static section revisited

Author: Oguzhan Katli

src/3-Static/static_usage.cpp

@@ -2,43 +2,36 @@
 #include <iostream>
 #include <sstream>
 #include <thread>
+#include <future>
 
 namespace StaticUsage {
 
  struct CountedObject {
- int data;
-
- static CountedObject CreateNew()
+ static CountedObject GetInstance()
  {
- std::cout << "called from thread: " << std::this_thread::get_id() << std::endl << std::flush;
- CountedObject::_id++; // increment totat creation count
- return CountedObject();
- }
-
- static unsigned int TotalCreationCount() {
- return CountedObject::_id;
+ // With C++11 static member initializations are thread safe
+ static CountedObject instance;
+ return instance;
  }
-
  private:
- CountedObject() = default;
- static unsigned int _id;
+ CountedObject()
+ {
+ std::cout << "CountedObject() thread: " << std::this_thread::get_id() << "\n";
+ }
  };
- //static
- unsigned int CountedObject::_id = 0;
 }
 
-ELEMENT_CODE(StaticUsageExample) {
+ELEMENT_CODE(StaticUsageExample) 
+{
  using namespace StaticUsage;
- std::thread t1([]() {
- for (size_t i = 0; i < 10; i++)
- {
- CountedObject::CreateNew();
- }
- });
- for (size_t i = 0; i < 10; i++)
- {
- CountedObject::CreateNew();
- }
+ std::promise<void> wait_flag;
+ auto watier = wait_flag.get_future();
+
+ std::thread t1([] (auto wait_flag) {
+ wait_flag.set_value();
+ CountedObject::GetInstance();
+ }, std::move(wait_flag));
+ watier.wait();
+ CountedObject::GetInstance();
  t1.join();
- printf("Total creation count: %d", CountedObject::TotalCreationCount());
 }