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5b5b011cdd
Summary: With the async_io option, the Seek happens in 2 phases. Phase 1 starts an asynchronous read on a block cache miss, and phase 2 waits for it to complete and finishes the seek. In both phases, BlockBasedTable::NewDataBlockIterator is called, which tries to lookup the block cache for the data block first before looking in the prefetch buffer. It's optimized by doing the block cache lookup only in the first phase and save some CPU. Pull Request resolved: https://github.com/facebook/rocksdb/pull/11616 Test Plan: Added unit test Reviewed By: jaykorean Differential Revision: D47477887 Pulled By: akankshamahajan15 fbshipit-source-id: 0355e0a68fc0ea2eb92340ae42735afcdbcbfd79
58 lines
2.1 KiB
C++
58 lines
2.1 KiB
C++
// 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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#include "table/block_based/index_reader_common.h"
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#include "block_cache.h"
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namespace ROCKSDB_NAMESPACE {
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Status BlockBasedTable::IndexReaderCommon::ReadIndexBlock(
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const BlockBasedTable* table, FilePrefetchBuffer* prefetch_buffer,
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const ReadOptions& read_options, bool use_cache, GetContext* get_context,
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BlockCacheLookupContext* lookup_context,
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CachableEntry<Block>* index_block) {
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PERF_TIMER_GUARD(read_index_block_nanos);
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assert(table != nullptr);
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assert(index_block != nullptr);
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assert(index_block->IsEmpty());
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const Rep* const rep = table->get_rep();
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assert(rep != nullptr);
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const Status s = table->RetrieveBlock(
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prefetch_buffer, read_options, rep->index_handle,
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UncompressionDict::GetEmptyDict(), &index_block->As<Block_kIndex>(),
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get_context, lookup_context, /* for_compaction */ false, use_cache,
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/* async_read */ false, /* use_block_cache_for_lookup */ true);
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return s;
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}
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Status BlockBasedTable::IndexReaderCommon::GetOrReadIndexBlock(
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bool no_io, GetContext* get_context,
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BlockCacheLookupContext* lookup_context, CachableEntry<Block>* index_block,
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const ReadOptions& ro) const {
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assert(index_block != nullptr);
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if (!index_block_.IsEmpty()) {
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index_block->SetUnownedValue(index_block_.GetValue());
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return Status::OK();
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}
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ReadOptions read_options = ro;
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if (no_io) {
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read_options.read_tier = kBlockCacheTier;
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}
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return ReadIndexBlock(table_, /*prefetch_buffer=*/nullptr, read_options,
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cache_index_blocks(), get_context, lookup_context,
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index_block);
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}
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} // namespace ROCKSDB_NAMESPACE
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