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rocksdb/utilities/blob_db/blob_db.h

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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).
#pragma once
#ifndef ROCKSDB_LITE
#include <functional>
#include <string>
#include <vector>
#include "rocksdb/db.h"
#include "rocksdb/status.h"
#include "rocksdb/utilities/stackable_db.h"
namespace rocksdb {
namespace blob_db {
// A wrapped database which puts values of KV pairs in a separate log
// and store location to the log in the underlying DB.
// It lacks lots of importatant functionalities, e.g. DB restarts,
// garbage collection, iterators, etc.
//
// The factory needs to be moved to include/rocksdb/utilities to allow
// users to use blob DB.
struct BlobDBOptions {
// name of the directory under main db, where blobs will be stored.
// default is "blob_dir"
std::string blob_dir;
// whether the blob_dir path is relative or absolute.
bool path_relative;
// is the eviction strategy fifo based
bool is_fifo;
// maximum size of the blob dir. Once this gets used, up
// evict the blob file which is oldest (is_fifo )
// 0 means no limits
uint64_t blob_dir_size;
// a new bucket is opened, for ttl_range. So if ttl_range is 600seconds
// (10 minutes), and the first bucket starts at 1471542000
// then the blob buckets will be
// first bucket is 1471542000 - 1471542600
// second bucket is 1471542600 - 1471543200
// and so on
uint32_t ttl_range_secs;
// at what size will the blobs be stored in separate log rather than
// inline
uint64_t min_blob_size;
// at what bytes will the blob files be synced to blob log.
uint64_t bytes_per_sync;
// the target size of each blob file. File will become immutable
// after it exceeds that size
uint64_t blob_file_size;
// how many files to use for simple blobs at one time
uint32_t num_concurrent_simple_blobs;
// this function is to be provided by client if they intend to
// use Put API to provide TTL.
// the first argument is the value in the Put API
// in case you want to do some modifications to the value,
// return a new Slice in the second.
// otherwise just copy the input value into output.
// the ttl should be extracted and returned in last pointer.
// otherwise assign it to -1
std::function<bool(const Slice&, Slice*, int32_t*)> extract_ttl_fn;
// eviction callback.
// this function will be called for every blob that is getting
// evicted.
std::function<void(const ColumnFamilyHandle*, const Slice&, const Slice&)>
gc_evict_cb_fn;
// default ttl extactor
bool default_ttl_extractor;
// what compression to use for Blob's
CompressionType compression;
// default constructor
BlobDBOptions();
BlobDBOptions(const BlobDBOptions& in) = default;
virtual ~BlobDBOptions() = default;
};
class BlobDB : public StackableDB {
public:
// the suffix to a blob value to represent "ttl:TTLVAL"
static const uint64_t kTTLSuffixLength = 8;
public:
using rocksdb::StackableDB::Put;
virtual Status Put(const WriteOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value) override = 0;
using rocksdb::StackableDB::Delete;
virtual Status Delete(const WriteOptions& options,
ColumnFamilyHandle* column_family,
const Slice& key) override = 0;
virtual Status PutWithTTL(const WriteOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value, int32_t ttl) = 0;
virtual Status PutWithTTL(const WriteOptions& options, const Slice& key,
const Slice& value, int32_t ttl) {
return PutWithTTL(options, DefaultColumnFamily(), key, value, ttl);
}
virtual Status PutUntil(const WriteOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value, int32_t expiration) = 0;
virtual Status PutUntil(const WriteOptions& options, const Slice& key,
const Slice& value, int32_t expiration) {
return PutUntil(options, DefaultColumnFamily(), key, value, expiration);
}
using rocksdb::StackableDB::Get;
virtual Status Get(const ReadOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
PinnableSlice* value) override = 0;
using rocksdb::StackableDB::MultiGet;
virtual std::vector<Status> MultiGet(
const ReadOptions& options,
const std::vector<ColumnFamilyHandle*>& column_family,
const std::vector<Slice>& keys,
std::vector<std::string>* values) override = 0;
using rocksdb::StackableDB::SingleDelete;
virtual Status SingleDelete(const WriteOptions& wopts,
ColumnFamilyHandle* column_family,
const Slice& key) override = 0;
using rocksdb::StackableDB::Merge;
virtual Status Merge(const WriteOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value) override {
return Status::NotSupported("Not supported operation in blob db.");
}
virtual Status Write(const WriteOptions& opts,
WriteBatch* updates) override = 0;
// Starting point for opening a Blob DB.
// changed_options - critical. Blob DB loads and inserts listeners
// into options which are necessary for recovery and atomicity
// Use this pattern if you need control on step 2, i.e. your
// BaseDB is not just a simple rocksdb but a stacked DB
// 1. ::OpenAndLoad
// 2. Open Base DB with the changed_options
// 3. ::LinkToBaseDB
static Status OpenAndLoad(const Options& options,
const BlobDBOptions& bdb_options,
const std::string& dbname, BlobDB** blob_db,
Options* changed_options);
// This is another way to open BLOB DB which do not have other
// Stackable DB's in play
// Steps.
// 1. ::Open
static Status Open(const Options& options, const BlobDBOptions& bdb_options,
const std::string& dbname, BlobDB** blob_db);
static Status Open(const DBOptions& db_options,
const BlobDBOptions& bdb_options,
const std::string& dbname,
const std::vector<ColumnFamilyDescriptor>& column_families,
std::vector<ColumnFamilyHandle*>* handles,
BlobDB** blob_db, bool no_base_db = false);
virtual BlobDBOptions GetBlobDBOptions() const = 0;
virtual ~BlobDB() {}
virtual Status LinkToBaseDB(DB* db_base) = 0;
protected:
explicit BlobDB(DB* db);
};
// Destroy the content of the database.
Status DestroyBlobDB(const std::string& dbname, const Options& options,
const BlobDBOptions& bdb_options);
} // namespace blob_db
} // namespace rocksdb
#endif // ROCKSDB_LITE