rocksdb/db/repair.cc
agiardullo 3bfd3d39a3 Use SST files for Transaction conflict detection
Summary:
Currently, transactions can fail even if there is no actual write conflict.  This is due to relying on only the memtables to check for write-conflicts.  Users have to tune memtable settings to try to avoid this, but it's hard to figure out exactly how to tune these settings.

With this diff, TransactionDB will use both memtables and SST files to determine if there are any write conflicts.  This relies on the fact that BlockBasedTable stores sequence numbers for all writes that happen after any open snapshot.  Also, D50295 is needed to prevent SingleDelete from disappearing writes (the TODOs in this test code will be fixed once the other diff is approved and merged).

Note that Optimistic transactions will still rely on tuning memtable settings as we do not want to read from SST while on the write thread.  Also, memtable settings can still be used to reduce how often TransactionDB needs to read SST files.

Test Plan: unit tests, db bench

Reviewers: rven, yhchiang, kradhakrishnan, IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb, yoshinorim

Differential Revision: https://reviews.facebook.net/D50475
2015-12-11 12:34:11 -08:00

473 lines
15 KiB
C++

// 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.
//
// Repairer does best effort recovery to recover as much data as possible after
// a disaster without compromising consistency. It does not guarantee bringing
// the database to a time consistent state.
//
// Repair process is broken into 4 phases:
// (a) Find files
// (b) Convert logs to tables
// (c) Extract metadata
// (d) Write Descriptor
//
// (a) Find files
//
// The repairer goes through all the files in the directory, and classifies them
// based on their file name. Any file that cannot be identified by name will be
// ignored.
//
// (b) Convert logs to table
//
// Every log file that is active is replayed. All sections of the file where the
// checksum does not match is skipped over. We intentionally give preference to
// data consistency.
//
// (c) Extract metadata
//
// We scan every table to compute
// (1) smallest/largest for the table
// (2) largest sequence number in the table
//
// If we are unable to scan the file, then we ignore the table.
//
// (d) Write Descriptor
//
// 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.
// (d) We can provide options for time consistent recovery and unsafe recovery
// (ignore checksum failure when applicable)
// Possible optimization 2:
// Store per-table metadata (smallest, largest, largest-seq#, ...)
// in the table's meta section to speed up ScanTable.
#ifndef ROCKSDB_LITE
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
#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/writebuffer.h"
#include "db/write_batch_internal.h"
#include "rocksdb/comparator.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/options.h"
#include "rocksdb/immutable_options.h"
#include "table/scoped_arena_iterator.h"
#include "util/file_reader_writer.h"
namespace rocksdb {
namespace {
class Repairer {
public:
Repairer(const std::string& dbname, const Options& options)
: dbname_(dbname),
env_(options.env),
icmp_(options.comparator),
options_(SanitizeOptions(dbname, &icmp_, options)),
ioptions_(options_),
raw_table_cache_(
// TableCache can be small since we expect each table to be opened
// once.
NewLRUCache(10, options_.table_cache_numshardbits)),
next_file_number_(1) {
GetIntTblPropCollectorFactory(options, &int_tbl_prop_collector_factories_);
table_cache_ =
new TableCache(ioptions_, env_options_, raw_table_cache_.get());
edit_ = new VersionEdit();
}
~Repairer() {
delete table_cache_;
raw_table_cache_.reset();
delete edit_;
}
Status Run() {
Status status = FindFiles();
if (status.ok()) {
ConvertLogFilesToTables();
ExtractMetaData();
status = WriteDescriptor();
}
if (status.ok()) {
uint64_t bytes = 0;
for (size_t i = 0; i < tables_.size(); i++) {
