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rocksdb/table/block_based/block_prefetcher.h

32 lines
1.3 KiB

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include "table/block_based/block_based_table_reader.h"
namespace ROCKSDB_NAMESPACE {
class BlockPrefetcher {
public:
explicit BlockPrefetcher(size_t compaction_readahead_size)
: compaction_readahead_size_(compaction_readahead_size) {}
void PrefetchIfNeeded(const BlockBasedTable::Rep* rep,
const BlockHandle& handle, size_t readahead_size,
bool is_for_compaction);
FilePrefetchBuffer* prefetch_buffer() { return prefetch_buffer_.get(); }
private:
// Readahead size used in compaction, its value is used only if
// lookup_context_.caller = kCompaction.
size_t compaction_readahead_size_;
size_t readahead_size_ = BlockBasedTable::kInitAutoReadaheadSize;
size_t readahead_limit_ = 0;
int64_t num_file_reads_ = 0;
std::unique_ptr<FilePrefetchBuffer> prefetch_buffer_;
};
} // namespace ROCKSDB_NAMESPACE