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rocksdb/utilities/backupable/backupable_db.cc
Lei Jin 5ef1ba7ff5 generic rate limiter 
Summary:
A generic rate limiter that can be shared by threads and rocksdb
instances. Will use this to smooth out write traffic generated by
compaction and flush. This will help us get better p99 behavior on flash
storage.

Test Plan:
unit test output
==== Test RateLimiterTest.Rate
request size [1 - 1023], limit 10 KB/sec, actual rate: 10.374969 KB/sec, elapsed 2002265
request size [1 - 2047], limit 20 KB/sec, actual rate: 20.771242 KB/sec, elapsed 2002139
request size [1 - 4095], limit 40 KB/sec, actual rate: 41.285299 KB/sec, elapsed 2202424
request size [1 - 8191], limit 80 KB/sec, actual rate: 81.371605 KB/sec, elapsed 2402558
request size [1 - 16383], limit 160 KB/sec, actual rate: 162.541268 KB/sec, elapsed 3303500

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D19359
2014-07-08 11:41:57 -07:00

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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.
#ifndef ROCKSDB_LITE
#include "utilities/backupable_db.h"
#include "db/filename.h"
#include "util/coding.h"
#include "util/crc32c.h"
#include "rocksdb/transaction_log.h"
#define __STDC_FORMAT_MACROS
#include <inttypes.h>
#include <algorithm>
#include <vector>
#include <map>
#include <string>
#include <limits>
#include <atomic>
#include <unordered_map>
namespace rocksdb {
namespace {
class BackupRateLimiter {
public:
BackupRateLimiter(Env* env, uint64_t max_bytes_per_second,
uint64_t bytes_per_check)
: env_(env),
max_bytes_per_second_(max_bytes_per_second),
bytes_per_check_(bytes_per_check),
micros_start_time_(env->NowMicros()),
bytes_since_start_(0) {}
void ReportAndWait(uint64_t bytes_since_last_call) {
bytes_since_start_ += bytes_since_last_call;
if (bytes_since_start_ < bytes_per_check_) {
// not enough bytes to be rate-limited
return;
}
uint64_t now = env_->NowMicros();
uint64_t interval = now - micros_start_time_;
uint64_t should_take_micros =
(bytes_since_start_ * kMicrosInSecond) / max_bytes_per_second_;
if (should_take_micros > interval) {
env_->SleepForMicroseconds(should_take_micros - interval);
now = env_->NowMicros();
}
// reset interval
micros_start_time_ = now;
bytes_since_start_ = 0;
}
private:
Env* env_;
uint64_t max_bytes_per_second_;
uint64_t bytes_per_check_;
uint64_t micros_start_time_;
uint64_t bytes_since_start_;
static const uint64_t kMicrosInSecond = 1000 * 1000LL;
};
} // namespace
void BackupableDBOptions::Dump(Logger* logger) const {
Log(logger, " Options.backup_dir: %s", backup_dir.c_str());
Log(logger, " Options.backup_env: %p", backup_env);
Log(logger, " Options.share_table_files: %d",
static_cast<int>(share_table_files));
Log(logger, " Options.info_log: %p", info_log);
Log(logger, " Options.sync: %d", static_cast<int>(sync));
Log(logger, " Options.destroy_old_data: %d",
static_cast<int>(destroy_old_data));
Log(logger, " Options.backup_log_files: %d",
static_cast<int>(backup_log_files));
Log(logger, " Options.backup_rate_limit: %" PRIu64, backup_rate_limit);
Log(logger, "Options.restore_rate_limit: %" PRIu64, restore_rate_limit);
}
// -------- BackupEngineImpl class ---------
class BackupEngineImpl : public BackupEngine {
public:
BackupEngineImpl(Env* db_env, const BackupableDBOptions& options,
bool read_only = false);
~BackupEngineImpl();
Status CreateNewBackup(DB* db, bool flush_before_backup = false);
Status PurgeOldBackups(uint32_t num_backups_to_keep);
Status DeleteBackup(BackupID backup_id);
void StopBackup() {
stop_backup_.store(true, std::memory_order_release);
}
void GetBackupInfo(std::vector<BackupInfo>* backup_info);
Status RestoreDBFromBackup(BackupID backup_id, const std::string& db_dir,
const std::string& wal_dir,
const RestoreOptions& restore_options =
RestoreOptions());
Status RestoreDBFromLatestBackup(const std::string& db_dir,
const std::string& wal_dir,
const RestoreOptions& restore_options =
RestoreOptions()) {
return RestoreDBFromBackup(latest_backup_id_, db_dir, wal_dir,
restore_options);
}
private:
void DeleteChildren(const std::string& dir, uint32_t file_type_filter = 0);
struct FileInfo {
FileInfo(const std::string& fname, uint64_t sz, uint32_t checksum)
: refs(0), filename(fname), size(sz), checksum_value(checksum) {}
int refs;
const std::string filename;
const uint64_t size;
uint32_t checksum_value;
};
class BackupMeta {
public:
BackupMeta(const std::string& meta_filename,
std::unordered_map<std::string, FileInfo>* file_infos, Env* env)
: timestamp_(0), size_(0), meta_filename_(meta_filename),
file_infos_(file_infos), env_(env) {}
~BackupMeta() {}
void RecordTimestamp() {
env_->GetCurrentTime(&timestamp_);
}
int64_t GetTimestamp() const {
return timestamp_;
}
uint64_t GetSize() const {
return size_;
}
void SetSequenceNumber(uint64_t sequence_number) {
sequence_number_ = sequence_number;
}
uint64_t GetSequenceNumber() {
return sequence_number_;
}
Status AddFile(const FileInfo& file_info);
void Delete(bool delete_meta = true);
bool Empty() {
return files_.empty();
}
const std::vector<std::string>& GetFiles() {
return files_;
}
Status LoadFromFile(const std::string& backup_dir);
Status StoreToFile(bool sync);
private:
int64_t timestamp_;
// sequence number is only approximate, should not be used
// by clients
uint64_t sequence_number_;
uint64_t size_;
std::string const meta_filename_;
// files with relative paths (without "/" prefix!!)
