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fb9fce4fc3
Summary: In this diff I present you BackupableDB v1. You can easily use it to backup your DB and it will do incremental snapshots for you. Let's first describe how you would use BackupableDB. It's inheriting StackableDB interface so you can easily construct it with your DB object -- it will add a method RollTheSnapshot() to the DB object. When you call RollTheSnapshot(), current snapshot of the DB will be stored in the backup dir. To restore, you can just call RestoreDBFromBackup() on a BackupableDB (which is a static method) and it will restore all files from the backup dir. In the next version, it will even support automatic backuping every X minutes. There are multiple things you can configure: 1. backup_env and db_env can be different, which is awesome because then you can easily backup to HDFS or wherever you feel like. 2. sync - if true, it *guarantees* backup consistency on machine reboot 3. number of snapshots to keep - this will keep last N snapshots around if you want, for some reason, be able to restore from an earlier snapshot. All the backuping is done in incremental fashion - if we already have 00010.sst, we will not copy it again. *IMPORTANT* -- This is based on assumption that 00010.sst never changes - two files named 00010.sst from the same DB will always be exactly the same. Is this true? I always copy manifest, current and log files. 4. You can decide if you want to flush the memtables before you backup, or you're fine with backing up the log files -- either way, you get a complete and consistent view of the database at a time of backup. 5. More things you can find in BackupableDBOptions Here is the directory structure I use: backup_dir/CURRENT_SNAPSHOT - just 4 bytes holding the latest snapshot 0, 1, 2, ... - files containing serialized version of each snapshot - containing a list of files files/*.sst - sst files shared between snapshots - if one snapshot references 00010.sst and another one needs to backup it from the DB, it will just reference the same file files/ 0/, 1/, 2/, ... - snapshot directories containing private snapshot files - current, manifest and log files All the files are ref counted and deleted immediatelly when they get out of scope. Some other stuff in this diff: 1. Added GetEnv() method to the DB. Discussed with @haobo and we agreed that it seems right thing to do. 2. Fixed StackableDB interface. The way it was set up before, I was not able to implement BackupableDB. Test Plan: I have a unittest, but please don't look at this yet. I just hacked it up to help me with debugging. I will write a lot of good tests and update the diff. Also, `make asan_check` Reviewers: dhruba, haobo, emayanke Reviewed By: dhruba CC: leveldb, haobo Differential Revision: https://reviews.facebook.net/D14295
162 lines
4.4 KiB
C++
162 lines
4.4 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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#pragma once
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#include "rocksdb/db.h"
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namespace rocksdb {
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// This class contains APIs to stack rocksdb wrappers.Eg. Stack TTL over base d
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class StackableDB : public DB {
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public:
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// StackableDB is the owner of db now!
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explicit StackableDB(DB* db) : db_(db) {}
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~StackableDB() {
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delete db_;
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}
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virtual DB* GetBaseDB() {
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return db_;
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}
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virtual Status Put(const WriteOptions& options,
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const Slice& key,
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const Slice& val) override {
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return db_->Put(options, key, val);
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}
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virtual Status Get(const ReadOptions& options,
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const Slice& key,
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std::string* value) override {
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return db_->Get(options, key, value);
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}
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virtual std::vector<Status> MultiGet(const ReadOptions& options,
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const std::vector<Slice>& keys,
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std::vector<std::string>* values)
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override {
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return db_->MultiGet(options, keys, values);
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}
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virtual bool KeyMayExist(const ReadOptions& options,
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const Slice& key,
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std::string* value,
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bool* value_found = nullptr) override {
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return db_->KeyMayExist(options, key, value, value_found);
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}
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virtual Status Delete(const WriteOptions& wopts, const Slice& key) override {
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return db_->Delete(wopts, key);
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}
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virtual Status Merge(const WriteOptions& options,
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const Slice& key,
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const Slice& value) override {
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return db_->Merge(options, key, value);
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}
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virtual Status Write(const WriteOptions& opts, WriteBatch* updates)
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override {
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return db_->Write(opts, updates);
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}
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virtual Iterator* NewIterator(const ReadOptions& opts) override {
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return db_->NewIterator(opts);
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}
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virtual const Snapshot* GetSnapshot() override {
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return db_->GetSnapshot();
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}
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virtual void ReleaseSnapshot(const Snapshot* snapshot) override {
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return db_->ReleaseSnapshot(snapshot);
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}
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virtual bool GetProperty(const Slice& property, std::string* value)
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override {
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return db_->GetProperty(property, value);
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}
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virtual void GetApproximateSizes(const Range* r, int n, uint64_t* sizes)
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override {
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return db_->GetApproximateSizes(r, n, sizes);
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}
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virtual void CompactRange(const Slice* begin, const Slice* end,
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bool reduce_level = false,
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int target_level = -1) override {
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return db_->CompactRange(begin, end, reduce_level, target_level);
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}
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virtual int NumberLevels() override {
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return db_->NumberLevels();
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}
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virtual int MaxMemCompactionLevel() override {
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return db_->MaxMemCompactionLevel();
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}
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virtual int Level0StopWriteTrigger() override {
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return db_->Level0StopWriteTrigger();
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}
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virtual const std::string& GetName() const override {
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return db_->GetName();
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}
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virtual Env* GetEnv() const override {
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return db_->GetEnv();
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}
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virtual const Options& GetOptions() const override {
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return db_->GetOptions();
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}
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virtual Status Flush(const FlushOptions& fopts) override {
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return db_->Flush(fopts);
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}
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virtual Status DisableFileDeletions() override {
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return db_->DisableFileDeletions();
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}
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virtual Status EnableFileDeletions() override {
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return db_->EnableFileDeletions();
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}
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virtual Status GetLiveFiles(std::vector<std::string>& vec, uint64_t* mfs,
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bool flush_memtable = true) override {
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return db_->GetLiveFiles(vec, mfs, flush_memtable);
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}
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virtual SequenceNumber GetLatestSequenceNumber() const override {
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return db_->GetLatestSequenceNumber();
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}
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virtual Status GetSortedWalFiles(VectorLogPtr& files) override {
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return db_->GetSortedWalFiles(files);
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}
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virtual Status DeleteFile(std::string name) override {
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return db_->DeleteFile(name);
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}
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virtual Status GetDbIdentity(std::string& identity) {
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return db_->GetDbIdentity(identity);
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}
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virtual Status GetUpdatesSince(SequenceNumber seq_number,
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unique_ptr<TransactionLogIterator>* iter)
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override {
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return db_->GetUpdatesSince(seq_number, iter);
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}
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protected:
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DB* db_;
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};
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} // namespace rocksdb
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