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rocksdb/db/repair.cc
Andrew Kryczka 4708a6875c Repair DBs with trailing slash in name 
Summary:
Problem:

- `DB::SanitizeOptions` strips trailing slash from `wal_dir` but not `dbname`
- We check whether `wal_dir` and `dbname` refer to the same directory using string equality: https://github.com/facebook/rocksdb/blob/master/db/repair.cc#L258
- Providing `dbname` with trailing slash causes default `wal_dir` to be misidentified as a separate directory.
- Then the repair tries to add all SST files to the `VersionEdit` twice (once for `dbname` dir, once for `wal_dir`) and fails with coredump.

Solution:

- Add a new `Env` function, `AreFilesSame`, which uses device and inode number to check whether files are the same. It's currently only implemented in `PosixEnv`.
- Migrate repair to use `AreFilesSame` to check whether `dbname` and `wal_dir` are same. If unsupported, falls back to string comparison.
Closes https://github.com/facebook/rocksdb/pull/2827

Differential Revision: D5761349

Pulled By: ajkr

fbshipit-source-id: c839d548678b742af1166d60b09abd94e5476238
2017-09-22 12:42:22 -07:00

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root 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/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 "options/cf_options.h"
#include "rocksdb/comparator.h"
#include "rocksdb/db.h"
#include "rocksdb/env.h"
#include "rocksdb/options.h"
#include "rocksdb/write_buffer_manager.h"
#include "table/scoped_arena_iterator.h"
#include "util/file_reader_writer.h"
#include "util/filename.h"
#include "util/string_util.h"
namespace rocksdb {
namespace {
class Repairer {
public:
Repairer(const std::string& dbname, const DBOptions& db_options,
const std::vector<ColumnFamilyDescriptor>& column_families,
const ColumnFamilyOptions& default_cf_opts,
const ColumnFamilyOptions& unknown_cf_opts, bool create_unknown_cfs)
: dbname_(dbname),
env_(db_options.env),
env_options_(),
db_options_(SanitizeOptions(dbname_, db_options)),
immutable_db_options_(db_options_),
icmp_(default_cf_opts.comparator),
default_cf_opts_(default_cf_opts),
default_cf_iopts_(
ImmutableCFOptions(immutable_db_options_, default_cf_opts)),
unknown_cf_opts_(unknown_cf_opts),
create_unknown_cfs_(create_unknown_cfs),
raw_table_cache_(
// TableCache can be small since we expect each table to be opened
// once.
NewLRUCache(10, db_options_.table_cache_numshardbits)),
table_cache_(new TableCache(default_cf_iopts_, env_options_,
raw_table_cache_.get())),
wb_(db_options_.db_write_buffer_size),
wc_(db_options_.delayed_write_rate),
vset_(dbname_, &immutable_db_options_, env_options_,
raw_table_cache_.get(), &wb_, &wc_),
next_file_number_(1) {
for (const auto& cfd : column_families) {
cf_name_to_opts_[cfd.name] = cfd.options;
}
}
const ColumnFamilyOptions* GetColumnFamilyOptions(
const std::string& cf_name) {
if (cf_name_to_opts_.find(cf_name) == cf_name_to_opts_.end()) {
if (create_unknown_cfs_) {
return &unknown_cf_opts_;
}
return nullptr;
}
return &cf_name_to_opts_[cf_name];
}
// Adds a column family to the VersionSet with cf_options_ and updates
// manifest.
Status AddColumnFamily(const std::string& cf_name, uint32_t cf_id) {
const auto* cf_opts = GetColumnFamilyOptions(cf_name);
if (cf_opts == nullptr) {
return Status::Corruption("Encountered unknown column family with name=" +
cf_name + ", id=" + ToString(cf_id));
}
Options opts(db_options_, *cf_opts);
MutableCFOptions mut_cf_opts(opts);
VersionEdit edit;
edit.SetComparatorName(opts.comparator->Name());
edit.SetLogNumber(0);
edit.SetColumnFamily(cf_id);
ColumnFamilyData* cfd;
cfd = nullptr;
edit.AddColumnFamily(cf_name);
mutex_.Lock();
Status status = vset_.LogAndApply(cfd, mut_cf_opts, &edit, &mutex_,
nullptr /* db_directory */,
false /* new_descriptor_log */, cf_opts);