std::vector<std::string> files_;
std::unordered_map<std::string, FileInfo>* file_infos_;
Env* env_;
static const size_t max_backup_meta_file_size_ = 10 * 1024 * 1024; // 10MB
}; // BackupMeta
inline std::string GetAbsolutePath(
const std::string &relative_path = "") const {
assert(relative_path.size() == 0 || relative_path[0] != '/');
return options_.backup_dir + "/" + relative_path;
}
inline std::string GetPrivateDirRel() const {
return "private";
}
inline std::string GetSharedChecksumDirRel() const {
return "shared_checksum";
}
inline std::string GetPrivateFileRel(BackupID backup_id,
bool tmp = false,
const std::string& file = "") const {
assert(file.size() == 0 || file[0] != '/');
return GetPrivateDirRel() + "/" + std::to_string(backup_id) +
(tmp ? ".tmp" : "") + "/" + file;
}
inline std::string GetSharedFileRel(const std::string& file = "",
bool tmp = false) const {
assert(file.size() == 0 || file[0] != '/');
return "shared/" + file + (tmp ? ".tmp" : "");
}
inline std::string GetSharedFileWithChecksumRel(const std::string& file = "",
bool tmp = false) const {
assert(file.size() == 0 || file[0] != '/');
return GetSharedChecksumDirRel() + "/" + file + (tmp ? ".tmp" : "");
}
inline std::string GetSharedFileWithChecksum(const std::string& file,
const uint32_t checksum_value,
const uint64_t file_size) const {
assert(file.size() == 0 || file[0] != '/');
std::string file_copy = file;
return file_copy.insert(file_copy.find_last_of('.'),
"_" + std::to_string(checksum_value)
+ "_" + std::to_string(file_size));
}
inline std::string GetFileFromChecksumFile(const std::string& file) const {
assert(file.size() == 0 || file[0] != '/');
std::string file_copy = file;
size_t first_underscore = file_copy.find_first_of('_');
return file_copy.erase(first_underscore,
file_copy.find_last_of('.') - first_underscore);
}
inline std::string GetLatestBackupFile(bool tmp = false) const {
return GetAbsolutePath(std::string("LATEST_BACKUP") + (tmp ? ".tmp" : ""));
}
inline std::string GetBackupMetaDir() const {
return GetAbsolutePath("meta");
}
inline std::string GetBackupMetaFile(BackupID backup_id) const {
return GetBackupMetaDir() + "/" + std::to_string(backup_id);
}
Status GetLatestBackupFileContents(uint32_t* latest_backup);
Status PutLatestBackupFileContents(uint32_t latest_backup);
// if size_limit == 0, there is no size limit, copy everything
Status CopyFile(const std::string& src,
const std::string& dst,
Env* src_env,
Env* dst_env,
bool sync,
BackupRateLimiter* rate_limiter,
uint64_t* size = nullptr,
uint32_t* checksum_value = nullptr,
uint64_t size_limit = 0);
// if size_limit == 0, there is no size limit, copy everything
Status BackupFile(BackupID backup_id,
BackupMeta* backup,
bool shared,
const std::string& src_dir,
const std::string& src_fname, // starts with "/"
BackupRateLimiter* rate_limiter,
uint64_t size_limit = 0,
bool shared_checksum = false);
Status CalculateChecksum(const std::string& src,
Env* src_env,
uint64_t size_limit,
uint32_t* checksum_value);
// Will delete all the files we don't need anymore
// If full_scan == true, it will do the full scan of files/ directory
// and delete all the files that are not referenced from backuped_file_infos__
void GarbageCollection(bool full_scan);
// backup state data
BackupID latest_backup_id_;
std::map<BackupID, BackupMeta> backups_;
std::unordered_map<std::string, FileInfo> backuped_file_infos_;
std::vector<BackupID> obsolete_backups_;
std::atomic<bool> stop_backup_;
// options data
BackupableDBOptions options_;
Env* db_env_;
Env* backup_env_;
// directories
unique_ptr<Directory> backup_directory_;
unique_ptr<Directory> shared_directory_;
unique_ptr<Directory> meta_directory_;
unique_ptr<Directory> private_directory_;
static const size_t kDefaultCopyFileBufferSize = 5 * 1024 * 1024LL; // 5MB
size_t copy_file_buffer_size_;
bool read_only_;
};
BackupEngine* BackupEngine::NewBackupEngine(
Env* db_env, const BackupableDBOptions& options) {
return new BackupEngineImpl(db_env, options);
}
BackupEngineImpl::BackupEngineImpl(Env* db_env,
const BackupableDBOptions& options,
bool read_only)
: stop_backup_(false),
options_(options),
db_env_(db_env),
backup_env_(options.backup_env != nullptr ? options.backup_env : db_env_),
copy_file_buffer_size_(kDefaultCopyFileBufferSize),
read_only_(read_only) {
if (read_only_) {
Log(options_.info_log, "Starting read_only backup engine");
}
options_.Dump(options_.info_log);
if (!read_only_) {
// create all the dirs we need
backup_env_->CreateDirIfMissing(GetAbsolutePath());
backup_env_->NewDirectory(GetAbsolutePath(), &backup_directory_);
if (options_.share_table_files) {
if (options_.share_files_with_checksum) {
backup_env_->CreateDirIfMissing(GetAbsolutePath(
