fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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38 lines
1.3 KiB
38 lines
1.3 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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#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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