add stats to Cache::LookUp()

Summary: basically for SimCache stats. I find most times it is hard to pass Statistics* to SimCache constructor.

Test Plan: make all check

Reviewers: andrewkr, sdong, yiwu

Reviewed By: yiwu

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D62193

include/rocksdb/cache.h

@@ -25,6 +25,7 @@
 #include <stdint.h>
 #include <memory>
 #include "rocksdb/slice.h"
+#include "rocksdb/statistics.h"
 #include "rocksdb/status.h"
 
 namespace rocksdb {
@@ -96,7 +97,9 @@ class Cache {
   // Else return a handle that corresponds to the mapping.  The caller
   // must call this->Release(handle) when the returned mapping is no
   // longer needed.
-  virtual Handle* Lookup(const Slice& key) = 0;
+  // If stats is not nullptr, relative tickers could be used inside the
+  // function.
+  virtual Handle* Lookup(const Slice& key, Statistics* stats = nullptr) = 0;
 
   // Release a mapping returned by a previous Lookup().
   // REQUIRES: handle must not have been released yet.

include/rocksdb/utilities/sim_cache.h

@@ -10,8 +10,8 @@
 #include <string>
 #include "rocksdb/cache.h"
 #include "rocksdb/slice.h"
+#include "rocksdb/statistics.h"
 #include "rocksdb/status.h"
-#include "util/statistics.h"
 
 namespace rocksdb {
 
@@ -31,9 +31,9 @@ class SimCache;
 // BlockBasedTableOptions.block_size = 4096 by default but is configurable,
 // Therefore, generally the actual memory overhead of SimCache is Less than
 // sim_capacity * 2%
-extern std::shared_ptr<SimCache> NewSimCache(
-    std::shared_ptr<Cache> cache, size_t sim_capacity, int num_shard_bits,
-    std::shared_ptr<Statistics> stats = nullptr);
+extern std::shared_ptr<SimCache> NewSimCache(std::shared_ptr<Cache> cache,
+                                             size_t sim_capacity,
+                                             int num_shard_bits);
 
 class SimCache : public Cache {
  public:

table/block_based_table_reader.cc

@@ -119,7 +119,7 @@ Cache::Handle* GetEntryFromCache(Cache* block_cache, const Slice& key,
                                  Tickers block_cache_miss_ticker,
                                  Tickers block_cache_hit_ticker,
                                  Statistics* statistics) {
-  auto cache_handle = block_cache->Lookup(key);
+  auto cache_handle = block_cache->Lookup(key, statistics);
   if (cache_handle != nullptr) {
     PERF_COUNTER_ADD(block_cache_hit_count, 1);
     // overall cache hit

util/sharded_cache.cc

@@ -46,7 +46,7 @@ Status ShardedCache::Insert(const Slice& key, void* value, size_t charge,
       ->Insert(key, hash, value, charge, deleter, handle, priority);
 }
 
-Cache::Handle* ShardedCache::Lookup(const Slice& key) {
+Cache::Handle* ShardedCache::Lookup(const Slice& key, Statistics* stats) {
   uint32_t hash = HashSlice(key);
   return GetShard(Shard(hash))->Lookup(key, hash);
 }

util/sharded_cache.h

@@ -60,7 +60,7 @@ class ShardedCache : public Cache {
   virtual Status Insert(const Slice& key, void* value, size_t charge,
                         void (*deleter)(const Slice& key, void* value),
                         Handle** handle, Priority priority) override;
-  virtual Handle* Lookup(const Slice& key) override;
+  virtual Handle* Lookup(const Slice& key, Statistics* stats) override;
   virtual void Release(Handle* handle) override;
   virtual void Erase(const Slice& key) override;
   virtual uint64_t NewId() override;

utilities/simulator_cache/sim_cache.cc

@@ -6,6 +6,7 @@
 #include "rocksdb/utilities/sim_cache.h"
 #include <atomic>
 #include "port/port.h"
+#include "util/statistics.h"
 
 namespace rocksdb {
 
@@ -16,12 +17,11 @@ class SimCacheImpl : public SimCache {
   // capacity for real cache (ShardedLRUCache)
   // test_capacity for key only cache
   SimCacheImpl(std::shared_ptr<Cache> cache, size_t sim_capacity,
-               int num_shard_bits, Statistics* stats)
+               int num_shard_bits)
       : cache_(cache),
         key_only_cache_(NewLRUCache(sim_capacity, num_shard_bits)),
         miss_times_(0),
-        hit_times_(0),
-        stats_(stats) {}
+        hit_times_(0) {}
 
   virtual ~SimCacheImpl() {}
   virtual void SetCapacity(size_t capacity) override {
@@ -51,17 +51,17 @@ class SimCacheImpl : public SimCache {
     return cache_->Insert(key, value, charge, deleter, handle, priority);
   }
 
-  virtual Handle* Lookup(const Slice& key) override {
+  virtual Handle* Lookup(const Slice& key, Statistics* stats) override {
     Handle* h = key_only_cache_->Lookup(key);
     if (h != nullptr) {
       key_only_cache_->Release(h);
       inc_hit_counter();
-      RecordTick(stats_, SIM_BLOCK_CACHE_HIT);
+      RecordTick(stats, SIM_BLOCK_CACHE_HIT);
     } else {
       inc_miss_counter();
-      RecordTick(stats_, SIM_BLOCK_CACHE_MISS);
+      RecordTick(stats, SIM_BLOCK_CACHE_MISS);
     }
-    return cache_->Lookup(key);
+    return cache_->Lookup(key, stats);
   }
 
   virtual void Release(Handle* handle) override { cache_->Release(handle); }
@@ -160,13 +160,11 @@ class SimCacheImpl : public SimCache {
 
 // For instrumentation purpose, use NewSimCache instead
 std::shared_ptr<SimCache> NewSimCache(std::shared_ptr<Cache> cache,
-                                      size_t sim_capacity, int num_shard_bits,
-                                      std::shared_ptr<Statistics> stats) {
+                                      size_t sim_capacity, int num_shard_bits) {
   if (num_shard_bits >= 20) {
     return nullptr;  // the cache cannot be sharded into too many fine pieces
   }
-  return std::make_shared<SimCacheImpl>(cache, sim_capacity, num_shard_bits,
-                                        stats.get());
+  return std::make_shared<SimCacheImpl>(cache, sim_capacity, num_shard_bits);
 }
 
 }  // end namespace rocksdb