GetSharedFileWithChecksumRel()));
backup_env_->NewDirectory(GetAbsolutePath(
GetSharedFileWithChecksumRel()), &shared_directory_);
} else {
backup_env_->CreateDirIfMissing(GetAbsolutePath(GetSharedFileRel()));
backup_env_->NewDirectory(GetAbsolutePath(GetSharedFileRel()),
&shared_directory_);
}
}
backup_env_->CreateDirIfMissing(GetAbsolutePath(GetPrivateDirRel()));
backup_env_->NewDirectory(GetAbsolutePath(GetPrivateDirRel()),
&private_directory_);
backup_env_->CreateDirIfMissing(GetBackupMetaDir());
backup_env_->NewDirectory(GetBackupMetaDir(), &meta_directory_);
}
std::vector<std::string> backup_meta_files;
backup_env_->GetChildren(GetBackupMetaDir(), &backup_meta_files);
// create backups_ structure
for (auto& file : backup_meta_files) {
BackupID backup_id = 0;
sscanf(file.c_str(), "%u", &backup_id);
if (backup_id == 0 || file != std::to_string(backup_id)) {
if (!read_only_) {
// invalid file name, delete that
backup_env_->DeleteFile(GetBackupMetaDir() + "/" + file);
}
continue;
}
assert(backups_.find(backup_id) == backups_.end());
backups_.insert(std::make_pair(
backup_id, BackupMeta(GetBackupMetaFile(backup_id),
&backuped_file_infos_, backup_env_)));
}
if (options_.destroy_old_data) { // Destory old data
assert(!read_only_);
for (auto& backup : backups_) {
backup.second.Delete();
obsolete_backups_.push_back(backup.first);
}
backups_.clear();
// start from beginning
latest_backup_id_ = 0;
// GarbageCollection() will do the actual deletion
} else { // Load data from storage
// load the backups if any
for (auto& backup : backups_) {
Status s = backup.second.LoadFromFile(options_.backup_dir);
if (!s.ok()) {
Log(options_.info_log, "Backup %u corrupted -- %s", backup.first,
s.ToString().c_str());
if (!read_only_) {
Log(options_.info_log, "-> Deleting backup %u", backup.first);
}
backup.second.Delete(!read_only_);
obsolete_backups_.push_back(backup.first);
}
}
// delete obsolete backups from the structure
for (auto ob : obsolete_backups_) {
backups_.erase(ob);
}
Status s = GetLatestBackupFileContents(&latest_backup_id_);
// If latest backup file is corrupted or non-existent
// set latest backup as the biggest backup we have
// or 0 if we have no backups
if (!s.ok() ||
backups_.find(latest_backup_id_) == backups_.end()) {
auto itr = backups_.end();
latest_backup_id_ = (itr == backups_.begin()) ? 0 : (--itr)->first;
}
}
// delete any backups that claim to be later than latest
for (auto itr = backups_.upper_bound(latest_backup_id_);
itr != backups_.end();) {
itr->second.Delete();
obsolete_backups_.push_back(itr->first);
itr = backups_.erase(itr);
}
if (!read_only_) {
PutLatestBackupFileContents(latest_backup_id_); // Ignore errors
GarbageCollection(true);
}
Log(options_.info_log, "Initialized BackupEngine, the latest backup is %u.",
latest_backup_id_);
}
BackupEngineImpl::~BackupEngineImpl() { LogFlush(options_.info_log); }
Status BackupEngineImpl::CreateNewBackup(DB* db, bool flush_before_backup) {
assert(!read_only_);
Status s;
std::vector<std::string> live_files;
VectorLogPtr live_wal_files;
uint64_t manifest_file_size = 0;
uint64_t sequence_number = db->GetLatestSequenceNumber();
s = db->DisableFileDeletions();
if (s.ok()) {
// this will return live_files prefixed with "/"
s = db->GetLiveFiles(live_files, &manifest_file_size, flush_before_backup);
}
// if we didn't flush before backup, we need to also get WAL files
if (s.ok() && !flush_before_backup && options_.backup_log_files) {
// returns file names prefixed with "/"
s = db->GetSortedWalFiles(live_wal_files);
}
if (!s.ok()) {
db->EnableFileDeletions(false);
return s;
}
BackupID new_backup_id = latest_backup_id_ + 1;
assert(backups_.find(new_backup_id) == backups_.end());
auto ret = backups_.insert(std::make_pair(
new_backup_id, BackupMeta(GetBackupMetaFile(new_backup_id),
&backuped_file_infos_, backup_env_)));
assert(ret.second == true);
auto& new_backup = ret.first->second;
new_backup.RecordTimestamp();
new_backup.SetSequenceNumber(sequence_number);
Log(options_.info_log, "Started the backup process -- creating backup %u",
new_backup_id);
// create temporary private dir
s = backup_env_->CreateDir(
GetAbsolutePath(GetPrivateFileRel(new_backup_id, true)));
unique_ptr<BackupRateLimiter> rate_limiter;
if (options_.backup_rate_limit > 0) {
copy_file_buffer_size_ = options_.backup_rate_limit / 10;
rate_limiter.reset(new BackupRateLimiter(db_env_,
options_.backup_rate_limit, copy_file_buffer_size_));
}
// copy live_files
for (size_t i = 0; s.ok() && i < live_files.size(); ++i) {
uint64_t number;
FileType type;
bool ok = ParseFileName(live_files[i], &number, &type);
if (!ok) {
assert(false);
return Status::Corruption("Can't parse file name. This is very bad");
