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This is done by simply not user-defining the copy constructor, copy-assignment operator and destructor. See [1] for more info. [1] http://accu.org/content/conf2014/Howard_Hinnant_Accu_2014.pdf For the benchmark below (compiled with the next commit to allow sorting SGPath instances), on Linux amd64 with g++ 6.3.0, I observe that enabling SGPath move operations with this commit increases the performance by 31% or 28% respectively, depending on whether I use this: // Typical code that creates a data structure in several steps and // benefits from move operations (the std::move() does nothing when // running the test with move operations disabled: a copy is made). auto p = SGPath::fromUtf8(randomString(0, 30)); v.emplace_back(std::move(p)); or that: v.emplace_back(randomString(0, 30)) for the initialization code. Now the benchmark code: using std::string; static std::default_random_engine randomNumbersGenerator; // Utility function: generate a random string whose length is in the // [minLen, maxLen] range. string randomString(string::size_type minLen, string::size_type maxLen) { std::uniform_int_distribution<string::size_type> sLenDist(minLen, maxLen); std::uniform_int_distribution<int> byteDist(0, 255); auto randomByte = std::bind(byteDist, randomNumbersGenerator); string::size_type len = sLenDist(randomNumbersGenerator); string str; while (str.size() < len) { str += std::char_traits<char>::to_char_type(randomByte()); } return str; } // The test function, run with nbIterations = 500000, minSize = 0 and // maxSize = 200 to obtain the figures given above. void SGPath_perfTest(std::size_t nbIterations, std::size_t minSize, std::size_t maxSize) { std::uniform_int_distribution<std::size_t> sizeDist(minSize, maxSize); auto randomSize = std::bind(sizeDist, randomNumbersGenerator); std::chrono::time_point<std::chrono::system_clock> start, end; start = std::chrono::system_clock::now(); vector<SGPath> v; for (std::size_t i=0; i < nbIterations; i++) { v = vector<SGPath>{}; // start anew for (std::size_t j=0; j < randomSize(); j++) { v.emplace_back(randomString(0, 30)); } std::shuffle(v.begin(), v.end(), randomNumbersGenerator); std::sort(v.begin(), v.end()); } end = std::chrono::system_clock::now(); std::chrono::duration<double> elapsedSecs = end - start; std::cout << elapsedSecs.count() << "\n"; // duration in seconds }
SimGear - Simulator Construction Tools ====================================== http://www.flightgear.org SimGear is a set of open-source libraries designed to be used as building blocks for quickly assembling 3d simulations, games, and visualization applications. SimGear is developed by the FlightGear project and also provides the base for the FlightGear Flight Simulator. Source code for SimGear is released under the GNU Library General Public License (LGPL) - see COPYING for license details. See INSTALL file for help on building SimGear.