); |
| current_->cleanup_mem_ = cleanup_mem; |
| v->next_ = NULL; |
| current_->next_ = v; |
| current_ = v; |
| } else { |
| delete v; |
| if (!new_manifest_file.empty()) { |
| delete descriptor_log_; |
| delete descriptor_file_; |
| descriptor_log_ = NULL; |
| descriptor_file_ = NULL; |
| env_->DeleteFile(new_manifest_file); |
| } |
| } |
| //Log(env_, options_->info_log, "State\n%s", current_->DebugString().c_str()); |
| |
| return s; |
| } |
| |
| Status VersionSet::Recover(uint64_t* log_number, |
| SequenceNumber* last_sequence) { |
| struct LogReporter : public log::Reader::Reporter { |
| Status* status; |
| virtual void Corruption(size_t bytes, const Status& s) { |
| if (this->status->ok()) *this->status = s; |
| } |
| }; |
| |
| // Read "CURRENT" file, which contains a pointer to the current manifest file |
| std::string current; |
| Status s = ReadFileToString(env_, CurrentFileName(dbname_), ¤t); |
| if (!s.ok()) { |
| return s; |
| } |
| if (current.empty() || current[current.size()-1] != '\n') { |
| return Status::Corruption("CURRENT file does not end with newline"); |
| } |
| current.resize(current.size() - 1); |
| |
| std::string dscname = dbname_ + "/" + current; |
| SequentialFile* file; |
| s = env_->NewSequentialFile(dscname, &file); |
| if (!s.ok()) { |
| return s; |
| } |
| |
| bool have_log_number = false; |
| bool have_next_file = false; |
| bool have_last_sequence = false; |
| uint64_t next_file = 0; |
| Builder builder(this, current_); |
| |
| { |
| LogReporter reporter; |
| reporter.status = &s; |
| log::Reader reader(file, &reporter, true/*checksum*/); |
| Slice record; |
| std::string scratch; |
| while (reader.ReadRecord(&record, &scratch) && s.ok()) { |
| VersionEdit edit; |
| s = edit.DecodeFrom(record); |
| if (s.ok()) { |
| if (edit.has_comparator_ && |
| edit.comparator_ != icmp_.user_comparator()->Name()) { |
| s = Status::InvalidArgument( |
| edit.comparator_ + "does not match existing comparator ", |
| icmp_.user_comparator()->Name()); |
| } |
| } |
| |
| if (s.ok()) { |
| builder.Apply(&edit); |
| } |
| |
| if (edit.has_log_number_) { |
| *log_number = edit.log_number_; |
| have_log_number = true; |
| } |
| |
| if (edit.has_next_file_number_) { |
| next_file = edit.next_file_number_; |
| have_next_file = true; |
| } |
| |
| if (edit.has_last_sequence_) { |
| *last_sequence = edit.last_sequence_; |
| have_last_sequence = true; |
| } |
| } |
| } |
| delete file; |
| file = NULL; |
| |
| if (s.ok()) { |
| if (!have_next_file) { |
| s = Status::Corruption("no meta-nextfile entry in descriptor"); |
| } else if (!have_log_number) { |
| s = Status::Corruption("no meta-lognumber entry in descriptor"); |
| } else if (!have_last_sequence) { |
| s = Status::Corruption("no last-sequence-number entry in descriptor"); |
| } |
| } |
| |
| if (s.ok()) { |
| Version* v = new Version(this); |
| builder.SaveTo(v); |
| s = Finalize(v); |
| if (!s.ok()) { |
| delete v; |
| } else { |
| // Install recovered version |
| v->next_ = NULL; |
| current_->next_ = v; |
| current_ = v; |
| manifest_file_number_ = next_file; |
| next_file_number_ = next_file + 1; |
| } |
| } |
| |
| return s; |
| } |
| |
| Status VersionSet::Finalize(Version* v) { |
| // Precomputed best level for next compaction |
| int best_level = -1; |
| double best_score = -1; |
| |
| Status s; |
| for (int level = 0; s.ok() && level < config::kNumLevels-1; level++) { |
| s = SortLevel(v, level); |
| |
| // Compute the ratio of current size to size limit. |
| uint64_t level_bytes = 0; |
| for (int i = 0; i < v->files_[level].size(); i++) { |
