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8ea0a2c1bd
Summary: Implement the ```WaitAll()``` interface in ```LRUCache``` to allow callers to issue multiple lookups in parallel and wait for all of them to complete. Modify ```MultiGet``` to use this to parallelize the secondary cache lookups in order to reduce the overall latency. A call to ```cache->Lookup()``` returns a handle that has an incomplete value (nullptr), and the caller can call ```cache->IsReady()``` to check whether the lookup is complete, and pass a vector of handles to ```WaitAll``` to wait for completion. If any of the lookups fail, ```MultiGet``` will read the block from the SST file. Another change in this PR is to rename ```SecondaryCacheHandle``` to ```SecondaryCacheResultHandle``` as it more accurately describes the return result of the secondary cache lookup, which is more like a future. Tests: 1. Add unit tests in lru_cache_test 2. Benchmark results with no secondary cache configured Master - ``` readrandom : 41.175 micros/op 388562 ops/sec; 106.7 MB/s (7277999 of 7277999 found) readrandom : 41.217 micros/op 388160 ops/sec; 106.6 MB/s (7274999 of 7274999 found) multireadrandom : 10.309 micros/op 1552082 ops/sec; (28908992 of 28908992 found) multireadrandom : 10.321 micros/op 1550218 ops/sec; (29081984 of 29081984 found) ``` This PR - ``` readrandom : 41.158 micros/op 388723 ops/sec; 106.8 MB/s (7290999 of 7290999 found) readrandom : 41.185 micros/op 388463 ops/sec; 106.7 MB/s (7287999 of 7287999 found) multireadrandom : 10.277 micros/op 1556801 ops/sec; (29346944 of 29346944 found) multireadrandom : 10.253 micros/op 1560539 ops/sec; (29274944 of 29274944 found) ``` Pull Request resolved: https://github.com/facebook/rocksdb/pull/8405 Reviewed By: zhichao-cao Differential Revision: D29190509 Pulled By: anand1976 fbshipit-source-id: 6f8eff6246712af8a297cfe22ea0d1c3b2a01bb0
56 lines
2 KiB
C++
56 lines
2 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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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->footer.index_handle(),
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UncompressionDict::GetEmptyDict(), index_block, BlockType::kIndex,
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get_context, lookup_context, /* for_compaction */ false, use_cache,
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/* wait_for_cache */ 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,
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CachableEntry<Block>* index_block) 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;
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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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