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RocksDB for Erlang

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rocksdb deps rocksdb util compression_context_cache.h
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deps/rocksdb/util/compression_context_cache.h 

// 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