Extend cachbench with value validation

cachelib/cachebench/cache/Cache-inl.h

@@ -50,8 +50,10 @@ uint64_t Cache<Allocator>::fetchNandWrites() const {
 template <typename Allocator>
 Cache<Allocator>::Cache(const CacheConfig& config,
                         ChainedItemMovingSync movingSync,
-                        std::string cacheDir)
+                        std::string cacheDir,
+                        bool touchValue)
     : config_(config),
+      touchValue_(touchValue),
       nandBytesBegin_{fetchNandWrites()},
       itemRecords_(config_.enableItemDestructorCheck) {
   constexpr size_t MB = 1024ULL * 1024ULL;
@@ -396,6 +398,18 @@ typename Cache<Allocator>::WriteHandle Cache<Allocator>::insertOrReplace(
   return rv;
 }
 
+template <typename Allocator>
+void Cache<Allocator>::touchValue(const ReadHandle& it) const {
+  XDCHECK(touchValueEnabled());
+
+  auto ptr = reinterpret_cast<const uint8_t*>(getMemory(it));
+
+  /* The accumulate call is intended to access all bytes of the value
+   * and nothing more. */
+  auto sum = std::accumulate(ptr, ptr + getSize(it), 0ULL);
+  folly::doNotOptimizeAway(sum);
+}
+
 template <typename Allocator>
 typename Cache<Allocator>::ReadHandle Cache<Allocator>::find(Key key) {
   auto findFn = [&]() {
@@ -406,6 +420,11 @@ typename Cache<Allocator>::ReadHandle Cache<Allocator>::find(Key key) {
     // find from cache and wait for the result to be ready.
     auto it = cache_->find(key);
     it.wait();
+
+    if (touchValueEnabled()) {
+      touchValue(it);
+    }
+
     return it;
   };
 
@@ -431,6 +450,11 @@ typename Cache<Allocator>::WriteHandle Cache<Allocator>::findToWrite(Key key) {
     // find from cache and wait for the result to be ready.
     auto it = cache_->findToWrite(key);
     it.wait();
+
+    if (touchValueEnabled()) {
+      touchValue(it);
+    }
+
     return it;
   };
 

cachelib/cachebench/cache/Cache.h

@@ -65,9 +65,11 @@ class Cache {
   //                      cache.
   // @param cacheDir      optional directory for the cache to enable
   //                      persistence across restarts.
+  // @param touchValue    read entire value on find
   explicit Cache(const CacheConfig& config,
                  ChainedItemMovingSync movingSync = {},
-                 std::string cacheDir = "");
+                 std::string cacheDir = "",
+                 bool touchValue = false);
 
   ~Cache();
 
@@ -179,6 +181,9 @@ class Cache {
     return getSize(item.get());
   }
 
+  // read entire value on find.
+  void touchValue(const ReadHandle& it) const;
+
   // returns the size of the item, taking into account ItemRecords could be
   // enabled.
   uint32_t getSize(const Item* item) const noexcept;
@@ -241,6 +246,9 @@ class Cache {
   // returns true if the consistency checking is enabled.
   bool consistencyCheckEnabled() const { return valueTracker_ != nullptr; }
 
+  // returns true if touching value is enabled.
+  bool touchValueEnabled() const { return touchValue_; }
+
   // return true if the key was previously detected to be inconsistent. This
   // is useful only when consistency checking is enabled by calling
   // enableConsistencyCheck()
@@ -363,6 +371,9 @@ class Cache {
   // tracker for consistency monitoring.
   std::unique_ptr<ValueTracker> valueTracker_;
 
+  // read entire value on find.
+  bool touchValue_{false};
+
   // reading of the nand bytes written for the benchmark if enabled.
   const uint64_t nandBytesBegin_{0};
 

cachelib/cachebench/runner/CacheStressor.h

@@ -95,7 +95,8 @@ class CacheStressor : public Stressor {
       cacheConfig.ticker = ticker_;
     }
 
-    cache_ = std::make_unique<CacheT>(cacheConfig, movingSync);
+    cache_ = std::make_unique<CacheT>(cacheConfig, movingSync, "",
+                                      config_.touchValue);
     if (config_.opPoolDistribution.size() > cache_->numPools()) {
       throw std::invalid_argument(folly::sformat(
           "more pools specified in the test than in the cache. "

cachelib/cachebench/util/Config.cpp

@@ -34,6 +34,7 @@ StressorConfig::StressorConfig(const folly::dynamic& configJson) {
   JSONSetVal(configJson, samplingIntervalMs);
 
   JSONSetVal(configJson, checkConsistency);
+  JSONSetVal(configJson, touchValue);
 
   JSONSetVal(configJson, numOps);
   JSONSetVal(configJson, numThreads);

cachelib/cachebench/util/Config.h

@@ -194,6 +194,10 @@ struct StressorConfig : public JSONConfig {
   // output stats after warmup.
   bool checkNvmCacheWarmUp{false};
 
+  // If enabled, each value will be read on find. This is useful for measuring
+  // performance of value access.
+  bool touchValue{false};
+
   uint64_t numOps{0};     // operation per thread
   uint64_t numThreads{0}; // number of threads that will run
   uint64_t numKeys{0};    // number of keys that will be used