mutex_.Unlock();
return status;
}
~Repairer() {
delete table_cache_;
}
Status Run() {
Status status = FindFiles();
if (status.ok()) {
// Discard older manifests and start a fresh one
for (size_t i = 0; i < manifests_.size(); i++) {
ArchiveFile(dbname_ + "/" + manifests_[i]);
}
// Just create a DBImpl temporarily so we can reuse NewDB()
DBImpl* db_impl = new DBImpl(db_options_, dbname_);
status = db_impl->NewDB();
delete db_impl;
}
if (status.ok()) {
// Recover using the fresh manifest created by NewDB()
status =
vset_.Recover({{kDefaultColumnFamilyName, default_cf_opts_}}, false);
}
if (status.ok()) {
// Need to scan existing SST files first so the column families are
// created before we process WAL files
ExtractMetaData();
// ExtractMetaData() uses table_fds_ to know which SST files' metadata to
// extract -- we need to clear it here since metadata for existing SST
// files has been extracted already
table_fds_.clear();
ConvertLogFilesToTables();
ExtractMetaData();
status = AddTables();
}
if (status.ok()) {
uint64_t bytes = 0;
for (size_t i = 0; i < tables_.size(); i++) {
bytes += tables_[i].meta.fd.GetFileSize();
}
ROCKS_LOG_WARN(db_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;
uint32_t column_family_id;
std::string column_family_name;
SequenceNumber min_sequence;
SequenceNumber max_sequence;
};
std::string const dbname_;
Env* const env_;
const EnvOptions env_options_;
const DBOptions db_options_;
const ImmutableDBOptions immutable_db_options_;
const InternalKeyComparator icmp_;
const ColumnFamilyOptions default_cf_opts_;
const ImmutableCFOptions default_cf_iopts_; // table_cache_ holds reference
const ColumnFamilyOptions unknown_cf_opts_;
const bool create_unknown_cfs_;
std::shared_ptr<Cache> raw_table_cache_;
TableCache* table_cache_;
WriteBufferManager wb_;
WriteController wc_;
VersionSet vset_;
std::unordered_map<std::string, ColumnFamilyOptions> cf_name_to_opts_;
InstrumentedMutex mutex_;
std::vector<std::string> manifests_;
std::vector<FileDescriptor> table_fds_;
std::vector<uint64_t> logs_;
std::vector<TableInfo> tables_;
uint64_t next_file_number_;
Status FindFiles() {
std::vector<std::string> filenames;
bool found_file = false;
std::vector<std::string> to_search_paths;
for (size_t path_id = 0; path_id < db_options_.db_paths.size(); path_id++) {
to_search_paths.push_back(db_options_.db_paths[path_id].path);
}
// search wal_dir if user uses a customize wal_dir
bool same = false;
Status status = env_->AreFilesSame(db_options_.wal_dir, dbname_, &same);
if (status.IsNotSupported()) {
same = db_options_.wal_dir == dbname_;
status = Status::OK();
} else if (!status.ok()) {
return status;
}
if (!same) {
to_search_paths.push_back(db_options_.wal_dir);
}
for (size_t path_id = 0; path_id < to_search_paths.size(); path_id++) {
status = env_->GetChildren(to_search_paths[path_id], &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) {
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_fds_.emplace_back(number, static_cast<uint32_t>(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++) {
// we should use LogFileName(wal_dir, logs_[i]) here. user might uses wal_dir option.
std::string logname = LogFileName(db_options_.wal_dir, logs_[i]);
Status status = ConvertLogToTable(logs_[i]);
if (!status.ok()) {
ROCKS_LOG_WARN(db_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.
ROCKS_LOG_ERROR(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(db_options_.wal_dir, log);
unique_ptr<SequentialFile> lfile;
Status status = env_->NewSequentialFile(
logname, &lfile, env_->OptimizeForLogRead(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 = db_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(db_options_.info_log, std::move(lfile_reader), &reporter,
true /*enable checksum*/, 0 /*initial_offset*/, log);
// Initialize per-column family memtables
