mirror of https://github.com/facebook/rocksdb.git
49 lines
2.0 KiB
C
49 lines
2.0 KiB
C
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// 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 "table/block_based/index_reader_common.h"
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namespace ROCKSDB_NAMESPACE {
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// Index that allows binary search lookup for the first key of each block.
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// This class can be viewed as a thin wrapper for `Block` class which already
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// supports binary search.
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class BinarySearchIndexReader : public BlockBasedTable::IndexReaderCommon {
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public:
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// Read index from the file and create an intance for
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// `BinarySearchIndexReader`.
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// On success, index_reader will be populated; otherwise it will remain
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// unmodified.
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static Status Create(const BlockBasedTable* table,
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FilePrefetchBuffer* prefetch_buffer, bool use_cache,
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bool prefetch, bool pin,
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BlockCacheLookupContext* lookup_context,
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std::unique_ptr<IndexReader>* index_reader);
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InternalIteratorBase<IndexValue>* NewIterator(
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const ReadOptions& read_options, bool /* disable_prefix_seek */,
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IndexBlockIter* iter, GetContext* get_context,
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BlockCacheLookupContext* lookup_context) override;
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size_t ApproximateMemoryUsage() const override {
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size_t usage = ApproximateIndexBlockMemoryUsage();
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#ifdef ROCKSDB_MALLOC_USABLE_SIZE
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usage += malloc_usable_size(const_cast<BinarySearchIndexReader*>(this));
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#else
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usage += sizeof(*this);
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#endif // ROCKSDB_MALLOC_USABLE_SIZE
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return usage;
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}
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private:
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BinarySearchIndexReader(const BlockBasedTable* t,
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CachableEntry<Block>&& index_block)
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: IndexReaderCommon(t, std::move(index_block)) {}
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};
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} // namespace ROCKSDB_NAMESPACE
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