| level_bytes += v->files_[level][i]->file_size; |
| } |
| double score = static_cast<double>(level_bytes) / MaxBytesForLevel(level); |
| |
| if (level == 0) { |
| // Level-0 file sizes are going to be often much smaller than |
| // MaxBytesForLevel(0) since we do not account for compression |
| // when producing a level-0 file; and too many level-0 files |
| // increase merging costs. So use a file-count limit for |
| // level-0 in addition to the byte-count limit. |
| double count_score = v->files_[level].size() / 4.0; |
| if (count_score > score) { |
| score = count_score; |
| } |
| } |
| |
| if (score > best_score) { |
| best_level = level; |
| best_score = score; |
| } |
| } |
| |
| v->compaction_level_ = best_level; |
| v->compaction_score_ = best_score; |
| return s; |
| } |
| |
| Status VersionSet::WriteSnapshot(log::Writer* log) { |
| // TODO: Break up into multiple records to reduce memory usage on recovery? |
| |
| // Save metadata |
| VersionEdit edit; |
| edit.SetComparatorName(icmp_.user_comparator()->Name()); |
| |
| // Save compaction pointers |
| for (int level = 0; level < config::kNumLevels; level++) { |
| if (!compact_pointer_[level].empty()) { |
| InternalKey key; |
| key.DecodeFrom(compact_pointer_[level]); |
| edit.SetCompactPointer(level, key); |
| } |
| } |
| |
| // Save files |
| for (int level = 0; level < config::kNumLevels; level++) { |
| const std::vector<FileMetaData*>& files = current_->files_[level]; |
| for (int i = 0; i < files.size(); i++) { |
| const FileMetaData* f = files[i]; |
| edit.AddFile(level, f->number, f->file_size, f->smallest, f->largest); |
| } |
| } |
| |
| // Save large value refs |
| for (LargeValueMap::const_iterator it = large_value_refs_.begin(); |
| it != large_value_refs_.end(); |
| ++it) { |
| const LargeValueRef& ref = it->first; |
| const LargeReferencesSet& pointers = it->second; |
| for (LargeReferencesSet::const_iterator j = pointers.begin(); |
| j != pointers.end(); |
| ++j) { |
| edit.AddLargeValueRef(ref, j->first, j->second); |
| } |
| } |
| |
| std::string record; |
| edit.EncodeTo(&record); |
| return log->AddRecord(record); |
| } |
| |
| // Helper to sort by tables_[file_number].smallest |
| struct VersionSet::BySmallestKey { |
| const InternalKeyComparator* internal_comparator; |
| |
| bool operator()(FileMetaData* f1, FileMetaData* f2) const { |
| return internal_comparator->Compare(f1->smallest, f2->smallest) < 0; |
| } |
| }; |
| |
| Status VersionSet::SortLevel(Version* v, uint64_t level) { |
| Status result; |
| BySmallestKey cmp; |
| cmp.internal_comparator = &icmp_; |
| std::sort(v->files_[level].begin(), v->files_[level].end(), cmp); |
| |
| if (result.ok() && level > 0) { |
| // There should be no overlap |
| for (int i = 1; i < v->files_[level].size(); i++) { |
| const InternalKey& prev_end = v->files_[level][i-1]->largest; |
| const InternalKey& this_begin = v->files_[level][i]->smallest; |
| if (icmp_.Compare(prev_end, this_begin) >= 0) { |
| result = Status::Corruption( |
| "overlapping ranges in same level", |
| (EscapeString(prev_end.Encode()) + " vs. " + |
| EscapeString(this_begin.Encode()))); |
| break; |
| } |
| } |
| } |
| return result; |
| } |
| |
| int VersionSet::NumLevelFiles(int level) const { |
| assert(level >= 0); |
| assert(level < config::kNumLevels); |
| return current_->files_[level].size(); |
| } |
| |
| uint64_t VersionSet::ApproximateOffsetOf(Version* v, const InternalKey& ikey) { |
| uint64_t result = 0; |
| for (int level = 0; level < config::kNumLevels; level++) { |
| const std::vector<FileMetaData*>& files = v->files_[level]; |
