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b555ed30a4
Summary: Use a customzied BlockBasedTableIterator and LevelIterator to replace current implementations leveraging two-level-iterator. Hope the customized logic will make code easier to understand. As a side effect, BlockBasedTableIterator reduces the allocation for the data block iterator object, and avoid the virtual function call to it, because we can directly reference BlockIter, a final class. Similarly, LevelIterator reduces virtual function call to the dummy iterator iterating the file metadata. It also enabled further optimization. The upper bound check is also moved from index block to data block. This implementation fits this iterator better. After the change, forwared iterator is slightly optimized to ensure we trim those iterators. The two-level-iterator now is only used by partitioned index, so it is simplified. Closes https://github.com/facebook/rocksdb/pull/3406 Differential Revision: D6809041 Pulled By: siying fbshipit-source-id: 7da3b9b1d3c8e9d9405302c15920af1fcaf50ffa
47 lines
1.8 KiB
C++
47 lines
1.8 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root 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/iterator.h"
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#include "rocksdb/env.h"
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#include "table/iterator_wrapper.h"
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namespace rocksdb {
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struct ReadOptions;
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class InternalKeyComparator;
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class Arena;
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struct TwoLevelIteratorState {
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TwoLevelIteratorState() {}
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virtual ~TwoLevelIteratorState() {}
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virtual InternalIterator* NewSecondaryIterator(const Slice& handle) = 0;
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};
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// Return a new two level iterator. A two-level iterator contains an
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// index iterator whose values point to a sequence of blocks where
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// each block is itself a sequence of key,value pairs. The returned
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// two-level iterator yields the concatenation of all key/value pairs
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// in the sequence of blocks. Takes ownership of "index_iter" and
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// will delete it when no longer needed.
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//
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// Uses a supplied function to convert an index_iter value into
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// an iterator over the contents of the corresponding block.
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// arena: If not null, the arena is used to allocate the Iterator.
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// When destroying the iterator, the destructor will destroy
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// all the states but those allocated in arena.
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// need_free_iter_and_state: free `state` and `first_level_iter` if
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// true. Otherwise, just call destructor.
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extern InternalIterator* NewTwoLevelIterator(
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TwoLevelIteratorState* state, InternalIterator* first_level_iter);
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} // namespace rocksdb
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