rocksdb/db/db_iter.h
Sagar Vemuri 7124268a09 Reduce the number of params needed to construct DBIter
Summary:
DBIter, and in-turn NewDBIterator and NewArenaWrappedDBIterator, take a  bunch of params. They can be reduced by passing in ReadOptions directly instead of passing in every new param separately. It also seems much cleaner as a bunch of the params towards the end seem to be optional.

(Recently I introduced max_skippable_internal_keys, which added one more to the already huge count).

Idea courtesy IslamAbdelRahman
Closes https://github.com/facebook/rocksdb/pull/2116

Differential Revision: D4857128

Pulled By: sagar0

fbshipit-source-id: 7d239df094b94bd9ea79d145cdf825478ac037a8
2017-04-10 11:14:14 -07:00

86 lines
3.3 KiB
C++

// Copyright (c) 2011-present, 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.
#pragma once
#include <stdint.h>
#include <string>
#include "db/dbformat.h"
#include "db/range_del_aggregator.h"
#include "options/cf_options.h"
#include "rocksdb/db.h"
#include "rocksdb/iterator.h"
#include "util/arena.h"
#include "util/autovector.h"
namespace rocksdb {
class Arena;
class DBIter;
class InternalIterator;
// Return a new iterator that converts internal keys (yielded by
// "*internal_iter") that were live at the specified "sequence" number
// into appropriate user keys.
extern Iterator* NewDBIterator(Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options,
const Comparator* user_key_comparator,
InternalIterator* internal_iter,
const SequenceNumber& sequence,
uint64_t max_sequential_skip_in_iterations,
uint64_t version_number);
// A wrapper iterator which wraps DB Iterator and the arena, with which the DB
// iterator is supposed be allocated. This class is used as an entry point of
// a iterator hierarchy whose memory can be allocated inline. In that way,
// accessing the iterator tree can be more cache friendly. It is also faster
// to allocate.
class ArenaWrappedDBIter : public Iterator {
public:
virtual ~ArenaWrappedDBIter();
// Get the arena to be used to allocate memory for DBIter to be wrapped,
// as well as child iterators in it.
virtual Arena* GetArena() { return &arena_; }
virtual RangeDelAggregator* GetRangeDelAggregator();
// Set the DB Iterator to be wrapped
virtual void SetDBIter(DBIter* iter);
// Set the internal iterator wrapped inside the DB Iterator. Usually it is
// a merging iterator.
virtual void SetIterUnderDBIter(InternalIterator* iter);
virtual bool Valid() const override;
virtual void SeekToFirst() override;
virtual void SeekToLast() override;
virtual void Seek(const Slice& target) override;
virtual void SeekForPrev(const Slice& target) override;
virtual void Next() override;
virtual void Prev() override;
virtual Slice key() const override;
virtual Slice value() const override;
virtual Status status() const override;
void RegisterCleanup(CleanupFunction function, void* arg1, void* arg2);
virtual Status GetProperty(std::string prop_name, std::string* prop) override;
private:
DBIter* db_iter_;
Arena arena_;
};
// Generate the arena wrapped iterator class.
extern ArenaWrappedDBIter* NewArenaWrappedDbIterator(
Env* env, const ReadOptions& read_options,
const ImmutableCFOptions& cf_options, const Comparator* user_key_comparator,
const SequenceNumber& sequence, uint64_t max_sequential_skip_in_iterations,
uint64_t version_number);
} // namespace rocksdb