| for (int i = 0; i < files.size(); i++) { |
| if (icmp_.Compare(files[i]->largest, ikey) <= 0) { |
| // Entire file is before "ikey", so just add the file size |
| result += files[i]->file_size; |
| } else if (icmp_.Compare(files[i]->smallest, ikey) > 0) { |
| // Entire file is after "ikey", so ignore |
| if (level > 0) { |
| // Files other than level 0 are sorted by meta->smallest, so |
| // no further files in this level will contain data for |
| // "ikey". |
| break; |
| } |
| } else { |
| // "ikey" falls in the range for this table. Add the |
| // approximate offset of "ikey" within the table. |
| Table* tableptr; |
| Iterator* iter = table_cache_->NewIterator( |
| ReadOptions(), files[i]->number, &tableptr); |
| if (tableptr != NULL) { |
| result += tableptr->ApproximateOffsetOf(ikey.Encode()); |
| } |
| delete iter; |
| } |
| } |
| } |
| |
| // Add in large value files which are references from internal keys |
| // stored in the table files |
| // |
| // TODO(opt): this is O(# large values in db). If this becomes too slow, |
| // we could store an auxiliary data structure indexed by internal key |
| for (LargeValueMap::const_iterator it = large_value_refs_.begin(); |
| it != large_value_refs_.end(); |
| ++it) { |
| const LargeValueRef& lref = it->first; |
| for (LargeReferencesSet::const_iterator it2 = it->second.begin(); |
| it2 != it->second.end(); |
| ++it2) { |
| if (icmp_.Compare(it2->second, ikey.Encode()) <= 0) { |
| // Internal key for large value is before our key of interest |
| result += lref.ValueSize(); |
| } |
| } |
| } |
| |
| |
| return result; |
| } |
| |
| bool VersionSet::RegisterLargeValueRef(const LargeValueRef& large_ref, |
| uint64_t fnum, |
| const InternalKey& internal_key) { |
| LargeReferencesSet* refs = &large_value_refs_[large_ref]; |
| bool is_first = refs->empty(); |
| refs->insert(make_pair(fnum, internal_key.Encode().ToString())); |
| return is_first; |
| } |
| |
| void VersionSet::CleanupLargeValueRefs(const std::set<uint64_t>& live_tables, |
| uint64_t log_file_num) { |
| for (LargeValueMap::iterator it = large_value_refs_.begin(); |
| it != large_value_refs_.end(); |
| ) { |
| LargeReferencesSet* refs = &it->second; |
| for (LargeReferencesSet::iterator ref_it = refs->begin(); |
| ref_it != refs->end(); |
| ) { |
| if (ref_it->first != log_file_num && // Not in log file |
| live_tables.count(ref_it->first) == 0) { // Not in a live table |
| // No longer live: erase |
| LargeReferencesSet::iterator to_erase = ref_it; |
| ++ref_it; |
| refs->erase(to_erase); |
| } else { |
| // Still live: leave this reference alone |
| ++ref_it; |
| } |
| } |
| if (refs->empty()) { |
| // No longer any live references to this large value: remove from |
| // large_value_refs |
| Log(env_, options_->info_log, "large value is dead: '%s'", |
| LargeValueRefToFilenameString(it->first).c_str()); |
| LargeValueMap::iterator to_erase = it; |
| ++it; |
| large_value_refs_.erase(to_erase); |
| } else { |
| ++it; |
| } |
| } |
| } |
| |
| bool VersionSet::LargeValueIsLive(const LargeValueRef& large_ref) { |
| LargeValueMap::iterator it = large_value_refs_.find(large_ref); |
| if (it == large_value_refs_.end()) { |
| return false; |
| } else { |
| assert(!it->second.empty()); |
| return true; |
| } |
| } |
| |
| void VersionSet::MaybeDeleteOldVersions() { |
| // Note: it is important to delete versions in order since a newer |
| // version with zero refs may be holding a pointer to a memtable |
| // that is used by somebody who has a ref on an older version. |
| while (oldest_ != current_ && oldest_->refs_ == 0) { |