bytes += tables_[i].meta.fd.GetFileSize();
}
Log(InfoLogLevel::WARN_LEVEL, options_.info_log,
"**** Repaired rocksdb %s; "
"recovered %" ROCKSDB_PRIszt " files; %" PRIu64
"bytes. "
"Some data may have been lost. "
"****",
dbname_.c_str(), tables_.size(), bytes);
}
return status;
}
private:
struct TableInfo {
FileMetaData meta;
SequenceNumber min_sequence;
SequenceNumber max_sequence;
};
std::string const dbname_;
Env* const env_;
const InternalKeyComparator icmp_;
std::vector<std::unique_ptr<IntTblPropCollectorFactory>>
int_tbl_prop_collector_factories_;
const Options options_;
const ImmutableCFOptions ioptions_;
std::shared_ptr<Cache> raw_table_cache_;
TableCache* table_cache_;
VersionEdit* edit_;
std::vector<std::string> manifests_;
std::vector<FileDescriptor> table_fds_;
std::vector<uint64_t> logs_;
std::vector<TableInfo> tables_;
uint64_t next_file_number_;
const EnvOptions env_options_;
Status FindFiles() {
std::vector<std::string> filenames;
bool found_file = false;
for (uint32_t path_id = 0; path_id < options_.db_paths.size(); path_id++) {
Status status =
env_->GetChildren(options_.db_paths[path_id].path, &filenames);
if (!status.ok()) {
return status;
}
if (!filenames.empty()) {
found_file = true;
}
uint64_t number;
FileType type;
for (size_t i = 0; i < filenames.size(); i++) {
if (ParseFileName(filenames[i], &number, &type)) {
if (type == kDescriptorFile) {
assert(path_id == 0);
manifests_.push_back(filenames[i]);
} else {
if (number + 1 > next_file_number_) {
next_file_number_ = number + 1;
}
if (type == kLogFile) {
assert(path_id == 0);
logs_.push_back(number);
} else if (type == kTableFile) {
table_fds_.emplace_back(number, path_id, 0);
} else {
// Ignore other files
}
}
}
}
}
if (!found_file) {
return Status::Corruption(dbname_, "repair found no files");
}
return Status::OK();
}
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(InfoLogLevel::WARN_LEVEL, options_.info_log,
"Log #%" PRIu64 ": ignoring conversion error: %s", logs_[i],
status.ToString().c_str());
}
ArchiveFile(logname);
}
}
Status ConvertLogToTable(uint64_t log) {
struct LogReporter : public log::Reader::Reporter {
Env* env;
std::shared_ptr<Logger> info_log;
uint64_t lognum;
virtual void Corruption(size_t bytes, const Status& s) override {
// We print error messages for corruption, but continue repairing.
Log(InfoLogLevel::ERROR_LEVEL, info_log,
"Log #%" PRIu64 ": dropping %d bytes; %s", lognum,
static_cast<int>(bytes), s.ToString().c_str());
}
};
// Open the log file
std::string logname = LogFileName(dbname_, log);
unique_ptr<SequentialFile> lfile;
Status status = env_->NewSequentialFile(logname, &lfile, env_options_);
if (!status.ok()) {
return status;
}
unique_ptr<SequentialFileReader> lfile_reader(
new SequentialFileReader(std::move(lfile)));
// Create the log reader.
LogReporter reporter;
reporter.env = env_;
reporter.info_log = options_.info_log;
reporter.lognum = log;
// We intentially 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(options_.info_log, std::move(lfile_reader), &reporter,
true /*enable checksum*/, 0 /*initial_offset*/, log);
// Read all the records and add to a memtable
std::string scratch;
Slice record;
WriteBatch batch;
WriteBuffer wb(options_.db_write_buffer_size);
MemTable* mem =
new MemTable(icmp_, ioptions_, MutableCFOptions(options_, ioptions_),
&wb, kMaxSequenceNumber);
auto cf_mems_default = new ColumnFamilyMemTablesDefault(mem);
mem->Ref();
int counter = 0;
while (reader.ReadRecord(&record, &scratch)) {
if (record.size() < 12) {
reporter.Corruption(
record.size(), Status::Corruption("log record too small"));
continue;
}
WriteBatchInternal::SetContents(&batch, record);
status = WriteBatchInternal::InsertInto(&batch, cf_mems_default);
if (status.ok()) {
counter += WriteBatchInternal::Count(&batch);
} else {
Log(InfoLogLevel::WARN_LEVEL,
options_.info_log, "Log #%" PRIu64 ": ignoring %s", log,
status.ToString().c_str());
status = Status::OK(); // Keep going with rest of file
