| // 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/types.h" |
| |
| namespace rocksdb { |
| |
| class Comparator; |
| class InternalIterator; |
| class Env; |
| class Arena; |
| |
| // 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 Comparator* 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 Comparator* 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 |