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rocksdb/db/repair.cc

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// 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 "util/scoped_arena_iterator.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 %zu 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;
}
// 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(std::move(lfile), &reporter, true /*enable checksum*/,
0/*initial_offset*/);
// 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);
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_, 0, 0,
kNoCompression, CompressionOptions(), false);
}
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()) {
Iterator* 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;
Status status = env_->NewWritableFile(
tmp, &file, env_->OptimizeForManifestWrite(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);
}
//fprintf(stderr, "NewDescriptor:\n%s\n", edit_.DebugString().c_str());
{
log::Writer log(std::move(file));
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