- Replace raw slice comparison with a call to user comparator. Added test for custom comparators. - Fix end of namespace comments. - Fixed bug in picking inputs for a level-0 compaction. When finding overlapping files, the covered range may expand as files are added to the input set. We now correctly expand the range when this happens instead of continuing to use the old range. For example, suppose L0 contains files with the following ranges: F1: a .. d F2: c .. g F3: f .. j and the initial compaction target is F3. We used to search for range f..j which yielded {F2,F3}. However we now expand the range as soon as another file is added. In this case, when F2 is added, we expand the range to c..j and restart the search. That picks up file F1 as well. This change fixes a bug related to deleted keys showing up incorrectly after a compaction as described in Issue 44. (Sync with upstream @25072954)
388 lines
12 KiB
C++
388 lines
12 KiB
C++
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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//
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// We recover the contents of the descriptor from the other files we find.
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// (1) Any log files are first converted to tables
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// (2) We scan every table to compute
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// (a) smallest/largest for the table
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// (b) largest sequence number in the table
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// (3) We generate descriptor contents:
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// - log number is set to zero
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// - next-file-number is set to 1 + largest file number we found
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// - last-sequence-number is set to largest sequence# found across
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// all tables (see 2c)
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// - compaction pointers are cleared
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// - every table file is added at level 0
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//
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// Possible optimization 1:
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// (a) Compute total size and use to pick appropriate max-level M
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// (b) Sort tables by largest sequence# in the table
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// (c) For each table: if it overlaps earlier table, place in level-0,
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// else place in level-M.
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// Possible optimization 2:
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// Store per-table metadata (smallest, largest, largest-seq#, ...)
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// in the table's meta section to speed up ScanTable.
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#include "db/builder.h"
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#include "db/db_impl.h"
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#include "db/dbformat.h"
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#include "db/filename.h"
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#include "db/log_reader.h"
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#include "db/log_writer.h"
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#include "db/memtable.h"
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#include "db/table_cache.h"
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#include "db/version_edit.h"
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#include "db/write_batch_internal.h"
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#include "leveldb/comparator.h"
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#include "leveldb/db.h"
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#include "leveldb/env.h"
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namespace leveldb {
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namespace {
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class Repairer {
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public:
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Repairer(const std::string& dbname, const Options& options)
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: dbname_(dbname),
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env_(options.env),
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icmp_(options.comparator),
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options_(SanitizeOptions(dbname, &icmp_, options)),
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owns_info_log_(options_.info_log != options.info_log),
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owns_cache_(options_.block_cache != options.block_cache),
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next_file_number_(1) {
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// TableCache can be small since we expect each table to be opened once.
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table_cache_ = new TableCache(dbname_, &options_, 10);
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}
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~Repairer() {
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delete table_cache_;
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if (owns_info_log_) {
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delete options_.info_log;
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}
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if (owns_cache_) {
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delete options_.block_cache;
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}
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}
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Status Run() {
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Status status = FindFiles();
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if (status.ok()) {
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ConvertLogFilesToTables();
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ExtractMetaData();
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status = WriteDescriptor();
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}
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if (status.ok()) {
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unsigned long long bytes = 0;
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for (size_t i = 0; i < tables_.size(); i++) {
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bytes += tables_[i].meta.file_size;
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}
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Log(options_.info_log,
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"**** Repaired leveldb %s; "
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"recovered %d files; %llu bytes. "
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"Some data may have been lost. "
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"****",
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dbname_.c_str(),
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static_cast<int>(tables_.size()),
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bytes);
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}
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return status;
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}
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private:
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struct TableInfo {
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FileMetaData meta;
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SequenceNumber max_sequence;
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};
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std::string const dbname_;
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Env* const env_;
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InternalKeyComparator const icmp_;
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Options const options_;
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bool owns_info_log_;
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bool owns_cache_;
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TableCache* table_cache_;