for (auto* cfd : *vset_.GetColumnFamilySet()) {
cfd->CreateNewMemtable(*cfd->GetLatestMutableCFOptions(),
kMaxSequenceNumber);
}
auto cf_mems = new ColumnFamilyMemTablesImpl(vset_.GetColumnFamilySet());
// Read all the records and add to a memtable
std::string scratch;
Slice record;
WriteBatch batch;
int counter = 0;
while (reader.ReadRecord(&record, &scratch)) {
if (record.size() < WriteBatchInternal::kHeader) {
reporter.Corruption(
record.size(), Status::Corruption("log record too small"));
continue;
}
WriteBatchInternal::SetContents(&batch, record);
status = WriteBatchInternal::InsertInto(&batch, cf_mems, nullptr);
if (status.ok()) {
counter += WriteBatchInternal::Count(&batch);
} else {
ROCKS_LOG_WARN(db_options_.info_log, "Log #%" PRIu64 ": ignoring %s",
log, status.ToString().c_str());
status = Status::OK(); // Keep going with rest of file
}
}
// Dump a table for each column family with entries in this log file.
for (auto* cfd : *vset_.GetColumnFamilySet()) {
// Do not record a version edit for this conversion to a Table
// since ExtractMetaData() will also generate edits.
MemTable* mem = cfd->mem();
if (mem->IsEmpty()) {
continue;
}
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));
EnvOptions optimized_env_options =
env_->OptimizeForCompactionTableWrite(env_options_, immutable_db_options_);
int64_t _current_time = 0;
status = env_->GetCurrentTime(&_current_time); // ignore error
const uint64_t current_time = static_cast<uint64_t>(_current_time);
status = BuildTable(
dbname_, env_, *cfd->ioptions(), *cfd->GetLatestMutableCFOptions(),
optimized_env_options, table_cache_, iter.get(),
std::unique_ptr<InternalIterator>(mem->NewRangeTombstoneIterator(ro)),
&meta, cfd->internal_comparator(),
cfd->int_tbl_prop_collector_factories(), cfd->GetID(), cfd->GetName(),
{}, kMaxSequenceNumber, kNoCompression, CompressionOptions(), false,
nullptr /* internal_stats */, TableFileCreationReason::kRecovery,
nullptr /* event_logger */, 0 /* job_id */, Env::IO_HIGH,
nullptr /* table_properties */, -1 /* level */, current_time);
ROCKS_LOG_INFO(db_options_.info_log,
"Log #%" PRIu64 ": %d ops saved to Table #%" PRIu64 " %s",
log, counter, meta.fd.GetNumber(),
status.ToString().c_str());
if (status.ok()) {
if (meta.fd.GetFileSize() > 0) {
table_fds_.push_back(meta.fd);
}
} else {
break;
}
}
delete cf_mems;
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(
db_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));
ROCKS_LOG_WARN(db_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(
db_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);
std::shared_ptr<const TableProperties> props;
if (status.ok()) {
status = table_cache_->GetTableProperties(env_options_, icmp_, t->meta.fd,
&props);
}
if (status.ok()) {
t->column_family_id = static_cast<uint32_t>(props->column_family_id);
if (t->column_family_id ==
TablePropertiesCollectorFactory::Context::kUnknownColumnFamily) {
ROCKS_LOG_WARN(
db_options_.info_log,
"Table #%" PRIu64
": column family unknown (probably due to legacy format); "
"adding to default column family id 0.",
t->meta.fd.GetNumber());
t->column_family_id = 0;
}
if (vset_.GetColumnFamilySet()->GetColumnFamily(t->column_family_id) ==
nullptr) {
status =
AddColumnFamily(props->column_family_name, t->column_family_id);
}
}
ColumnFamilyData* cfd = nullptr;
if (status.ok()) {
cfd = vset_.GetColumnFamilySet()->GetColumnFamily(t->column_family_id);
if (cfd->GetName() != props->column_family_name) {
ROCKS_LOG_ERROR(
db_options_.info_log,
"Table #%" PRIu64
": inconsistent column family name '%s'; expected '%s' for column "
"family id %" PRIu32 ".",
t->meta.fd.GetNumber(), props->column_family_name.c_str(),
cfd->GetName().c_str(), t->column_family_id);
status = Status::Corruption(dbname_, "inconsistent column family name");
}
}
if (status.ok()) {
