fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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66 lines
2.6 KiB
66 lines
2.6 KiB
// 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/block_based_table_reader.h"
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namespace ROCKSDB_NAMESPACE {
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class BlockPrefetcher {
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public:
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explicit BlockPrefetcher(size_t compaction_readahead_size)
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: compaction_readahead_size_(compaction_readahead_size) {}
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void PrefetchIfNeeded(const BlockBasedTable::Rep* rep,
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const BlockHandle& handle, size_t readahead_size,
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bool is_for_compaction, bool async_io);
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FilePrefetchBuffer* prefetch_buffer() { return prefetch_buffer_.get(); }
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void UpdateReadPattern(const uint64_t& offset, const size_t& len) {
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prev_offset_ = offset;
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prev_len_ = len;
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}
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bool IsBlockSequential(const uint64_t& offset) {
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return (prev_len_ == 0 || (prev_offset_ + prev_len_ == offset));
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}
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void ResetValues() {
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num_file_reads_ = 1;
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// Since initial_auto_readahead_size_ can be different from
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// kInitAutoReadaheadSize in case of adaptive_readahead, so fallback the
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// readahead_size_ to kInitAutoReadaheadSize in case of reset.
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initial_auto_readahead_size_ = BlockBasedTable::kInitAutoReadaheadSize;
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readahead_size_ = initial_auto_readahead_size_;
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readahead_limit_ = 0;
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return;
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}
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void SetReadaheadState(ReadaheadFileInfo::ReadaheadInfo* readahead_info) {
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num_file_reads_ = readahead_info->num_file_reads;
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initial_auto_readahead_size_ = readahead_info->readahead_size;
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TEST_SYNC_POINT_CALLBACK("BlockPrefetcher::SetReadaheadState",
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&initial_auto_readahead_size_);
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}
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private:
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// Readahead size used in compaction, its value is used only if
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// lookup_context_.caller = kCompaction.
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size_t compaction_readahead_size_;
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// readahead_size_ is used if underlying FS supports prefetching.
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size_t readahead_size_ = BlockBasedTable::kInitAutoReadaheadSize;
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size_t readahead_limit_ = 0;
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// initial_auto_readahead_size_ is used if RocksDB uses internal prefetch
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// buffer.
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uint64_t initial_auto_readahead_size_ =
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BlockBasedTable::kInitAutoReadaheadSize;
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int64_t num_file_reads_ = 0;
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uint64_t prev_offset_ = 0;
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size_t prev_len_ = 0;
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std::unique_ptr<FilePrefetchBuffer> prefetch_buffer_;
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};
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} // namespace ROCKSDB_NAMESPACE
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