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35ad531be3
Summary: Separate a new class InternalIterator from class Iterator, when the look-up is done internally, which also means they operate on key with sequence ID and type. This change will enable potential future optimizations but for now InternalIterator's functions are still the same as Iterator's. At the same time, separate the cleanup function to a separate class and let both of InternalIterator and Iterator inherit from it. Test Plan: Run all existing tests. Reviewers: igor, yhchiang, anthony, kradhakrishnan, IslamAbdelRahman, rven Reviewed By: rven Subscribers: leveldb, dhruba Differential Revision: https://reviews.facebook.net/D48549
61 lines
2 KiB
C++
61 lines
2 KiB
C++
// Copyright (c) 2013, 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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