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diff --git a/src/kv/rocksdb_cache/ShardedCache.h b/src/kv/rocksdb_cache/ShardedCache.h
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+++ b/src/kv/rocksdb_cache/ShardedCache.h
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+// Copyright (c) 2018-Present Red Hat Inc.  All rights reserved.
+//
+// Copyright (c) 2011-2018, Facebook, Inc.  All rights reserved.
+// This source code is licensed under both the GPLv2 and Apache 2.0 License
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#ifndef ROCKSDB_SHARDED_CACHE
+#define ROCKSDB_SHARDED_CACHE
+
+#include <atomic>
+#include <string>
+#include <mutex>
+
+#include "rocksdb/cache.h"
+#include "include/ceph_hash.h"
+#include "common/PriorityCache.h"
+//#include "hash.h"
+
+#ifndef CACHE_LINE_SIZE
+#define CACHE_LINE_SIZE 64 // XXX arch-specific define 
+#endif
+#define ROCKSDB_PRIszt "zu"
+
+namespace rocksdb_cache {
+
+// Single cache shard interface.
+class CacheShard {
+ public:
+  CacheShard() = default;
+  virtual ~CacheShard() = default;
+
+  virtual rocksdb::Status Insert(const rocksdb::Slice& key, uint32_t hash, void* value,
+                                 size_t charge,
+                                 void (*deleter)(const rocksdb::Slice& key, void* value),
+                                 rocksdb::Cache::Handle** handle, rocksdb::Cache::Priority priority) = 0;
+  virtual rocksdb::Cache::Handle* Lookup(const rocksdb::Slice& key, uint32_t hash) = 0;
+  virtual bool Ref(rocksdb::Cache::Handle* handle) = 0;
+  virtual bool Release(rocksdb::Cache::Handle* handle, bool force_erase = false) = 0;
+  virtual void Erase(const rocksdb::Slice& key, uint32_t hash) = 0;
+  virtual void SetCapacity(size_t capacity) = 0;
+  virtual void SetStrictCapacityLimit(bool strict_capacity_limit) = 0;
+  virtual size_t GetUsage() const = 0;
+  virtual size_t GetPinnedUsage() const = 0;
+  virtual void ApplyToAllCacheEntries(void (*callback)(void*, size_t),
+                                      bool thread_safe) = 0;
+  virtual void EraseUnRefEntries() = 0;
+  virtual std::string GetPrintableOptions() const { return ""; }
+};
+
+// Generic cache interface which shards cache by hash of keys. 2^num_shard_bits
+// shards will be created, with capacity split evenly to each of the shards.
+// Keys are sharded by the highest num_shard_bits bits of hash value.
+class ShardedCache : public rocksdb::Cache, public PriorityCache::PriCache {
+ public:
+  ShardedCache(size_t capacity, int num_shard_bits, bool strict_capacity_limit);
+  virtual ~ShardedCache() = default;
+  virtual const char* Name() const override = 0;
+  virtual CacheShard* GetShard(int shard) = 0;
+  virtual const CacheShard* GetShard(int shard) const = 0;
+  virtual void* Value(Handle* handle) override = 0;
+  virtual size_t GetCharge(Handle* handle) const = 0;
+  virtual uint32_t GetHash(Handle* handle) const = 0;
+  virtual void DisownData() override = 0;
+
+  virtual void SetCapacity(size_t capacity) override;
+  virtual void SetStrictCapacityLimit(bool strict_capacity_limit) override;
+
+  virtual rocksdb::Status Insert(const rocksdb::Slice& key, void* value, size_t charge,
+                                 void (*deleter)(const rocksdb::Slice& key, void* value),
+                                 rocksdb::Cache::Handle** handle, Priority priority) override;
+  virtual rocksdb::Cache::Handle* Lookup(const rocksdb::Slice& key, rocksdb::Statistics* stats) override;
+  virtual bool Ref(rocksdb::Cache::Handle* handle) override;
+  virtual bool Release(rocksdb::Cache::Handle* handle, bool force_erase = false) override;
+  virtual void Erase(const rocksdb::Slice& key) override;
+  virtual uint64_t NewId() override;
+  virtual size_t GetCapacity() const override;
+  virtual bool HasStrictCapacityLimit() const override;
+  virtual size_t GetUsage() const override;
+  virtual size_t GetUsage(rocksdb::Cache::Handle* handle) const override;
+  virtual size_t GetPinnedUsage() const override;
+  virtual void ApplyToAllCacheEntries(void (*callback)(void*, size_t),
+                                      bool thread_safe) override;
+  virtual void EraseUnRefEntries() override;
+  virtual std::string GetPrintableOptions() const override;
+
+  int GetNumShardBits() const { return num_shard_bits_; }
+
+  // PriCache
+  virtual int64_t get_cache_bytes(PriorityCache::Priority pri) const {
+    return cache_bytes[pri];
+  }
+  virtual int64_t get_cache_bytes() const {
+    int64_t total = 0;
+    for (int i = 0; i < PriorityCache::Priority::LAST + 1; i++) {
+      PriorityCache::Priority pri = static_cast<PriorityCache::Priority>(i);
+      total += get_cache_bytes(pri);
+    }
+    return total;
+  }
+  virtual void set_cache_bytes(PriorityCache::Priority pri, int64_t bytes) {
+    cache_bytes[pri] = bytes;
+  }
+  virtual void add_cache_bytes(PriorityCache::Priority pri, int64_t bytes) {
+    cache_bytes[pri] += bytes;
+  }
+  virtual double get_cache_ratio() const {
+    return cache_ratio;
+  }
+  virtual void set_cache_ratio(double ratio) {
+    cache_ratio = ratio;
+  }
+  virtual std::string get_cache_name() const = 0;
+
+ private:
+  static inline uint32_t HashSlice(const rocksdb::Slice& s) {
+     return ceph_str_hash(CEPH_STR_HASH_RJENKINS, s.data(), s.size());
+//    return Hash(s.data(), s.size(), 0);
+  }
+
+  uint32_t Shard(uint32_t hash) {
+    // Note, hash >> 32 yields hash in gcc, not the zero we expect!
+    return (num_shard_bits_ > 0) ? (hash >> (32 - num_shard_bits_)) : 0;
+  }
+
+  int64_t cache_bytes[PriorityCache::Priority::LAST+1] = {0};
+  double cache_ratio = 0;
+
+  int num_shard_bits_;
+  mutable std::mutex capacity_mutex_;
+  size_t capacity_;
+  bool strict_capacity_limit_;
+  std::atomic<uint64_t> last_id_;
+};
+
+extern int GetDefaultCacheShardBits(size_t capacity);
+
+}  // namespace rocksdb_cache
+#endif // ROCKSDB_SHARDED_CACHE