Merge pull request #85 from igchor/touch_value_develop

Extend cachbench with touch value

Author: igchor

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;
@@ -325,22 +327,13 @@ template <typename Allocator>
 void Cache<Allocator>::enableConsistencyCheck(
     const std::vector<std::string>& keys) {
   XDCHECK(valueTracker_ == nullptr);
-  XDCHECK(!valueValidatingEnabled());
   valueTracker_ =
       std::make_unique<ValueTracker>(ValueTracker::wrapStrings(keys));
   for (const std::string& key : keys) {
     invalidKeys_[key] = false;
   }
 }
 
-template <typename Allocator>
-void Cache<Allocator>::enableValueValidating(
-    const std::string &expectedValue) {
-  XDCHECK(!valueValidatingEnabled());
-  XDCHECK(!consistencyCheckEnabled());
-  this->expectedValue_ = expectedValue;
-}
-
 template <typename Allocator>
 typename Cache<Allocator>::RemoveRes Cache<Allocator>::remove(Key key) {
   if (!consistencyCheckEnabled()) {
@@ -434,17 +427,15 @@ typename Cache<Allocator>::ItemHandle Cache<Allocator>::insertOrReplace(
 }
 
 template <typename Allocator>
-void Cache<Allocator>::validateValue(const ItemHandle &it) const {
-  XDCHECK(valueValidatingEnabled());
-
-  const auto &expected = expectedValue_.value();
+void Cache<Allocator>::touchValue(const ItemHandle& it) const {
+  XDCHECK(touchValueEnabled());
 
   auto ptr = reinterpret_cast<const uint8_t*>(getMemory(it));
-  auto cmp = std::memcmp(ptr, expected.data(), std::min<size_t>(expected.size(),
-    getSize(it)));
-  if (cmp != 0) {
-    throw std::runtime_error("Value does not match!");
-  }
+
+  /* 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>
@@ -459,9 +450,8 @@ typename Cache<Allocator>::ItemHandle Cache<Allocator>::find(Key key,
     auto it = cache_->find(key, mode);
     it.wait();
 
-    if (valueValidatingEnabled()) {
-      XDCHECK(!consistencyCheckEnabled());
-      validateValue(it);
+    if (touchValueEnabled()) {
+      touchValue(it);
     }
 
     return it;
@@ -472,8 +462,6 @@ typename Cache<Allocator>::ItemHandle Cache<Allocator>::find(Key key,
     return it;
   }
 
-  XDCHECK(!valueValidatingEnabled());
-
   auto opId = valueTracker_->beginGet(key);
   auto it = findFn();
   if (checkGet(opId, it)) {

cachelib/cachebench/cache/Cache.h

@@ -64,9 +64,11 @@ 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 = true);
 
   ~Cache();
 
@@ -168,8 +170,8 @@ class Cache {
     return getSize(item.get());
   }
 
-  // checks if values stored in it matches expectedValue_.
-  void validateValue(const ItemHandle &it) const;
+  // read entire value on find.
+  void touchValue(const ItemHandle& it) const;
 
   // returns the size of the item, taking into account ItemRecords could be
   // enabled.
@@ -228,14 +230,11 @@ class Cache {
   // @param keys  list of keys that the stressor uses for the workload.
   void enableConsistencyCheck(const std::vector<std::string>& keys);
 
-  // enables validating all values on find. Each value is compared to
-  // expected Value.
-  void enableValueValidating(const std::string &expectedValue);
-
   // returns true if the consistency checking is enabled.
   bool consistencyCheckEnabled() const { return valueTracker_ != nullptr; }
 
-  bool valueValidatingEnabled() const { return expectedValue_.has_value(); }
+  // 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
@@ -359,8 +358,8 @@ class Cache {
   // tracker for consistency monitoring.
   std::unique_ptr<ValueTracker> valueTracker_;
 
-  // exceptected value of all items in Cache.
-  std::optional<std::string> expectedValue_;
+  // read entire value on find.
+  bool touchValue_{true};
 
   // reading of the nand bytes written for the benchmark if enabled.
   const uint64_t nandBytesBegin_{0};

cachelib/cachebench/runner/CacheStressor.h

@@ -93,7 +93,8 @@ 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. "
@@ -110,9 +111,6 @@ class CacheStressor : public Stressor {
     if (config_.checkConsistency) {
       cache_->enableConsistencyCheck(wg_->getAllKeys());
     }
-    if (config_.validateValue) {
-      cache_->enableValueValidating(hardcodedString_);
-    }
     if (config_.opRatePerSec > 0) {
       rateLimiter_ = std::make_unique<folly::BasicTokenBucket<>>(
           config_.opRatePerSec, config_.opRatePerSec);

cachelib/cachebench/util/Config.cpp

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

cachelib/cachebench/util/Config.h

@@ -195,6 +195,10 @@ struct StressorConfig : public JSONConfig {
   // Mutually exclusive with checkConsistency
   bool validateValue{false};
 
+  // If enabled, each value will be read on find. This is useful for measuring
+  // performance of value access.
+  bool touchValue{true};
+
   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