exercise 2

lesson_6/Timer.hpp

@@ -0,0 +1,37 @@
+/*
+ * Timer.hpp
+ *
+ *  Created on: 12 окт. 2021 г.
+ *      Author: alexander
+ */
+
+#pragma once
+
+#include <iostream>
+#include <chrono>
+
+class Timer
+{
+private:
+    using clock_t = std::chrono::high_resolution_clock;
+    using second_t = std::chrono::duration<double, std::ratio<1> >;
+
+    std::string m_name;
+    std::chrono::time_point<clock_t> m_beg;
+    double elapsed() const
+    {
+        return std::chrono::duration_cast<second_t>(clock_t::now() -m_beg).count();
+    }
+
+public:
+    Timer() : m_beg(clock_t::now()) { }
+    Timer(std::string name) : m_name(name), m_beg(clock_t::now()) { }
+
+    void start(std::string name) {
+        m_name = name;
+        m_beg = clock_t::now();
+    }
+    void print() const {
+        std::cout << m_name << ":\t" << elapsed() * 1000 << " ms" << '\n';
+    }
+};

lesson_6/exercise_2.hpp

@@ -0,0 +1,92 @@
+/*
+ * exercise_2.hpp
+ *
+ *  Created on: 11 окт. 2021 г.
+ *      Author: alexander
+ */
+
+#pragma once
+
+#include <iostream>
+#include <thread>
+#include <vector>
+#include <mutex>
+#include "Timer.hpp"
+
+bool isPrime(size_t num)
+{
+    size_t limit = num / 2;
+
+    if (num > 2)
+    {
+        for (size_t i = 2; i <= limit; ++i)
+        {
+            if (num % i == 0)
+            {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+void exercise_2()
+{
+
+    size_t maxValue = 500000;
+    size_t counThreads = 30;
+    std::vector<size_t> answers;
+    std::mutex m;
+
+    Timer timer("With threads");
+
+    for (size_t i = 0; i < maxValue;)
+    {
+        std::vector<std::thread> v;
+
+        for (size_t j = i + counThreads; i <= j; ++i)
+        {
+            v.push_back(std::thread([=, &m, &answers]()
+            {
+                if (isPrime(i))
+                {
+                    std::lock_guard lg(m);
+                    answers.push_back(i);
+                }
+            }));
+        }
+
+        for (auto &t : v)
+        {
+            t.join();
+        }
+    }
+
+//    for (const auto &a : answers)
+//    {
+//        std::cout << "Число " << a << " простое" << std::endl;
+//    }
+
+    timer.print();
+
+    answers.clear();
+    answers.shrink_to_fit();
+
+    timer.start("Without threads");
+
+    for (size_t i = 0; i < maxValue; ++i)
+    {
+        if (isPrime(i))
+        {
+            answers.push_back(i);
+        }
+    }
+
+//    for (const auto &a : answers)
+//    {
+//        std::cout << "Число " << a << " простое" << std::endl;
+//    }
+
+    timer.print();
+}

lesson_6/main.cpp

@@ -5,10 +5,12 @@
  *      Author: alexander
  */
 #include "exercise_1.hpp"
+#include "exercise_2.hpp"
 
 int main()
 {
-    exercise_1();
+//    exercise_1();
+    exercise_2();
 
     return 0;
 }