}
}
// Do not record a version edit for this conversion to a Table
// since ExtractMetaData() will also generate edits.
FileMetaData meta;
meta.fd = FileDescriptor(next_file_number_++, 0, 0);
{
ReadOptions ro;
ro.total_order_seek = true;
Arena arena;
ScopedArenaIterator iter(mem->NewIterator(ro, &arena));
status = BuildTable(
dbname_, env_, ioptions_, env_options_, table_cache_, iter.get(),
&meta, icmp_, &int_tbl_prop_collector_factories_,
TablePropertiesCollectorFactory::Context::kUnknownColumnFamily, {},
kMaxSequenceNumber, kNoCompression, CompressionOptions(), false,
nullptr);
}
delete mem->Unref();
delete cf_mems_default;
mem = nullptr;
if (status.ok()) {
if (meta.fd.GetFileSize() > 0) {
table_fds_.push_back(meta.fd);
}
}
Log(InfoLogLevel::INFO_LEVEL, options_.info_log,
"Log #%" PRIu64 ": %d ops saved to Table #%" PRIu64 " %s",
log, counter, meta.fd.GetNumber(), status.ToString().c_str());
return status;
}
void ExtractMetaData() {
for (size_t i = 0; i < table_fds_.size(); i++) {
TableInfo t;
t.meta.fd = table_fds_[i];
Status status = ScanTable(&t);
if (!status.ok()) {
std::string fname = TableFileName(
options_.db_paths, t.meta.fd.GetNumber(), t.meta.fd.GetPathId());
char file_num_buf[kFormatFileNumberBufSize];
FormatFileNumber(t.meta.fd.GetNumber(), t.meta.fd.GetPathId(),
file_num_buf, sizeof(file_num_buf));
Log(InfoLogLevel::WARN_LEVEL, options_.info_log,
"Table #%s: ignoring %s", file_num_buf,
status.ToString().c_str());
ArchiveFile(fname);
} else {
tables_.push_back(t);
}
}
}
Status ScanTable(TableInfo* t) {
std::string fname = TableFileName(options_.db_paths, t->meta.fd.GetNumber(),
t->meta.fd.GetPathId());
int counter = 0;
uint64_t file_size;
Status status = env_->GetFileSize(fname, &file_size);
t->meta.fd = FileDescriptor(t->meta.fd.GetNumber(), t->meta.fd.GetPathId(),
file_size);
if (status.ok()) {
InternalIterator* iter = table_cache_->NewIterator(
ReadOptions(), env_options_, icmp_, t->meta.fd);
bool empty = true;
ParsedInternalKey parsed;
t->min_sequence = 0;
t->max_sequence = 0;
for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
Slice key = iter->key();
if (!ParseInternalKey(key, &parsed)) {
Log(InfoLogLevel::ERROR_LEVEL,
options_.info_log, "Table #%" PRIu64 ": unparsable key %s",
t->meta.fd.GetNumber(), EscapeString(key).c_str());
continue;
}
counter++;
if (empty) {
empty = false;
t->meta.smallest.DecodeFrom(key);
}
t->meta.largest.DecodeFrom(key);
if (parsed.sequence < t->min_sequence) {
t->min_sequence = parsed.sequence;
}
if (parsed.sequence > t->max_sequence) {
t->max_sequence = parsed.sequence;
}
}
if (!iter->status().ok()) {
status = iter->status();
}
delete iter;
}
Log(InfoLogLevel::INFO_LEVEL,
options_.info_log, "Table #%" PRIu64 ": %d entries %s",
t->meta.fd.GetNumber(), counter, status.ToString().c_str());
return status;
}
Status WriteDescriptor() {
std::string tmp = TempFileName(dbname_, 1);
unique_ptr<WritableFile> file;
EnvOptions env_options = env_->OptimizeForManifestWrite(env_options_);
Status status = env_->NewWritableFile(tmp, &file, env_options);
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.fd.GetNumber(), t.meta.fd.GetPathId(),
t.meta.fd.GetFileSize(), t.meta.smallest, t.meta.largest,
t.min_sequence, t.max_sequence,
t.meta.marked_for_compaction);
}
//fprintf(stderr, "NewDescriptor:\n%s\n", edit_.DebugString().c_str());
{
unique_ptr<WritableFileWriter> file_writer(
new WritableFileWriter(std::move(file), env_options));
log::Writer log(std::move(file_writer), 0, false);
std::string record;
edit_->EncodeTo(&record);
status = log.AddRecord(record);
}
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, nullptr);
} 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 != nullptr) {
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 == nullptr) ? fname.c_str() : slash + 1);
Status s = env_->RenameFile(fname, new_file);
Log(InfoLogLevel::INFO_LEVEL,
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 rocksdb
#endif // ROCKSDB_LITE