Summary: Use a std::priority_queue in merger.cc instead of doing a o(n) search every time. Currently only the ForwardIteration uses a Priority Queue. Test Plan: make all check Reviewers: dhruba Reviewed By: dhruba CC: emayanke, zshao Differential Revision: https://reviews.facebook.net/D7629main
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// Copyright 2008-present Facebook. All Rights Reserved.
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#ifndef STORAGE_LEVELDB_ITER_HEAP_H_ |
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#define STORAGE_LEVELDB_ITER_HEAP_H_ |
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#include <queue> |
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#include "leveldb/comparator.h" |
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#include "table/iterator_wrapper.h" |
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namespace leveldb { |
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// Return the max of two keys.
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class MaxIteratorComparator { |
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public: |
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MaxIteratorComparator(const Comparator* comparator) : |
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comparator_(comparator) {} |
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bool operator()(IteratorWrapper* a, IteratorWrapper* b) { |
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return comparator_->Compare(a->key(), b->key()) <= 0; |
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} |
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private: |
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const Comparator* comparator_; |
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}; |
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// Return the max of two keys.
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class MinIteratorComparator { |
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public: |
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// if maxHeap is set comparator returns the max value.
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// else returns the min Value.
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// Can use to create a minHeap or a maxHeap.
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MinIteratorComparator(const Comparator* comparator) : |
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comparator_(comparator) {} |
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bool operator()(IteratorWrapper* a, IteratorWrapper* b) { |
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return comparator_->Compare(a->key(), b->key()) > 0; |
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} |
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private: |
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const Comparator* comparator_; |
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}; |
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typedef std::priority_queue< |
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IteratorWrapper*, |
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std::vector<IteratorWrapper*>, |
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MaxIteratorComparator> MaxIterHeap; |
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typedef std::priority_queue< |
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IteratorWrapper*, |
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std::vector<IteratorWrapper*>, |
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MinIteratorComparator> MinIterHeap; |
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// Return's a new MaxHeap of IteratorWrapper's using the provided Comparator.
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MaxIterHeap NewMaxIterHeap(const Comparator* comparator) { |
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return MaxIterHeap(MaxIteratorComparator(comparator)); |
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} |
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// Return's a new MinHeap of IteratorWrapper's using the provided Comparator.
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MinIterHeap NewMinIterHeap(const Comparator* comparator) { |
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return MinIterHeap(MinIteratorComparator(comparator)); |
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} |
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} // namespace leveldb
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#endif // STORAGE_LEVELDB_ITER_HEAP_H_
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