| Version* next = oldest_->next_; |
| delete oldest_; |
| oldest_ = next; |
| } |
| } |
| |
| void VersionSet::AddLiveFiles(std::set<uint64_t>* live) { |
| for (Version* v = oldest_; v != NULL; v = v->next_) { |
| for (int level = 0; level < config::kNumLevels; level++) { |
| const std::vector<FileMetaData*>& files = v->files_[level]; |
| for (int i = 0; i < files.size(); i++) { |
| live->insert(files[i]->number); |
| } |
| } |
| } |
| } |
| |
| int64 VersionSet::MaxNextLevelOverlappingBytes() { |
| int64 result = 0; |
| std::vector<FileMetaData*> overlaps; |
| for (int level = 0; level < config::kNumLevels - 1; level++) { |
| for (int i = 0; i < current_->files_[level].size(); i++) { |
| const FileMetaData* f = current_->files_[level][i]; |
| GetOverlappingInputs(level+1, f->smallest, f->largest, &overlaps); |
| int64 sum = 0; |
| for (int j = 0; j < overlaps.size(); j++) { |
| sum += overlaps[j]->file_size; |
| } |
| if (sum > result) { |
| result = sum; |
| } |
| } |
| } |
| return result; |
| } |
| |
| // Store in "*inputs" all files in "level" that overlap [begin,end] |
| void VersionSet::GetOverlappingInputs( |
| int level, |
| const InternalKey& begin, |
| const InternalKey& end, |
| std::vector<FileMetaData*>* inputs) { |
| inputs->clear(); |
| Slice user_begin = begin.user_key(); |
| Slice user_end = end.user_key(); |
| const Comparator* user_cmp = icmp_.user_comparator(); |
| for (int i = 0; i < current_->files_[level].size(); i++) { |
| FileMetaData* f = current_->files_[level][i]; |
| if (user_cmp->Compare(f->largest.user_key(), user_begin) < 0 || |
| user_cmp->Compare(f->smallest.user_key(), user_end) > 0) { |
| // Either completely before or after range; skip it |
| } else { |
| inputs->push_back(f); |
| } |
| } |
| } |
| |
| // Stores the minimal range that covers all entries in inputs in |
| // *smallest, *largest. |
| // REQUIRES: inputs is not empty |
| void VersionSet::GetRange(const std::vector<FileMetaData*>& inputs, |
| InternalKey* smallest, |
| InternalKey* largest) { |
| assert(!inputs.empty()); |
| smallest->Clear(); |
| largest->Clear(); |
| for (int i = 0; i < inputs.size(); i++) { |
| FileMetaData* f = inputs[i]; |
| if (i == 0) { |
| *smallest = f->smallest; |
| *largest = f->largest; |
| } else { |
| if (icmp_.Compare(f->smallest, *smallest) < 0) { |
| *smallest = f->smallest; |
| } |
| if (icmp_.Compare(f->largest, *largest) > 0) { |
| *largest = f->largest; |
| } |
| } |
| } |
| } |
| |
| // Stores the minimal range that covers all entries in inputs1 and inputs2 |
| // in *smallest, *largest. |
| // REQUIRES: inputs is not empty |
| void VersionSet::GetRange2(const std::vector<FileMetaData*>& inputs1, |
| const std::vector<FileMetaData*>& inputs2, |
| InternalKey* smallest, |
| InternalKey* largest) { |
| std::vector<FileMetaData*> all = inputs1; |
| all.insert(all.end(), inputs2.begin(), inputs2.end()); |
| GetRange(all, smallest, largest); |
| } |
| |
| Iterator* VersionSet::MakeInputIterator(Compaction* c) { |
| ReadOptions options; |
| options.verify_checksums = options_->paranoid_checks; |
| options.fill_cache = false; |
| |
| // Level-0 files have to be merged together. For other levels, |
| // we will make a concatenating iterator per level. |
| // TODO(opt): use concatenating iterator for level-0 if there is no overlap |
| const int space = (c->level() == 0 ? c->inputs_[0].size() + 1 : 2); |
| Iterator** list = new Iterator*[space]; |
| int num = 0; |
| for (int which = 0; which < 2; which++) { |
| if (!c->inputs_[which].empty()) { |
| if (c->level() + which == 0) { |
| const std::vector<FileMetaData*>& files = c->inputs_[which]; |
