ceph/src/kv/rocksdb_cache/ShardedCache.h

   1 // Copyright (c) 2018-Present Red Hat Inc.  All rights reserved.
   2 //
   3 // Copyright (c) 2011-2018, Facebook, Inc.  All rights reserved.
   4 // This source code is licensed under both the GPLv2 and Apache 2.0 License
   5 //
   6 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
   7 // Use of this source code is governed by a BSD-style license that can be
   8 // found in the LICENSE file. See the AUTHORS file for names of contributors.
   9
  10 #ifndef ROCKSDB_SHARDED_CACHE
  11 #define ROCKSDB_SHARDED_CACHE
  12
  13 #include <atomic>
  14 #include <string>
  15 #include <mutex>
  16
  17 #include "rocksdb/cache.h"
  18 #include "include/ceph_hash.h"
  19 #include "common/PriorityCache.h"
  20 //#include "hash.h"
  21
  22 #ifndef CACHE_LINE_SIZE
  23 #define CACHE_LINE_SIZE 64 // XXX arch-specific define
  24 #endif
  25 #define ROCKSDB_PRIszt "zu"
  26
  27 namespace rocksdb_cache {
  28
  29 // Single cache shard interface.
  30 class CacheShard {
  31  public:
  32   CacheShard() = default;
  33   virtual ~CacheShard() = default;
  34
  35   virtual rocksdb::Status Insert(const rocksdb::Slice& key, uint32_t hash, void* value,
  36                                  size_t charge,
  37                                  void (*deleter)(const rocksdb::Slice& key, void* value),
  38                                  rocksdb::Cache::Handle** handle, rocksdb::Cache::Priority priority) = 0;
  39   virtual rocksdb::Cache::Handle* Lookup(const rocksdb::Slice& key, uint32_t hash) = 0;
  40   virtual bool Ref(rocksdb::Cache::Handle* handle) = 0;
  41   virtual bool Release(rocksdb::Cache::Handle* handle, bool force_erase = false) = 0;
  42   virtual void Erase(const rocksdb::Slice& key, uint32_t hash) = 0;
  43   virtual void SetCapacity(size_t capacity) = 0;
  44   virtual void SetStrictCapacityLimit(bool strict_capacity_limit) = 0;
  45   virtual size_t GetUsage() const = 0;
  46   virtual size_t GetPinnedUsage() const = 0;
  47   virtual void ApplyToAllCacheEntries(void (*callback)(void*, size_t),
  48                                       bool thread_safe) = 0;
  49   virtual void EraseUnRefEntries() = 0;
  50   virtual std::string GetPrintableOptions() const { return ""; }
  51 };
  52
  53 // Generic cache interface which shards cache by hash of keys. 2^num_shard_bits
  54 // shards will be created, with capacity split evenly to each of the shards.
  55 // Keys are sharded by the highest num_shard_bits bits of hash value.
  56 class ShardedCache : public rocksdb::Cache, public PriorityCache::PriCache {
  57  public:
  58   ShardedCache(size_t capacity, int num_shard_bits, bool strict_capacity_limit);
  59   virtual ~ShardedCache() = default;
  60   virtual const char* Name() const override = 0;
  61   virtual CacheShard* GetShard(int shard) = 0;
  62   virtual const CacheShard* GetShard(int shard) const = 0;
  63   virtual void* Value(Handle* handle) override = 0;
  64   virtual size_t GetCharge(Handle* handle) const = 0;
  65   virtual uint32_t GetHash(Handle* handle) const = 0;
  66   virtual void DisownData() override = 0;
  67
  68   virtual void SetCapacity(size_t capacity) override;
  69   virtual void SetStrictCapacityLimit(bool strict_capacity_limit) override;
  70
  71   virtual rocksdb::Status Insert(const rocksdb::Slice& key, void* value, size_t charge,
  72                                  void (*deleter)(const rocksdb::Slice& key, void* value),
  73                                  rocksdb::Cache::Handle** handle, Priority priority) override;
  74   virtual rocksdb::Cache::Handle* Lookup(const rocksdb::Slice& key, rocksdb::Statistics* stats) override;
  75   virtual bool Ref(rocksdb::Cache::Handle* handle) override;
  76   virtual bool Release(rocksdb::Cache::Handle* handle, bool force_erase = false) override;
  77   virtual void Erase(const rocksdb::Slice& key) override;
  78   virtual uint64_t NewId() override;
  79   virtual size_t GetCapacity() const override;
  80   virtual bool HasStrictCapacityLimit() const override;
  81   virtual size_t GetUsage() const override;
  82   virtual size_t GetUsage(rocksdb::Cache::Handle* handle) const override;
  83   virtual size_t GetPinnedUsage() const override;
  84   virtual void ApplyToAllCacheEntries(void (*callback)(void*, size_t),
  85                                       bool thread_safe) override;
  86   virtual void EraseUnRefEntries() override;
  87   virtual std::string GetPrintableOptions() const override;
  88
  89   int GetNumShardBits() const { return num_shard_bits_; }
  90
  91   // PriCache
  92   virtual int64_t get_cache_bytes(PriorityCache::Priority pri) const {
  93     return cache_bytes[pri];
  94   }
  95   virtual int64_t get_cache_bytes() const {
  96     int64_t total = 0;
  97     for (int i = 0; i < PriorityCache::Priority::LAST + 1; i++) {
  98       PriorityCache::Priority pri = static_cast<PriorityCache::Priority>(i);
  99       total += get_cache_bytes(pri);
 100     }
 101     return total;
 102   }
 103   virtual void set_cache_bytes(PriorityCache::Priority pri, int64_t bytes) {
 104     cache_bytes[pri] = bytes;
 105   }
 106   virtual void add_cache_bytes(PriorityCache::Priority pri, int64_t bytes) {
 107     cache_bytes[pri] += bytes;
 108   }
 109   virtual double get_cache_ratio() const {
 110     return cache_ratio;
 111   }
 112   virtual void set_cache_ratio(double ratio) {
 113     cache_ratio = ratio;
 114   }
 115   virtual std::string get_cache_name() const = 0;
 116
 117  private:
 118   static inline uint32_t HashSlice(const rocksdb::Slice& s) {
 119      return ceph_str_hash(CEPH_STR_HASH_RJENKINS, s.data(), s.size());
 120 //    return Hash(s.data(), s.size(), 0);
 121   }
 122
 123   uint32_t Shard(uint32_t hash) {
 124     // Note, hash >> 32 yields hash in gcc, not the zero we expect!
 125     return (num_shard_bits_ > 0) ? (hash >> (32 - num_shard_bits_)) : 0;
 126   }
 127
 128   int64_t cache_bytes[PriorityCache::Priority::LAST+1] = {0};
 129   double cache_ratio = 0;
 130
 131   int num_shard_bits_;
 132   mutable std::mutex capacity_mutex_;
 133   size_t capacity_;
 134   bool strict_capacity_limit_;
 135   std::atomic<uint64_t> last_id_;
 136 };
 137
 138 extern int GetDefaultCacheShardBits(size_t capacity);
 139
 140 }  // namespace rocksdb_cache
 141 #endif // ROCKSDB_SHARDED_CACHE