}
// we should only get sst, manifest and current files here
assert(type == kTableFile || type == kDescriptorFile ||
type == kCurrentFile);
// rules:
// * if it's kTableFile, then it's shared
// * if it's kDescriptorFile, limit the size to manifest_file_size
s = BackupFile(new_backup_id,
&new_backup,
options_.share_table_files && type == kTableFile,
db->GetName(), /* src_dir */
live_files[i], /* src_fname */
rate_limiter.get(),
(type == kDescriptorFile) ? manifest_file_size : 0,
options_.share_files_with_checksum && type == kTableFile);
}
// copy WAL files
for (size_t i = 0; s.ok() && i < live_wal_files.size(); ++i) {
if (live_wal_files[i]->Type() == kAliveLogFile) {
// we only care about live log files
// copy the file into backup_dir/files/<new backup>/
s = BackupFile(new_backup_id,
&new_backup,
false, /* not shared */
db->GetOptions().wal_dir,
live_wal_files[i]->PathName(),
rate_limiter.get());
}
}
// we copied all the files, enable file deletions
db->EnableFileDeletions(false);
if (s.ok()) {
// move tmp private backup to real backup folder
s = backup_env_->RenameFile(
GetAbsolutePath(GetPrivateFileRel(new_backup_id, true)), // tmp
GetAbsolutePath(GetPrivateFileRel(new_backup_id, false)));
}
if (s.ok()) {
// persist the backup metadata on the disk
s = new_backup.StoreToFile(options_.sync);
}
if (s.ok()) {
// install the newly created backup meta! (atomic)
s = PutLatestBackupFileContents(new_backup_id);
}
if (s.ok() && options_.sync) {
unique_ptr<Directory> backup_private_directory;
backup_env_->NewDirectory(
GetAbsolutePath(GetPrivateFileRel(new_backup_id, false)),
&backup_private_directory);
if (backup_private_directory != nullptr) {
backup_private_directory->Fsync();
}
if (private_directory_ != nullptr) {
private_directory_->Fsync();
}
if (meta_directory_ != nullptr) {
meta_directory_->Fsync();
}
if (shared_directory_ != nullptr) {
shared_directory_->Fsync();
}
if (backup_directory_ != nullptr) {
backup_directory_->Fsync();
}
}
if (!s.ok()) {
// clean all the files we might have created
Log(options_.info_log, "Backup failed -- %s", s.ToString().c_str());
backups_.erase(new_backup_id);
GarbageCollection(true);
return s;
}
// here we know that we succeeded and installed the new backup
// in the LATEST_BACKUP file
latest_backup_id_ = new_backup_id;
Log(options_.info_log, "Backup DONE. All is good");
return s;
}
Status BackupEngineImpl::PurgeOldBackups(uint32_t num_backups_to_keep) {
assert(!read_only_);
Log(options_.info_log, "Purging old backups, keeping %u",
num_backups_to_keep);
while (num_backups_to_keep < backups_.size()) {
Log(options_.info_log, "Deleting backup %u", backups_.begin()->first);
backups_.begin()->second.Delete();
obsolete_backups_.push_back(backups_.begin()->first);
backups_.erase(backups_.begin());
}
GarbageCollection(false);
return Status::OK();
}
Status BackupEngineImpl::DeleteBackup(BackupID backup_id) {
assert(!read_only_);
Log(options_.info_log, "Deleting backup %u", backup_id);
auto backup = backups_.find(backup_id);
if (backup == backups_.end()) {
return Status::NotFound("Backup not found");
}
backup->second.Delete();
obsolete_backups_.push_back(backup_id);
backups_.erase(backup);
GarbageCollection(false);
return Status::OK();
}
void BackupEngineImpl::GetBackupInfo(std::vector<BackupInfo>* backup_info) {
backup_info->reserve(backups_.size());
for (auto& backup : backups_) {
if (!backup.second.Empty()) {
backup_info->push_back(BackupInfo(
backup.first, backup.second.GetTimestamp(), backup.second.GetSize()));
}
}
}
Status BackupEngineImpl::RestoreDBFromBackup(
BackupID backup_id, const std::string& db_dir, const std::string& wal_dir,
const RestoreOptions& restore_options) {
auto backup_itr = backups_.find(backup_id);
if (backup_itr == backups_.end()) {
return Status::NotFound("Backup not found");
}
auto& backup = backup_itr->second;
if (backup.Empty()) {
return Status::NotFound("Backup not found");
}
Log(options_.info_log, "Restoring backup id %u\n", backup_id);
Log(options_.info_log, "keep_log_files: %d\n",
static_cast<int>(restore_options.keep_log_files));
// just in case. Ignore errors
db_env_->CreateDirIfMissing(db_dir);
db_env_->CreateDirIfMissing(wal_dir);
if (restore_options.keep_log_files) {
// delete files in db_dir, but keep all the log files
DeleteChildren(db_dir, 1 << kLogFile);
// move all the files from archive dir to wal_dir
std::string archive_dir = ArchivalDirectory(wal_dir);
std::vector<std::string> archive_files;
db_env_->GetChildren(archive_dir, &archive_files); // ignore errors
for (const auto& f : archive_files) {
uint64_t number;
FileType type;
bool ok = ParseFileName(f, &number, &type);
if (ok && type == kLogFile) {
