rocksdb/table/merging_iterator.h
mrambacher 13ae16c315 Cleanup includes in dbformat.h (#8930)
Summary:
This header file was including everything and the kitchen sink when it did not need to.  This resulted in many places including this header when they needed other pieces instead.

Cleaned up this header to only include what was needed and fixed up the remaining code to include what was now missing.

Hopefully, this sort of code hygiene cleanup will speed up the builds...

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8930

Reviewed By: pdillinger

Differential Revision: D31142788

Pulled By: mrambacher

fbshipit-source-id: 6b45de3f300750c79f751f6227dece9cfd44085d
2021-09-29 04:04:40 -07:00

65 lines
2.1 KiB
C++

// 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).
//
// 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 "rocksdb/slice.h"
#include "rocksdb/types.h"
namespace ROCKSDB_NAMESPACE {
class Arena;
class InternalKeyComparator;
template <class TValue>
class InternalIteratorBase;
using InternalIterator = InternalIteratorBase<Slice>;
// Return an iterator that provided the union of the data in
// children[0,n-1]. Takes ownership of the child iterators and
// will delete them when the result iterator is deleted.
//
// The result does no duplicate suppression. I.e., if a particular
// key is present in K child iterators, it will be yielded K times.
//
// REQUIRES: n >= 0
extern InternalIterator* NewMergingIterator(
const InternalKeyComparator* comparator, InternalIterator** children, int n,
Arena* arena = nullptr, bool prefix_seek_mode = false);
class MergingIterator;
// A builder class to build a merging iterator by adding iterators one by one.
class MergeIteratorBuilder {
public:
// comparator: the comparator used in merging comparator
// arena: where the merging iterator needs to be allocated from.
explicit MergeIteratorBuilder(const InternalKeyComparator* comparator,
Arena* arena, bool prefix_seek_mode = false);
~MergeIteratorBuilder();
// Add iter to the merging iterator.
void AddIterator(InternalIterator* iter);
// Get arena used to build the merging iterator. It is called one a child
// iterator needs to be allocated.
Arena* GetArena() { return arena; }
// Return the result merging iterator.
InternalIterator* Finish();
private:
MergingIterator* merge_iter;
InternalIterator* first_iter;
bool use_merging_iter;
Arena* arena;
};
} // namespace ROCKSDB_NAMESPACE