| for (int i = 0; i < files.size(); i++) { |
| list[num++] = table_cache_->NewIterator(options, files[i]->number); |
| } |
| } else { |
| // Create concatenating iterator for the files from this level |
| list[num++] = NewTwoLevelIterator( |
| new Version::LevelFileNumIterator( |
| c->input_version_, &c->inputs_[which]), |
| &GetFileIterator, table_cache_, options); |
| } |
| } |
| } |
| assert(num <= space); |
| Iterator* result = NewMergingIterator(&icmp_, list, num); |
| delete[] list; |
| return result; |
| } |
| |
| Compaction* VersionSet::PickCompaction() { |
| if (!NeedsCompaction()) { |
| return NULL; |
| } |
| const int level = current_->compaction_level_; |
| assert(level >= 0); |
| assert(level+1 < config::kNumLevels); |
| |
| Compaction* c = new Compaction(level); |
| c->input_version_ = current_; |
| c->input_version_->Ref(); |
| |
| // Pick the first file that comes after compact_pointer_[level] |
| for (int i = 0; i < current_->files_[level].size(); i++) { |
| FileMetaData* f = current_->files_[level][i]; |
| if (compact_pointer_[level].empty() || |
| icmp_.Compare(f->largest.Encode(), compact_pointer_[level]) > 0) { |
| c->inputs_[0].push_back(f); |
| break; |
| } |
| } |
| if (c->inputs_[0].empty()) { |
| // Wrap-around to the beginning of the key space |
| c->inputs_[0].push_back(current_->files_[level][0]); |
| } |
| |
| // Files in level 0 may overlap each other, so pick up all overlapping ones |
| if (level == 0) { |
| InternalKey smallest, largest; |
| GetRange(c->inputs_[0], &smallest, &largest); |
| // Note that the next call will discard the file we placed in |
| // c->inputs_[0] earlier and replace it with an overlapping set |
| // which will include the picked file. |
| GetOverlappingInputs(0, smallest, largest, &c->inputs_[0]); |
| assert(!c->inputs_[0].empty()); |
| } |
| |
| SetupOtherInputs(c); |
| |
| return c; |
| } |
| |
| void VersionSet::SetupOtherInputs(Compaction* c) { |
| const int level = c->level(); |
| InternalKey smallest, largest; |
| GetRange(c->inputs_[0], &smallest, &largest); |
| |
| GetOverlappingInputs(level+1, smallest, largest, &c->inputs_[1]); |
| |
| // Get entire range covered by compaction |
| InternalKey all_start, all_limit; |
| GetRange2(c->inputs_[0], c->inputs_[1], &all_start, &all_limit); |
| |
| // See if we can grow the number of inputs in "level" without |
| // changing the number of "level+1" files we pick up. |
| if (!c->inputs_[1].empty()) { |
| std::vector<FileMetaData*> expanded0; |
| GetOverlappingInputs(level, all_start, all_limit, &expanded0); |
| if (expanded0.size() > c->inputs_[0].size()) { |
| InternalKey new_start, new_limit; |
| GetRange(expanded0, &new_start, &new_limit); |
| std::vector<FileMetaData*> expanded1; |
| GetOverlappingInputs(level+1, new_start, new_limit, &expanded1); |
| if (expanded1.size() == c->inputs_[1].size()) { |
| Log(env_, options_->info_log, |
| "Expanding@%d %d+%d to %d+%d\n", |
| level, |
| int(c->inputs_[0].size()), |
| int(c->inputs_[1].size()), |
| int(expanded0.size()), |
| int(expanded1.size())); |
| smallest = new_start; |
| largest = new_limit; |
| c->inputs_[0] = expanded0; |
| c->inputs_[1] = expanded1; |
| GetRange2(c->inputs_[0], c->inputs_[1], &all_start, &all_limit); |
| } |
| } |
| } |
| |
| // Compute the set of grandparent files that overlap this compaction |
| // (parent == level+1; grandparent == level+2) |
| if (level + 2 < config::kNumLevels) { |
| GetOverlappingInputs(level + 2, all_start, all_limit, &c->grandparents_); |
| } |
| |
| if (false) { |
| Log(env_, options_->info_log, "Compacting %d '%s' .. '%s'", |
