data race test

CMakeLists.txt

@@ -11,8 +11,8 @@ file(GLOB prj_src src/*)
 
 target_sources(${PROJECT_NAME} PRIVATE ${prj_src})
 
-# target_compile_options(${PROJECT_NAME} PRIVATE -fsanitize=thread)
+target_compile_options(${PROJECT_NAME} PRIVATE -fsanitize=thread)
-# target_link_options(${PROJECT_NAME} PRIVATE -fsanitize=thread)
+target_link_options(${PROJECT_NAME} PRIVATE -fsanitize=thread)
 
 add_subdirectory(bench)
 add_subdirectory(tests)

bench/CMakeLists.txt

@@ -12,5 +12,5 @@ target_link_libraries(${NAME} PRIVATE
     ${PROJECT_NAME}
 )
 
-# target_compile_options(${NAME} PRIVATE -fsanitize=thread)
+target_compile_options(${NAME} PRIVATE -fsanitize=thread)
-# target_link_options(${NAME} PRIVATE -fsanitize=thread)
+target_link_options(${NAME} PRIVATE -fsanitize=thread)

include/logger.hh

@@ -36,8 +36,7 @@ class Logger {
   template <typename Metric,
             typename = std::enable_if_t<std::is_arithmetic_v<Metric>>>
   void add(const std::string& field, Metric metric) {
-    auto locked = active.load(std::memory_order_acquire);
+    std::shared_ptr<map_type> locked = active.load(std::memory_order_acquire);
-    // auto locked = active;
     auto it = locked->find(field);
     if (it == locked->end()) {
       throw configErrorMsg;  // additional 30ns on bench ?

src/logger.cc

@@ -68,18 +68,22 @@ void Logger::Worker::unroll() {
   if (!parent.isConfigured())
     return;
 
-  auto tmp = parent.active.load(std::memory_order_acquire);
+  auto tmp = parent.active.load(std::memory_order_relaxed);
-  // auto tmp = parent.active;
   auto toBeActive = tmp == parent.m1 ? parent.m2 : parent.m1;
-  while (!parent.active.compare_exchange_weak(tmp, toBeActive)) {
-    std::this_thread::yield();
-  }
-  // parent.active = toBeActive;
 
+  parent.active.store(toBeActive, std::memory_order_release);
+
+  // hmm, seems that we can receive situation here there use_count is less or
+  // equal 2 but in reality we still have instance how? store and load is
+  // tighted, so we have guarantee that this check will be happens before
   while (tmp.use_count() > 2) {
     std::this_thread::yield();
   }
 
+  // it's needed thread fence to guarantee use count change
+  // __tsan_acquire(tmp.use_count());
+  std::atomic_thread_fence(std::memory_order_acquire);
+
   // at this place we are guarantee that tmp is only ours or not?
   std::string output;
   bool haveToPush{false};

tests/CMakeLists.txt

@@ -12,5 +12,5 @@ target_link_libraries(${NAME} PRIVATE
     ${PROJECT_NAME}
 )
 
-# target_compile_options(${NAME} PRIVATE -fsanitize=thread)
+target_compile_options(${NAME} PRIVATE -fsanitize=thread)
-# target_link_options(${NAME} PRIVATE -fsanitize=thread)
+target_link_options(${NAME} PRIVATE -fsanitize=thread)