InternalIterator* iter = table_cache_->NewIterator(
ReadOptions(), env_options_, cfd->internal_comparator(), t->meta.fd,
nullptr /* range_del_agg */);
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)) {
ROCKS_LOG_ERROR(db_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->min_sequence = parsed.sequence;
}
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;
ROCKS_LOG_INFO(db_options_.info_log, "Table #%" PRIu64 ": %d entries %s",
t->meta.fd.GetNumber(), counter,
status.ToString().c_str());
}
return status;
}
Status AddTables() {
std::unordered_map<uint32_t, std::vector<const TableInfo*>> cf_id_to_tables;
SequenceNumber max_sequence = 0;
for (size_t i = 0; i < tables_.size(); i++) {
cf_id_to_tables[tables_[i].column_family_id].push_back(&tables_[i]);
if (max_sequence < tables_[i].max_sequence) {
max_sequence = tables_[i].max_sequence;
}
}
vset_.SetLastToBeWrittenSequence(max_sequence);
vset_.SetLastSequence(max_sequence);
for (const auto& cf_id_and_tables : cf_id_to_tables) {
auto* cfd =
vset_.GetColumnFamilySet()->GetColumnFamily(cf_id_and_tables.first);
VersionEdit edit;
edit.SetComparatorName(cfd->user_comparator()->Name());
edit.SetLogNumber(0);
edit.SetNextFile(next_file_number_);
edit.SetColumnFamily(cfd->GetID());
// TODO(opt): separate out into multiple levels
for (const auto* table : cf_id_and_tables.second) {
edit.AddFile(0, table->meta.fd.GetNumber(), table->meta.fd.GetPathId(),
table->meta.fd.GetFileSize(), table->meta.smallest,
table->meta.largest, table->min_sequence,
table->max_sequence, table->meta.marked_for_compaction);
}
mutex_.Lock();
Status status = vset_.LogAndApply(
cfd, *cfd->GetLatestMutableCFOptions(), &edit, &mutex_,
nullptr /* db_directory */, false /* new_descriptor_log */);
mutex_.Unlock();
if (!status.ok()) {
return status;
}
}
return Status::OK();
}
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);
ROCKS_LOG_INFO(db_options_.info_log, "Archiving %s: %s\n", fname.c_str(),
s.ToString().c_str());
}
};
Status GetDefaultCFOptions(
const std::vector<ColumnFamilyDescriptor>& column_families,
ColumnFamilyOptions* res) {
assert(res != nullptr);
auto iter = std::find_if(column_families.begin(), column_families.end(),
[](const ColumnFamilyDescriptor& cfd) {
return cfd.name == kDefaultColumnFamilyName;
});
if (iter == column_families.end()) {
return Status::InvalidArgument(
"column_families", "Must contain entry for default column family");
}
*res = iter->options;
return Status::OK();
}
} // anonymous namespace
Status RepairDB(const std::string& dbname, const DBOptions& db_options,
const std::vector<ColumnFamilyDescriptor>& column_families) {
ColumnFamilyOptions default_cf_opts;
Status status = GetDefaultCFOptions(column_families, &default_cf_opts);
if (status.ok()) {
Repairer repairer(dbname, db_options, column_families, default_cf_opts,
ColumnFamilyOptions() /* unknown_cf_opts */,
false /* create_unknown_cfs */);
status = repairer.Run();
}
return status;
}
Status RepairDB(const std::string& dbname, const DBOptions& db_options,
const std::vector<ColumnFamilyDescriptor>& column_families,
const ColumnFamilyOptions& unknown_cf_opts) {
ColumnFamilyOptions default_cf_opts;
Status status = GetDefaultCFOptions(column_families, &default_cf_opts);
if (status.ok()) {
Repairer repairer(dbname, db_options, column_families, default_cf_opts,
unknown_cf_opts, true /* create_unknown_cfs */);
status = repairer.Run();
}
return status;
}
Status RepairDB(const std::string& dbname, const Options& options) {
DBOptions db_options(options);
ColumnFamilyOptions cf_options(options);
Repairer repairer(dbname, db_options, {}, cf_options /* default_cf_opts */,
cf_options /* unknown_cf_opts */,
true /* create_unknown_cfs */);
return repairer.Run();
}
} // namespace rocksdb
#endif // ROCKSDB_LITE
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