| level, |
| EscapeString(smallest.Encode()).c_str(), |
| EscapeString(largest.Encode()).c_str()); |
| } |
| |
| // Update the place where we will do the next compaction for this level. |
| // We update this immediately instead of waiting for the VersionEdit |
| // to be applied so that if the compaction fails, we will try a different |
| // key range next time. |
| compact_pointer_[level] = largest.Encode().ToString(); |
| c->edit_.SetCompactPointer(level, largest); |
| } |
| |
| Compaction* VersionSet::CompactRange( |
| int level, |
| const InternalKey& begin, |
| const InternalKey& end) { |
| std::vector<FileMetaData*> inputs; |
| GetOverlappingInputs(level, begin, end, &inputs); |
| if (inputs.empty()) { |
| return NULL; |
| } |
| |
| Compaction* c = new Compaction(level); |
| c->input_version_ = current_; |
| c->input_version_->Ref(); |
| c->inputs_[0] = inputs; |
| SetupOtherInputs(c); |
| return c; |
| } |
| |
| Compaction::Compaction(int level) |
| : level_(level), |
| max_output_file_size_(MaxFileSizeForLevel(level)), |
| input_version_(NULL), |
| grandparent_index_(0), |
| output_start_(-1) { |
| for (int i = 0; i < config::kNumLevels; i++) { |
| level_ptrs_[i] = 0; |
| } |
| } |
| |
| Compaction::~Compaction() { |
| if (input_version_ != NULL) { |
| input_version_->Unref(); |
| } |
| } |
| |
| bool Compaction::IsTrivialMove() const { |
| // Avoid a move if there are lots of overlapping grandparent files. |
| // Otherwise, the move could create a parent file that will require |
| // a very expensive merge later on. |
| return (num_input_files(0) == 1 |
| && num_input_files(1) == 0 |
| && grandparents_.size() <= kMaxGrandParentFiles); |
| } |
| |
| void Compaction::AddInputDeletions(VersionEdit* edit) { |
| for (int which = 0; which < 2; which++) { |
| for (int i = 0; i < inputs_[which].size(); i++) { |
| edit->DeleteFile(level_ + which, inputs_[which][i]->number); |
| } |
| } |
| } |
| |
| bool Compaction::IsBaseLevelForKey(const Slice& user_key) { |
| // Maybe use binary search to find right entry instead of linear search? |
| const Comparator* user_cmp = input_version_->vset_->icmp_.user_comparator(); |
| for (int lvl = level_ + 2; lvl < config::kNumLevels; lvl++) { |
| const std::vector<FileMetaData*>& files = input_version_->files_[lvl]; |
| for (; level_ptrs_[lvl] < files.size(); ) { |
| FileMetaData* f = files[level_ptrs_[lvl]]; |
| if (user_cmp->Compare(user_key, f->largest.user_key()) <= 0) { |
| // We've advanced far enough |
| if (user_cmp->Compare(user_key, f->smallest.user_key()) >= 0) { |
| // Key falls in this file's range, so definitely not base level |
| return false; |
| } |
| break; |
| } |
| level_ptrs_[lvl]++; |
| } |
| } |
| return true; |
| } |
| |
| bool Compaction::ShouldStopBefore(const InternalKey& key) { |
| // Scan to find earliest grandparent file that contains key. |
| const InternalKeyComparator* icmp = &input_version_->vset_->icmp_; |
| while (grandparent_index_ < grandparents_.size() && |
| icmp->Compare(key, grandparents_[grandparent_index_]->largest) > 0) { |
| grandparent_index_++; |
| } |
| |
| // First call? |
| if (output_start_ < 0) { |
| output_start_ = grandparent_index_; |
| } |
| |
| if (grandparent_index_ - output_start_ + 1 > kMaxGrandParentFiles) { |
| // Too many overlaps for current output; start new output |
| output_start_ = grandparent_index_; |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| void Compaction::ReleaseInputs() { |
| if (input_version_ != NULL) { |
| input_version_->Unref(); |
| input_version_ = NULL; |
| } |
| } |
| |
| } |