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// Copyright (c) 2013, 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.
#pragma once
#include <stdint.h>
#include <memory>
#include <string>
#include "rocksdb/env.h"
#include "rocksdb/slice.h"
#include "rocksdb/statistics.h"
#include "rocksdb/status.h"
namespace rocksdb {
// PersistentCache
// Persistent cache interface for caching IO pages on a persistent medium. The
// cache interface is specifically designed for persistent read cache.
class PersistentCache {
typedef std::vector<std::map<std::string, double>> StatsType;
virtual ~PersistentCache() {}
// Insert to page cache
// page_key Identifier to identify a page uniquely across restarts
// data Page data
// size Size of the page
virtual Status Insert(const Slice& key, const char* data,
const size_t size) = 0;
// Lookup page cache by page identifier
// page_key Page identifier
// buf Buffer where the data should be copied
// size Size of the page
virtual Status Lookup(const Slice& key, std::unique_ptr<char[]>* data,
size_t* size) = 0;
// Is cache storing uncompressed data ?
// True if the cache is configured to store uncompressed data else false
virtual bool IsCompressed() = 0;
// Return stats as map of {string, double} per-tier
// Persistent cache can be initialized as a tier of caches. The stats are per
// tire top-down
virtual StatsType Stats() = 0;
virtual std::string GetPrintableOptions() const = 0;
// Factor method to create a new persistent cache
Status NewPersistentCache(Env* const env, const std::string& path,
const uint64_t size,
const std::shared_ptr<Logger>& log,
const bool optimized_for_nvm,
std::shared_ptr<PersistentCache>* cache);
} // namespace rocksdb