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VersionEdit edit_;
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std::vector<std::string> manifests_;
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std::vector<uint64_t> table_numbers_;
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std::vector<uint64_t> logs_;
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std::vector<TableInfo> tables_;
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uint64_t next_file_number_;
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Status FindFiles() {
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std::vector<std::string> filenames;
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Status status = env_->GetChildren(dbname_, &filenames);
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if (!status.ok()) {
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return status;
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}
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if (filenames.empty()) {
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return Status::IOError(dbname_, "repair found no files");
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}
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uint64_t number;
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FileType type;
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for (size_t i = 0; i < filenames.size(); i++) {
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if (ParseFileName(filenames[i], &number, &type)) {
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if (type == kDescriptorFile) {
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manifests_.push_back(filenames[i]);
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} else {
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if (number + 1 > next_file_number_) {
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next_file_number_ = number + 1;
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}
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if (type == kLogFile) {
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logs_.push_back(number);
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} else if (type == kTableFile) {
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table_numbers_.push_back(number);
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} else {
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// Ignore other files
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}
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}
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}
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}
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return status;
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}
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void ConvertLogFilesToTables() {
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for (size_t i = 0; i < logs_.size(); i++) {
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std::string logname = LogFileName(dbname_, logs_[i]);
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Status status = ConvertLogToTable(logs_[i]);
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if (!status.ok()) {
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Log(options_.info_log, "Log #%llu: ignoring conversion error: %s",
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(unsigned long long) logs_[i],
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status.ToString().c_str());
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}
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ArchiveFile(logname);
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}
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}
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Status ConvertLogToTable(uint64_t log) {
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struct LogReporter : public log::Reader::Reporter {
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Env* env;
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Logger* info_log;
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uint64_t lognum;
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virtual void Corruption(size_t bytes, const Status& s) {
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// We print error messages for corruption, but continue repairing.
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Log(info_log, "Log #%llu: dropping %d bytes; %s",
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(unsigned long long) lognum,
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static_cast<int>(bytes),
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s.ToString().c_str());
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}
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};
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// Open the log file
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std::string logname = LogFileName(dbname_, log);
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SequentialFile* lfile;
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Status status = env_->NewSequentialFile(logname, &lfile);
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if (!status.ok()) {
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return status;
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}
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// Create the log reader.
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LogReporter reporter;
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reporter.env = env_;
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reporter.info_log = options_.info_log;
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reporter.lognum = log;
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// We intentially make log::Reader do checksumming so that
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// corruptions cause entire commits to be skipped instead of
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// propagating bad information (like overly large sequence
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// numbers).
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log::Reader reader(lfile, &reporter, false/*do not checksum*/,
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0/*initial_offset*/);
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// Read all the records and add to a memtable
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std::string scratch;
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Slice record;
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WriteBatch batch;
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MemTable* mem = new MemTable(icmp_);
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mem->Ref();
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int counter = 0;
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while (reader.ReadRecord(&record, &scratch)) {
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if (record.size() < 12) {
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reporter.Corruption(
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record.size(), Status::Corruption("log record too small"));
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continue;
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}
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WriteBatchInternal::SetContents(&batch, record);
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status = WriteBatchInternal::InsertInto(&batch, mem);
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if (status.ok()) {
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counter += WriteBatchInternal::Count(&batch);
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} else {
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Log(options_.info_log, "Log #%llu: ignoring %s",
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(unsigned long long) log,
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status.ToString().c_str());
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status = Status::OK(); // Keep going with rest of file
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}
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}
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delete lfile;
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// Do not record a version edit for this conversion to a Table
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// since ExtractMetaData() will also generate edits.
