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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
64 lines
2.1 KiB
C++
64 lines
2.1 KiB
C++
// Copyright (c) 2011-present, 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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#pragma once
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#include <string>
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#include "table/block_based_table_reader.h"
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#include "util/statistics.h"
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namespace rocksdb {
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struct BlockContents;
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// PersistentCacheOptions
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//
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// This describe the caching behavior for page cache
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// This is used to pass the context for caching and the cache handle
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struct PersistentCacheOptions {
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PersistentCacheOptions() {}
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explicit PersistentCacheOptions(
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const std::shared_ptr<PersistentCache>& _persistent_cache,
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const std::string _key_prefix, Statistics* const _statistics)
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: persistent_cache(_persistent_cache),
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key_prefix(_key_prefix),
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statistics(_statistics) {}
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virtual ~PersistentCacheOptions() {}
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std::shared_ptr<PersistentCache> persistent_cache;
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std::string key_prefix;
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Statistics* statistics = nullptr;
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};
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// PersistentCacheHelper
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//
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// Encapsulates some of the helper logic for read and writing from the cache
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class PersistentCacheHelper {
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public:
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// insert block into raw page cache
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static void InsertRawPage(const PersistentCacheOptions& cache_options,
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const BlockHandle& handle, const char* data,
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const size_t size);
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// insert block into uncompressed cache
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static void InsertUncompressedPage(
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const PersistentCacheOptions& cache_options, const BlockHandle& handle,
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const BlockContents& contents);
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// lookup block from raw page cacge
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static Status LookupRawPage(const PersistentCacheOptions& cache_options,
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const BlockHandle& handle,
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std::unique_ptr<char[]>* raw_data,
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const size_t raw_data_size);
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// lookup block from uncompressed cache
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static Status LookupUncompressedPage(
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const PersistentCacheOptions& cache_options, const BlockHandle& handle,
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BlockContents* contents);
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};
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} // namespace rocksdb
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