f8c685c4fc
Summary: We have three layers of block cache that often use the same key but map to different physical data: * BlockBasedTableOptions::block_cache * BlockBasedTableOptions::block_cache_compressed * BlockBasedTableOptions::persistent_cache If any two of these happen to share an underlying implementation and key space (insertion into one shows up in another), then memory safety is broken. The simplest case is block_cache == block_cache_compressed. (Credit mrambacher for asking about this case in a review.) With this change, we explicitly check for overlap and preemptively and safely fail with a Status code. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9172 Test Plan: test added. Crashes without new check Reviewed By: anand1976 Differential Revision: D32465659 Pulled By: pdillinger fbshipit-source-id: 3876b45b6dce6167e5a7a642725ddc86b96f8e40
74 lines
2.6 KiB
C++
74 lines
2.6 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root 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 <string>
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#include "rocksdb/env.h"
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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_NAMESPACE {
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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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using StatsType = std::vector<std::map<std::string, double>>;
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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 to copy (caller retains ownership)
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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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// Return stats as map of {string, double} per-tier
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//
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// Persistent cache can be initialized as a tier of caches. The stats are per
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// tire top-down
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virtual StatsType Stats() = 0;
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virtual std::string GetPrintableOptions() const = 0;
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// Return a new numeric id. May be used by multiple clients who are
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// sharding the same persistent cache to partition the key space. Typically
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// the client will allocate a new id at startup and prepend the id to its
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// cache keys.
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virtual uint64_t NewId() = 0;
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};
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// Factor method to create a new persistent cache
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Status NewPersistentCache(Env* const env, const std::string& path,
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const uint64_t size,
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const std::shared_ptr<Logger>& log,
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const bool optimized_for_nvm,
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std::shared_ptr<PersistentCache>* cache);
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} // namespace ROCKSDB_NAMESPACE
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