Log(options_.info_log, "Moving log file from archive/ to wal_dir: %s",
f.c_str());
Status s =
db_env_->RenameFile(archive_dir + "/" + f, wal_dir + "/" + f);
if (!s.ok()) {
// if we can't move log file from archive_dir to wal_dir,
// we should fail, since it might mean data loss
return s;
}
}
}
} else {
DeleteChildren(wal_dir);
DeleteChildren(ArchivalDirectory(wal_dir));
DeleteChildren(db_dir);
}
unique_ptr<BackupRateLimiter> rate_limiter;
if (options_.restore_rate_limit > 0) {
copy_file_buffer_size_ = options_.restore_rate_limit / 10;
rate_limiter.reset(new BackupRateLimiter(db_env_,
options_.restore_rate_limit, copy_file_buffer_size_));
}
Status s;
for (auto& file : backup.GetFiles()) {
std::string dst;
// 1. extract the filename
size_t slash = file.find_last_of('/');
// file will either be shared/<file>, shared_checksum/<file_crc32_size>
// or private/<number>/<file>
assert(slash != std::string::npos);
dst = file.substr(slash + 1);
// if the file was in shared_checksum, extract the real file name
// in this case the file is <number>_<checksum>_<size>.<type>
if (file.substr(0, slash) == GetSharedChecksumDirRel()) {
dst = GetFileFromChecksumFile(dst);
}
// 2. find the filetype
uint64_t number;
FileType type;
bool ok = ParseFileName(dst, &number, &type);
if (!ok) {
return Status::Corruption("Backup corrupted");
}
// 3. Construct the final path
// kLogFile lives in wal_dir and all the rest live in db_dir
dst = ((type == kLogFile) ? wal_dir : db_dir) +
"/" + dst;
Log(options_.info_log, "Restoring %s to %s\n", file.c_str(), dst.c_str());
uint32_t checksum_value;
s = CopyFile(GetAbsolutePath(file), dst, backup_env_, db_env_, false,
rate_limiter.get(), nullptr /* size */, &checksum_value);
if (!s.ok()) {
break;
}
const auto iter = backuped_file_infos_.find(file);
assert(iter != backuped_file_infos_.end());
if (iter->second.checksum_value != checksum_value) {
s = Status::Corruption("Checksum check failed");
break;
}
}
Log(options_.info_log, "Restoring done -- %s\n", s.ToString().c_str());
return s;
}
// latest backup id is an ASCII representation of latest backup id
Status BackupEngineImpl::GetLatestBackupFileContents(uint32_t* latest_backup) {
Status s;
unique_ptr<SequentialFile> file;
s = backup_env_->NewSequentialFile(GetLatestBackupFile(),
&file,
EnvOptions());
if (!s.ok()) {
return s;
}
char buf[11];
Slice data;
s = file->Read(10, &data, buf);
if (!s.ok() || data.size() == 0) {
return s.ok() ? Status::Corruption("Latest backup file corrupted") : s;
}
buf[data.size()] = 0;
*latest_backup = 0;
sscanf(data.data(), "%u", latest_backup);
if (backup_env_->FileExists(GetBackupMetaFile(*latest_backup)) == false) {
s = Status::Corruption("Latest backup file corrupted");
}
return Status::OK();
}
// this operation HAS to be atomic
// writing 4 bytes to the file is atomic alright, but we should *never*
// do something like 1. delete file, 2. write new file
// We write to a tmp file and then atomically rename
Status BackupEngineImpl::PutLatestBackupFileContents(uint32_t latest_backup) {
assert(!read_only_);
Status s;
unique_ptr<WritableFile> file;
EnvOptions env_options;
env_options.use_mmap_writes = false;
s = backup_env_->NewWritableFile(GetLatestBackupFile(true),
&file,
env_options);
if (!s.ok()) {
backup_env_->DeleteFile(GetLatestBackupFile(true));
return s;
}
char file_contents[10];
int len = sprintf(file_contents, "%u\n", latest_backup);
s = file->Append(Slice(file_contents, len));
if (s.ok() && options_.sync) {
file->Sync();
}
if (s.ok()) {
s = file->Close();
}
if (s.ok()) {
// atomically replace real file with new tmp
s = backup_env_->RenameFile(GetLatestBackupFile(true),
GetLatestBackupFile(false));
}
return s;
}
Status BackupEngineImpl::CopyFile(
const std::string& src,
const std::string& dst, Env* src_env,
Env* dst_env, bool sync,
BackupRateLimiter* rate_limiter, uint64_t* size,
uint32_t* checksum_value,
uint64_t size_limit) {
Status s;
unique_ptr<WritableFile> dst_file;
unique_ptr<SequentialFile> src_file;
EnvOptions env_options;
env_options.use_mmap_writes = false;
env_options.use_os_buffer = false;
if (size != nullptr) {
*size = 0;
}
if (checksum_value != nullptr) {
*checksum_value = 0;
}
// Check if size limit is set. if not, set it to very big number
if (size_limit == 0) {
size_limit = std::numeric_limits<uint64_t>::max();
}
s = src_env->NewSequentialFile(src, &src_file, env_options);
if (s.ok()) {
s = dst_env->NewWritableFile(dst, &dst_file, env_options);
}
if (!s.ok()) {
return s;
}
unique_ptr<char[]> buf(new char[copy_file_buffer_size_]);
Slice data;
do {
if (stop_backup_.load(std::memory_order_acquire)) {
return Status::Incomplete("Backup stopped");
}
size_t buffer_to_read = (copy_file_buffer_size_ < size_limit) ?
