Add mutex to fix race condition

src/blockstore/implementations/caching/CachingBlockStore.cpp

@@ -13,6 +13,8 @@ using boost::optional;
 using cpputils::unique_ref;
 using cpputils::make_unique_ref;
 using boost::none;
+using std::mutex;
+using std::unique_lock;
 
 namespace blockstore {
 namespace caching {
@@ -96,10 +98,12 @@ void CachingBlockStore::forEachBlock(std::function<void (const Key &)> callback)
 }
 
 void CachingBlockStore::registerNewBlock(NewBlock *newBlock) {
+  unique_lock<mutex> lock(_newBlocksMutex);
   _newBlocks.insert(newBlock);
 }
 
 void CachingBlockStore::unregisterNewBlock(NewBlock *newBlock) {
+  unique_lock<mutex> lock(_newBlocksMutex);
   _newBlocks.erase(newBlock);
 }
 

src/blockstore/implementations/caching/CachingBlockStore.h

@@ -38,6 +38,7 @@ private:
   cpputils::unique_ref<BlockStore> _baseBlockStore;
   std::unordered_set<NewBlock*> _newBlocks; // List of all new blocks that aren't in the base store yet.
   Cache<Key, cpputils::unique_ref<Block>, 1000> _cache;
+  std::mutex _newBlocksMutex;
 
   DISALLOW_COPY_AND_ASSIGN(CachingBlockStore);
 };

src/blockstore/implementations/versioncounting/VersionCountingBlock.h

@@ -55,6 +55,7 @@ private:
   cpputils::Data _dataWithHeader;
   uint64_t _version;
   bool _dataChanged;
+  std::mutex _mutex;
 
   void _storeToBaseBlock();
   static cpputils::Data _prependHeaderToData(uint32_t myClientId, uint64_t version, cpputils::Data data);
@@ -66,8 +67,6 @@ private:
   // This header is prepended to blocks to allow future versions to have compatibility.
   static constexpr uint16_t FORMAT_VERSION_HEADER = 0;
 
-  std::mutex _mutex;
-
   DISALLOW_COPY_AND_ASSIGN(VersionCountingBlock);
 
 public: