threadsafety_singleton

Singleton/Counter.h

@@ -15,4 +15,4 @@ class Counter {
     }
 };
 
-
+ 

ThreadSafety_Singleton/Client.cpp

@@ -0,0 +1,22 @@
+#include<iostream>
+#include<string>
+#include <thread>
+#include "Counter.h"
+using namespace std;
+
+int main() {
+thread task1([]() {
+    Counter* counter1 = Counter::GetInstance();
+    counter1 -> addOne();
+    cout << "Counter1: " + to_string(counter1 -> count) << endl;
+});
+
+thread task2([]() {
+    Counter* counter2 = Counter::GetInstance();
+    counter2 -> addOne();
+    cout << "Counter2: " + to_string(counter2 -> count) << endl;
+});
+
+task1.join();
+task2.join();
+}

ThreadSafety_Singleton/Counter.cpp

@@ -0,0 +1,6 @@
+#include "Counter.h"
+#include <mutex>
+using namespace std;
+
+Counter* Counter::instance = nullptr;
+mutex Counter::lockObj;

ThreadSafety_Singleton/Counter.h

@@ -0,0 +1,21 @@
+#include <mutex>
+
+class Counter {
+    static Counter* instance;
+    static std::mutex lockObj;
+    Counter() {}
+
+public:
+    int count = 0;
+    static Counter* GetInstance() {
+        std::lock_guard<std::mutex> guard(lockObj);  // lock the mutex
+        if(instance == nullptr)
+            instance = new Counter();
+        return instance;
+    }
+
+    void addOne() {
+        count++;
+    }
+
+};