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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).
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
//
// Compression context cache allows to cache compression/uncompression contexts
// This helps with Random Read latencies and reduces CPU utilization
// Caching is implemented using CoreLocal facility. Compression/Uncompression
// instances are cached on a per core basis using CoreLocalArray. A borrowed
// instance is atomically replaced with a sentinel value for the time of being
// used. If it turns out that another thread is already makes use of the
// instance we still create one on the heap which is later is destroyed.
#pragma once
#include <stdint.h>
namespace rocksdb {
class ZSTDUncompressCachedData;
class CompressionContextCache {
public:
// Singleton
static CompressionContextCache* Instance();
static void InitSingleton();
CompressionContextCache(const CompressionContextCache&) = delete;
CompressionContextCache& operator=(const CompressionContextCache&) = delete;
ZSTDUncompressCachedData GetCachedZSTDUncompressData();
void ReturnCachedZSTDUncompressData(int64_t idx);
private:
// Singleton
CompressionContextCache();
~CompressionContextCache();
class Rep;
Rep* rep_;
};
} // namespace rocksdb
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