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Diffstat (limited to 'src/leveldb/db/repair.cc')
-rw-r--r-- | src/leveldb/db/repair.cc | 461 |
1 files changed, 461 insertions, 0 deletions
diff --git a/src/leveldb/db/repair.cc b/src/leveldb/db/repair.cc new file mode 100644 index 0000000000..7281e3d345 --- /dev/null +++ b/src/leveldb/db/repair.cc @@ -0,0 +1,461 @@ +// 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. +// +// We recover the contents of the descriptor from the other files we find. +// (1) Any log files are first converted to tables +// (2) We scan every table to compute +// (a) smallest/largest for the table +// (b) largest sequence number in the table +// (3) We generate descriptor contents: +// - log number is set to zero +// - next-file-number is set to 1 + largest file number we found +// - last-sequence-number is set to largest sequence# found across +// all tables (see 2c) +// - compaction pointers are cleared +// - every table file is added at level 0 +// +// Possible optimization 1: +// (a) Compute total size and use to pick appropriate max-level M +// (b) Sort tables by largest sequence# in the table +// (c) For each table: if it overlaps earlier table, place in level-0, +// else place in level-M. +// Possible optimization 2: +// Store per-table metadata (smallest, largest, largest-seq#, ...) +// in the table's meta section to speed up ScanTable. + +#include "db/builder.h" +#include "db/db_impl.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/table_cache.h" +#include "db/version_edit.h" +#include "db/write_batch_internal.h" +#include "leveldb/comparator.h" +#include "leveldb/db.h" +#include "leveldb/env.h" + +namespace leveldb { + +namespace { + +class Repairer { + public: + Repairer(const std::string& dbname, const Options& options) + : dbname_(dbname), + env_(options.env), + icmp_(options.comparator), + ipolicy_(options.filter_policy), + options_(SanitizeOptions(dbname, &icmp_, &ipolicy_, options)), + owns_info_log_(options_.info_log != options.info_log), + owns_cache_(options_.block_cache != options.block_cache), + next_file_number_(1) { + // TableCache can be small since we expect each table to be opened once. + table_cache_ = new TableCache(dbname_, &options_, 10); + } + + ~Repairer() { + delete table_cache_; + if (owns_info_log_) { + delete options_.info_log; + } + if (owns_cache_) { + delete options_.block_cache; + } + } + + Status Run() { + Status status = FindFiles(); + if (status.ok()) { + ConvertLogFilesToTables(); + ExtractMetaData(); + status = WriteDescriptor(); + } + if (status.ok()) { + unsigned long long bytes = 0; + for (size_t i = 0; i < tables_.size(); i++) { + bytes += tables_[i].meta.file_size; + } + Log(options_.info_log, + "**** Repaired leveldb %s; " + "recovered %d files; %llu bytes. " + "Some data may have been lost. " + "****", + dbname_.c_str(), + static_cast<int>(tables_.size()), + bytes); + } + return status; + } + + private: + struct TableInfo { + FileMetaData meta; + SequenceNumber max_sequence; + }; + + std::string const dbname_; + Env* const env_; + InternalKeyComparator const icmp_; + InternalFilterPolicy const ipolicy_; + Options const options_; + bool owns_info_log_; + bool owns_cache_; + TableCache* table_cache_; + VersionEdit edit_; + + std::vector<std::string> manifests_; + std::vector<uint64_t> table_numbers_; + std::vector<uint64_t> logs_; + std::vector<TableInfo> tables_; + uint64_t next_file_number_; + + Status FindFiles() { + std::vector<std::string> filenames; + Status status = env_->GetChildren(dbname_, &filenames); + if (!status.ok()) { + return status; + } + if (filenames.empty()) { + return Status::IOError(dbname_, "repair found no files"); + } + + uint64_t number; + FileType type; + for (size_t i = 0; i < filenames.size(); i++) { + if (ParseFileName(filenames[i], &number, &type)) { + if (type == kDescriptorFile) { + manifests_.push_back(filenames[i]); + } else { + if (number + 1 > next_file_number_) { + next_file_number_ = number + 1; + } + if (type == kLogFile) { + logs_.push_back(number); + } else if (type == kTableFile) { + table_numbers_.push_back(number); + } else { + // Ignore other files + } + } + } + } + return status; + } + + void