a08c8c851a
Summary: Added a new abstraction to cache page to RocksDB designed for the read cache use. RocksDB current block cache is more of an object cache. For the persistent read cache project, what we need is a page cache equivalent. This changes adds a cache abstraction to RocksDB to cache pages called PersistentCache. PersistentCache can cache uncompressed pages or raw pages (content as in filesystem). The user can choose to operate PersistentCache either in COMPRESSED or UNCOMPRESSED mode. Blame Rev: Test Plan: Run unit tests Reviewers: sdong Subscribers: andrewkr, dhruba, leveldb Differential Revision: https://reviews.facebook.net/D55707
50 lines
1.6 KiB
C++
50 lines
1.6 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include <stdint.h>
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#include <memory>
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#include "rocksdb/slice.h"
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#include "rocksdb/statistics.h"
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#include "rocksdb/status.h"
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namespace rocksdb {
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// PersistentCache
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//
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// Persistent cache interface for caching IO pages on a persistent medium. The
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// cache interface is specifically designed for persistent read cache.
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class PersistentCache {
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public:
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virtual ~PersistentCache() {}
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// Insert to page cache
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//
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// page_key Identifier to identify a page uniquely across restarts
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// data Page data
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// size Size of the page
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virtual Status Insert(const Slice& key, const char* data,
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const size_t size) = 0;
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// Lookup page cache by page identifier
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//
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// page_key Page identifier
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// buf Buffer where the data should be copied
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// size Size of the page
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virtual Status Lookup(const Slice& key, std::unique_ptr<char[]>* data,
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size_t* size) = 0;
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// Is cache storing uncompressed data ?
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//
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// True if the cache is configured to store uncompressed data else false
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virtual bool IsCompressed() = 0;
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};
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} // namespace rocksdb
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