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Diffstat (limited to '')
-rw-r--r-- | src/rocksdb/table/block_based/block_prefetcher.h | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/src/rocksdb/table/block_based/block_prefetcher.h b/src/rocksdb/table/block_based/block_prefetcher.h new file mode 100644 index 000000000..518868a30 --- /dev/null +++ b/src/rocksdb/table/block_based/block_prefetcher.h @@ -0,0 +1,72 @@ +// 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, + size_t initial_auto_readahead_size) + : compaction_readahead_size_(compaction_readahead_size), + readahead_size_(initial_auto_readahead_size), + initial_auto_readahead_size_(initial_auto_readahead_size) {} + + void PrefetchIfNeeded(const BlockBasedTable::Rep* rep, + const BlockHandle& handle, size_t readahead_size, + bool is_for_compaction, + const bool no_sequential_checking, + Env::IOPriority rate_limiter_priority); + FilePrefetchBuffer* prefetch_buffer() { return prefetch_buffer_.get(); } + + void UpdateReadPattern(const uint64_t& offset, const size_t& len) { + prev_offset_ = offset; + prev_len_ = len; + } + + bool IsBlockSequential(const uint64_t& offset) { + return (prev_len_ == 0 || (prev_offset_ + prev_len_ == offset)); + } + + void ResetValues(size_t initial_auto_readahead_size) { + num_file_reads_ = 1; + // Since initial_auto_readahead_size_ can be different from + // the value passed to BlockBasedTableOptions.initial_auto_readahead_size in + // case of adaptive_readahead, so fallback the readahead_size_ to that value + // in case of reset. + initial_auto_readahead_size_ = initial_auto_readahead_size; + readahead_size_ = initial_auto_readahead_size_; + readahead_limit_ = 0; + return; + } + + void SetReadaheadState(ReadaheadFileInfo::ReadaheadInfo* readahead_info) { + num_file_reads_ = readahead_info->num_file_reads; + initial_auto_readahead_size_ = readahead_info->readahead_size; + TEST_SYNC_POINT_CALLBACK("BlockPrefetcher::SetReadaheadState", + &initial_auto_readahead_size_); + } + + private: + // Readahead size used in compaction, its value is used only if + // lookup_context_.caller = kCompaction. + size_t compaction_readahead_size_; + + // readahead_size_ is used if underlying FS supports prefetching. + size_t readahead_size_; + size_t readahead_limit_ = 0; + // initial_auto_readahead_size_ is used if RocksDB uses internal prefetch + // buffer. + uint64_t initial_auto_readahead_size_; + uint64_t num_file_reads_ = 0; + uint64_t prev_offset_ = 0; + size_t prev_len_ = 0; + std::unique_ptr<FilePrefetchBuffer> prefetch_buffer_; +}; +} // namespace ROCKSDB_NAMESPACE |