Extend cachbench with value validation

Author: igchor

cachelib/cachebench/cache/Cache-inl.h

@@ -327,13 +327,22 @@ 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()) {
@@ -426,6 +435,20 @@ typename Cache<Allocator>::ItemHandle Cache<Allocator>::insertOrReplace(
   return rv;
 }
 
+template <typename Allocator>
+void Cache<Allocator>::validateValue(const ItemHandle &it) const {
+  XDCHECK(valueValidatingEnabled());
+
+  const auto &expected = expectedValue_.value();
+
+  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!");
+  }
+}
+
 template <typename Allocator>
 typename Cache<Allocator>::ItemHandle Cache<Allocator>::find(Key key,
                                                              AccessMode mode) {
@@ -441,9 +464,15 @@ typename Cache<Allocator>::ItemHandle Cache<Allocator>::find(Key key,
   };
 
   if (!consistencyCheckEnabled()) {
-    return findFn();
+    auto it = findFn();
+    if (valueValidatingEnabled()) {
+      validateValue(it);
+    }
+    return it;
   }
 
+  XDCHECK(!valueValidatingEnabled());
+
   auto opId = valueTracker_->beginGet(key);
   auto it = findFn();
   if (checkGet(opId, it)) {

cachelib/cachebench/cache/Cache.h

@@ -163,6 +163,9 @@ class Cache {
     return getSize(item.get());
   }
 
+  // checks if values stored in it matches expectedValue_.
+  void validateValue(const ItemHandle &it) const;
+
   // returns the size of the item, taking into account ItemRecords could be
   // enabled.
   uint32_t getSize(const Item* item) const noexcept;
@@ -220,9 +223,15 @@ 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(); }
+
   // return true if the key was previously detected to be inconsistent. This
   // is useful only when consistency checking is enabled by calling
   // enableConsistencyCheck()
@@ -345,6 +354,9 @@ class Cache {
   // tracker for consistency monitoring.
   std::unique_ptr<ValueTracker> valueTracker_;
 
+  // exceptected value of all items in Cache.
+  std::optional<std::string> expectedValue_;
+
   // reading of the nand bytes written for the benchmark if enabled.
   const uint64_t nandBytesBegin_{0};
 

cachelib/cachebench/runner/CacheStressor.h

@@ -110,6 +110,9 @@ 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

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

cachelib/cachebench/util/Config.h

@@ -188,8 +188,13 @@ struct StressorConfig : public JSONConfig {
   uint64_t samplingIntervalMs{1000};
 
   // If enabled, stressor will verify operations' results are consistent.
+  // Mutually exclusive with validateValue
   bool checkConsistency{false};
 
+  // If enable, stressos will verify if value read is equal to value written.
+  // Mutually exclusive with checkConsistency
+  bool validateValue{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