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FileMetaData meta;
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meta.number = next_file_number_++;
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Iterator* iter = mem->NewIterator();
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status = BuildTable(dbname_, env_, options_, table_cache_, iter, &meta);
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delete iter;
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mem->Unref();
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mem = NULL;
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if (status.ok()) {
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if (meta.file_size > 0) {
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table_numbers_.push_back(meta.number);
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}
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}
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Log(options_.info_log, "Log #%llu: %d ops saved to Table #%llu %s",
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(unsigned long long) log,
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counter,
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(unsigned long long) meta.number,
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status.ToString().c_str());
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return status;
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}
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void ExtractMetaData() {
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std::vector<TableInfo> kept;
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for (size_t i = 0; i < table_numbers_.size(); i++) {
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TableInfo t;
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t.meta.number = table_numbers_[i];
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Status status = ScanTable(&t);
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if (!status.ok()) {
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std::string fname = TableFileName(dbname_, table_numbers_[i]);
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Log(options_.info_log, "Table #%llu: ignoring %s",
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(unsigned long long) table_numbers_[i],
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status.ToString().c_str());
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ArchiveFile(fname);
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} else {
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tables_.push_back(t);
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}
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}
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}
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Status ScanTable(TableInfo* t) {
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std::string fname = TableFileName(dbname_, t->meta.number);
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int counter = 0;
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Status status = env_->GetFileSize(fname, &t->meta.file_size);
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if (status.ok()) {
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Iterator* iter = table_cache_->NewIterator(
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ReadOptions(), t->meta.number, t->meta.file_size);
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bool empty = true;
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ParsedInternalKey parsed;
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t->max_sequence = 0;
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for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
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Slice key = iter->key();
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if (!ParseInternalKey(key, &parsed)) {
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Log(options_.info_log, "Table #%llu: unparsable key %s",
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(unsigned long long) t->meta.number,
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EscapeString(key).c_str());
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continue;
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}
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counter++;
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if (empty) {
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empty = false;
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t->meta.smallest.DecodeFrom(key);
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}
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t->meta.largest.DecodeFrom(key);
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if (parsed.sequence > t->max_sequence) {
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t->max_sequence = parsed.sequence;
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}
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}
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if (!iter->status().ok()) {
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status = iter->status();
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}
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delete iter;
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}
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Log(options_.info_log, "Table #%llu: %d entries %s",
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(unsigned long long) t->meta.number,
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counter,
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status.ToString().c_str());
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return status;
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}
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Status WriteDescriptor() {
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std::string tmp = TempFileName(dbname_, 1);
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WritableFile* file;
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Status status = env_->NewWritableFile(tmp, &file);
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if (!status.ok()) {
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return status;
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}
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SequenceNumber max_sequence = 0;
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for (size_t i = 0; i < tables_.size(); i++) {
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if (max_sequence < tables_[i].max_sequence) {
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max_sequence = tables_[i].max_sequence;
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}
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}
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edit_.SetComparatorName(icmp_.user_comparator()->Name());
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edit_.SetLogNumber(0);
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edit_.SetNextFile(next_file_number_);
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edit_.SetLastSequence(max_sequence);
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for (size_t i = 0; i < tables_.size(); i++) {
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// TODO(opt): separate out into multiple levels
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const TableInfo& t = tables_[i];
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edit_.AddFile(0, t.meta.number, t.meta.file_size,
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t.meta.smallest, t.meta.largest);
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}
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//fprintf(stderr, "NewDescriptor:\n%s\n", edit_.DebugString().c_str());
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{
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log::Writer log(file);
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std::string record;
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edit_.EncodeTo(&record);
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status = log.AddRecord(record);
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}
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if (status.ok()) {
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status = file->Close();
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}
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delete file;
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file = NULL;
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if (!status.ok()) {
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env_->DeleteFile(tmp);
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} else {
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// Discard older manifests
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for (size_t i = 0; i < manifests_.size(); i++) {
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ArchiveFile(dbname_ + "/" + manifests_[i]);
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}
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// Install new manifest
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status = env_->RenameFile(tmp, DescriptorFileName(dbname_, 1));
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if (status.ok()) {
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status = SetCurrentFile(env_, dbname_, 1);
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} else {
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env_->DeleteFile(tmp);
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}
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}
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return status;
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}
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void ArchiveFile(const std::string& fname) {
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// Move into another directory. E.g., for
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// dir/foo
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// rename to
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// dir/lost/foo
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const char* slash = strrchr(fname.c_str(), '/');
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std::string new_dir;
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if (slash != NULL) {
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new_dir.assign(fname.data(), slash - fname.data());
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}
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new_dir.append("/lost");
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env_->CreateDir(new_dir); // Ignore error
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std::string new_file = new_dir;
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new_file.append("/");
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new_file.append((slash == NULL) ? fname.c_str() : slash + 1);
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Status s = env_->RenameFile(fname, new_file);
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Log(options_.info_log, "Archiving %s: %s\n",
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fname.c_str(), s.ToString().c_str());
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}
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};
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} // namespace
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Status RepairDB(const std::string& dbname, const Options& options) {
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Repairer repairer(dbname, options);
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return repairer.Run();
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}
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} // namespace leveldb
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