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// 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).
#pragma once
#include <cassert>
#include <cstdint>
#include <memory>
#include <unordered_map>
#include "file/file_prefetch_buffer.h"
#include "rocksdb/rocksdb_namespace.h"
namespace ROCKSDB_NAMESPACE {
// A class that owns a collection of FilePrefetchBuffers using the file number
// as key. Used for implementing compaction readahead for blob files. Designed
// to be accessed by a single thread only: every (sub)compaction needs its own
// buffers since they are guaranteed to read different blobs from different
// positions even when reading the same file.
class PrefetchBufferCollection {
public:
explicit PrefetchBufferCollection(uint64_t readahead_size)
: readahead_size_(readahead_size) {
assert(readahead_size_ > 0);
}
FilePrefetchBuffer* GetOrCreatePrefetchBuffer(uint64_t file_number);
private:
uint64_t readahead_size_;
std::unordered_map<uint64_t, std::unique_ptr<FilePrefetchBuffer>>
prefetch_buffers_; // maps file number to prefetch buffer
};
} // namespace ROCKSDB_NAMESPACE
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