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rocksdb/db/blob/blob_source.h

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3.0 KiB

// 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 <cinttypes>
#include "cache/cache_helpers.h"
#include "cache/cache_key.h"
#include "db/blob/blob_file_cache.h"
#include "rocksdb/cache.h"
#include "rocksdb/rocksdb_namespace.h"
#include "table/block_based/cachable_entry.h"
namespace ROCKSDB_NAMESPACE {
struct ImmutableOptions;
class Status;
class FilePrefetchBuffer;
class Slice;
// BlobSource is a class that provides universal access to blobs, regardless of
// whether they are in the blob cache, secondary cache, or (remote) storage.
// Depending on user settings, it always fetch blobs from multi-tier cache and
// storage with minimal cost.
class BlobSource {
public:
BlobSource(const ImmutableOptions* immutable_options,
const std::string& db_id, const std::string& db_session_id,
BlobFileCache* blob_file_cache);
BlobSource(const BlobSource&) = delete;
BlobSource& operator=(const BlobSource&) = delete;
~BlobSource();
Status GetBlob(const ReadOptions& read_options, const Slice& user_key,
uint64_t file_number, uint64_t offset, uint64_t file_size,
uint64_t value_size, CompressionType compression_type,
FilePrefetchBuffer* prefetch_buffer, PinnableSlice* value,
uint64_t* bytes_read);
bool TEST_BlobInCache(uint64_t file_number, uint64_t file_size,
uint64_t offset) const;
private:
Status GetBlobFromCache(const Slice& cache_key,
CachableEntry<std::string>* blob) const;
Status PutBlobIntoCache(const Slice& cache_key,
CachableEntry<std::string>* cached_blob,
PinnableSlice* blob) const;
inline CacheKey GetCacheKey(uint64_t file_number, uint64_t file_size,
uint64_t offset) const {
OffsetableCacheKey base_cache_key(db_id_, db_session_id_, file_number,
file_size);
return base_cache_key.WithOffset(offset);
}
inline Cache::Handle* GetEntryFromCache(const Slice& key) const {
return blob_cache_->Lookup(key, statistics_);
}
inline Status InsertEntryIntoCache(const Slice& key, std::string* value,
size_t charge,
Cache::Handle** cache_handle,
Cache::Priority priority) const {
return blob_cache_->Insert(key, value, charge,
&DeleteCacheEntry<std::string>, cache_handle,
priority);
}
const std::string db_id_;
const std::string db_session_id_;
Statistics* statistics_;
// A cache to store blob file reader.
BlobFileCache* blob_file_cache_;
// A cache to store uncompressed blobs.
std::shared_ptr<Cache> blob_cache_;
};
} // namespace ROCKSDB_NAMESPACE