mirror of
https://github.com/facebook/rocksdb.git
synced 2024-11-25 22:44:05 +00:00
269478ee46
Summary: This PR implements support for a three tier cache - primary block cache, compressed secondary cache, and a nvm (local flash) secondary cache. This allows more effective utilization of the nvm cache, and minimizes the number of reads from local flash by caching compressed blocks in the compressed secondary cache. The basic design is as follows - 1. A new secondary cache implementation, ```TieredSecondaryCache```, is introduced. It keeps the compressed and nvm secondary caches and manages the movement of blocks between them and the primary block cache. To setup a three tier cache, we allocate a ```CacheWithSecondaryAdapter```, with a ```TieredSecondaryCache``` instance as the secondary cache. 2. The table reader passes both the uncompressed and compressed block to ```FullTypedCacheInterface::InsertFull```, allowing the block cache to optionally store the compressed block. 3. When there's a miss, the block object is constructed and inserted in the primary cache, and the compressed block is inserted into the nvm cache by calling ```InsertSaved```. This avoids the overhead of recompressing the block, as well as avoiding putting more memory pressure on the compressed secondary cache. 4. When there's a hit in the nvm cache, we attempt to insert the block in the compressed secondary cache and the primary cache, subject to the admission policy of those caches (i.e admit on second access). Blocks/items evicted from any tier are simply discarded. We can easily implement additional admission policies if desired. Todo (In a subsequent PR): 1. Add to db_bench and run benchmarks 2. Add to db_stress Pull Request resolved: https://github.com/facebook/rocksdb/pull/11812 Reviewed By: pdillinger Differential Revision: D49461842 Pulled By: anand1976 fbshipit-source-id: b40ac1330ef7cd8c12efa0a3ca75128e602e3a0b
62 lines
2.1 KiB
C++
62 lines
2.1 KiB
C++
// Copyright (c) Meta Platforms, Inc. and affiliates.
|
|
// 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).
|
|
|
|
#pragma once
|
|
|
|
#include <string>
|
|
|
|
#include "port/port.h"
|
|
#include "rocksdb/advanced_cache.h"
|
|
|
|
namespace ROCKSDB_NAMESPACE {
|
|
|
|
class ConcurrentCacheReservationManager;
|
|
|
|
// A cache interface which wraps around another cache and takes care of
|
|
// reserving space in block cache towards a single global memory limit, and
|
|
// forwards all the calls to the underlying cache.
|
|
class ChargedCache : public CacheWrapper {
|
|
public:
|
|
ChargedCache(std::shared_ptr<Cache> cache,
|
|
std::shared_ptr<Cache> block_cache);
|
|
|
|
Status Insert(
|
|
const Slice& key, ObjectPtr obj, const CacheItemHelper* helper,
|
|
size_t charge, Handle** handle = nullptr,
|
|
Priority priority = Priority::LOW, const Slice& compressed_val = Slice(),
|
|
CompressionType type = CompressionType::kNoCompression) override;
|
|
|
|
Cache::Handle* Lookup(const Slice& key, const CacheItemHelper* helper,
|
|
CreateContext* create_context,
|
|
Priority priority = Priority::LOW,
|
|
Statistics* stats = nullptr) override;
|
|
|
|
void WaitAll(AsyncLookupHandle* async_handles, size_t count) override;
|
|
|
|
bool Release(Cache::Handle* handle, bool useful,
|
|
bool erase_if_last_ref = false) override;
|
|
bool Release(Cache::Handle* handle, bool erase_if_last_ref = false) override;
|
|
|
|
void Erase(const Slice& key) override;
|
|
void EraseUnRefEntries() override;
|
|
|
|
static const char* kClassName() { return "ChargedCache"; }
|
|
const char* Name() const override { return kClassName(); }
|
|
|
|
void SetCapacity(size_t capacity) override;
|
|
|
|
inline Cache* GetCache() const { return target_.get(); }
|
|
|
|
inline ConcurrentCacheReservationManager* TEST_GetCacheReservationManager()
|
|
const {
|
|
return cache_res_mgr_.get();
|
|
}
|
|
|
|
private:
|
|
std::shared_ptr<ConcurrentCacheReservationManager> cache_res_mgr_;
|
|
};
|
|
|
|
} // namespace ROCKSDB_NAMESPACE
|