ConvertLogFilesToTables() { + for (size_t i = 0; i < logs_.size(); i++) { + std::string logname = LogFileName(dbname_, logs_[i]); + Status status = ConvertLogToTable(logs_[i]); + if (!status.ok()) { + Log(options_.info_log, "Log #%llu: ignoring conversion error: %s", + (unsigned long long) logs_[i], + status.ToString().c_str()); + } + ArchiveFile(logname); + } + } + + Status ConvertLogToTable(uint64_t log) { + struct LogReporter : public log::Reader::Reporter { + Env* env; + Logger* info_log; + uint64_t lognum; + virtual void Corruption(size_t bytes, const Status& s) { + // We print error messages for corruption, but continue repairing. + Log(info_log, "Log #%llu: dropping %d bytes; %s", + (unsigned long long) lognum, + static_cast<int>(bytes), + s.ToString().c_str()); + } + }; + + // Open the log file + std::string logname = LogFileName(dbname_, log); + SequentialFile* lfile; + Status status = env_->NewSequentialFile(logname, &lfile); + if (!status.ok()) { + return status; + } + + // Create the log reader. + LogReporter reporter; + reporter.env = env_; + reporter.info_log = options_.info_log; + reporter.lognum = log; + // We intentionally make log::Reader do checksumming so that + // corruptions cause entire commits to be skipped instead of + // propagating bad information (like overly large sequence + // numbers). + log::Reader reader(lfile, &reporter, false/*do not checksum*/, + 0/*initial_offset*/); + + // Read all the records and add to a memtable + std::string scratch; + Slice record; + WriteBatch batch; + MemTable* mem = new MemTable(icmp_); + mem->Ref(); + int counter = 0; + while (reader.ReadRecord(&record, &scratch)) { + if (record.size() < 12) { + reporter.Corruption( + record.size(), Status::Corruption("log record too small", logname)); + continue; + } + WriteBatchInternal::SetContents(&batch, record); + status = WriteBatchInternal::InsertInto(&batch, mem); + if (status.ok()) { + counter += WriteBatchInternal::Count(&batch); + } else { + Log(options_.info_log, "Log #%llu: ignoring %s", + (unsigned long long) log, + status.ToString().c_str()); + status = Status::OK(); // Keep going with rest of file + } + } + delete lfile; + + // Do not record a version edit for this conversion to a Table + // since ExtractMetaData() will also generate edits. + FileMetaData meta; + meta.number = next_file_number_++; + Iterator* iter = mem->NewIterator(); + status = BuildTable(dbname_, env_, options_, table_cache_, iter, &meta); + delete iter; + mem->Unref(); + mem = NULL; + if (status.ok()) { + if (meta.file_size > 0) { + table_numbers_.push_back(meta.number); + } + } + Log(options_.info_log, "Log #%llu: %d ops saved to Table #%llu %s", + (unsigned long long) log, + counter, + (unsigned long long) meta.number, + status.ToString().c_str()); + return status; + } + + void ExtractMetaData() { + for (size_t i = 0; i < table_numbers_.size(); i++) { + ScanTable(table_numbers_[i]); + } + } + + Iterator* NewTableIterator(const FileMetaData& meta) { + // Same as compaction iterators: if paranoid_checks are on, turn + // on checksum verification. + ReadOptions r; + r.verify_checksums = options_.paranoid_checks; + return table_cache_->NewIterator(r, meta.number, meta.file_size); + } + + void ScanTable(uint64_t number) { + TableInfo t; + t.meta.number = number; + std::string fname = TableFileName(dbname_, number); + Status status = env_->GetFileSize(fname, &t.meta.file_size); + if (!status.ok()) { + // Try alternate file name. + fname = SSTTableFileName(dbname_, number); + Status s2 = env_->GetFileSize(fname, &t.meta.file_size); + if (s2.ok()) { + status = Status::OK(); + } + } + if (!status.ok()) { + ArchiveFile(TableFileName(dbname_, number)); + ArchiveFile(SSTTableFileName(dbname_, number)); + Log(options_.info_log, "Table #%llu: dropped: %s", + (unsigned long long) t.meta.number, + status.ToString().c_str()); + return; + } + + // Extract metadata by scanning through table. + int counter = 0; + Iterator* iter = NewTableIterator(t.meta); + bool empty = true; + ParsedInternalKey parsed; + t.max_sequence = 0; + for (iter->SeekToFirst(); iter->Valid(); iter->Next()) { + Slice key = iter->key(); + if (!ParseInternalKey(key, &parsed)) { + Log(options_.info_log, "Table #%llu: unparsable key %s", + (unsigned long long) t.meta.number, + EscapeString(key).c_str()); + continue; + } + + counter++; + if (empty) { + empty = false; + t.meta.smallest.DecodeFrom(key); + } + t.meta.largest.DecodeFrom(key); + if (parsed.sequence > t.max_sequence) { + t.max_sequence = parsed.sequence; + } + } + if (!iter->status().ok()) { + status = iter->status(); + } + delete iter; + Log(options_.info_log, "Table #%llu: %d entries %s", + (unsigned long long) t.meta.number, + counter, + status.ToString().c_str()); + + if (status.ok()) { + tables_.push_back(t); + } else { + RepairTable(fname, t); // RepairTable archives input file. + } + } + + void RepairTable(const std::string& src, TableInfo t) { + // We will copy src contents to a new table and then rename the + // new table over the source. + + // Create builder. + std::string copy = TableFileName(dbname_, next_file_number_++); + WritableFile* file; + Status s = env_->NewWritableFile(copy, &file); + if (!s.ok()) { + return; + } + TableBuilder* builder = new TableBuilder(options_, file); + + // Copy data. + Iterator* iter = NewTableIterator(t.meta); + int counter = 0; + for (iter->SeekToFirst(); iter->Valid(); iter->Next()) { + builder->Add(iter->key(), iter->value()); + counter++; + } + delete iter; + + ArchiveFile(src); + if (counter == 0) { + builder->Abandon(); // Nothing to save + } else { + s = builder->Finish(); + if (s.ok()) { + t.meta.file_size = builder->FileSize(); + } + } + delete builder; + builder = NULL; + + if (s.ok()) { + s = file->Close(); + } + delete file; + file = NULL; + + if (counter > 0 && s.ok()) { + std::string orig = TableFileName(dbname_, t.meta.number); + s = env_->RenameFile(copy, orig); + if (s.ok()) { + Log(options_.info_log, "Table #%llu: %d entries repaired", + (unsigned long long) t.meta.number, counter); + tables_.push_back(t); + } + } + if (!s.ok()) { + env_->DeleteFile(copy); + } + } + + Status WriteDescriptor() { + std::string tmp = TempFileName(dbname_, 1); + WritableFile* file; + Status status = env_->NewWritableFile(tmp, &file); + if (!status.ok()) { + return status; + } + + SequenceNumber max_sequence = 0; + for (size_t i = 0; i < tables_.size(); i++) { + if (max_sequence < tables_[i].max_sequence) { + max_sequence = tables_[i].max_sequence; + } + } + + edit_.SetComparatorName(icmp_.user_comparator()->Name()); + edit_.SetLogNumber(0); + edit_.SetNextFile(next_file_number_); + edit_.SetLastSequence(max_sequence); + + for (size_t i = 0; i < tables_.size(); i++) { + // TODO(opt): separate out into multiple levels + const TableInfo& t = tables_[i]; + edit_.AddFile(0, t.meta.number, t.meta.file_size, + t.meta.smallest, t.meta.largest); + } + + //fprintf(stderr, "NewDescriptor:\n%s\n", edit_.DebugString().c_str()); + { + log::Writer log(file); + std::string record; + edit_.EncodeTo(&record); + status = log.AddRecord(record); + } + if (status.ok()) { + status = file->Close(); + } + delete file; + file = NULL; + + if (!status.ok()) { + env_->DeleteFile(tmp); + } else { + // Discard older manifests + for (size_t i = 0; i < manifests_.size(); i++) { + ArchiveFile(dbname_ + "/" + manifests_[i]); + } + + // Install new manifest + status = env_->RenameFile(tmp, DescriptorFileName(dbname_, 1)); + if (status.ok()) { + status = SetCurrentFile(env_, dbname_, 1); + } else { + env_->DeleteFile(tmp); + } + } + return status; + } + + void ArchiveFile(const std::string& fname) { + // Move into another directory. E.g., for + // dir/foo + // rename to + // dir/lost/foo + const char* slash = strrchr(fname.c_str(), '/'); + std::string new_dir; + if (slash != NULL) { + new_dir.assign(fname.data(), slash - fname.data()); + } + new_dir.append("/lost"); + env_->CreateDir(new_dir); // Ignore error + std::string new_file = new_dir; + new_file.append("/"); + new_file.append((slash == NULL) ? fname.c_str() : slash + 1); + Status s = env_->RenameFile(fname, new_file); + Log(options_.info_log, "Archiving %s: %s\n", + fname.c_str(), s.ToString().c_str()); + } +}; +} // namespace + +Status RepairDB(const std::string& dbname, const Options& options) { + Repairer repairer(dbname, options); + return repairer.Run(); +} + +} // namespace leveldb |