dc5de45af8
Summary: The patch adds a new BlobDB configuration option `blob_compaction_readahead_size` that can be used to enable prefetching data from blob files during compaction. This is important when using storage with higher latencies like HDDs or remote filesystems. If enabled, prefetching is used for all cases when blobs are read during compaction, namely garbage collection, compaction filters (when the existing value has to be read from a blob file), and `Merge` (when the value of the base `Put` is stored in a blob file). Pull Request resolved: https://github.com/facebook/rocksdb/pull/9187 Test Plan: Ran `make check` and the stress/crash test. Reviewed By: riversand963 Differential Revision: D32565512 Pulled By: ltamasi fbshipit-source-id: 87be9cebc3aa01cc227bec6b5f64d827b8164f5d
39 lines
1.3 KiB
C++
39 lines
1.3 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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#pragma once
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#include <cassert>
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#include <cstdint>
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#include <memory>
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#include <unordered_map>
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#include "file/file_prefetch_buffer.h"
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#include "rocksdb/rocksdb_namespace.h"
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namespace ROCKSDB_NAMESPACE {
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// A class that owns a collection of FilePrefetchBuffers using the file number
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// as key. Used for implementing compaction readahead for blob files. Designed
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// to be accessed by a single thread only: every (sub)compaction needs its own
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// buffers since they are guaranteed to read different blobs from different
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// positions even when reading the same file.
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class PrefetchBufferCollection {
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public:
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explicit PrefetchBufferCollection(uint64_t readahead_size)
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: readahead_size_(readahead_size) {
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assert(readahead_size_ > 0);
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}
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FilePrefetchBuffer* GetOrCreatePrefetchBuffer(uint64_t file_number);
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private:
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uint64_t readahead_size_;
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std::unordered_map<uint64_t, std::unique_ptr<FilePrefetchBuffer>>
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prefetch_buffers_; // maps file number to prefetch buffer
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};
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} // namespace ROCKSDB_NAMESPACE
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