task8

ex3/seq/thread_17/gh_main.cpp

@@ -0,0 +1,101 @@
+// C++ Vorlesung  xxx
+// C++-17: Threads, execution policies
+//   Great web pages, great book by Filipek:   https://www.bfilipek.com/2018/06/parstl-tests.html
+
+/*
+ g++ -O3 -std=c++17 gh_main.cpp -ltbb
+ g++ -O3 -std=c++17 -pedantic -Weffc++ -Wall -Wextra -pedantic -Wswitch-default -Wfloat-equal -Wundef -Wredundant-decls -Winit-self -Wshadow -Wparentheses -Wshadow -Wunreachable-code -Wuninitialized -Wmaybe-uninitialized gh_main.cpp -ltbb
+ ---
+ cppcheck --enable=all --inconclusive --std=c++11 --std=posix --suppress=missingIncludeSystem gh_main.cpp
+ clang++ -O3 -std=c++17 -ltbb gh_main.cpp
+ clang++ -std=c++17 -fsyntax-only -Wdocumentation -Wconversion -Wshadow -Wfloat-conversion -pedantic gh_main.cpp
+ clang++ -std=c++17 -Weverything -Wno-c++98-compat -Wno-padded -ltbb gh_main.cpp
+ clang++ -cc1 --help
+ ---
+ icpc -O3 -std=c++17 -ltbb -Wall -Wextra -pedantic gh_main.cpp
+*/
+#include <algorithm>
+#include <chrono>
+#include <execution>          // execution policy
+#include <iostream>
+#include <list>               // list
+#include <numeric>            // accumulate
+#include <random>
+#include <vector>
+using namespace std;
+using namespace std::chrono;  // timing
+
+
+/** \brief Prints the whole vector of base class pointers
+ *  \param[in,out]  s   output stream
+ *  \param[in]      v   vector
+ *  \return        changed output stream
+ */
+template <class T>
+ostream& operator<<(ostream &s, const vector<T>& v)
+{
+    for (const auto& it: v)             // Reference is required with unique_ptr. No copy constructor for unique_ptr available!
+    {
+        cout << *it << " ";
+    }
+    return s;
+}
+
+
+int main()
+{
+    cout << "Threads C++17" << endl;
+
+    size_t const N = 1<<25;
+    vector<double> v(N);
+    //list<double> v(N);       // execution::par not possible : missing 'operator-'
+    iota(v.begin(), v.end(), 1);
+    std::shuffle(v.begin(), v.end(), std::mt19937{std::random_device{}()});
+
+    auto const v_bak(v);
+
+    {
+        v = v_bak;
+        cout << "----   sort old   ----" << endl;
+        auto t1 = system_clock::now();
+        sort(v.begin(), v.end());
+        auto t2 = system_clock::now();
+        auto duration = duration_cast<microseconds>(t2 - t1);
+        cout << "sort old   : " << static_cast<double>(duration.count()) / 1e6 << " sec." << endl;
+    }
+
+    {
+        v = v_bak;
+        cout << "----   sort seq   ----" << endl;
+        auto t1 = system_clock::now();
+        sort(std::execution::seq, v.begin(), v.end());
+        auto t2 = system_clock::now();
+        auto duration = duration_cast<microseconds>(t2 - t1);
+        cout << "sort seq   : " << static_cast<double>(duration.count()) / 1e6 << " sec." << endl;
+    }
+
+    {
+        v = v_bak;
+        cout << "----   sort par   ----" << endl;
+        auto t1 = system_clock::now();
+        sort(std::execution::par, v.begin(), v.end());
+        //auto cnt = count(std::execution::par, v.begin(), v.end(), 17);
+        auto t2 = system_clock::now();
+        auto duration = duration_cast<microseconds>(t2 - t1);
+        cout << "sort par   : " << static_cast<double>(duration.count()) / 1e6 << " sec." << endl;
+    }
+    
+    {
+        v = v_bak;
+        cout << "----   sort par_unseq   ----" << endl;
+        auto t1 = system_clock::now();
+        sort(std::execution::par_unseq, v.begin(), v.end());
+        auto t2 = system_clock::now();
+        auto duration = duration_cast<microseconds>(t2 - t1);
+        cout << "sort par_unseq: " << static_cast<double>(duration.count()) / 1e6 << " sec." << endl;
+    }
+
+
+    return 0;
+}
+