mirror of
https://github.com/facebook/rocksdb.git
synced 2024-11-27 02:44:18 +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
116 lines
3.5 KiB
C++
116 lines
3.5 KiB
C++
// Copyright (c) 2011-present, 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).
|
|
|
|
#include "rocksdb/secondary_cache.h"
|
|
#include "util/random.h"
|
|
#include "util/thread_local.h"
|
|
|
|
namespace ROCKSDB_NAMESPACE {
|
|
|
|
// This class implements a custom SecondaryCache that randomly injects an
|
|
// error status into Inserts/Lookups based on a specified probability.
|
|
// Its used by db_stress to verify correctness in the presence of
|
|
// secondary cache errors.
|
|
//
|
|
class FaultInjectionSecondaryCache : public SecondaryCache {
|
|
public:
|
|
explicit FaultInjectionSecondaryCache(
|
|
const std::shared_ptr<SecondaryCache>& base, uint32_t seed, int prob)
|
|
: base_(base),
|
|
seed_(seed),
|
|
prob_(prob),
|
|
thread_local_error_(new ThreadLocalPtr(DeleteThreadLocalErrorContext)) {
|
|
if (std::strcmp(base_->Name(), "CompressedSecondaryCache") == 0) {
|
|
base_is_compressed_sec_cache_ = true;
|
|
}
|
|
}
|
|
|
|
virtual ~FaultInjectionSecondaryCache() override {}
|
|
|
|
const char* Name() const override { return "FaultInjectionSecondaryCache"; }
|
|
|
|
Status Insert(const Slice& key, Cache::ObjectPtr value,
|
|
const Cache::CacheItemHelper* helper,
|
|
bool force_insert) override;
|
|
|
|
Status InsertSaved(const Slice& /*key*/, const Slice& /*saved*/,
|
|
CompressionType /*type*/, CacheTier /*source*/) override {
|
|
return Status::OK();
|
|
}
|
|
|
|
std::unique_ptr<SecondaryCacheResultHandle> Lookup(
|
|
const Slice& key, const Cache::CacheItemHelper* helper,
|
|
Cache::CreateContext* create_context, bool wait, bool advise_erase,
|
|
bool& kept_in_sec_cache) override;
|
|
|
|
bool SupportForceErase() const override { return base_->SupportForceErase(); }
|
|
|
|
void Erase(const Slice& key) override;
|
|
|
|
void WaitAll(std::vector<SecondaryCacheResultHandle*> handles) override;
|
|
|
|
Status SetCapacity(size_t capacity) override {
|
|
return base_->SetCapacity(capacity);
|
|
}
|
|
|
|
Status GetCapacity(size_t& capacity) override {
|
|
return base_->GetCapacity(capacity);
|
|
}
|
|
|
|
std::string GetPrintableOptions() const override {
|
|
return base_->GetPrintableOptions();
|
|
}
|
|
|
|
private:
|
|
class ResultHandle : public SecondaryCacheResultHandle {
|
|
public:
|
|
ResultHandle(FaultInjectionSecondaryCache* cache,
|
|
std::unique_ptr<SecondaryCacheResultHandle>&& base)
|
|
: cache_(cache), base_(std::move(base)), value_(nullptr), size_(0) {}
|
|
|
|
~ResultHandle() override {}
|
|
|
|
bool IsReady() override;
|
|
|
|
void Wait() override;
|
|
|
|
Cache::ObjectPtr Value() override;
|
|
|
|
size_t Size() override;
|
|
|
|
static void WaitAll(FaultInjectionSecondaryCache* cache,
|
|
std::vector<SecondaryCacheResultHandle*> handles);
|
|
|
|
private:
|
|
static void UpdateHandleValue(ResultHandle* handle);
|
|
|
|
FaultInjectionSecondaryCache* cache_;
|
|
std::unique_ptr<SecondaryCacheResultHandle> base_;
|
|
Cache::ObjectPtr value_;
|
|
size_t size_;
|
|
};
|
|
|
|
static void DeleteThreadLocalErrorContext(void* p) {
|
|
ErrorContext* ctx = static_cast<ErrorContext*>(p);
|
|
delete ctx;
|
|
}
|
|
|
|
const std::shared_ptr<SecondaryCache> base_;
|
|
uint32_t seed_;
|
|
int prob_;
|
|
bool base_is_compressed_sec_cache_{false};
|
|
|
|
struct ErrorContext {
|
|
Random rand;
|
|
|
|
explicit ErrorContext(uint32_t seed) : rand(seed) {}
|
|
};
|
|
std::unique_ptr<ThreadLocalPtr> thread_local_error_;
|
|
|
|
ErrorContext* GetErrorContext();
|
|
};
|
|
|
|
} // namespace ROCKSDB_NAMESPACE
|