copy_file_buffer_size_ : size_limit;
s = src_file->Read(buffer_to_read, &data, buf.get());
size_limit -= data.size();
if (!s.ok()) {
return s;
}
if (size != nullptr) {
*size += data.size();
}
if (checksum_value != nullptr) {
*checksum_value = crc32c::Extend(*checksum_value, data.data(),
data.size());
}
s = dst_file->Append(data);
if (rate_limiter != nullptr) {
rate_limiter->ReportAndWait(data.size());
}
} while (s.ok() && data.size() > 0 && size_limit > 0);
if (s.ok() && sync) {
s = dst_file->Sync();
}
return s;
}
// src_fname will always start with "/"
Status BackupEngineImpl::BackupFile(BackupID backup_id, BackupMeta* backup,
bool shared, const std::string& src_dir,
const std::string& src_fname,
BackupRateLimiter* rate_limiter,
uint64_t size_limit,
bool shared_checksum) {
assert(src_fname.size() > 0 && src_fname[0] == '/');
std::string dst_relative = src_fname.substr(1);
std::string dst_relative_tmp;
Status s;
uint64_t size;
uint32_t checksum_value = 0;
if (shared && shared_checksum) {
// add checksum and file length to the file name
s = CalculateChecksum(src_dir + src_fname,
db_env_,
size_limit,
&checksum_value);
if (s.ok()) {
s = db_env_->GetFileSize(src_dir + src_fname, &size);
}
if (!s.ok()) {
return s;
}
dst_relative = GetSharedFileWithChecksum(dst_relative, checksum_value,
size);
dst_relative_tmp = GetSharedFileWithChecksumRel(dst_relative, true);
dst_relative = GetSharedFileWithChecksumRel(dst_relative, false);
} else if (shared) {
dst_relative_tmp = GetSharedFileRel(dst_relative, true);
dst_relative = GetSharedFileRel(dst_relative, false);
} else {
dst_relative_tmp = GetPrivateFileRel(backup_id, true, dst_relative);
dst_relative = GetPrivateFileRel(backup_id, false, dst_relative);
}
std::string dst_path = GetAbsolutePath(dst_relative);
std::string dst_path_tmp = GetAbsolutePath(dst_relative_tmp);
// if it's shared, we also need to check if it exists -- if it does,
// no need to copy it again
if (shared && backup_env_->FileExists(dst_path)) {
if (shared_checksum) {
Log(options_.info_log,
"%s already present, with checksum %u and size %" PRIu64,
src_fname.c_str(), checksum_value, size);
} else {
backup_env_->GetFileSize(dst_path, &size); // Ignore error
Log(options_.info_log, "%s already present, calculate checksum",
src_fname.c_str());
s = CalculateChecksum(src_dir + src_fname,
db_env_,
size_limit,
&checksum_value);
}
} else {
Log(options_.info_log, "Copying %s", src_fname.c_str());
s = CopyFile(src_dir + src_fname,
dst_path_tmp,
db_env_,
backup_env_,
options_.sync,
rate_limiter,
&size,
&checksum_value,
size_limit);
if (s.ok() && shared) {
s = backup_env_->RenameFile(dst_path_tmp, dst_path);
}
}
if (s.ok()) {
s = backup->AddFile(FileInfo(dst_relative, size, checksum_value));
}
return s;
}
Status BackupEngineImpl::CalculateChecksum(const std::string& src, Env* src_env,
uint64_t size_limit,
uint32_t* checksum_value) {
*checksum_value = 0;
if (size_limit == 0) {
size_limit = std::numeric_limits<uint64_t>::max();
}
EnvOptions env_options;
env_options.use_mmap_writes = false;
env_options.use_os_buffer = false;
std::unique_ptr<SequentialFile> src_file;
Status s = src_env->NewSequentialFile(src, &src_file, env_options);
if (!s.ok()) {
return s;
}
std::unique_ptr<char[]> buf(new char[copy_file_buffer_size_]);
Slice data;
do {
if (stop_backup_.load(std::memory_order_acquire)) {
return Status::Incomplete("Backup stopped");
}
size_t buffer_to_read = (copy_file_buffer_size_ < size_limit) ?
copy_file_buffer_size_ : size_limit;
s = src_file->Read(buffer_to_read, &data, buf.get());
if (!s.ok()) {
return s;
}
size_limit -= data.size();
*checksum_value = crc32c::Extend(*checksum_value, data.data(), data.size());
} while (data.size() > 0 && size_limit > 0);
return s;
}
void BackupEngineImpl::DeleteChildren(const std::string& dir,
uint32_t file_type_filter) {
std::vector<std::string> children;
db_env_->GetChildren(dir, &children); // ignore errors
for (const auto& f : children) {
uint64_t number;
FileType type;
bool ok = ParseFileName(f, &number, &type);
if (ok && (file_type_filter & (1 << type))) {
// don't delete this file
continue;
}
db_env_->DeleteFile(dir + "/" + f); // ignore errors
}
}
void BackupEngineImpl::GarbageCollection(bool full_scan) {
assert(!read_only_);
Log(options_.info_log, "Starting garbage collection");
std::vector<std::string> to_delete;
for (auto& itr : backuped_file_infos_) {
if (itr.second.refs == 0) {
Status s = backup_env_->DeleteFile(GetAbsolutePath(itr.first));
Log(options_.info_log, "Deleting %s -- %s", itr.first.c_str(),
s.ToString().c_str());
to_delete.push_back(itr.first);
}
}
for (auto& td : to_delete) {
backuped_file_infos_.erase(td);
}
if (!full_scan) {
// take care of private dirs -- if full_scan == true, then full_scan will
// take care of them
for (auto backup_id : obsolete_backups_) {
std::string private_dir = GetPrivateFileRel(backup_id);
Status s = backup_env_->DeleteDir(GetAbsolutePath(private_dir));
Log(options_.info_log, "Deleting private dir %s -- %s",
private_dir.c_str(), s.ToString().c_str());
}
}
obsolete_backups_.clear();
if (full_scan) {
Log(options_.info_log, "Starting full scan garbage collection");
// delete obsolete shared files
std::vector<std::string> shared_children;
backup_env_->GetChildren(GetAbsolutePath(GetSharedFileRel()),
&shared_children);
for (auto& child : shared_children) {
std::string rel_fname = GetSharedFileRel(child);
// if it's not refcounted, delete it
if (backuped_file_infos_.find(rel_fname) == backuped_file_infos_.end()) {
// this might be a directory, but DeleteFile will just fail in that
// case, so we're good
Status s = backup_env_->DeleteFile(GetAbsolutePath(rel_fname));
if (s.ok()) {
Log(options_.info_log, "Deleted %s", rel_fname.c_str());
}
}
}
// delete obsolete private files
std::vector<std::string> private_children;
backup_env_->GetChildren(GetAbsolutePath(GetPrivateDirRel()),
&private_children);
for (auto& child : private_children) {
BackupID backup_id = 0;
bool tmp_dir = child.find(".tmp") != std::string::npos;
sscanf(child.c_str(), "%u", &backup_id);
if (!tmp_dir && // if it's tmp_dir, delete it
(backup_id == 0 || backups_.find(backup_id) != backups_.end())) {
// it's either not a number or it's still alive. continue
continue;
}
// here we have to delete the dir and all its children
std::string full_private_path =
GetAbsolutePath(GetPrivateFileRel(backup_id, tmp_dir));
std::vector<std::string> subchildren;
backup_env_->GetChildren(full_private_path, &subchildren);
for (auto& subchild : subchildren) {
Status s = backup_env_->DeleteFile(full_private_path + subchild);
if (s.ok()) {
Log(options_.info_log, "Deleted %s",
(full_private_path + subchild).c_str());
}
}
// finally delete the private dir
Status s = backup_env_->DeleteDir(full_private_path);
Log(options_.info_log, "Deleted dir %s -- %s", full_private_path.c_str(),
s.ToString().c_str());
}
}
}
// ------- BackupMeta class --------
Status BackupEngineImpl::BackupMeta::AddFile(const FileInfo& file_info) {
size_ += file_info.size;
files_.push_back(file_info.filename);
auto itr = file_infos_->find(file_info.filename);
if (itr == file_infos_->end()) {
auto ret = file_infos_->insert({file_info.filename, file_info});
if (ret.second) {
ret.first->second.refs = 1;
} else {
// if this happens, something is seriously wrong
return Status::Corruption("In memory metadata insertion error");
}
} else {
if (itr->second.checksum_value != file_info.checksum_value) {
return Status::Corruption("Checksum mismatch for existing backup file");
}
++itr->second.refs; // increase refcount if already present
}
return Status::OK();
}
void BackupEngineImpl::BackupMeta::Delete(bool delete_meta) {
for (const auto& file : files_) {
auto itr = file_infos_->find(file);
assert(itr != file_infos_->end());
--(itr->second.refs); // decrease refcount
}
files_.clear();
// delete meta file
if (delete_meta) {
env_->DeleteFile(meta_filename_);
}
timestamp_ = 0;
}
// each backup meta file is of the format:
// <timestamp>
// <seq number>
// <number of files>
// <file1> <crc32(literal string)> <crc32_value>
// <file2> <crc32(literal string)> <crc32_value>
// ...
Status BackupEngineImpl::BackupMeta::LoadFromFile(
const std::string& backup_dir) {
assert(Empty());
Status s;
unique_ptr<SequentialFile> backup_meta_file;
s = env_->NewSequentialFile(meta_filename_, &backup_meta_file, EnvOptions());
if (!s.ok()) {
return s;
}
unique_ptr<char[]> buf(new char[max_backup_meta_file_size_ + 1]);
Slice data;
s = backup_meta_file->Read(max_backup_meta_file_size_, &data, buf.get());
if (!s.ok() || data.size() == max_backup_meta_file_size_) {
return s.ok() ? Status::Corruption("File size too big") : s;
}
buf[data.size()] = 0;
uint32_t num_files = 0;
int bytes_read = 0;
sscanf(data.data(), "%" PRId64 "%n", &timestamp_, &bytes_read);
data.remove_prefix(bytes_read + 1); // +1 for '\n'
sscanf(data.data(), "%" PRIu64 "%n", &sequence_number_, &bytes_read);
data.remove_prefix(bytes_read + 1); // +1 for '\n'
sscanf(data.data(), "%u%n", &num_files, &bytes_read);
data.remove_prefix(bytes_read + 1); // +1 for '\n'
std::vector<FileInfo> files;
for (uint32_t i = 0; s.ok() && i < num_files; ++i) {
auto line = GetSliceUntil(&data, '\n');
std::string filename = GetSliceUntil(&line, ' ').ToString();
uint64_t size;
s = env_->GetFileSize(backup_dir + "/" + filename, &size);
if (!s.ok()) {
return s;
}
if (line.empty()) {
return Status::Corruption("File checksum is missing");
}
uint32_t checksum_value = 0;
if (line.starts_with("crc32 ")) {
line.remove_prefix(6);
sscanf(line.data(), "%u", &checksum_value);
if (memcmp(line.data(), std::to_string(checksum_value).c_str(),
line.size() - 1) != 0) {
return Status::Corruption("Invalid checksum value");
