mirror of https://github.com/facebook/rocksdb.git
61 lines
2.0 KiB
C++
61 lines
2.0 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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// 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/types.h"
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namespace rocksdb {
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class Comparator;
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class InternalIterator;
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class Env;
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class Arena;
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// Return an iterator that provided the union of the data in
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// children[0,n-1]. Takes ownership of the child iterators and
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// will delete them when the result iterator is deleted.
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//
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// The result does no duplicate suppression. I.e., if a particular
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// key is present in K child iterators, it will be yielded K times.
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//
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// REQUIRES: n >= 0
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extern InternalIterator* NewMergingIterator(const Comparator* comparator,
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InternalIterator** children, int n,
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Arena* arena = nullptr);
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class MergingIterator;
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// A builder class to build a merging iterator by adding iterators one by one.
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class MergeIteratorBuilder {
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public:
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// comparator: the comparator used in merging comparator
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// arena: where the merging iterator needs to be allocated from.
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explicit MergeIteratorBuilder(const Comparator* comparator, Arena* arena);
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~MergeIteratorBuilder() {}
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// Add iter to the merging iterator.
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void AddIterator(InternalIterator* iter);
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// Get arena used to build the merging iterator. It is called one a child
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// iterator needs to be allocated.
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Arena* GetArena() { return arena; }
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// Return the result merging iterator.
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InternalIterator* Finish();
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private:
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MergingIterator* merge_iter;
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InternalIterator* first_iter;
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bool use_merging_iter;
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Arena* arena;
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};
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} // namespace rocksdb
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