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4e60663b31
Summary: In C++, `extern` is redundant in a number of cases: * "Global" function declarations and definitions * "Global" variable definitions when already declared `extern` For consistency and simplicity, I've removed these in code that *we own*. In a couple of cases, I removed obsolete declarations, and for MagicNumber constants, I have consolidated the declarations into a header file (format.h) as standard best practice would prescribe. Pull Request resolved: https://github.com/facebook/rocksdb/pull/12300 Test Plan: no functional changes, CI Reviewed By: ajkr Differential Revision: D53148629 Pulled By: pdillinger fbshipit-source-id: fb8d927959892e03af09b0c0d542b0a3b38fd886
99 lines
4.2 KiB
C++
99 lines
4.2 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 "db/range_del_aggregator.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/types.h"
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#include "table/iterator_wrapper.h"
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namespace ROCKSDB_NAMESPACE {
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class Arena;
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class ArenaWrappedDBIter;
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class InternalKeyComparator;
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template <class TValue>
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class InternalIteratorBase;
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using InternalIterator = InternalIteratorBase<Slice>;
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// Return an iterator that provides 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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InternalIterator* NewMergingIterator(const InternalKeyComparator* comparator,
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InternalIterator** children, int n,
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Arena* arena = nullptr,
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bool prefix_seek_mode = false);
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// The iterator returned by NewMergingIterator() and
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// MergeIteratorBuilder::Finish(). MergingIterator handles the merging of data
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// from different point and/or range tombstone iterators.
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class MergingIterator;
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// A builder class to for an iterator that provides the union of data
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// of input iterators. Two APIs are provided to add input iterators. User should
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// only call one of them exclusively depending on if range tombstone should be
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// processed.
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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 InternalKeyComparator* comparator,
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Arena* arena, bool prefix_seek_mode = false,
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const Slice* iterate_upper_bound = nullptr);
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~MergeIteratorBuilder();
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// Add point key iterator `iter` to the merging iterator.
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void AddIterator(InternalIterator* iter);
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// Add a point key iterator and a range tombstone iterator.
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// `tombstone_iter_ptr` should and only be set by LevelIterator.
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// *tombstone_iter_ptr will be set to where the merging iterator stores
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// `tombstone_iter` when MergeIteratorBuilder::Finish() is called. This is
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// used by LevelIterator to update range tombstone iters when switching to a
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// different SST file. If a single point iterator with a nullptr range
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// tombstone iterator is provided, and the point iterator is not a level
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// iterator, then this builder will return the point iterator directly,
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// instead of creating a merging iterator on top of it. Internally, if all
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// point iterators are not LevelIterator, then range tombstone iterator is
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// only added to the merging iter if there is a non-null `tombstone_iter`.
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void AddPointAndTombstoneIterator(
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InternalIterator* point_iter, TruncatedRangeDelIterator* tombstone_iter,
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TruncatedRangeDelIterator*** tombstone_iter_ptr = nullptr);
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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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// If db_iter is not nullptr, then db_iter->SetMemtableRangetombstoneIter()
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// will be called with pointer to where the merging iterator
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// stores the memtable range tombstone iterator.
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// This is used for DB iterator to refresh memtable range tombstones.
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InternalIterator* Finish(ArenaWrappedDBIter* db_iter = nullptr);
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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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// Used to set LevelIterator.range_tombstone_iter_.
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// See AddRangeTombstoneIterator() implementation for more detail.
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std::vector<std::pair<size_t, TruncatedRangeDelIterator***>>
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range_del_iter_ptrs_;
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};
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} // namespace ROCKSDB_NAMESPACE
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