}
} else {
return Status::Corruption("Unknown checksum type");
}
files.emplace_back(filename, size, checksum_value);
}
if (s.ok() && data.size() > 0) {
// file has to be read completely. if not, we count it as corruption
s = Status::Corruption("Tailing data in backup meta file");
}
if (s.ok()) {
for (const auto& file_info : files) {
s = AddFile(file_info);
if (!s.ok()) {
break;
}
}
}
return s;
}
Status BackupEngineImpl::BackupMeta::StoreToFile(bool sync) {
Status s;
unique_ptr<WritableFile> backup_meta_file;
EnvOptions env_options;
env_options.use_mmap_writes = false;
s = env_->NewWritableFile(meta_filename_ + ".tmp", &backup_meta_file,
env_options);
if (!s.ok()) {
return s;
}
unique_ptr<char[]> buf(new char[max_backup_meta_file_size_]);
int len = 0, buf_size = max_backup_meta_file_size_;
len += snprintf(buf.get(), buf_size, "%" PRId64 "\n", timestamp_);
len += snprintf(buf.get() + len, buf_size - len, "%" PRIu64 "\n",
sequence_number_);
len += snprintf(buf.get() + len, buf_size - len, "%zu\n", files_.size());
for (const auto& file : files_) {
const auto& iter = file_infos_->find(file);
assert(iter != file_infos_->end());
// use crc32 for now, switch to something else if needed
len += snprintf(buf.get() + len, buf_size - len, "%s crc32 %u\n",
file.c_str(), iter->second.checksum_value);
}
s = backup_meta_file->Append(Slice(buf.get(), (size_t)len));
if (s.ok() && sync) {
s = backup_meta_file->Sync();
}
if (s.ok()) {
s = backup_meta_file->Close();
}
if (s.ok()) {
s = env_->RenameFile(meta_filename_ + ".tmp", meta_filename_);
}
return s;
}
// -------- BackupEngineReadOnlyImpl ---------
class BackupEngineReadOnlyImpl : public BackupEngineReadOnly {
public:
BackupEngineReadOnlyImpl(Env* db_env, const BackupableDBOptions& options)
: backup_engine_(new BackupEngineImpl(db_env, options, true)) {}
virtual ~BackupEngineReadOnlyImpl() {}
virtual void GetBackupInfo(std::vector<BackupInfo>* backup_info) {
backup_engine_->GetBackupInfo(backup_info);
}
virtual Status RestoreDBFromBackup(
BackupID backup_id, const std::string& db_dir, const std::string& wal_dir,
const RestoreOptions& restore_options = RestoreOptions()) {
return backup_engine_->RestoreDBFromBackup(backup_id, db_dir, wal_dir,
restore_options);
}
virtual Status RestoreDBFromLatestBackup(
const std::string& db_dir, const std::string& wal_dir,
const RestoreOptions& restore_options = RestoreOptions()) {
return backup_engine_->RestoreDBFromLatestBackup(db_dir, wal_dir,
restore_options);
}
private:
std::unique_ptr<BackupEngineImpl> backup_engine_;
};
BackupEngineReadOnly* BackupEngineReadOnly::NewReadOnlyBackupEngine(
Env* db_env, const BackupableDBOptions& options) {
if (options.destroy_old_data) {
assert(false);
return nullptr;
}
return new BackupEngineReadOnlyImpl(db_env, options);
}
// --- BackupableDB methods --------
BackupableDB::BackupableDB(DB* db, const BackupableDBOptions& options)
: StackableDB(db),
backup_engine_(new BackupEngineImpl(db->GetEnv(), options)) {}
BackupableDB::~BackupableDB() {
delete backup_engine_;
}
Status BackupableDB::CreateNewBackup(bool flush_before_backup) {
return backup_engine_->CreateNewBackup(this, flush_before_backup);
}
void BackupableDB::GetBackupInfo(std::vector<BackupInfo>* backup_info) {
backup_engine_->GetBackupInfo(backup_info);
}
Status BackupableDB::PurgeOldBackups(uint32_t num_backups_to_keep) {
return backup_engine_->PurgeOldBackups(num_backups_to_keep);
}
Status BackupableDB::DeleteBackup(BackupID backup_id) {
return backup_engine_->DeleteBackup(backup_id);
}
void BackupableDB::StopBackup() {
backup_engine_->StopBackup();
}
// --- RestoreBackupableDB methods ------
RestoreBackupableDB::RestoreBackupableDB(Env* db_env,
const BackupableDBOptions& options)
: backup_engine_(new BackupEngineImpl(db_env, options)) {}
RestoreBackupableDB::~RestoreBackupableDB() {
delete backup_engine_;
}
void
RestoreBackupableDB::GetBackupInfo(std::vector<BackupInfo>* backup_info) {
backup_engine_->GetBackupInfo(backup_info);
}
Status RestoreBackupableDB::RestoreDBFromBackup(
BackupID backup_id, const std::string& db_dir, const std::string& wal_dir,
const RestoreOptions& restore_options) {
return backup_engine_->RestoreDBFromBackup(backup_id, db_dir, wal_dir,
restore_options);
}
Status RestoreBackupableDB::RestoreDBFromLatestBackup(
const std::string& db_dir, const std::string& wal_dir,
const RestoreOptions& restore_options) {
return backup_engine_->RestoreDBFromLatestBackup(db_dir, wal_dir,
restore_options);
}
Status RestoreBackupableDB::PurgeOldBackups(uint32_t num_backups_to_keep) {
return backup_engine_->PurgeOldBackups(num_backups_to_keep);
}
Status RestoreBackupableDB::DeleteBackup(BackupID backup_id) {
return backup_engine_->DeleteBackup(backup_id);
}
} // namespace rocksdb
#endif // ROCKSDB_LITE
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